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Architectural Forensics


ABOUT THE AUTHOR Sam A. A. Kubba, Ph.D., is an award-winning architect whose practice includes projects in the United States, the United Kingdom, and the Middle East. He has more than 30 years of experience in all aspects of design, construction, and property condition assessments. A member of the American Institute of Architects, the American Society of Interior Designers, and the Royal Institute of British Architects, he has lectured widely on architecture, interior design, and construction. Dr. Kubba is the principal partner of The Consultants’ Collaborative, a firm noted for its work in architecture, interior design, and project management. He is also the author of several books, including Mesopotamian Furniture, Space Planning for Commercial and Residential Interiors, and Property Condition Assessments.

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Architectural Forensics

Sam A. A. Kubba, Ph.D.

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Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-159612-7 The material in this eBook also appears in the print version of this title: 0-07-149842-7. All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please contact George Hoare, Special Sales, at george_hoare@mcgraw-hill.com or (212) 904-4069. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your right to use the work may be terminated if you fail to comply with these terms. THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise. DOI: 10.1036/0071498427


This book is dedicated to My mother and father, Who bestowed on me the gift of life . . . And to my wife and four children, Whose love and affection inspired me on . . .


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CONTENTS ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiii INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xv

CHATPER 1: DEFINING ARCHITECTURAL FORENSICS 1.1 1.2 1.3 1.4

General—Defining Architectural Forensics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 Qualifications of the Forensic Architect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Professional Responsibilities and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Professional Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

CHAPTER 2: THE ASSIGNMENT/INVESTIGATION 2.1 2.2 2.3 2.4 2.5 2.6 2.7

7

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 Accepting the Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Purpose & Scope of Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Forensic Consultant’s Agreement With Client . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Consultant’s Fees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 The Project Assignment—Miscellaneous Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Shop & Assembly Drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

CHAPTER 3: THE FORENSIC ARCHITECT’S ROLE & SCOPE IN EVALUATIONS & ACQUISITIONS 3.1 3.2 3.3 3.4 3.5 3.6 3.7

19

General Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Introduction to Building Systems Evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 The Role of the Forensic Architect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Evaluations for Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 When to Conduct an Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 Variations of Scope in Evaluations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 Preventative Maintenance Program Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

CHAPTER 4: THE EVALUATION/INVESTIGATION PROCESS 4.1 4.2 4.3 4.4

1

29

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 The Investigative Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 Opinions of Probable Costs to Remedy Deficiencies and Failures . . . . . . . . . . . . . . . . . . . . . . . . . . .43 Reserves Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

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CHAPTER 5: NONDESTRUCTIVE AND DESTRUCTIVE TESTING 5.1 5.2 5.3

5.4 5.5 5.6

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 Testing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55 Nondestructive Testing (NDT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 5.3.1 Visual Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 5.3.2 Ultrasonic Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62 5.3.3 Thermal Infrared Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63 5.3.4 Acoustic Emission (AE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65 5.3.5 X-Ray Scanning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 5.3.6 Eddy Current (Electromagnetic) Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67 5.3.7 Penetrant Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69 5.3.8 Magnetic Particle (Magnetic Flux) Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 5.3.9 Radiographic Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72 Destructive Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73 Laboratory Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76 Standards, Codes, and Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

CHAPTER 6: FORENSIC PHOTOGRAMMETRY 6.1 6.2 6.3 6.4 6.5 6.6 6.7

8.4 8.5

113

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113 Building Structural Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 Structural Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119 8.3.1 Below Grade Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 8.3.2 Wall Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124 Typical Deficiencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .128 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129

CHAPTER 9: ROOFING SYSTEMS 9.1

101

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101 Components to Be Evaluated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103 Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111

CHAPTER 8: STRUCTURAL SYSTEMS 8.1 8.2 8.3

79

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79 Principles of Photogrammetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80 Photographic Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85 Measurements From Photographs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93 Reconstruction Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Laboratory Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97 General Guidelines for Effective Forensic Photography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97

CHAPTER 7: THE BUILDING SITE 7.1 7.2 7.3 7.4

53

133

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133


Contents

9.2

9.3 9.4 9.5

Roofing System Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134 9.2.1 Shingles and Tile Roofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134 9.2.2 Built-up (Multi-ply) Roofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136 9.2.3 Single-ply Roofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137 9.2.4 Modified Bitumen (MB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139 9.2.5 Metal Panels Roofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142 9.2.6 Other Roofing Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143 Components to Be Evaluated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143 Typical Deficiencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152

CHAPTER 10: HEATING, VENTILATING & AIR CONDITIONING (HVAC) SYSTEMS 10.1 10.2 10.3 10.4 10.5 10.6 10.7

11.7 11.8

183

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183 Understanding Currents, Amps, Volts & Watts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185 Components to Be Evaluated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .186 Building Automation & Intelligent Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191 Interior and Exterior Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194 Solar Energy Electric Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197 11.6.1 Solar Electric System Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197 11.6.2 Types of Solar Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .198 Harmonics Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .199 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

CHAPTER 12: PLUMBING SYSTEMS 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 12.10

157

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157 Refrigerants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159 Types of HVAC Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159 HVAC System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169 Common Deficiencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169 HVAC Components and Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .179

CHAPTER 11: ELECTRICAL & LIGHTING SYSTEMS 11.1 11.2 11.3 11.4 11.5 11.6

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203

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .203 Cold Water Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205 Hot Water Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206 Plumbing Fixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206 Natural Gas & Fuel Oil Distribution Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .211 Sanitary Sewer System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .211 Storm Drain System (Rainwater Sewer) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .212 Fittings & Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213 Backflow Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .216


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Architectural Forensics

CHAPTER 13: VERTICAL TRANSPORTATION SYSTEMS 13.1 13.2 13.3 13.4 13.5 13.6 13.7

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219 Elevator Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220 Escalators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227 Moving Walks and Ramps (Inclined Moving Walks) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .228 Building Codes and ADA Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229 Basic Component Groups to Be Evaluated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .233

CHAPTER 14: INTERIOR SYSTEMS 14.1 14.2

14.3

15.3

15.4 15.5

16.4 16.5

253

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253 Exterior Wall Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254 15.2.1 Masonry Wall Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254 15.2.2 Stone Wall Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259 15.2.3 Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261 15.2.4 Exterior Insulation and Finish System (EIFS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262 15.2.5 Curtain Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263 15.2.6 Siding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .269 15.2.7 Exterior Doors, Windows & Glazing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .270 Weatherproofing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .272 15.3.1 Air Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273 15.3.2 Control/Expansion Joints, Sealants & Caulking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .273 Typical Deficiencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .274 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .275

CHAPTER 16: INTERIOR AIR QUALITY—ENVIRONMENTAL ISSUES 16.1 16.2 16.3

235

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235 Components to Be Evaluated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235 14.2.1 Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235 14.2.2 Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .237 14.2.3 Interior Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240 14.2.4 Stairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .242 14.2.5 Finishes: Floor, Wall & Ceiling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .244 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251

CHAPTER 15: EXTERIOR CLOSURE SYSTEMS—BUILDING ENVELOPE 15.1 15.2

219

277

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .277 Sick Building Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .280 Inorganic Contaminants—Asbestos, Radon, Lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281 16.3.1 Asbestos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282 16.3.2 Radon (Rn) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .283 16.3.3 Lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .285 Combustion-Generated Contaminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .286 Organic Contaminants—Aldehydes, VOCS/SVOCS, Pesticides . . . . . . . . . . . . . . . . . . . . . . . . . . . .288


Contents

16.6

16.7

xi

Biological Contaminants—Mold and Mildew, Viruses, Bacteria, and Exposures to Mite, Insect, and Animal Allergens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291 16.6.1 Mold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .291 16.6.2 Bacteria and Viruses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .294 16.6.3 Mites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .294 16.6.4 Insect, Rodent and Animal Allergens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .296 16.6.5 Allergens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297

CHAPTER 17: NATURAL HAZARDS

299

General Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299 17.1 Earthquakes—Seismic Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .299 17.2 Hurricanes, Tornadoes, Floods, Etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306 CHAPTER 18: ADDITIONAL ISSUES 18.1

18.2

18.3

18.4 18.5

Life Safety Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313 18.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313 18.1.2 Fire Life/Safety Systems and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315 Sprinkler Systems Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315 Standpipe & Fire-Hose Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .317 Hand-Held Fire Extinguishers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .318 Smoke & Heat Detection Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319 Fire Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .320 Exit Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .321 Fire Stopping—Compartmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .322 Alarm Systems & Notification Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .323 18.1.3 System Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .325 Property Security Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .326 18.2.1 Types of Security Threats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .328 18.2.2 Defining Security Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .331 18.2.3 Types of Access Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .333 18.2.4 Miscellaneous Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334 Building Code Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .336 18.3.1 Building Codes Today . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .337 18.3.2 Model Codes Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338 18.3.3 Institutes & Standards Organizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340 18.3.4 Code Elements & Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .341 Barrier Free Design—ADA Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .348 Deterioration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .367

CHAPTER 19: YOUR OWN OFFICE AND WEB SITE 19.1 19.2 19.3 19.4

313

369

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .369 Choosing the Office . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .370 Preparing a Business Strategy & Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .371 Start-up Costs and Capitalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .375


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19.5 19.6 19.7 19.8 19.9 19.10

Architectural Forensics

Business Forms, Taxes, Licenses, Permits & Insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380 Creating a Professional Image—Sample Letters & Brochure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .383 Selling Yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .385 Identify and Track Sources for Leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .387 Consultant Fee Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .389 The Internet, The Web Site, and Forming an Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .390

CHAPTER 20: LITIGATION, DISPUTE RESOLUTION, AND THE EXPERT WITNESS 20.1 20.2 20.3 20.4 20.5 20.6 20.7

397

General—Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .397 First Steps to Be Taken After a Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .399 Responsibility for Failure, Claim Analysis, Negligence, and Standard of Care . . . . . . . . . . . . . . . .402 Traditional Litigation—Pretrial and Trial Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .404 Ethical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .406 Alternative Dispute Resolution—Arbitration, Mediation, Etc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .408 The Architect and Engineer as Expert Witness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .410

ACRONYMS & GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .417 BIBLIOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .429 INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .433


ACKNOWLEDGMENTS Architectural Forensics would not have been possible without the support and assistance of numerous individuals—friends, colleagues, architects/engineers and contractors who have contributed greatly to the formation and crystallization of my thoughts and insights on many of the topics and issues discussed during the preparation of this book. I am also indebted to the innumerable people and organizations that have contributed ideas, comments, photographs, illustrations, and other items that have gone a long way to help make this book a reality. I must also clearly state that without the continuous enthusiasm, encouragement and wisdom of Mr. Roger Woodson, president of Lone Wolf Enterprises Ltd., and Ms. Joy Bramble, senior editor with McGraw-Hill, this book may not have materialized and taken the shape it has. It is both gratifying and a real pleasure working with them. I also wish to thank Ms. Jacquie Wallace, who edited the manuscript and did the layout and composition, for her unwavering commitment and humor under often difficult conditions. I must likewise acknowledge the wonderful work of Lone Wolf copyeditor Joseph Staples, Ph.D., and proofreader Alan Ingano for their invaluable assistance and determination. The author is especially appreciative of numerous other individuals including, but not limited to, Mr. Carl de Stefanis, president of the distinguished consulting firm Inspection & Valuation International (IVI), Mr. Michael Paruti of IVI for providing me with a number of useful photographs, and Mr. Steve Millnick of Gerard Engineering for reviewing Chapter 10. Finally, I would like to thank my wife, Ibtesam, for her loving companionship and support and for helping me prepare some of the CAD and line illustrations. I also wish to record my gratitude to all those that came to my assistance during the final stretch of this work—the many nameless persons who kept me going with their enthusiasm, support, and technical expertise. I relied upon them in so many ways and while no words can express my appreciation to all of the above for their assistance and advice, in the final analysis, I alone must bear responsibility for whatever mistakes, omissions, or errors may have found their way into the text.

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INTRODUCTION With owners and facilities managers increasingly focused on bottom-line results, the lessons learned from forensic architecture and engineering offer tools that can bring about significant building operating and maintenance cost savings. Forensic architecture and engineering are essentially processes of diagnosing facility problems and providing appropriate solutions that take into account all the building elements. Perhaps more importantly, the forensic architect can be employed as part of a preventive strategy, helping to anticipate problems and implement corrective actions before failures occur. In attempting to define architectural forensics, most people relate it to a court trial. In reality, few of the cases actually ever reach the courtroom. While court cases may often attract the most attention, in reality, they actually account for a small percentage of most forensic architects’ work. Most frequently, forensic investigations involve the resolution of other issues such as: whether a building has problems that will affect a real estate transaction or acquisition, or the cause of mold growing on the walls, and how to stop it and eradicate it, or whether the terms of a construction contract have been fulfilled. Being a fairly new discipline, I was pleasantly surprised to find that there are a substantial number of architectural consultant firms now on the Internet that offer architectural forensic services. One of the most important lessons emerging from forensic architecture and engineering investigation is the importance of periodic inspection programs that evaluate the condition of a building’s assets (e.g., building systems and structures and all equipment for operating the building, including vertical transport systems). Normally, the process requires a trained forensics expert with intimate knowledge of the systems being analyzed and is outside the expertise of the forensic architect. In such cases, the forensic architect needs to bring in a system-specific engineer that can solve the particular problem, and who will also look at the broader picture to understand the environment in which the component must successfully operate. Most prudent building owners and managers today consider the application of due diligence services to be a prerequisite prior to making a meaningful financial commitment. The process itself rarely involves a decision or recommendation, but rather it primarily confirms that requisite tasks pertaining to the property have been executed, pertinent issues addressed, and critical information identified and disclosed. The due diligence investigation in essence attests compliance with designated standards, including acquisition policies and criteria, as well as legal and regulatory guidelines, and also that the decision process has been appropriately adhered to. Forensic architects are often employed to uncover construction, design, and/or maintenance deficiencies. The process frequently brings to light areas in which a building contractor failed to implement design specifications. In addition, forensic architects can frequently reveal design flaws, and looking ahead, forensic architecture practices will continue to advise clients to apply better maintenance and record-keeping procedures which will help forestall such situations. Forensic architects also have at their disposal both non-destructive methods and invasive methods by which an investigation is conducted. The non-destructive methods include a detailed visual examination by an expert and use of electromagnetic detection equipment, infrared imaging, ground-penetrating radar, and x-ray imaging. Invasive methods of investiga-

xv Copyright Š 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.


xvi

Architectural Forensics

tion require cutting into building materials to inspect concealed details in the construction. The bottom line is that material testing is often required to determine the proper specifications for repair, especially when dealing with structural and architectural systems. But structural failure does not necessarily have to consist of a structural collapse; it may consist of nonconformity with design expectations or deficient performance. Collapse is usually attributed to inadequate strength and/or stability; while deficient performances are usually attributed to abnormal deterioration, excessive deformation, and signs of distress. In short, failure may be characterized as the unacceptable difference between intended and actual performance. Since nearly all structural deficiencies and failures create claims of damages, disputes, and legal entanglements, the forensic architect often operates in an adversarial environment, and hence, in addition to his/her technical expertise, the forensic architect needs to have at least some familiarity with the relevant legal processes and needs to know how to work effectively with attorneys. Forensic architectural efforts can also benefit new buildings, providing recommendations for elements to incorporate into the design that will enhance life-cycle rates and result in lower maintenance costs. This could include the use of conventionally reinforced structures instead of cast-in-place reinforced concrete that uses rebar or post-tensioned concrete. Both types will fail when the reinforcement is exposed to moisture, plus repairing post-tensioned structures is usually far more expensive. However, the additional material cost of a conventionally reinforced structure that uses more concrete and steel is often offset over the service life of the building. Whether it concerns the analysis of existing building systems or as it applies to new construction, forensic architecture offers a necessary means to evaluate system performance. The process results in enhancements that can solve immediate problems as well as bring about cost savings and efficiencies for the long term. Sophisticated post-failure testing to structural failures techniques are continuously being developed and improved to help the investigation process. The forensic architect’s duties also often include assigning financial responsibility to the parties involved. Architectural Forensics is a unique handbook in that it deals with virtually all of the topics needed to enter the forensic architecture profession. Much of the information contained herein will not be found in most textbooks currently on the market. Topics covered include conducting investigations and evaluations, and the forensic architect’s role in these investigations and evaluations, preparing reports, material testing, forensic photogrammetry, different building and mechanical systems, air quality issues, natural hazard issues, building codes and ADA regulations, and life safety and security systems. Litigation, including expert witness issues, setting up a private practice, and marketing of services are also covered. While no single Handbook can provide everything you need to know to evaluate building systems or investigate building failures, Architectural Forensics is the best introduction and information source on the subject available at this time. It expounds a standard procedure and methodology developed over years of field experience and proven effective for this emerging field of forensic architecture. Not only does it provide valuable technical information regarding investigative techniques on subjects like forensic photogrammetry, nondestructive testing, and other topics, it also provides invaluable tips on the whole property condition evaluation and investigative process. But while forensic experts cannot be specialists in all technical aspects of a property evaluation or failure, the forensic architect has nevertheless carved a significant niche in this assessment process which requires that every system and feature of a property be evaluated with the same level of consistency and concern. Sam A. A. Kubba, Ph.D.


Architectural Forensics


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CHAPTER

1 Defining Architectural Forensics 1.1

GENERAL—DEFINING ARCHITECTURAL FORENSICS

Although architecture as a discipline is primarily associated in most people’s minds with the design and renovations of buildings and related structures, there is a growing field emerging within architecture that involves itself not with the “aesthetics” of a new building, but with the completed existing structure and its ongoing operations‚ to ensure longevity and preservation of the asset. This growing field is termed, “Forensic Architecture.” It is an area of building study that allows the architect to focus on ways in which a building can best maintain itself and prolong its life in a cost-efficient manner. A forensic architect is essentially a professional architect who applies the art and science of the profession to various aspects of architecture, construction, and legal issues. Activities associated with architectural forensics include the investigation, determination and causes for deterioration, deficiencies, and failures, in addition to the preparation of reports, and testimony under oath, or offer advisory opinions that assist in resolution of related disputes. The forensic architect may also be asked to render a professional opinion regarding responsibility for failure or deficiency. In the author’s opinion, the forensic architect’s job description should also include: failure and deficiency prevention and cure. Typical potential clients of failures or deficiencies include all parties affected by the failure or deficiency. Sometimes a general inspection is requested and this is typically performed according to the methods and procedures described herein and which are primarily based on visual observation, not necessarily intended to be technically exhaustive, in order to identify and disclose each and every condition of the property inspected. The forensic architect is also often required to work for attorneys representing plaintiffs or defendants, who may be individuals, corporations, or governmental agencies. The forensic architect may likewise decide to work independently, using other specialist consultants as required. On larger assignments, the forensic architect may be part of an investigative team. It should be noted that while the term is associated with litigation and indeed the majority of forensic investigations are conducted under the threat of litigation, most disputes are resolved prior to going to court.

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With facilities managers today increasingly focused on bottom-line results, forensic architecture has proven that it offers tools that can bring about significant building operating and maintenance cost savings. Both forensic architecture and engineering are essentially processes of diagnosing facility problems and providing solutions, employing a total approach that takes into account all the elements of a building. Perhaps more importantly, architectural forensics can be employed as part of a preventive strategy, helping to anticipate problems and implement corrective actions before failures occur. Also, the dissemination of knowledge learned from architectural forensics, coupled with a reliability-centered maintenance process, enables facility managers to adjust the scope and frequency of periodic maintenance and preventive maintenance based on the past performance of existing equipment. Forensic architects and engineers also have an important duty to disseminate information (based on their investigations) to design professionals and industrialists to improve design procedure and products so that failures or accidents may be avoided.

1.2

QUALIFICATIONS OF THE FORENSIC ARCHITECT

The forensic architect often possesses unusual if not unique expertise and technical capabilities. This is evidenced by the many qualifications and skills necessary to succeed in the profession such as academic degrees, professional registration, certification, and/or extensive experience in addition to other skills outlined below: Technical competency: It is imperative that the forensic architect demonstrates competency in his or her specialized field. In construction litigation for example, most state statutes require that a witness be “qualified” as an expert in order to testify regarding his opinion pertaining to the evidence in a trial. To do so, it must be proved that the expert has the knowledge, skill, training, experience, education, and ability to assist the judge or jury in understanding the evidence or in determining a fact which is at issue in the case. The trial court has the discretion to decide whether a witness possesses sufficient qualifications to offer an expert opinion or not. The expert’s qualifications are also subject to inquiry by opposing counsel typically prior to the expert providing his opinion. Counsel may request the court to disallow the testimony of the “expert” based upon a showing of inadequate qualifications. In such circumstances the expert must be prepared to defend his credibility, education, experience, etc. If a forensic architect is to offer expert testimony in federal court, the qualification criterions are basically the same. Courts, moreover, generally distinguish between architects and engineers regarding their qualifications to testify on certain matters. Thus to satisfy the requirements of technical competency the forensic architect must unequivocally show that he/she has the necessary education and experience. Credibility is further enhanced if the forensic architect or engineer is both licensed and registered (membership of an appropriate professional society such as the American Institute of Architects [AIA] for architects or the American Society of Civil Engineers [ASCE] for civil engineers). Furthermore, an architect or engineer with years of professional experience and practice is likely to be more effective in courtroom testimony. Knowledge of codes, contracts, construction techniques, cost control, systems evaluation, and safety factors are also important requirements but these can only be gained through a determined effort in continuing education and direct experience. Communication skills: The forensic expert needs to be an effective communicator in both written and oral presentations. Oral skills are particularly important to effective testimony in court or in public hearings. Often, the forensic architect must explain complex technical issues in a manner that is readily comprehensible by the layperson with no technical background. If the expert witness fails to do this or cannot survive cross-examination, even the best investigative work can be negated. This is why ineffective oral


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communication and written skills can have a detrimental impact on a case’s outcome. The main documentation of the investigation or inspection is the written report. Until this is submitted to the client the work remains incomplete and of limited value. Depending on the assignment, its scope and complexity, the report may include a mere couple of pages or it may consist of a multi-volume set of documents. Knowledge of legal procedures: It is important for the forensic architect/engineer to have a working knowledge and concept of legal procedures and vocabulary used in litigation (e.g., standard of care and negligence, statute of limitations, strict liability, etc.). This is particularly important when writing reports, discussing evidence, etc. Written reports are typically written after the forensic investigation takes place. Reports become tangible records of investigations, and the quality of the report reflects on the competency of the investigator. A more detailed discussion is presented in Chapter 20 which covers litigation. Ethical standards: Having high ethical standards is one of the characteristics of a successful forensic architect. The Preamble of the AIA Code of Ethics & Professional Conduct states that, “Members of The American Institute of Architects are dedicated to the highest standards of professionalism, integrity, and competence.� These ethical and professional principles should be meticulously followed even though they are continuously being put to the test in the face of constant pressures to take an emotional or advocacy position. The forensic architect should also avoid taking any positions that may reflect a no conflict of interest and should refrain from engaging in any business that may be considered a conflict of interest. Likewise, it is imperative that the forensic expert maintains objectivity and impartiality in seeking the truth. Such objectivity implies the ability to discard preconceived notions when the facts to the investigation do not support initial hypotheses. In addition to objectivity and impartiality, the forensic expert should be able to work effectively with others, whether in a supporting, cooperating or coordinating team capacity. Research and investigative skills: The primary goal of an investigation is usually to find the source of the problem, i.e. failure or deficiency, and propose a solution. Research and investigative skills are therefore one of the prerequisites of being a good forensic architect or engineer. Care must be exercised in collecting pertinent facts from the field and from documents to ensure that the evidence is protected and that no damage or alteration to the evidence takes place. Sometimes even minor alteration of the evidence can have a profound effect on the outcome of the investigation or litigation concerned. Also, investigations into failures in connection with claims or disputes must seek to establish the causes of failure, and whether the failure can be attributed to normal deterioration or defects in construction or maintenance. Such investigations may also involve, among other things, laboratory examination and analysis of samples. The forensic architect must therefore be familiar with forensic data collection tools and techniques including both non-destructive methods and invasive methods by which an investigation is conducted. Nondestructive methods may include a detailed visual examination and use of electromagnetic detection equipment, infrared imaging, ground-penetrating radar, and x-ray imaging. Invasive methods of investigation normally require cutting into building materials to inspect concealed details in the construction. Tools such as borescopes, fluorescopes, and videoscopes are often used to minimize the amount of material to be removed for inspection. In addition, the expert should pay close attention to detail and documentation (collection documentation, chains of custody, etc.) as much of the investigation involves interpretation of the data collected. It is also necessary for the expert to separate contributing factors from irrelevant items during the analysis. An important aspect of data collection is the protection of physical evidence which must be preserved at all costs. In this respect, timing is a critical factor to the collection of reliable data. Evidence is sometimes destroyed immediately after a fire, hurricane, or major structural failure during the rescue and cleanup operations. As is the case in most investigations, the expert needs to research into design standards and material properties existing at the time the failed product or situation was created. The importance of acute detec-


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tive skills, as opposed to design skills, cannot be overemphasized. An excellent designer is not necessarily a good forensic expert. Unlike most designer architects, the forensic architect approaches a failure investigation from the perspective of a physical causation and the given project as designed and constructed. Other miscellaneous skills: There are a number of other skills that would be useful for the forensic architect to have. For example, good photographic skills are important to any investigation. The alternative would be to bring in a professional photographer. It is also important for the forensic architect to have pleasant personality traits and be able to work effectively with others.

1.3

PROFESSIONAL RESPONSIBILITIES AND STANDARDS

Litigation surrounding failures and accidents has reached an unprecedented level of activity in the past decade or so. With this increased litigation has come an increased demand for engineering professionals to serve as expert witnesses. Many individuals have been attracted to the field of architectural forensics by the financial rewards and by the apparent limited exposure to liability when compared with the increasing liability exposure facing architects and design engineers. To meet this challenge, several professional societies are working to maintain guidelines for ethical practices in forensic engineering. Thus for example, the National Academy of Forensic Engineers (NAFE) was established, in part, to address the need for ethical standards in forensic practice (Section 1.4). In addition, the National Society of Professional Engineers (NSPE) has published Guidelines for the Professional Engineer as a Forensic Engineer. The Association of Soil and Foundation Engineers (ASFE) has also prepared a document entitled Recommended Practices for Design Professionals Engaged as Experts in the Resolution of Construction Industry Disputes (ICED 1988). Ethical conflicts in forensic practice arise from the fact that forensic experts are usually retained by parties in the dispute. While attorneys are retained to be advocates for their clients, forensic experts are required to remain impartial and seek the truth even when that truth is in conflict with the client’s interest. The forensic expert is required by ethical principles to maintain objectivity. But the expert’s future income and reputation as a valuable expert witness relies on client satisfaction. However, not all attorneys pressure forensic consultants to act in an advocacy role. Some attorneys actively seek experts with dissenting viewpoints. Adverse information can be helpful to the client and assist the decision-making process resulting in settlement of the dispute. An objective, impartial forensic consultant serves the client best by identifying weaknesses in the client’s position. Such an approach is valued in the long run, and helps to establish a reputation for integrity and credibility. Dissenting viewpoints among competent forensic experts is not unusual. Disagreement does not necessarily imply dishonesty or incompetence on the part of one of the witnesses. There is often more than one way to see a problem and more than one method to resolve it. Failures and accidents are often the result of several complex, interrelated factors. An honest expression of diversity of opinion, through the introduction of testimony by multiple experts, is a healthy approach to seeking truth. It is important to give appropriate consideration to all contributing factors. Particular care should be exercised in cases involving malpractice charges. The forensic architect has a responsibility to protect the professional reputations of all parties until the investigation is complete. Unclear or premature statements to the media can irreparably damage the professional reputations of innocent parties. As stated earlier, where competency of the design professional is in question, it is the investigator’s responsibility to determine the standard of practice at the time of design. Current standards and the forensic engineer’s own design preferences are not relevant to the question of competency.


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Ethical practices require the forensic engineer to be thorough, cross-checking all conclusions. Questions beyond those asked by the client should be addressed. All calculations should be studied for reasonable variances in data, and all ranges of uncertainty should be expressed. All of these issues clearly test the professional integrity of the forensic consultant. The forensic expert who can perform these tasks with distinction has a unique opportunity to represent the highest ideals of the architectural/engineering profession to the general public.

1.4

PROFESSIONAL ORGANIZATIONS

There are many national and international professional architectural, engineering, and scientific societies and organizations that are of particular relevance to the construction industry. Some of the more active of these societies and organizations include the following: American Academy of Forensic Sciences (AAFS) American Arbitration Association (AAA) American Bar Association (ABA) American Institute of Architects (AIA) American Society of Civil Engineers: Technical Council on Forensic Engineering (ASCE/TCFE) Architectural Engineering Institute (AEI) Association of Soil and Foundation Engineers (ASFE): The Association of Engineering Firms Practicing in the Geosciences Canadian Society of Forensic Science (CSFS) Construction Specification Institute (CSI) Expert Witness Institute EWI (United Kingdom) Expert Witness Institute EWIA (Australia) Forensic Expert Witness Association (FEWA) Institution of Civil Engineers (ICE) (United Kingdom) Institution of Structural Engineers (IStructE) (United Kingdom) International Council for Building Research Studies and Documentation (CIB) (The Netherlands) International Society for Technology, Law and Insurance (ISTLI) National Academy of Forensic Engineers (NAFE) National Academy of Sciences (NAS) National Association of Mold Professionals (NAMP) National Council Architectural Registration Board (NCARB) National Society of Professional Engineers (NSPE) Society of Forensic Engineers and Scientists (SFES) Standing Committee on Structural Safety (SCOSS) (United Kingdom) The Technology and Construction Solicitors’ Association (TeCSA)


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CHAPTER

2 The Assignment/ Investigation 2.1

GENERAL

Inspections and surveys are typically performed prior to a real estate transaction for commercial properties. It is what any astute potential buyer or mortgagee would employ prior to making a meaningful financial commitment. The process does not involve a decision or recommendation, but rather is a confirmation that requisite tasks have been performed, pertinent issues have been addressed, and critical information has been identified and disclosed. It further confirms that the decision process has been appropriately adhered to. Due diligence of prospective acquisitions is therefore crucial, irrespective of whatever investment strategy might be pursued. The objective of an architectural/engineering inspection is to observe and document pertinent information and deficiencies on the subject property to enable a proper assessment of the factors that are important to the “due diligence” process. A standard methodology is used to satisfy the intent of the due diligence. The use of standard forms and checklists is important to this process to ensure that all necessary observations have been made and recorded. It is recognized that real property is by nature unique and unforeseen situations arise. Therefore, the standard methodologies may require adjustment to meet the intent of the due diligence. As outlined earlier, a property condition evaluation essentially identifies physical deficiencies of a subject property’s material systems, components, or equipment as observed at the time of the walk-through survey. The term physical deficiency refers to conspicuous defects or material deferred maintenance. It is also designed to provide a professional opinion regarding future anticipated issues which may result in a financial risk or liability to the client. The process includes a visual walk-through to observe existing conditions and a review of available public records, construction documentation, and current budgets. This information is then analyzed and presented with recommendations for repair or further detailed review (i.e., additional mechanical, structural, or civil survey) if the issues cannot be determined through visual observation alone.

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A property condition evaluation may be conducted for newly constructed or converted multi-family residential properties at the time the developer transfers the property over to the association. In the multifamily residential industry the assessment is commonly referred to as an Engineering/Developer Transition Study. The assessment typically identifies material and design defects, poor workmanship, and deviations from standard construction practices. This enables the association to pursue repairs or compensation from the developer for deficiencies that may exist.

2.2

ACCEPTING THE ASSIGNMENT

The following is a typical sequence of events upon being awarded a building inspection assignment. Upon initial client contact and expression of interest in the award of a project, a project file is created and a project number is assigned. This file will be maintained through the development and award of the assignment. The sequence of activities is as follows: 1. 2. 3. 4. 5. 6. 7.

The client typically calls or emails expressing interest in receiving a quotation on an assignment. A standard proposal is prepared and sent to the prospective client. Upon acceptance of the proposal, mobilization of the assignment begins. All information regarding the proposal is entered into the firm’s database. The assignment is given a project number which is used for anything relating to the job. The scope and objectives of the assignment are determined. The consultant mobilizes for the project and then conducts the investigation and prepares the report for the client.

If the assignment was not awarded, that information should be entered into the database and any debriefing as to why the assignment was not awarded is noted.

2.3

PURPOSE & SCOPE OF ASSIGNMENT

As with many consulting assignments, the project typically originates with a meeting or phone call during which a potential client outlines his/her needs and objectives for an initial investigation. At this point, the forensic architect should carefully examine the client’s objectives and check that there is no conflict of interest to accepting the assignment. If, for example, the client declares an intention to use the forensic architect to support a certain point of view as an expert in trial, and the expert feels uncomfortable or unlikely to be able to support that point of view, the client should be informed from the outset. It is always better to be honest up front, even if it means possibly losing the assignment. Property evaluations consist of three chief components: the walk-through survey, document reviews and interviews, and the property condition report. A walk-through survey is normally conducted by the professional to visually identify and evaluate the subject property’s material physical deficiencies. Specifically, the forensic architect’s scope will include identifying physical deficiencies (i.e., conspicuous defects or deferred maintenance of a subject property’s material systems, components, or equipment) observed during the walk-through survey of the property. The forensic architect will record deficiencies that may be remedied with routine maintenance, and miscellaneous minor repairs, but exclude insignificant conditions that


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would not generally be considered to be material physical deficiencies. The document reviews and interviews phase of the assessment consists of the professional’s review of various public records and private documents pertaining to the property and interviews with persons knowledgeable of the property. Finally, the property evaluation report describes the type and condition of the building components, identifies those areas that require immediate remedial work, and assigns each an estimated remedial cost. The PCA report also establishes an estimated replacement reserve over the indicated term of the loan or ownership period. The property evaluation allows property owners or buyers to make informed decisions on the current relative value of a property and/or project the residual value of the property after 10 or 20 years of ownership. Many firms with fairly substantial portfolios often have their own prepared scope of services and protocols for property evaluations which they send to the consultant upon being awarded the assignment, and which is incorporated into the contract (e.g., as an attachment) between the client and consultant. Below is one such scope of work: I. GENERAL A. The consultant shall execute the owner’s terms and conditions for professional consulting services for a property condition evaluation/inspection and this scope of work shall become part of that agreement. B. The consultant shall perform a full property condition evaluation/inspection for the property or for each property contained in the list of properties attached hereto as Attachment I. C. The consultant shall provide an inspection and report for the property or for each property in the list of properties, including capital improvements, deferred maintenance, and budgets. The consultant shall clearly identify the property in each report by name and address. D. The consultant may be required, at owner’s option, to address each report to several different entities. E. The consultant shall, if required by owner, provide for a phased review of the inspections and a written report for owner. Consultant shall submit a report format for approval by owner. G. The following information shall be included in each report: 1. Property name 2. Property address 3. Site area (acres) 4. General description of improvements a. Number of buildings b. Number of stories c. Square footage d. Number of auxiliary structures e. Number of parking spaces f. Year constructed g. Owner h. Contact II. CONSULTANT SERVICES The consultant shall perform the following services for owner: A. Review available as-built plans and specifications, plot plan, legal boundary, survey and appraisal reports if available. B. Interview the building maintenance supervisor and review maintenance logs to report on any problem areas or suspected deficiencies. C. Perform a complete non-destructive inspection of the property to observe and evaluate the current condition of the site and building improvements.


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D. Inspect and evaluate all major exterior and interior building systems as to condition, quality, adequacy, deficiencies, maintenance, and code compliance. E. Provide a facilities checklist, listing condition, and comments. F. Prepare a written Property Condition Evaluation report with an executive summary containing the consultant’s overall analysis, systems evaluation, comments on needed repairs or maintenance (and probable costs thereof) and photographs. The written Property Condition Evaluation report shall specifically address the condition, quality, adequacy, deficiencies, needed repairs or maintenance, and estimated remaining service life, where applicable, of the following items: 1. Site improvements including, but not limited to, code adequacy and number of parking spaces, paving, sidewalks, steps, stairs, landscaping, irrigation, fencing, retaining walls, signage, exterior lighting, drainage, waste collection and removal, traffic flow, site utilities, specialty features, and security. 2. Building and parking deck (if applicable) structure including foundations, floor systems, framing system, load bearing walls, and roof structure. 3. Building exterior including, but not limited to, roofing, parapets, exterior walls, thermal insulation, windows, vents, finishes, caulking, flashing, soffits, skylights, hardware, and exterior doors and frames. 4. Interior improvements, including, but not limited to, lobby and building core finishes and typical tenant finishes including floor, wall and ceiling finishes, doors, hardware, and window treatment. 5. HVAC system including description of system(s) and capacities, age, condition, problems, and expected life. 6. Electrical system including description of system(s) and capacity, condition, problems, and expected life. 7. Plumbing system including description of system, condition, problems, and expected life. 8. Life safety systems including a description of all system(s), condition, and code compliance. 9. Conveying systems including description of types, capacity, equipment, speed, and maintenance records. 10. Accessibility describing physical features incorporated into the improvements and code compliance issues. 11. Specialties, identifying any special features, attached or detached, and their appearance, condition, and operating reliability. 12. Provide photographs of the site, building exteriors and interiors, and any problem areas. 13. Classify all items recommended for replacement or repair to indicate level of urgency and recommended timing. 14. Provide opinion as to recommended timing of project capital items, such as roof replacement, facilities upgrading, and parking lot resurfacing. 15. If further testing of materials or systems is required or recommended, specify items to be tested and the reasons for concern. 16. Provide an executive summary stating conclusions and basic recommendations and including an estimate of reasonable cost to repair, replace, or otherwise address appropriately specific areas or items of concern. 17. The written report shall be signed and dated by a professional(s) who performed the services, a


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principal of the consultant and a member of the firm licensed or certified to do business in the state where the property is located. G. For buildings located within seismic zones 3 or 4, as depicted on the seismic zone map of the U.S. of the Uniform Building Code (UBS), the consultant shall also provide a structural review in accordance with the following requirements: 1. Review and report on available geotechnical information (geotechnical reports, soil borings, foundation, system studies, etc.) and comment on the soil type, geotechnical features and the potential of soil liquefaction in the event of an earthquake. 2. Identify and report on any catalogued active faults that may affect the property. Report magnitude estimates and distance from the subject to such faults. 3. Determine the building type and under which code the building was designed. 4. Review and report on available drawings as they pertain to the designed gravity (dead and live) and lateral (earthquake or wind, whichever is greater) loads and on the existing gravity and lateral force resisting systems of the structures. 5. Conduct a site visit to visually review as-built conditions as they comply with the drawings submitted, if any, and to identify structural deficiencies as they pertain to inadequate gravity and horizontal loading under current code requirements. 6. Render an opinion of the Aggregate Probable Maximum Loss (PML) as a percentage of the current building replacement cost as a result of an earthquake, complete with a general description of the anticipated damage for the structure, the PML is to be based on a 10 percent probability of being exceeded in a 50-year period. 7. Provide recommendations for mitigating structural deficiencies to incur a PML of not more than 15 percent complete with preliminary cost estimates based upon nominal quantity take-off calculations for the recommended work. The analysis and recommendations are to be based upon a visual review of the drawings and structure and do not involve performing analytical structural calculations of testing. 8. Take representative photographs of typical conditions and pertinent deficiencies. Such photos are to be annotated to adequately describe the deficiency. 9. Prepare a written report evaluation on all of the above. The above “scope of work� is designed mainly for general property condition evaluations and is not suitable for specific building deficiencies or failures. Of note, while the above scope of work is designed for baseline surveys, it nevertheless includes items that are not typically included in such surveys such as code compliance, traffic flow, structural reviews, etc. The final report of the forensic architect is extremely important in the due diligence process, and is often the basis for real estate financial decisions involving millions of dollars. It is essential that the inspection be conducted professionally, and that the report is comprehensive, informative, and accurate. Real estate transactions are normally conducted on a tight schedule, typically within 30 to 45 days, with success dependent on the timely performance of the various activities and consultants.

2.4

FORENSIC CONSULTANT’S AGREEMENT WITH CLIENT

The majority of standard-form agreements used by architects and engineers in the construction industry are not well suited for forensic work. Most are intended for new constructed works or renovations, and in-


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clude provisions that do not apply; but perhaps more importantly, they may not include provisions that are critical on forensic assignments. Such relevant provisions may include the right of entry at the site, disposition of samples, standard of care, and conflicts of interest. Standard provisions for forensic assignments should be developed with the assistance of an attorney and professional liability carrier. Forensic assignments differ from the majority of design projects in that it is rarely possible from the outset of an investigative assignment to define with any precision the scope and cost of work involved. Yet it is bad business practice to proceed with an assignment without a written agreement with your client on the scope, time, and expenditures. In such circumstances it may be prudent to try and proceed with your client in phases, so that the scope of estimated costs of subsequent phases is determined and agreed to at the end of each phase, as the work unfolds and the direction of the investigation becomes clear. If the forensic architect decides on the use of AIA contract documents he/she is strongly encouraged to consult an attorney before completing the document. The use of B141™ (Standard Form of Agreement Between Owner and Architect with Standard Form of Architect’s Services) or B151™ (Abbreviated Standard Form of Agreement Between Owner and Architect) will require modification, but this should only be attempted with the assistance of legal counsel to fully comply with state or local laws regulating these matters. The B151™ is intended for use on construction projects of limited scope where the complexity and detail of AIA Document B141™ is not required, and where services are based on five main phases: schematic design, design development, construction documents, bidding and negotiation, and construction. This document may be used with a variety of compensation methods, including percentage of construction costs, multiple of direct personnel expense, and stipulated sum. The B151™ AIA Document is intended to be used in conjunction with the A201™ AIA Document (General Conditions of the Contract for Construction) which is an integral part of the relationships of the owner, contractor, and architect. This document is typically adopted by reference into other AIA documents, such as owner-architect agreements, owner-contractor agreements and contractor-subcontractor agreements.

2.5

CONSULTANT’S FEES

One of the factors that can significantly impact the success of your consultancy practice is how much you charge for your expert services. Fee amounts will vary based on the complexity and size of the project and whether or not one uses an AIA contract form. Issues often to be considered regarding fees is whether you should vary your rate depending on the work type, charge a retainer, or use a fee agreement? Competitive pricing levels can be determined in a number of ways. One method is to discretely conduct some research to find out what other experts are charging including reviewing pertinent court records for information, as experts are required to disclose their rates. But whatever approach is used, readers are strongly advised to consult an attorney for advice regarding any matter related to contract terms. Most forensic architects appear to resort to negotiating fees based on the anticipated time expenditure. For many, that can be hard to do realistically. Furthermore, to engage a client, who will likely know even less about the intricacies and demands of architectural practice, in a dialogue about the projected hours, can be problematic. Another faulty assumption is that the value to a client of an expert’s services is necessarily based on the time required to deliver a project. Whether it takes you 50 or 500 hours to complete a project is far less important to a client than the level of service and responsiveness you provide, and the results the client receives. The Expert Pages Web site recently conducted a survey on the hourly rates charged by forensic professionals. The survey suggests that in the fields of Engineering, Environmental & Science, the average hourly rate was $230, for Investigative & Forensic, it was $220 per hour, and for Construction & Architec-


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ture, it was $207 per hour. It was also noted in the survey that rates generally increase with experience, although they did not vary that much. Also of interest is that in the survey no one reported using flat rates for their expert witness work. With owners such as retail clients and developers, whose benefits are directly linked to financial results, it may be best to tie the marginal costs of higher fees to the added results they can expect from your services. Other rate influencing factors apart from the type of work involved include time pressures, the client’s ability to afford the rate, and client/expert relationship. In an expert witness capacity influencing factors include experience with the attorneys hiring the expert, previous experience with the issues involved, whether the expert has to pay a referral fee, and whether the client is a government agency. Below is a list of some of the main issues to be addressed by the forensic architect to ensure that the fees billed for are received: 1. Get it in writing: The first step is to have a letter of engagement that clearly identifies and outlines your rates and business terms. The letter should be clear and precise on how and when payments will be made, and whether customary or unique fee arrangements will apply for: a. Research, testing and analysis b. Consulting c. Testifying in deposition and trial d. Travel and other costs. A list should also be provided of additional services and reimbursable expenses not included in the base fee, such as additional meetings with third parties, destructive/non-destructive testing, need for additional experts, etc., as well as billing procedures for such services. 2. The forensic architect should confirm verbally whether expense estimates are required, and whether the expert has authority to use other consultants or subcontractors and whether the expert has the freedom to conduct, perform, or create any testing, interviews, or demonstrative aids, etc. 3. Establish minimum fee: Regardless of the job size, the consultant has to set aside all other work in order to concentrate on the case in question. As a matter of policy, it may be prudent to consider setting a 5 or 10 hour minimum for smaller jobs. This policy will reimburse you for the value you provide to your client. 4. Obtain a retainer: It is wise to request a retainer that gets replenished as funds are drawn down over the course of the assignment. 5. Bill regularly: Submit detailed bills without disclosing work product in your description of services. 6. Implement a cancellation fee: This is particularly important with expert witness assignments as most litigation cases are settled out of court. The cancellation fee may vary with the degree of notice received. 7. Rate review: An annual rate increase is a fairly common business practice but this will also depend on what the market will bear. Take a look at your rates every December and update your rate card as of January 1 of every year. Test higher rates first on your new clients. Normally you have some room to increase your rates if none of your clients complain about them. In fee determination, the forensic architect should try to cite projected results, not projected hours. The client should view the forensic architect’s fees in terms of the knowledge, experience, judgment, and skills obtained over many years of practice. The bottom line is that the value of services rendered by the foren-


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sic architect is solely in the eyes of the beholder (i.e., your client). So it may not always be wise to base your fees on projected costs or on a specific profit target. And while the approximate number of hours a project may require tells you the minimum fee to charge, it doesn’t tell you or your clients anything of what you are really worth.

2.6

THE PROJECT ASSIGNMENT—MISCELLANEOUS ASPECTS

Drawings and specifications: Project documents and specifications are pivotal to understanding not only how the structure was built, but also how it was maintained and modified over time; without such documents the job is almost impossible for complex projects. Whenever possible the forensic architect should obtain and review the main design documents prior to an investigation. Project documents are also instrumental when the forensic architect is asked to opine on the procedural causes of the failure in that they offer a better understanding into the actions of those tasked for the design, construction, and operation of the facility. Some of the sources that should be able to furnish copies of various project documents include: • • • • • • • •

The architect or engineer of record involved in the original design, modification, or repair of facility. Current building owners and building managers General contractors, construction managers, and subcontractors Facility developer Building department Construction mortgagee of facility Materials or systems suppliers for original construction, modification, or repair of facility Testing agency involved in the original construction, modification, or repair of facility.

Project-specific documents that will be required by the forensic architect in the carrying out of an assignment will depend largely on the scope of work agreed upon with the client prior to the investigation (for example, whether the assignment consists of conducting a baseline evaluation or a structural or system failure). Generally, these documents may include: • • •

Contract drawings including authorized revisions (architectural, structural, mechanical, electrical, lighting, plumbing) Contracts between owner and architect and other relevant contract documents Contract specifications (including general conditions and technical sections of interest)

• Consultant reports—feasibility studies, progress reports, soil consultant reports, etc. • Shop drawings and other submissions • As-built drawings • Field and shop reports to include construction photos • Material strength reports or certification • Relevant project correspondence • Primary calculations—structural, etc. • All records relating to maintenance and modifications. Compliance with contract documents: It is almost always a client’s concern whether construction of


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the project was executed in accordance with the contract documents, i.e. the plans and specifications, and it is one of the forensic architect’s duties to thoroughly check this. It is especially important where there is a permanent lender involved. Any major deviations should be noted and how if at all, these deviations may have impacted the quality of the project. With existing buildings, one will find that as-built drawings rarely coincide with the approved construction drawings. Frequently, deviations from the original plans and specifications have been made, usually for good reason. Deviations may be the result of a business decision or a technical reconsideration. In new construction and existing buildings, the forensic architect should also look for low quality workmanship and if the assignment concerns a failure or deficiency, poor workmanship may be the major cause. In reporting poor or defective workmanship, care must be taken in offering an objective opinion and this should preferably be technically supported. Documents required for project closeout (new construction or renovations): 1. 2. 3. 4. 5. 6. 7. 8. 9.

10. 11. 12. 13. 14.

List of all subcontractors and material vendors List of outstanding retainages due to subcontractors As-built survey Signed/sealed as-built or record drawings which show all changes from the original plans Contractor’s Certificate of Compliance with Plans and Specifications All specified labor and material warranties and guarantees Architect’s Certificate of Substantial Completion and/or final acceptance Architect’s certified copy of the final punchlist of itemized work stating that each item has been satisfactorily addressed Developer Certification that all close-out requirements including, but not limited to, as-built drawings, warranties, manuals, keys, etc. have been received, reviewed, and approved for each subcontractor. All other regulatory approvals (if any, such as Electrical Underwriter’s Certificate and mechanical approval) Consents of surety for final payments, if any bonds are provided Final lien waivers in a form satisfactory to the lender and title company from the general contractor and all subcontractors, and suppliers Provide instruction on proper equipment operation Certificates of use, occupancy or operation.

These documents should be edited as required by client and depending on the project. Building code compliance: Building codes have been around for nearly 4,000 years, ever since the time of Babylonian King Hammurabi (ca.1792–1750 BC) who promulgated one of the first building codes in history. Building codes are designed to govern the construction of all types of buildings—public, commercial, retail, residential, etc. Building codes are a set of rules designed with two main objectives in mind: 1. Save lives, protect public health, safety and general welfare as they relate to the construction and occupancy of buildings, and 2. Protect property in all its shapes and forms. To do this, building codes generally stipulate minimum standards for safety and comfort that must be met in new construction and major renovations. The various codes are discussed in greater detail in Chapter 18. Building codes continue to evolve and are generally intended to be applied by architects, engineers,


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and other related professionals including safety inspectors, forensic experts, real estate developers, contractors and subcontractors, manufacturers of building products and materials, insurance companies, facility managers, tenants, and other categories of users. Building codes are typically updated every few years taking into account advances in technology and construction techniques as well as knowledge gained from natural hazards, terrorist attacks, etc. Code compliance is normally the responsibility of the building owner or manager. The inclusion of building code compliance issues is frequently an issue of debate when considering the scope of a normal baseline evaluation and it remains undecided as to what degree building code issues should be included in the various levels of evaluations. For the forensic architect, the review of code issues is important and in most cases can identify several facility construction areas which if corrected could significantly improve the facility operations and safety. It is unfortunate, therefore, that code compliance issues continue to constitute the second largest category of law suits against due diligence firms in the United States. It may also be why a number of major consultant firms have decided to omit this category from their normal baseline property condition surveys. A review of code-related issues can vary in depth from a cursory review of the base code aspects for each system to a comprehensive review of detailed issues such as fire-door hardware or plumbing fitting information. It is usually sufficient to include a cursory review of code related issues, with the scope limited to significant safety violations or issues for which fines may be involved if discovered by regulatory officials. With no real increase in the cost or effort involved in the evaluation/inspection, these issues can usually be addressed by any competent forensic architect or engineer. In the case of failures, it is important to determine whether a building code violation was the main cause. Warranties and guarantees: Warranties are neither maintenance contracts nor insurance policies. A warranty is a written statement that attests to the integrity of a product and pledges to the purchaser that the provider will be responsible for repairing or replacing (if defective) the product for a period of time. A warranty in essence defines specific legal rights and obligations of the building owner and warrantor. Warranties also typically include remedies and exclusions. For example, in the general conditions section of a contract, the contractor warrants that the material and equipment furnished will be new and of good quality and that the work will be free of defects and be in conformance to the contract documents. However, the contractor’s warranty excludes defects caused by owner’s negligence, such as incorrect operation or inadequate maintenance. Warranty period: Most of today’s warranties have become marketing tools rather than true reflections of construction or system performance. In the construction industry the customary warranty period is for one year from the date of final acceptance of the work. If the owner or his representative takes possession of any part of the work before final acceptance, the warranty normally continues for a period of one year from the date that possession is taken. Warranty periods depend largely on the type of warranty, whether it is related to a construction contract, to a building system, or electro/mechanical equipment/system, etc. For roofing systems for example, it is common for longer warranties that extend up to 20 years or more. It is normally specified that the warranty include both the roof membrane materials (and perhaps other roof system components such as roof insulation) and the roofing contractor’s workmanship. For low-slope systems, the length of coverage for a manufacturer’s warranty is typically 5 to 25 years, with 10 years being the most common. Material-only warranties are also available from manufacturers. A manufacturer’s warranty establishes a direct contractual relationship between the building owner and manufacturer. Warranty benefits: A warranty may have some merit if it means that the manufacturer will take steps to minimize the potential for future problems (such as reviewing the architect’s specification and details and providing meaningful inspection during application). A warranty may also enhance the likelihood that a roof


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will be installed by a professional contractor. However, rather than relying on a warranty to obtain a qualified contractor, architects should specify contractor qualification requirements as discussed in the next section. If a problem that is covered by the warranty occurs, and the warrantor is still in business, the presence of the warranty may lead to a quick resolution of the problem. Most warranties issued by a manufacturer cover repairs caused by defective materials and workmanship (if the warranty is not for materials-only) provided that the cause(s) of the deficiency is covered under the terms of the warranty. Without a warranty, the building owner might have to pursue legal action to obtain relief, which may be too costly if the problem is small. Also, the presence of a warranty provides a direct avenue for the building owner to pursue a claim with the manufacturer if the manufacturer does not respond to a problem covered under the warranty. It is standard practice to specify backup to the general contractor’s warranty. This takes the form of written warranties from the main subcontractors, manufacturers, and suppliers such as electrical, roofing, plumbing, and HVAC systems. Warranty limitations: Most warranties contain several unfavorable provisions, the most significant being: • • • • • •

Exclusion of consequential damages (such as damage to building interiors and contents, and business interruption) Limitation of wind coverage to wind speeds that are typically well below the design wind speed prescribed in the building code Exclusion of hail damage Limitation of leak repairs to patching the membrane rather than removing and replacing wet insulation Determine applicability of warranty by the manufacturer Inclusion of several provisions that could result in the building owner’s inadvertent nullification of the warranty.

However, if the warrantor has gone bankrupt or ceased to be in business when a problem covered by the warranty is experienced, it ends up usually becoming worthless. Also of note, a warranty does not ensure that the building will not have deficiencies, or that damage caused by flooding or a hurricane will not occur. Warranties are only as good as the contractors that have executed them, and when architects rely on warranties for performance rather than paying attention to the factors that actually affect performance, the potential for premature failure dramatically increases.

2.7

SHOP & ASSEMBLY DRAWINGS

Shop and assembly drawings are detailed construction and fabrication drawings, diagrams, illustrations, schedules, brochures, performance charts, and other data specially prepared for the work by the contractor, subcontractor, sub-subcontractor, manufacturer, supplier, or distributor, to illustrate the proposed material to be used and how specific portions of the work are to be fabricated and/or installed. Shop drawings reflect the contractor’s understanding and interpretation of the construction documents for the fabrication and installation of the various components used in the construction of the project. These drawings are detailed to indicate the sequence of assembly of various components of the project as well as its final form or position within the project. When specified in the contract documents, shop drawings are submitted to the consultant for review


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prior to the actual fabrication or assembly of construction components. Since time is of the essence, return of the shop drawings within a specified time is essential to the contractor. Delays in approval of shop drawings may impact the construction schedule and further prevent other trades from continuing their work. Nevertheless, both the consultant and the contractor find them time-consuming and costly to administer, and although often necessary, they have become a significant source of professional liability claims against architects. Undiscovered errors in shop drawings will often lead to unexpected or undesired construction results as well as possible financial claims against architects, engineers, and contractors. Some shop drawing anomalies have resulted in costly construction defects, tragic personal injuries, and catastrophic loss of life. Submittal procedures of shop drawings depends on the requirements stipulated in the contract documents. In AIA documents, the contractor is obligated by the contract documents to submit shop drawings, product data, and samples for certain parts of the work. The architect is obligated by the owner-architect agreement to “review and approve or take other appropriate action upon contractor’s submittals such as shop drawings, product data and samples. . .” This is included among the architect’s contract administration services. In any case, the submitted shop drawings shall be appropriately detailed and dimensioned with types, sizes, and gauges of materials noted. Furthermore, they shall be neatly, accurately, and legibly drawn, noted, and referenced. Each item contained in the submittal shall be clearly referenced and noted establishing the item’s location in the finished work. These and similar submittals are not considered to be contract documents. The only documents that can be considered to be part of the contract documents are those that were incorporated by reference into the contract at the time of the signing of the construction contract and those that are added later, for example, as change orders and construction change directives as contract modifications and that are signed by the consultant and the contractor. Often drawings and specifications prepared by the consultant may show the general design concept of the project and each of the major components and their relationships to each other, but are lacking in detail. This is why contractors and their subcontractors and suppliers are sometimes required to prepare additional drawings, diagrams, schedules, and other data to illustrate the specific way in which their particular company or shop will furnish, fabricate, assemble, or install their products. But even when the consultant does not stipulate shop drawing submittal for approval, they are still needed by the fabrication shops for their own use in instructing their employees on how to implement the requirements of the contract documents. The main advantage of producing and submitting shop drawings for review is that it allows the consultant to ascertain that the contractor, producer, and supplier understand the architectural and engineering design concepts and to correct any misinterpretations before they are manufactured in the shop or field. The shop drawings should confirm to the consultant’s satisfaction that the work of the contract will be correctly executed. If the shop drawings indicate that the work proposed does not comply with the intent of the contract drawings and specifications, the consultant has an opportunity to notify the contractor before the costs of fabrication, purchase, or installation have been incurred. The consultant’s approval of the shop drawings will often be conditioned on the modification or correction of various errors or misinterpretations of the contract documents. In the event that the corrections are extensive the consultant may completely disapprove them and request correction and resubmission, after which they are sent back to the general contractor, approved, conditionally approved, or disapproved. The contractor is not to be relieved of responsibility for any deviation from the requirements of the contract documents by the consultant’s review of shop drawings, product data, and samples unless the contractor has specifically informed the consultant in writing of such deviation at the time of submission and the consultant has given written acceptance to the specific deviation.


CHAPTER

3 The Forensic Architect’s Role & Scope in Evaluations & Acquisitions 3.1

GENERAL OVERVIEW

Today many firms have developed their own set of evaluation guidelines and protocols that are typically performed according to the ASTM Standard Guide for Property Condition Assessments. Because of the complexity and/or age of some properties, a more comprehensive assessment of some or all building systems may be recommended. As a result, clients (buyers) may choose to enhance the ASTM’s baseline survey by supplementing the consultant with specialty consultants to conduct the inspection of the proposed acquisition. This allows these firms to provide a more exact and detailed inspection of both residential and commercial property, thereby improving the service they are able to deliver to their clients. The quality of a property condition evaluation depends to a very large degree on the qualifications and capabilities of the forensic architect and the evaluation team. In the majority of commercial real estate acquisitions that are subject to a property evaluation, the forensic architect or engineer assigned by the consultant to conduct the walk-through survey most likely will be a single individual having a general, well rounded knowledge of pertinent building systems and components; unfortunately however, a single individual will seldom have an all-embracing knowledge, expertise or experience of all building codes, building systems and asset types that are applicable in the various jurisdictions. Therefore, any decision to supplement the forensic architect/assessor with specialty consultants, building system mechanics, specialized service personnel, or any other specialized field observers should be a shared decision made by the consultant and the client. This decision should be made in accordance with the requirements, risk tolerance level, and budgetary constraints of the client. The level of due diligence inspection applied is often adjusted to the risk tolerance of the client.

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Acquisition surveys typically include reviewing a facility for building deficiencies which will significantly affect the value or operation of the property. The forensic architect should review building department files in order to disclose any outstanding code violations and may conduct an abbreviated survey for ADA compliance. The forensic architect would then prepare a thorough report with prioritized recommended repairs and replacements, including cost estimates to remedy deferred maintenance and for necessary capital improvements. Real estate sellers are increasingly performing evaluations during the preparation for the real estate transaction. These disclosure studies reveal to the potential buyer the quality of the property and alleviate some of the typical fears experienced in the transaction. The disclosure study can also result in third-party verification of the worth and quality of the building systems. Additionally, a forensic architectural report can often be used as a negotiation tool in a real estate transaction by having most of the recommended remedial work in the evaluation either being performed by the seller or having the purchase price lowered by the estimated cost of these repairs. Should the seller agree to perform the work, it is important for precautions to be taken by the buyer to ensure that the work is done to acceptable industry standards. It is important to be very precise on negotiated work to be performed by the seller, including specificity on materials, construction methodology, and quality of work. It is difficult keeping pace with the vicissitudes of the mortgage industry, with the changes in the real estate field bringing about significant shifts in real estate transaction assessments. The savings and loan industry is now implementing more stringent loan strategies as it continues to come under increased regulation, drastically limiting availability of commercial lending. Furthermore, commercial lending by banks and insurance companies is not expected to make up for the decline in savings and loan lending. Increased caution on the part of pension funds and foreign investors has also slowed real estate equity funding. Given the condition of the real estate market today, and the scarcity of available financing, building evaluations have taken on increasing importance for owners and investors. Owners currently prefer maximizing on the facilities they already have as efficiently and as long as possible in order to defer purchasing or constructing a new facility. Transactions are more closely scrutinized, with increased depth and caution required in evaluations. As has been proven time after time, the more detailed an evaluation, the more secure the investment. Indeed, a properly performed evaluation serves to protect and limit the liability of bank and mortgage companies having a vested interest in the property. It can facilitate setting up a loan taking into account major deficiencies identified beforehand, making it easier for the borrower to pay back and less likely to default on the loan. The prime objective of an architectural/engineering inspection is to observe and document pertinent information and deficiencies on the subject property to enable a proper assessment of the factors that are important to the “due diligence� process. A standard methodology is used to satisfy the intent of the due diligence. The use of standard forms and checklists is important to this process to ensure that all necessary observations have been made and recorded.

3.2

INTRODUCTION TO BUILDING SYSTEMS EVALUATIONS

Depending on the role of the facilities professional, whether it is a property owner, facilities manager, real estate seller or real estate buyer, the evaluation of existing building systems offers many advantages. With each group of professionals utilizing evaluations for varying reasons, the evaluation and report must be designed and coordinated to reflect this. Property evaluations help minimize the surprises and headaches


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normally associated with facilities acquisition and management (Figure 3.1). In addition to overseeing a facility’s operations and maintenance, one of the main roles of the facilities professional is typically crisis management. One may suddenly find that there is an air conditioning problem and the board of directors is scheduled to meet in less than an hour, or the roof of a warehouse starts leaking just before the weekend break. For the above reasons, it is vital to have periodic maintenance inspections. Property managers and building owners conduct building systems evaluations for a variety of reasons, the most important of which revolve around improvFigure 3.1 Some of the reasons why property ing the financial viability, operational efficiency, qualcondition evaluations are conducted and are a ity and safety of the facility. Evaluations are instrunecessary prerequisite for the real estate owner mental in affirming that the building owner is aware of and investor. what to do to take the most effective care of the property as an operational facility and as an investment. For example, one of the results of a typical evaluation may be recommendations for energy-saving measures. Owners who are concerned for their tenants’ comfort and safety also have a lot to gain from building evaluations. Building systems evaluations typically highlight issues and conditions of safety which, in the day-to-day management of the facility, may be missed by the on-site staff. Not only do evaluations enable the building owners and managers to better plan and manage a facility, and based on the survey report findings and recommendations they also help them to prioritize and perform any required repair work in a competent and efficient manner. Additionally, facility evaluations often bring to light potential money saving measures. In a comprehensive survey, existing unsafe conditions, such as deficient structural members or overloaded electrical equipment, are discovered and addressed, thus reducing the potential for accidents and liability. An evaluation is thus a planning tool which provides owners and managers an opportunity to identify the status of the systems in a facility and recommend a course of action to address any deficiencies discovered at the building. Evaluation surveys provide information and recommendations on what to do with each deficient building system and why the work needs to be performed. As a result of the building systems survey, decisions can be based on objective data and reason, and not simply subjective interpretation. The typical building survey can be designed in a manner that removes everyday decisions regarding maintenance and repairs from the realm of crisis management and into the realm of objective efficiency. These sound decisions enable future planning and forward thinking which will minimize the pitfalls and mistakes encountered during the operational performance of the facility. In conducting an acquisition survey, the forensic architect typically includes reviewing a facility for building deficiencies which will significantly affect the value or operation of the property. A limited acquisition survey may include a general review of specific systems, such as roofing and air conditioning, which tend to require more frequent repair or replacement. Comprehensive acquisition evaluations include a review of each building system and recommendations addressing any remedial work which will be required at the facility within the foreseeable future. The property condition evaluation report will provide the buyer with specific cost estimates on deficient systems or components requiring remediation immediately or in the upcoming years. Figure 3.2 is an example of a summary checklist of a facility and its various systems.


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Figure 3.2 One of several different types of property condition evaluation checklists that the forensic architect can use during a baseline walk-through survey.


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23

THE ROLE OF THE FORENSIC ARCHITECT

A forensic architect is charged with inspecting and testing the entire building envelope, which would include roofs, stucco, drywall, windows and doors, and the interiors. The expert is not only looking for code compliance, but also ensuring that the building was built in conformance with the approved plans. Comprehensive in-depth inspections of systems outside the forensic architect’s specialization will require bringing in other forensic specialists such as a structural engineer, plumbing and mechanical expert, electrical expert, and geotechnical expert. The forensic architect shall also investigate, inspect, research, analyze, assess, and deliver a property condition evaluation that includes all information and attachments necessary to substantiate the expert’s depth of inquiry, source of materials, observations, findings, and recommendations for further actions. The forensic architect shall clearly separate facts and observations from inferences and conclusions. As the forensic architect most often represents the client who is usually the building owner or manager and with whom there is a fiduciary responsibility, it is important for the forensic architect to certify that no conflict of interest exists in being commissioned to conduct the property inspection, failure, or deficiency in question.

3.4

EVALUATIONS FOR ACQUISITION

The sale or transfer of commercial property involves a series of decisions usually based on a set of complex analyses and while the process is unique to each real estate transaction, several aspects, in one form or another, occur during most property acquisitions. Evaluating the physical integrity and condition of the property itself with specific emphasis on the condition of the physical plant, quantifying significant defects, required repairs and upgrades, deferred maintenance, reserve calculations, and preparation of estimates of the probable costs for replacement and repair of deficiencies, is one such analysis that is pivotal to the acquisition process. In larger acquisitions, the forensic architect will often have to bring in other specialists to complete the evaluation process. During property acquisition the successful forensic architect should also be in a position to provide property investors, facility owners, and lending institutions with project management and oversight of remedial work, a determination of probable cost of repairs and improvements over the term of the loan or projected life of the property, identification of local building codes, scheduling of required capital improvements and tenant requirements, and property conversion requirement analysis. These evaluations, along with the lender’s appraisal, are often necessary to establish a property’s value. The site selection process goes into effect once the determination has been made to make an acquisition and the necessary financing has been arranged. During the site selection phase it is common for a buyer to review several different properties before a final decision to acquire is made. Of these properties, a good percentage is physically reviewed in some form of cursory evaluation. Eventually a property is selected and the negotiation and due diligence process begins. This period, which lasts anywhere from seven to sixty days, provides the opportunity for the prospective buyer to verify the quality, condition, and worth of the property. It is during this phase that the services of the forensic architect and others are required to perform an evaluation. This typically includes both standard building evaluations, as well as environmental evaluations. Prior to acquisition, the forensic architect may also be retained by potential investors, building owners, developers, home owner, and insurance companies to review the causes and liabilities for the construction


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defects or failures. The forensic architecture survey, the report preparation and the performance of any follow-up evaluation or testing work that may be needed must be completed within the time period agreed with the client. Finally, when the buyer is convinced that he/she possesses a good understanding of the property, and the negotiations are fruitful, the transaction can be finalized and executed. Upon completion of the real estate transaction, the buyer may commission the forensic architect to continue as a consultant and oversee the repairs or renovation, etc.

3.5

WHEN TO CONDUCT AN EVALUATION

It is only prudent for prospective buyers of real estate to evaluate the condition and value of properties they intend to purchase. Certain evaluations or in-depth examinations of a property frequently reveal problems or potential problems that were not evident at first glance. However, the initial series of limited surveys may require nothing more than a drive-by review of the facility so as to produce a list of potential properties for acquisition. These limited “windshield surveys� denote the relative depth of this type of evaluation. In reality, most investors do perform a cursory review of the property at this stage, but in-depth evaluation is not normally conducted until later. Once the acquisition process of a property has moved into the negotiation and due diligence phase, it is time for the typical building assessment. When a consultant is hired to perform a building evaluation, the scope of services to be covered can be customized to address any special requirements or concerns an owner or prospective purchaser may have. Ideally, this phase allocates enough time to thoroughly evaluate the property. As a rule of thumb, the field observer requires approximately one day per 50,000 square feet reviewed. Adequate access to the facility should then be arranged. If there is a need for further evaluation, this is performed within the original due diligence period also. The majority of the deficiencies identified in acquisition surveys relate to the roofing, HVAC, building envelope, site, and interior systems. It often seems like the time allocated to conduct a thorough and comprehensive survey is less than adequate. This needs to be taken into account when both designing and agreeing to a time schedule, as well as in making a choice of who will perform the evaluation. In the current state of the real estate market, the need for comprehensive acquisition evaluations and improved communication in the evaluation process has increased. During the due diligence period it is becoming commonplace for daily communication to occur between the investor’s representative and the assessor. Significant issues identified by the forensic architect are then discussed immediately with the buyer instead of simply waiting to present the issues in the report. This allows any additional testing and analysis to be performed within the agreed time schedule. With older property acquisitions in particular, a prospective buyer typically wants to know as much about the property as possible, notably major items such as the useful life of the HVAC system or the existing roof, as replacing these would be a major expense. He would also want to know if the vertical transport and electrical systems are working properly. The investor may feel that the time is right for a renovation or upgrade. But what needs to be upgraded and how much will it cost? Investors are often full of questions like these and for answers a full assessment of the facility and all of its components is required. A competent building evaluation, performed by a professional, should identify all significant building system deficiencies. In some facilities, minor issues may be missed but because of their relatively insignificant nature it will not impact the value or benefits of the evaluation. Examples of these issues might include a non-working electrical receptacle or light fixture, anomalies in building systems which are otherwise in good operating condition.


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In nearly all evaluations, no matter how comprehensive, some minor issues are missed. Due to the intricacy and interrelationship of the systems, there may be issues which could never be addressed in an evaluation performed by an individual or a team of engineers over a time period of just a few weeks. Some issues will only be noticed during ongoing observation in everyday situations.

3.6

VARIATIONS OF SCOPE IN EVALUATIONS

There are many ways to design an evaluation. They can involve all major building systems of a facility or simply one or two. Moreover, they can be limited, cursory reviews or comprehensive examinations that include test documentation, laboratory analysis, non-destructive testing, hazardous material review, or a building code compliance review. The scope is determined by several factors including the intended result of the evaluation, which needs to be identified and the evaluation designed accordingly. If the evaluation is to be used in a real estate transaction, the scope and emphasis will differ from an annual resurvey evaluation for a property manager. An evaluation of a specific property deficiency, such as damaged paving, will not be designed in the same manner that a review of existing conditions to establish a preventive maintenance program is. Therefore, when a forensic architect is to be engaged, the scope of service required for the project needs to be clarified prior to appointment. A detailed description of the consultant(s) services and the level of detail should be provided from the initial planning stages through to the completion of the contract. Generally, facilities can be reviewed in three accepted levels of detail: 1. Single system evaluations, 2. Multiple system assessments, and 3. Comprehensive evaluations. Of these, the single system and comprehensive evaluations are the most common. Single system evaluations typically consist of a review of a single system, usually relating to the roofing, HVAC, structural or paving systems. These are cost-effective and very useful if there is only one issue of concern or deficiencies involving only one system at a facility. However, because building systems are typically interactive in nature, a deficiency in one system can at some point impact the other systems. Multiple system surveys include a number of systems. This type of evaluation is cost effective, with only the systems with known deficiencies being surveyed. While this type of evaluation may be more focused and specifically directed to the systems with known deficiencies, an obvious limitation is that systems which may contain deficiencies which are not apparent from a walk-through survey may be missed. Comprehensive evaluations typically consist of a complete review of the facility and all its systems and subsystems. The cost is usually greater than the two previous types of evaluation because of the extra expertise and time required to adequately evaluate the systems. This extra cost is mitigated by the value of determining the present condition of the facility in its entirety which is often a prerequisite in acquisitions as it ensures that the owner or potential purchaser is not faced with any operational or budgetary surprises later down the road.

3.7

PREVENTATIVE MAINTENANCE PROGRAM DEVELOPMENT

Preventive maintenance (PM) is the application of planned services, inspections, adjustments, and replacements designed to ensure that maximum utilization of equipment and systems is obtained at minimum cost. For standard facility surveys that include buildings and assets, preventive maintenance is a


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Architectural Forensics

mandatory process to ensure the longevity of an asset. In some assessments, a preventive maintenance program is established, the objective of which is to control and reduce repair and replacement costs by providing a scheduled program of inspections, repairs, and maintenance. Specifically, preventive maintenance of equipment and systems includes cleaning, adjustments, lubrication, minor repairs, parts replacement, and inspections which are periodically performed in accordance with written preventive maintenance instructions (PMI). Major repair requirements identified by the preventive maintenance process are performed as planned maintenance projects through the normal work order system. Below are some of the major components and building systems that require PM: 1. Heating, ventilation and air conditioning (HVAC) systems 2. Roofing systems 3. Surfaces 4. Electrical systems 5. Plumbing systems 6. Structural systems 7. Interior systems 8. Exterior systems 9. Special equipment. A PM program should be designed to take advantage of the facility owner’s maintenance operations, whether centralized or decentralized. The evaluation team, working with facility maintenance representatives, should establish both short-term and long-term goals and priorities that enable the facility to avoid costly breakdowns and emergency repairs. Historical policies and preferences should be researched and organized, and current staffing levels should be reviewed in addition to projected staffing requirements to develop long-range staffing and efficiency goals. A proactive approach to PM avoids system failure and can improve the financial and operational performance of that asset. The use of preventive maintenance software such as CMMS (computerized maintenance management solution) can significantly help achieve increased productivity, reduced downtime, and extended equipment life. Effective budgeting for PM is vital and some organizations today apply a basic rule-of-thumb annualized maintenance of 2 to 4 percent of operating budget to funnel back into deferred maintenance. But this figure may increase significantly for older buildings that have been poorly maintained over a period of years. Deferred maintenance (DM) is maintenance that was not performed when it should have been, that was scheduled and not performed, or that was delayed for a future period, future budget cycle, or postponed due to lack of funding. Maintenance is the act of keeping property, plant, and equipment in acceptable operating condition, including preventive maintenance, normal repairs, replacement of parts and structural elements, and other activities required to preserve the asset so that it continues to provide satisfactory services and achieves its expected life. Maintenance excludes activities aimed at expanding the capabilities of an asset or otherwise upgrading it to serve needs different from, or significantly greater than, those originally intended. In order to address the maintenance backlog and develop a deferred maintenance program, facility managers must: 1. Determine causation of deferred maintenance and repairs: The main reason for deferring maintenance is usually due to lack of available funding. If budget planning does not allocate adequate funding, if maintenance would interfere with business operations, or if allocated funding is


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diverted to pay for emergencies and more visible projects, the risk of equipment failure and building deterioration increases. Maintenance may also be postponed due to lack of adequate manpower, lack of personnel with the expertise to perform necessary maintenance, lack of necessary parts to conduct maintenance, or because major renovations are planned for the near future which would address necessary repairs and upgrades. 2. Understand and assess the scale of the problem: Understanding the extent of the backlog is pivotal to reducing the volume of deferred maintenance and substantiating the need for funding. A facility evaluation (also called a facility audit) can help eliminate any unknowns and provide a clearer picture of the extent of the deferred maintenance problem. In addition to evaluating the building’s condition, the survey should evaluate the performance and age of all finishes, systems, and equipment as well as code compliance. The result should be a building inventory and list of necessary projects, repairs, and system upgrades for each facility. When conducting an assessment, consult with the facilities professionals that are most familiar with each building and its particular systems. 3. Quantify and communicate the financial impact of DM: The consequences of DM must be calculated and communicated to the owner and facility manager. The most convincing argument against deferring maintenance is one that outlines the estimated risk potential that may result in liability, an increase in safety hazards, and a decrease in tenant satisfaction and employee productivity. Additionally, an estimation of DM escalation of costs for future expenses as a result of postponed maintenance should be prepared. 4. Project prioritization—develop a strategy to secure adequate funding: Prioritize deferred maintenance projects if it is unlikely that sufficient funding will be provided to immediately address the entire backlog in one year. A set of criteria should be developed to facilitate prioritizing projects (for example: 1. Currently critical, 2. Potentially critical, and 3. Necessary, but not yet critical). However, even the best preparation and presentation skills may not result in adequate financing to complete all of the deferred maintenance projects classified as “potentially critical.” Other means should be investigated. For example, if a project reduces peak demand or increases energy efficiency it may qualify for rebates offered by utility companies. There may also be grants to upgrade the efficiency of lighting or heating and cooling systems through local power authorities. Utilities may provide partial funding to have certain systems upgraded to improve energy efficiency and lower energy costs. 5. PM and repairs should be performed promptly: Deferred maintenance tends to accrue, even under the best circumstances. To prevent this, an effective PM program needs to be in place to minimize a facility’s rate of deterioration and dysfunction. When the building owner understands the potential escalation of costs, obtaining adequate funds is often less difficult to attain. By making the business case for funding and proactively managing maintenance, the owner can avoid a potential deferred maintenance backlog. A proposed PM program should include recommendations for capital improvements, identification of items for deferred maintenance, and step-by-step implementation guidelines for establishment of the program. More specifically, the PM program should specify the location of each maintenance item, its type, tasks to be performed and frequency of maintenance, the cost for maintenance of each item, and the number of personnel hours required to conduct each maintenance item. For residential high-rise buildings, as well as other commercial and institutional facilities, predictive maintenance plays a key role in maintaining property value and reducing risk for the building owner. Although higher property value is often thought to


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be a result of attractive building appearance or amenities, it is the building systems behind the façade that have the greatest impact on value. How to develop an effective PM program: 1. Having the right building equipment: One of the first steps to preventing unnecessary failures and maximizing a property’s value is specifying appropriate equipment that matches a building’s needs. 2. Creating a predictive maintenance schedule: Developing a maintenance schedule that systematically checks a building’s vital systems is a crucial step in reducing breakdowns and unnecessary repair costs. Ideally, predictive maintenance should be performed on all equipment but when not possible, maintenance should be performed on the systems that represent the greatest risk of exposure to resident safety and real estate value. Creating checklists for each piece of equipment is the simplest method of tracking maintenance and guarantees that the appropriate work is being performed in order to meet warranty requirements. 3. Document all maintenance: Record-keeping plays the most significant role in predictive maintenance and warranty management. Once inspection schedules have been created, the maintenance engineer should document all completed work and ensure that reports specifying the exact work performed are signed and dated as these may be required by the manufacturer to validate a warranty. 4. Follow-up: Maintenance records not only serve as recommendations for necessary repairs; they provide a reference for building owners to track maintenance and repair history and serve as evidence to the manufacturer that all necessary maintenance has been performed.


CHAPTER

4 The Evaluation/Investigation Process 4.1

GENERAL

As a forensic expert you are paid more for your knowledge than for your actions. Investigations into failures in connection with claims or disputes are generally conducted to establish the causes of failure, and whether such failures can be attributed to normal deterioration or defects in construction or maintenance. Such investigations are rarely limited to site inspections but also involve laboratory examination and analysis of samples, as well as evaluations related to construction, maintenance, and normal good practice as regulated by applicable building codes and standards. The most dangerous failures are usually those that happen without warning—suddenly and unexpectedly. These collapses are often the direct result of some natural or man-made disaster such as a hurricane, flood, or earthquake. Failures can also be the result of defective design, or temporary occupant, or construction overloading. Sometimes, evidence of potential failures is indicated by symptoms such as cracks, deformity, corrosion, or sagging, and other times the failure is progressive and difficult to detect. But the most important impact of major failures is the imminent threat they pose to life and property and therefore should be avoided at all costs. As for assignments relating to acquisitions, most prudent investors and lending institutions rely on property condition evaluations to provide pertinent information and analysis of the integrity and physical condition of a property, and to minimize the risk associated with the acquisition. It is important therefore for the forensic architect to understand how the investigation, inspection, research, and analysis of the physical portions of the building and site are used to assess the current condition, remaining useful life, and cost estimates for the repair and/or replacement of individual elements and systems, and learn how this information can be used by property owners and facility managers once the property has been purchased.

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Experience has shown that one of the main key advantages in becoming familiar with a commercial property before conducting a thorough property condition evaluation is that it can help provide the assessor with useful information not yet known for making recommendations to the client that can save money without sacrificing any quality in the service provided. Additionally, based upon a pre-inspection of the property which can take up to an hour, the forensic architect should have a reasonable understanding of the property even before a proposal is submitted. Also, the pre-inspection can provide an effective negotiating tool for the investor or potential purchaser by placing the onus on the owner to bear the cost for repairs as well as the expense of having the remaining HVAC and other systems professionally examined by others. With the industry moving toward a standard protocol for property condition evaluations, the forensic architect should be aware that the majority of today’s property evaluations are performed according to the American Society for Testing and Materials (ASTM) Standard Guide for Property Condition Assessments which provides little more than a basic overall cursory inspection of the property being evaluated. This has encouraged many firms to develop their own set of more stringent and detailed inspection guidelines and protocols, thereby providing a much improved service to their clients.

4.2

THE INVESTIGATIVE PROCESS

One of the first steps to be taken by the forensic architect after being awarded an investigative assignment is to determine the scope of work. Other than for property condition assessments, the types of cases normally assigned to forensic expert consultants can be categorized into three main groups: 1. When a collapse occurred, 2. When a “problem” became evident, and 3. When litigation is already in progress. Typical scopes of work, and hence the activities of the forensic architect consultant, in these cases would vary depending on several factors including the client’s requirements and/or severity of the situation. However, for litigation that is already in progress, the usual scope of work may include: • • • • • • • • • • •

Review and cataloguing of documents Architectural/engineering analyses Meetings with attorney/client Review of deposition transcripts Review of other experts’ reports Writing the report Assisting the attorney with expert disclosure and preparing for trial Assisting the attorney with questions for depositions of others Preparing for and participating in dispute resolution Preparing for and giving a deposition Giving expert testimony at trial.

It should be noted that except for litigation support, the processes depend on the nature and magnitude of the failure, fatalities, if any, the dollar amount of damages and claims, and often on the experts and attorneys involved. Investigation time factors: There are several factors that will impact the time required to conduct a property condition evaluation or failure investigation. These include:


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Type of failure and scope of assignment: The type of failure and scope of the investigation play a role in estimating the time that should be allocated to conduct the investigation and produce a final report. Size of the facility: The size of the facility is one of the most discerning factors that determines the amount of time required to make an evaluation; all things being equal, the greater a building’s square footage, the longer it will take to evaluate. Age of the facility: As buildings age, so do their systems. This usually implies a greater number of deficiencies are present that need to be identified and diagnosed, unlike the case with newer construction. The more deficiencies identified, the more time needed to evaluate them. Condition of the facility: Well maintained facilities require less time and effort to assess than those that have fallen into disrepair. Moreover, properties in good condition require less time for both the physical inspection and the report writing process. Configuration and facility design: The configuration and design attributes of a facility can significantly impact the time required to make an evaluation. A facility consisting of several floors all having similar interior finishes and layout will require less time to survey than a facility where the floors have varied finishes and floor layouts. Number of buildings: A project consisting of several buildings to be inspected will require more time than a project with a single building. Proximity of buildings: The length of time required to inspect and evaluate multiple buildings is impacted by the physical location of each building relative to one another. Facilities consisting of several buildings within a single complex will require less time and effort than if the same number of buildings were scattered throughout a city or region. Type of assessment: The type of assessment, whether for acquisition, for establishing a preventive maintenance program, or for a failure investigation, impacts the time that needs to be allocated for an evaluation. The greater the depth and extensive nature of an inspection, the greater the time required. Type of report: The type of report required by the client also impacts the time required for an evaluation. If a letter report or short form is agreed upon, the evaluation process will need less time than for a fully bound report with color photographic documentation. Pre-survey and planning phase: For property condition assessment assignments, the consultant will, depending on the size of the firm, initiate the project by establishing an investigative plan and delegate the project to a project manager. The project manager starts by commencing with a review and research of the property’s history. The research undertaken as part of the survey should be appropriate for its purpose and should seek to inform the assessor/investigator about issues regarding location, the site, construction, use and occupation of the building. Prior to commencing with the physical investigation, the consultant should provide the owner with a pre-survey questionnaire, and a disclosure schedule and information checklist. These are to be filled by the owner or the owner’s representative and returned to the consultant who will include them in the final report. Property documentary historical research: Whenever possible, the investigator should review property records as furnished by the owner and other sources prior to the survey. Documentary information will generally consist of files containing descriptive information on construction materials and systems. Sometimes prior engineering assessment reports are available. If an ADA assessment has been conducted, review its principal findings and note the major deficiencies identified. Any relevant reports should be incorporated into the report appendix. Where available, the owner will provide the following information for review by the assessing investigator: •

Certificate of occupancy

Drawings and specifications (as-built or construction)


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• • • • • •

Records indicating age of systems including roofing, HVAC, plumbing, electrical, etc. Safety inspection records and any outstanding code violations Previous assessments or studies and the status of previously identified repair needs Costs of previous repairs, improvements, replacements, etc. Description of proposed work and contracts and proposals for planned capital projects Warranty information.

Upon assigning a project manager to the project and filling out the project assignment data sheet (Figure 4.1), a project file is created with an exterior label stating the project name, project number, city/state and client. Depending on the terms of the agreement and the type and level of survey requested, it should also contain: • • • • • •

Contract agreement to include scope of work and terms Site contact information Property manager interview form Tenant survey forms (for retail buildings) or parameter/measurement schedules (for residential buildings) Condition assessment checklist (for building type: generic; multi-family, hotel, suburban office, high-rise office, shopping center/mall) ADA checklist

Upon setting up the project file, the project manager (PM) will call the client for site contact information if this has not been provided. The PM will then phone or email the site contact to arrange an inspection date. Once this is confirmed, the PM will fax or email the client a client site inspection confirmation letter which includes the date and time of the site inspection (Figure 4.2). The client should have received by now the presurvey questionnaire and documentation checklist. Also, as part of the project research to be initiated prior to the site visit, is the preparation and delivery of the following requests for municipal documentation: • • • • •

Flood plain map Building department FOIL (freedom of information letter—Figure 4.3A) Fire department FOIL (Figure 4.3B) Zoning department FOIL (Figure 4.3C) Other inquiries as necessary

Field investigation phase: Before traveling to the site the project manager/forensic architect should have reviewed the project working file to understand the scope of work, including reporting requirements and the appropriate protocol. An inspection pack should be prepared to include basic needs such as: moisture meter, combustible gas meter, digital camera, tape measure, electric current tester, flashlight, binoculars, screwdriver and pocket knife. Persons to interview: The assessor’s research/interview skills play a pivotal role in this phase of the property survey and cannot be over estimated as a source for gathering pertinent information about the property’s condition. As a technical investigator the most salient, yet obscure, information about the property will come to light as a result of the research and interviews undertaken. An interview with the client’s representative is important and if the owner/building manager has as-built drawings, these should be re-


Chapter 4 - The Evaluation/Investigation Process

Figure 4.1 Example of an assignment data sheet which should be filled out upon being awarded a project.

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Figure 4.2 Example of a site inspection confirmation letter that should be sent to the client once arrangements are made for the project site visit.


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Figure 4.3A Project research includes requests for municipal documentation: A. Building department FOIL.


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Figure 4.3B Project research includes requests for municipal documentation: B. Fire department FOIL.


Chapter 4 - The Evaluation/Investigation Process

Figure 4.3C Project research includes requests for municipal documentation: C. Zoning department FOIL.

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viewed at this time. During the site inspection the opportunity may arise to interview tenants or maintenance personnel. These interviews should be documented and the individuals identified. The persons to interview generally include the building’s “engineer” or superintendent, the property manager, tenants, local building department and engineering department officials, past designers of record, service company personnel, manufacturer representatives, etc. It is also wise that prior to the site visit the investigating consultant ask the owner or user to identify a person or persons knowledgeable of the physical characteristics, maintenance, and repair of the property. If a property manager or agent of the owner is identified, the consultant should contact that individual to inquire about the subject property’s historical repairs and replacements and their costs, level of preventive maintenance exercised, pending repairs and improvements, frequency of repairs and replacements, and whether there is any existing or pending litigation related to the subject property’s physical condition. As a result of the consultant’s research or walk-through survey, the consultant may also decide to question others who are knowledgeable of the subject property’s physical condition and operation. It is within the discretion of the consultant to decide which questions to ask before, during, or after the site visit. While the consultant will make inquiries as deemed necessary, the persons to whom the questions are addressed may have no obligation to cooperate. Should the owner or the property manager, building/facility engineer, or maintenance supervisor not be available for an interview, whether by intent or inconvenience, or not respond in full or in part to questions posed by the consultant, the consultant should disclose such within the final report. Furthermore, should any party not grant such authorization in interview, restrict such authorization, or should the person to whom the questions are addressed not be knowledgeable about the subject property this should also be noted in the final report. Contact with facility representatives, staff, and users: During the physical inspection, daily communication with the facility representative should be conducted to address any misunderstandings or confusion which may arise with the staff or users of the facility. Regular meetings should be conducted and dialogue should be encouraged during the pre-survey phase. Weekly progress reports should be produced during the report preparation phase. Professional interaction with all facility personnel ensures that normal facility operations will not be disturbed throughout the duration of the evaluation project. Field investigators should wear identification badges which assist the communication process. Professional and courteous communication and appropriate attire assist with the smooth interaction with the facility users. Safety: Personal safety and comfort is an important consideration and good safety practices are to be exercised at all times. Always be aware of the nature of your surroundings and avoid dangerous conditions. Do not enter confined or other hazardous spaces. Equipment should not be operated that is otherwise unavailable to the general public. Likewise, do not conduct exploratory probing or testing or expose yourself to hazardous materials or conditions and report any and all accidents to your superior or client’s representative immediately. The survey/inspection: The previously prepared checklists are to be used during the site inspection to document observations. Other notes or field sketches should be made as well. The information on the forms and checklists should be completed as the site survey progresses. Names and/or positions should be attributed to individuals from whom information is obtained. The forensic architect should observe property components, systems, and elements for evidence of significant physical deficiencies. Physical deficiencies qualifying as significant should be deemed to be present if they represent a cited or apparent code violation, an immediate life safety or health hazard to the occupants or users of the property, or a fire safety hazard to the property itself. Other physical deficiencies of a lesser nature should also be observed and individually noted for inclusion in an aggregated cost to cure estimate which will otherwise be furnished by the investigative consultant. Field observations will consist of one or a combination of the following activities.


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a. Walk around exterior visual inspections • Building exteriors—all as visible from grade and accessed roofs and setbacks • Principal hard surface areas • Representative roofs and roof area • Landscaped areas b. Walk around interior visual inspections Common area spaces • Entries and entry lobbies (all) • Toilet rooms (sample) • Multi tenant area corridors and elevator lobbies (sample) • Egress stairs and exit ways (sample at various levels) • Elevator interiors (typical of each bank) Leased area spaces • Vacant tenant areas (typical; if residential, one of each type) • Occupied tenant areas (typical; up to 10 percent of space. No occupied residential units) Service areas • Typical service spaces and corridors • Central service facilities (main equipment rooms and pad areas) c. Equipment and system observations. Random operation of equipment, fixtures, and systems on a sample basis to determine system operability which may include: Plumbing • Fixtures in toilet room—sample operation • Piping and insulation incidental to mechanical areas Mechanical equipment (HVAC) • Central equipment • Typical residential, retail, or office unit installations (5 percent of total) • Typical floor or zone installations and equipment (one or two floors) • Typical rooftop installations (on floors inspected) • EMS system console Electrical equipment • Central equipment including transformer vaults and pads • Typical unit installations (residential, office, retail) • Typical floor or zone installations • Typical pattern of outlets, switches, jacks, lighting, (5 percent of area) Elevator equipment central equipment and control room Life safety system equipment • Central consoles and annunciator panels • Fire pump and central valve stations • Typical standpipes, sprinklers, smoke detectors, alarm stations, etc. (5 percent of area) • Central security and surveillance consoles.


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d. Non destructive, non invasive testing, sounding or detailed observation to determine representative conditions. e. Recording of physical deficiencies. At the conclusion of the site/facility inspection and before leaving the area of the project site it is important to organize and review all relevant notes and to complete all field documentation. If information is missing, it can often be easily obtained before leaving the site. Upon return to the office, the project manager shall send the client a debriefing letter (Figure 4.4). The project manager may call the client as appropriate to discuss the inspection and findings. Report preparation phase—format and contents: The report form shall be determined by the intended use of the report, the client protocol, the type of property being surveyed, and the necessary level of diligence. Most firms have formulated standard report formats and language to ensure the quality and consistency of the final report product. Many large due diligence firms use proprietary software systems to assist in generating the initial draft report and serve to expedite the process of report preparation, while maintaining quality and consistency. The report preparation phase will require among other things, close interaction with the facility representatives to ensure that the report is responsive to facility needs and that the recommendations provide workable solutions to the facility’s concerns. Moreover, the writing of a property condition report requires concentration and attention to detail. The need for comprehensive documentation is paramount and should include both the documentation available for review and analysis during the evaluation and the reported information at the culmination of the assessment process. The value of comprehensiveness cannot be overstressed. The degree of confidence in a decision to acquire a facility is directly related to the thoroughness of the documentation review. If the document review is cursory, the chances are much greater that issues will be missed. A cursory review could mean that certain building systems or components of these systems are not reviewed or not reviewed in a manner which will identify anything but the most superficial deficiencies. Comprehensive documentation means that the review of the available documentation, from soils reports to structural drawings, is imperative for the evaluation to be of significant value (This is particularly appropriate for an in-depth inspection as opposed to a standard walk-through survey). The more vantage points a facility is viewed from, the more likely the chance of noticing deficiencies or issues to be addressed. At times the structural system deficiencies will be discovered by the assessor crawling into the ceiling cavity. Other times, the issue will arise upon review of the construction drawings or specifications. The more documentation sources that are reviewed, the more valuable and accurate the survey report commentary and recommendations. The other aspect of comprehensive documentation is the verification of evaluation findings and recommendations. The acquisition evaluation is the ideal time to begin what could be referred to as a working operations and maintenance manual. This may be the one time that the facility is reviewed comprehensively and the documentation of this effort can become a benchmark of the facility for the useful life of the facility. Photographs: Today, digital cameras are almost exclusively used in field work. Consultants typically use one of two templates—one which consists of two photos per page or one which consists of six photos per page (Figure 4.5). Captions explaining each photo are helpful to more clearly explain the subject. It is also sometimes helpful to add an arrow pointing to the particular item of interest in the photograph. The expert should record representative conditions with photographs and use reasonable efforts to document typical conditions present including material physical deficiencies, if any. Photographs should include as a minimum: front and typical elevations and exteriors, site work, parking areas, roofing, structural systems, plumbing, mechanical systems, electrical systems, conveyance systems, life safety systems, rep-


Chapter 4 - The Evaluation/Investigation Process

Figure 4.4 Sample debriefing letter to be sent to the client after completing the site visit.

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Figure 4.5 Typical template using six photographs per page. For this hotel evaluation project in Chicago, Illinois, 30 digital colored photographs were required for the report.


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resentative interiors, and any special or unusual conditions present. Photographs can provide information detail that would be difficult to convey otherwise. For most assignments (depending on the size, complexity and condition of facility), the number of photographs will range from 20 to 40. Formation of the final product—the final report: After completing the report, check it for spelling, grammar, style conformance and consistency. The style check should focus on both format and content. The writer is expected to submit a finished product. Whenever possible, the finished report should be submitted to a third-party reviewer. The reviewer will examine the report to ensure that the scope of work and all other client and firm’s criteria have been satisfied. The reviewer will consult with the assessor on substantive report issues or if quality problems need to be addressed. The report will be returned to the assessor for rework and resubmission if the quality standards are not met. Once the reviewer passes the report, the report is finalized, set for production and issued. Depending on the size of the firm, the project manager or the administration/production staff accomplishes production of the report. The report is prepared, copied, collated, and assembled into a final product. The production staff supervisor will give the report copies a final quality check before sending to the client. A project billing report will be sent to accounting upon the release of the report product and accounting will send a billing invoice to the Client. Client follow-up and closeout: The project manager or the administrative staff will call the client within three business days of sending the report to confirm its receipt. The project manager will field any questions or comments from the client, and revise and resubmit the report to the client as appropriate. Upon direction from the client the report will be issued as final.

4.3

OPINIONS OF PROBABLE COSTS TO REMEDY DEFICIENCIES AND FAILURES

A deficiency can be defined as a condition that adversely affects the function of the component for which it was designed. When it comes to architectural components, this might be wear and tear and general appearance. In the case of building systems, this would be the performance of the system. Poor or inefficient design is not necessarily a deficiency. A remedy of a deficiency is the work needed to restore the building component to the condition for which it was designed. To upgrade or redesign a building component to improve its function is beyond the scope of a remedy. When determining an appropriate remedy, the investigating professional should base the decision on value and use this as the basis for an opinion of cost. Component condition & age evaluation: Evaluating the condition and age of property components can involve many investigative techniques. Determination of the age of a system component can often prove a challenge since information may not be reliable or available. Thus, in addition to examining the components first hand, the consultant should cross check the information gathered from the different sources and determine if they agree and can be relied upon. The determination of condition also involves a combination of investigative means, including the review of operation and maintenance records, interviewing maintenance personnel and occupants, and comparison of technical data with industrial standards. Ultimately, the assessor/forensic architect must weigh the available information and make a judgment call based on his/her knowledge and experience. Cost schedule estimates to remedy deficiencies: Before the consultant can establish an opinion on cost to remedy identified deficiencies, it is necessary to establish a scope of work. The scope can be worked up from elements of work that can be quantified or classified by other means. Quantities or capacities do not have to be exact, but should reflect a reasonable approximation. The opinions of cost are supported by the breakdown provided in the cost schedule. The cost schedule should show the scope of work to remedy


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a particular deficiency. The work should be broken down to provide a reasonable explanation of the situation and the costs used in calculations should reflect the work and market rates at the time of the study. The consultant will be required to prepare a general scope and preliminary cost estimates for each physical deficiency based on observations during the site visit and the information received from interviews with building management, tenants, and service personnel, that for purposes of the report will be deemed to be reliable. The consultant must describe the physical deficiency and also provide its location and offer an appropriate recommended remedy that is commensurate with the subject and considered a prudent expenditure. These estimates are mainly for components or systems that show signs of either patent defects, significant deferred maintenance, or requiring major repairs or replacement. Repairs or improvements that may be categorized as a routine operating expense, normal building preventive maintenance, part of parcel of a building renovation program, or that are essentially the responsibility of tenants are not to be considered. Cost estimates for deficiencies generally fall into two categories: 1. Immediate, and 2. Short term. 1. Immediate: These are physical deficiencies that require immediate action as a result of existing or potentially unsafe conditions—significant negative conditions substantially impacting marketability or habitability. Also in this category are material building code violations, poor or deteriorated condition of a critical element or system, and a condition that if not remedied, would result in or contribute to a critical element or system failure within one year or a significant escalation in repair costs. 2. Short term (0–1 year): These consist of physical deficiencies which are inclusive of deferred maintenance, that may not warrant immediate attention, but that require repairs or replacements that should be performed on a priority basis, taking precedence over routine preventive maintenance work. Included are such deficiencies resulting from improper design, faulty installation and/or quality of original system or materials. Components or systems that have realized or exceeded their expected useful life (EUL) and that may require replacement within one year are also to be included. All estimated costs by the consultant are considered to be preliminary and are to be net of general conditions, construction management fees, and design fees. Market costs or documented costs incurred by the borrower need to be substantiated to the consultant’s satisfaction. The borrower should document these costs by submitting paid invoices, executed or pending bona fide proposals, etc.

4.4

RESERVES ANALYSIS

Reserves refer to actual (or projected) funds at a given point in time identified by the organization to defray the future repair or replacement costs of those major components the organization is obligated to maintain. It further refers to accounts into which an organization or business regularly sets aside interest earning payments to ensure that there are funds available when required to pay for necessary replacements and capital improvements of a property during the loan term. Reserves usually represent a fixed amount that is deposited at periodic intervals into a dedicated bank account (typically an escrow) earmarked for future repairs or replacements of building systems or components that deteriorate with time. Most often, reserve schedules, and particularly reserve categories, are established in liaison with the user. It is important that the scope of work included in each reserve schedule category be well defined. There are two main reserves categories: 1. Operating (current year) reserves and 2. Capital reserves. 1. Operating (current year) reserves: These reserves should include the current year component transferred from the capital reserve account and the contingency reserves. The contingency reserves are intended to provide a hedge for unforeseen events and budget estimate errors for any


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given year. There is no set rule for the amount of contingency to be set aside other than the use of common sense based on experience. 2. The capital reserves: These reserves are intended to cover major repairs, overhauls, and replacements at managed times in the future. The capital reserves should include individual line time entries for each reserved common element category, engineering services, and contingency (say 10 percent). The total amount of the monthly reserve portion of the maintenance collected should be apportioned to each line item and accumulated over time (Figure 4.6). An organization’s budgeting planning process requires a careful analysis of the revenue and expense items over time. Likewise, the capital budgeting planning process also requires a careful analysis of the incoming reserves and expenditures over time. Through experience a non-profit organization can build budgets and capital reserves that have the ingredients for effective management. But management of the capital reserves can be a fairly complex matter and it is rarely possible to determine exact reserve amounts because of the many varying factors involved. Thus, variations in inflation and interest rates, and fluctuations in useful life estimate result from changing conditions and use patterns. Should a major failure of a capital reserve item occur prematurely, that line item may not contain enough funds to cover the work that needs to be done. This would necessitate funds being transferred from the capital reserve account to the operating reserve after which a special assessment must be levied to make up the difference. The importance of a reserve study: A reserve study provides a current estimate of the costs of repairing and replacing major common area components (such as roofs or pavement) over the long term. Ideally, all major repair and replacement costs will be covered by funds set aside by the association as reserves, so that funds are there when needed. This requires an examination of the association’s repair and replacement obligations, as well as a determination of costs and timing of replacement; and a determination of the availability of necessary (reserve) cash resources. The basic premise upon which all common interest realty associations (CIRA) are founded is that they bear the responsibility for maintaining common property as defined in their declaration and covenants. In

Figure 4.6 Examples of operating reserves and capital reserves expenses.


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addition, the board has a fiduciary duty to manage association funds and property and to ensure that funds are adequately accumulated and held in a reserve fund for future expenditures. Not only does this information supplement the annual pro forma operating budget in providing owners with financial information; the reserve study is also an important management information tool as the association strives to balance and optimize long-term property values and costs for the membership. For association members, reserve planning helps assure property values by protecting against declining property values due to deferred maintenance and the inability to keep up with the aging of components. A well prepared reserve study offers owners and potential buyers a more accurate and complete picture of the association’s financial strength and market value. The reserve study should disclose to buyers, lenders, and others the manner in which management of the association (i.e., the board and outside management, if any) is making provisions for non-annual maintenance requirements. Preparing a reserve study calls for explicit association decisions on how to provide for long-term funding, and on the extent to which the association will set aside funds on a regular basis for non-annual maintenance requirements. A good reserve study may also function as a maintenance planning tool for the association. Indeed, without a reserve study, the association could possibly be either overfunding or underfunding the reserve fund. In the case of overfunding, then the owners are paying more than their fair share of the common elements, whereas if not enough money is being collected, the association may find itself having to defer maintenance and/or require a special assessment or loan. To address this issue, several states such as California have passed legislation requiring that reserve studies be performed and information be included in the annual association budget. But not every state has a law pertaining to reserve funds. And of the states that do have laws, the law varies from state to state. The American Institute of Certified Public Accountants (AICPA) audit guidelines identify several advantages to accumulating funds in advance through periodic assessments. For example, having funds available to make repairs and replacements when needed helps to avoid the need for a special assessment. In addition, current and future owners equally share in the repair and replacement costs. This means that the owners are paying for the use of the common elements during their tenure. Likewise, the market value of the units or shares is preserved. Contrarily, the lack of reserves or inadequate funding for major future repairs or replacements has significant disadvantages. It may handicap the unit owners by adversely affecting their ability to sell because of concerns that a prospective buyer may have. It may also adversely affect the unit owner’s ability to refinance because of federal or quasi-federal lending restrictions. To address this, the board may be required to levy special assessments to fund needed repairs or replacements. Reserve study procedures & analysis: Elements normally surveyed for a reserve study include the common site areas, the building exteriors and interiors, and the mechanical (including HVAC and vertical transport systems), electrical, and plumbing systems in order to develop an estimate of their remaining useful lives. Specific problems and conditions which require corrective maintenance should be noted in the report. Also, the association’s management should ensure that they are included in the operating budget and maintenance system. Where financing is involved, the lender may elect to exclude from the reserve study any item with a remaining useful life exceeding the life of the loan by some fixed amount. Minor maintenance items need not be included in a reserve analysis. These items should be incorporated in the consultant’s report in a punch list. Inspection will normally be based on visual observation and need not be provided to the level of detail required for technical specifications. Another key consideration is the review and comparison of both capital repairs and operating maintenance. A clear distinction is required between capital repairs (reserve fund) and operating maintenance (maintenance budget). Summary of data to be included in report: 1. A brief description of the common and limited common elements that are surveyed providing, where possible, the name, manufacturer, model, serial number, and


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ratings. 2. Extract the quantities to be used in the reserve study by analyzing the plans or by field estimates. The development of this information drives the cost of the reserve study. 3. The condition estimate should discuss the problems and defects noted and provide a qualitative estimate such as poor, fair, good, or excellent. Specific deficiencies should be recorded with sufficient detail to estimate their impact on useful life and to provide a reasonable idea of the scope of the needed repairs. If possible, the age of the common element should be provided. 4. Important maintenance or repairs that need to be undertaken immediately or in the near term should be noted, and problems arising from deferred maintenance should be called to the owner’s attention. Elements requiring minor repairs should also be recorded and presented in a punch list. If failure to take remedial action will negatively impact the useful life of any common element, this should be noted in the report. 5. Remaining useful life (EUL) should be estimated as a function of the conditions observed. Remaining life is significantly impacted by several factors, particularly the quality of the maintenance program. A standard reserve study is made up of two essential elements: the physical analysis, and the financial analysis. 1. The physical analysis or field assessment involves a general, visual inspection to determine component inventory of the property’s elements and to identify material specifications, assess their general current condition, and take measurements to determine quantities for repair or replacement and provides information about the physical status and repair/replacement cost of the area components the association is obligated to maintain. The physical analysis consists of the component inventory, condition evaluation, age adjustment (based on useful life and remaining life of the components) and the costs to replace. The component inventory will remain relatively unchanged from year to year, while the condition evaluation, age adjustment and cost to replace, and valuation will clearly change from year to year. 2. The financial or reserve analysis is the analysis of the association’s reserve income and expenses. Upon determining the current status of the fund, a funding plan needs to be set up based on a schedule of future repair or replacement costs for each of the elements included in the study. The field assessment and reserve analysis will generate a narrative report documenting assumptions, general conditions, observed deficiencies, useful lifetimes, and remaining useful lifetimes for each element included in the study. The narrative portion of the report will also include graphs, summaries, and photographs that will add to the report’s usefulness and make it an easy to use tool for the client to utilize during the budgeting process. How often should a reserve study be performed? A reserve study is essentially a financial planning tool for the future replacement of commonly owned property that wears out during the life of the development. The annual contributions made to the reserve fund are a means for an association to compensate for the difference between the ongoing deterioration of a property and its finances. Because elements deteriorate at varying rates and the finances of the association typically change yearly, the need to maintain balance between the two is an ongoing process. To maintain this balance, most associations have the reserve study updated every two or three years. When an association is relatively new in age and is not performing any major repairs or replacements, it may have the reserve study updated approximately every three years to maintain the validity of the estimates. However, if the association is older and is experiencing major repairs or replacements, then it may be wise to update the study on an annual basis. An update to a previous reserve study can typically be performed for a percentage of the original cost of the study. The re-evaluation can include an on-site inspection of the property or simply an update to the tables.


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Typical estimated useful life data: Repair needs may not simply reflect physical deficiencies but may be required due to age and maintenance costs. When the annualized cost to maintain a building system or component exceeds its annualized replacement cost, then it has exceeded its expected useful life (EUL). In these circumstances a suitable repair requirement should be identified, which will usually be replacement of the system or component. Several organizations have published standard guides for use in calculating EUL data for various building systems and components. Assessors should use these guides when identifying EUL information. Assessors should make adjustments to the standard EUL data to reflect individual conditions, such as location, exposure, levels of maintenance, etc. (Figure 4.7). A reserve data analysis (RDA) study provides the client with an on-site survey in which the consultant completes a detailed inventory of all assets for which the client is responsible. Using localized cost guides, economic and investment parameters, and consultant’s detailed inventory of the client’s assets, a complete reserve analysis study is produced which includes detailed reports for each asset, a summary of assets by category, a distribution of accumulated reserves report, a required monthly contribution report and 30-year projections. RDA reserve studies begin with a comprehensive analysis of the client’s operating guidelines and other governing documents to determine the extent of the client’s maintenance and reserve responsibilities. The borrower shall provide the consultant with a schedule of all building expenses. Inasmuch as operating expenses may be expensed to tenants as additional rent, or assumed by tenants under a net lease structure, these costs are to be excluded from the consultant’s replacement reserve schedule. However, any item that has a predictable expected useful life and/or is not subject to routine preventive maintenance must be included. Establishing reserve schedules: The community association typically has the responsibility of maintaining the common area facilities that also includes providing a replacement funding program that considers the aging process, anticipates future costs, and provides a method of meeting those future costs, and also to set aside adequate funds from its annual budget to meet its long term obligations. This is a necessary step to maximize the useful life of common area facilities and mitigate their deterioration as they age. When required, the consultant shall prepare a replacement reserve schedule that encompasses shortlived, mid-lived and long-lived recurring systems and components. Short-term recurring systems and components are typically such items as exterior caulking, carpeting, pavement sealing and striping, domestic hot water heaters, etc. Mid-lived recurring systems are typically cooling towers, roofing, paving, appliances, etc. Long-lived items are typically boilers, chillers, electrical systems, infrastructure components, supply and drainage piping, etc. One of the more common methodologies used to complete the replacement reserve schedule is outlined below. These schedules should be typed in a spreadsheet format when submitting. Figure 4.8 is an example of a typical modified capital reserve schedule. 1. Avoid the double-dip: Thus, if the consultant determines that the roof requires replacement as a short-term item under Section IV—Cost Estimates to Remedy Deficiencies—do not require its replacement under year one in the replacement reserve schedule. Treat the roof as if it were new with a remaining useful life (RUL) equal to its commonly anticipated expected useful life (EUL). 2. Opine on EUL and EFF age: A consultant’s professional judgment is paramount in determining when a system or component will require replacement. There are numerous factors that may impact the RUL of a system or component; these include inclement weather, exposure to the elements, initial quality and installation, degree of preventive maintenance exercised, and extent of use. As a result of the aforementioned items, a system or component may have an effective age


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Figure 4.7 Suggested approximate EUL data for different products and systems.

(EFF AGE) greater or less than its actual age (ACT AGE). For instance, a parking lot with an EUL of 18 years that has been religiously sealed with a squeegee applied asphalt emulsion slurry coat may have an EFF AGE equal to eight years although its ACT AGE is 12 years. Therefore, its RUL will be 10 years (18 minus 8) instead of six years (18 minus 12). Occasionally, the borrower or


50 Architectural Forensics

Figure 4.8 Example of modified capital reserve schedule.


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4.

5.

6.

7.

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client may differ with the consultant as to a component or system’s EUL, in which case they need to substantiate their opinion by schedules, invoices, etc. The consultant should not accept or be swayed by unsubstantiated EULs. Phase replacements: The consultant may sometimes be asked to exercise professional judgment as to the rate or recommend phasing of replacements. For instance, suppose that an office complex has an extensive quantity of paving that will realize its EUL in year eight. Instead of requiring the replacement of all paving in year eight, which may be a significant cost to be incurred in any single year, the consultant may phase the work over three years; i.e., the consultant may replace 40 percent in year eight, 30 percent in year nine and 30 percent in year 10. It is useful in this case to ensure that any other recommended replacements that complement it are also completed during this phase, which essentially means that if the paving overlay is to be completed in phases, so should the striping. Component replacements: Most mechanical systems lend themselves to be broken down into commonly replaced components so that funding for replacing the entire system or equipment at one time is unnecessary. The total cost for a boiler may take into account items like pumps, a burner, etc., with each element having a different RUL and therefore requiring a replacement schedule different from that for replacing the entire boiler. Replacements made to date: The consultant will take into consideration any management instigated replacements of multiple or single components that have realized their EUL through maintenance or other programs. If, as a result of research or maintenance records, the consultant learns the extent of such replacements made to date, the consultant shall take this into consideration. The onus here is on management to substantiate the replacements made and the reported costs incurred by submitting documentation to the consultant and such documents should be included as exhibits to the report. Term of loan: The length of the replacement reserve schedule term may significantly impact reserve requirements. Normally, it should be completed for the term of the loan plus two years. Thus, a 17-year reserve “window” would not include replacement of roofing (RUL-20 years) for a subject that has a one-year-old roof, whereas a 22-year “window” would include such a cost. Generally, the smaller the window, the less the reserve monies are required. Cost to replace: Component or equipment replacement costs shall be based on market costs or substantiated client or third-party costs. In cases where the replacement costs of components or systems by the client differ from those recommended by the consultant, the client must substantiate this opinion by submitting paid invoices, executed proposals, receipts, bona fide pending proposals, etc. Unsubstantiated replacement costs offered by the client should not be accepted. Moreover, projected future expenditures should incorporate an acceptable rate of inflation.


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CHAPTER

5 Nondestructive and Destructive Testing 5.1

GENERAL

Construction failures and building evaluations often utilize either or both destructive or non-destructive testing. In destructive testing, the building material or construction conditions are modified and/or damaged during the investigative process of the building’s condition. Concrete core sampling or removing portions of walls which conceal building components to be evaluated are examples of destructive testing. The destruction of the test object usually makes destructive testing more costly and it is also inappropriate in some circumstances. But although it is typically more costly than nondestructive testing, when appropriate, the cost brings with it an additional assurance that the building is being comprehensively investigated. Destructive testing is not normally required unless an initial evaluation has identified a deficiency requiring further investigation, confirmation, and analysis. Nondestructive testing (NDT) is a noninvasive technique to determine the integrity of a material, component or structure or to quantitatively measure some characteristic of an object. In contrast to destructive testing, NDT is an evaluation without doing harm, stress or destroying the test specimen. NDT plays a crucial role in ensuring cost effective operation, safety, and reliability of a building or facility, with resultant benefit to the community. NDT is used in a wide range of industrial areas and is used at almost any stage in the production or life cycle of many components. The mainstream applications are in aerospace, power generation, automotive, railway, petrochemical, and pipeline markets. NDT of welds is one of the most used applications. It is very difficult to weld or mold a solid object that has no risk of breaking in service, so testing at manufacture and during use is often essential. NDT is a cardinal factor in the effective conduct of current research, development, design, and manufacturing programs. Only with appropriate use of NDT techniques can the benefits of advanced materials science be fully realized. However, the information required for appreciating the broad scope of NDT is widely scattered in a multitude of publications and reports. Figure 5.1 shows a table which summarizes in-

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Figure 5.1 Various nondestructive testing applications and limitations (source: Rolf Diederichs). (continued on next page)


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Figure 5.1 Various nondestructive testing applications and limitations (source, Rolf Diederichs).

formation about NDT methods arranged to show their purposes and similarities. The term method as used here refers to the body of specialized procedures, techniques, and instruments associated with each NDT approach. There are usually many techniques or procedures associated with each method.

5.2

TESTING EQUIPMENT

NDT uses many methods and instruments to achieve the required results. The main types of equipment commonly used by forensic experts are briefly outlined below: Break-off tester: The break-off tester measures the force required to break off a cylindrical core from a larger concrete mass. The test involves casting cylindrical plastic forms into fresh concrete. The break-


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Figure 5.2 Various types of NDT instruments: A. Break-off tester, B. Concrete test hammer, C. Crack measuring microscope, D. Borescope, E. Ultrasonic pulse velocity tester.

Figure 5.3 Technicians use a rigid borescope with a video camera to inspect dimensions.

Architectural Forensics

off tester can also be used for other purposes including: evaluation of bond strength between concrete and overlay materials, control of concrete strength, checking strength against specification, measurement of strength development in prestressed concrete, assessment of concrete strength in existing structures, and control of curing (Figure 5.2A). Standard procedures for using this method are given in ASTM C1150. Concrete test hammer: Also named a rebound hammer, this is often used for quick measurement of the quality and compressive strength of concrete. It meets the testing standard ASTM C805 and BS1881 (Figure 5.2B). But while the rebound number test is simple, inexpensive, and quick to perform, there are many factors other than concrete strength that influence the test result such as smoothness of surface, size and shape of specimen, type of cement and aggregate, moisture condition of the concrete, and extent of carbonation of the surface. These need to be taken into consideration during evaluation when using this method. Crack measuring microscope—digital x-ray microscope: These microscopes are specially designed for surface inspection and crack width determination in concrete and consist of high definition microscopes that operate via an adjustable light source provided by high-power batteries (Figure 5.2C). Different magnifications are usually available with scales graduated in millimeters. Its internal illumination allows the user to determine the crack width by simply counting the number of graduations and calculating the value. Borescope with cold light supply & camera: These are precision instruments that come in a variety of models and are used for inspecting cracks in narrow and dark places. Flexible borescopes are ideal for inspecting complex parts and castings where the view is not straight ahead. Tiny semi-rigid borescopes can examine very small parts and openings not accessible to the naked eye. Operators can expand the benefits of borescope video inspection through specialized software on the market (Figures 5.2D, 5.3). Borescopes are commonly used for the inspection of objects that have areas of inaccessibility. They are prevalent in the mechanical engineering field


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Figure 5.4A Example of a

Figure 5.4B An inspector utilizes a profometer to locate and measure

commercial profometer.

steel reinforcement within concrete (courtesy, Proceq USA, Inc.).

more than any other area and are instrumental in the inspection and condition assessment of engines and engine parts. However, borescopes are valuable to civil/structural inspectors and are commonly employed in the inspection of inaccessible structural elements, such as the interior of masonry block or multi-wythe brick walls. Rebar locator, profometer & covermeter: These consist of electromagnetic cover devices used for determining the position and direction of reinforcement bars. These instruments give precise measurements of the concrete cover and estimation of the rebar diameter. They detect reinforcement bars and mesh to measure their cover depth and determine the bar diameter. Typically, a profometer is used to perform checks after formwork is removed, for quality control purposes, and to assist in the evaluation of remedial or repair work. A profometer uses nondestructive pulse-induction technology to locate and measure (Figure 5.4A,B), and the analysis software allows fast and easy data transfer to a laptop or PC. Pipe & cable fault locator: This device is designed for detecting and accurately locating buried metal pipes and cables. It detects and traces metallic objects using the receiver to sense the transmitter signal which is coupled to the object to be traced. It is used in various applications including: locating discrete metallic objects, tracing of pipes & cables, determining depth of pipes and cables, and tracing wires in building (Figure 5.5). Pull off tester & limpet: A pull off tester is a microprocessor-based, portable hand-operated and mechanical unit used for measuring the tensile strength of in situ concrete. It is also used for determining the bond strength of a wide variety of materials including concrete, screeds, repair mortar and epoxy resin coating. It is also sometimes used to measure the strength of the adhesive applied. Ultrasonic pulse velocity tester: Figure 5.2E shows a “Pundit� portable ultrasonic nondestructive digital indicating Figure 5.5 The Radiodetection RD4000 tester. The ultrasonic pulse velocity test, as prescribed in pipe and cable locator (courtesy, Radiodetection Ltd.). ASTM C597, determines the propagation velocity of a pulse


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of vibrational energy through a concrete member. The operational principle of modern testing equipment is illustrated in Figure 5.6. A short-duration, high-voltage signal is sent to a transducer, causing the transducer to vibrate at its resonant frequency. At the start of the electrical pulse an electronic timer is switched on. The transducer vibrations are transferred to the concrete through a viscous coupling fluid. The vibrational pulse travels through the member and is detected by a receiving transducer coupled to the opposite concrete surface. When the pulse is received, the electronic timer is turned off and the elapsed travel time is displayed. The direct path length between the Figure 5.6 Schematic of apparatus to measure ultrasonic transducers is divided by the travel time to pulse velocity (source, American Concrete Institute 228.1Robtain the pulse velocity through the con95-In-Place Methods to Estimate Concrete Strength). crete. A transducer is device that changes sound waves into electrical energy that can be displayed as visual signals on a cathode ray tube (CRT) or liquid display screen. An ultrasonic device is commonly used for crack and void detection, measurement of layer thickness and elastic modulus, and uniformity and deterioration of concrete. The unit, which may be operated from the main electrical supply or via an internal battery, generates low frequency pulses and measures the time taken for the pulses to pass between the two transducers placed at the end of the specimen being tested. It meets the testing standards ASTM C597 and BS1881: Part 203. Figure 5.7 shows another ultrasonic device, the MAC Ultrasonic Rotary, which is designed to inspect tube and bars for flaws or dimensional variations at high throughput speeds. Porosimeter: Mercury porosimeters characterize a material’s porosity by applying various levels of pressure to a sample immersed in mercury. Mercury does not wet most substances and will not spontaneously penetrate pores by capillary action. Pressure is required to intrude mercury into the sample’s pores. The pressure required to fill the pores completely is inversely proportional to the size of the pores. The relationship is: D ⫽ ⫺(1/P)4g cos q. Where D is the pore diameter, P is the applied pressure, g is the surface tension, and q is the contact angle, all in consistent units. The volume of mercury (V) penetrating the pores is measured directly as a function of applied pressure. This D-V information serves as a unique characterization of pore structure. A porosimeter’s main limitation is that the material to be Figure 5.7 Echomac Rotary Ultrasonic analyzed must not react with mercury. The porosimeter meas- Series UT 510 10 Channel System ures only those pores which open to the outside surface. (courtesy, Magnetic Analysis Corporation).


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A Figure 5.8 A. Destructive testing: a compression machine normally used for testing concrete cubes and cylinders. B. Destructive testing: UTS (universal testing system) destructive testing.

B

Destructive testing equipment—compression machine: This machine is capable of compressing specimens to a maximum load of 2,000 kN (Figure 5.8A). This digital controlled machine allows the user to set the rate of loading according to the loading requirements. It is commonly used for testing 150 mm and 100 mm concrete cubes and 150 mm and 100 mm diameter concrete cylinders. This machine also facilitates tensile splitting tests on standard concrete cylinders. Universal testing system: These systems have the capacity of loading up to 2,000 kN and 5,000 kN respectively (Figure 5.8B). They consist of a four column load frame, servo-controlled actuator, load cell, hydraulic power pack, and a controller. The actuators are powered by an 80 litre/min air cooled power pack. The controller is linked to a front control panel and a computer. The fast-track software is used to control, operate, and capture data.

5.3

NONDESTRUCTIVE TESTING (NDT)

Sometimes called nondestructive evaluation (NDE) and nondestructive inspection (NDI) is testing that does not destroy the test object and is the preferred method of evaluation for the vast majority of situations concerning building inspections and failures. NDE is vital for constructing and maintaining all types of a facility’s components and structures. To detect different defects such as cracking and corrosion, there are numerous methods of testing available, such as x-ray scanning (where cracks show up on the film) and ultrasound (where cracks show up as an echo blip on the screen). Other techniques are also available to measure surface displacements, crack propagation or simply detect the presence of defects or deficiencies such as moisture penetration. These techniques include acoustic emission, electrical strain gauging and optical techniques. Increased sensitivity, higher computing power, and better imaging continue to improve the quality of information and ease of use. In this type of evaluation, building components concealed or rendered inaccessible by the building construction are not typically evaluated. While it may seem as though the building and its systems would not be sufficiently investigated unless destructive testing is employed, experience has shown that in most


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cases the condition of a building can be ascertained accurately by careful, nondestructive testing and/or visual observation. NDT was originally applied for safety reasons only, although today it is widely accepted as a cost saving technique in the quality assurance process. For implementation of NDT it is important to describe what shall be found and what to reject. A completely flawless production is almost never possible. For this reason testing specifications are indispensable. Today there are a great number of standards and acceptance regulations. They describe the limit between good and bad conditions, but also often which specific NDT method has to be used. The reliability of an NDT method is an essential issue. But a comparison of methods is only significant if it is referring to the same task. Each NDT technique has its own set of advantages and disadvantages and, therefore, some are better suited than others for a particular application. By use of artificial flaws, the threshold of the sensitivity of a testing system has to be determined. If the sensitivity is too low, defective test objects are not always recognized. If the sensitivity is too high parts with smaller flaws are rejected which would have been of no consequence to the serviceability of the component. With statistical methods it is possible to look closer into the field of uncertainty. Methods such as probability of detection (POD) or the ROC-method “relative operating characteristics” are examples of the statistical analysis methods. Also, the aspect of human errors has to be taken into account when determining the overall reliability. Personnel qualification is an important aspect of nondestructive evaluation, as NDT techniques rely heavily on human skill and knowledge for the correct assessment and interpretation of test results. Proper and adequate training and certification of NDT personnel is therefore necessary to ensure that the capabilities of the techniques are fully exploited. There are several published international and regional standards covering the certification of competence of personnel. EN 473 (Qualification and Certification of NDT personnel—General Principles) was developed for the European Union for which the SNT-TC-1A is the American equivalent. Nondestructive testing is used to investigate the material integrity of the test object. A number of other technologies such as radio astronomy, voltage and amperage measurement and rheometry (flow measurement) are nondestructive but are not used to evaluate material properties specifically. Nondestructive testing is concerned in a practical way with the performance of the test piece—how long may the piece be used and when does it need to be checked again? Another gray area that invites various interpretations in defining nondestructive testing is that of future usefulness. Some material investigations involve taking a sample of the inspected part for testing that is inherently destructive. A non-critical part of a pressure vessel may be scraped or shaved to get a sample for electron microscopy, for example. Although future usefulness of the vessel is not impaired by the loss of material, the procedure is inherently destructive and the shaving itself—in one sense the true “test object”— has been removed from service permanently. Hardness testing by indentation provides an interesting test case for the definition of nondestructive testing. Hardness testing machines look somewhat like drill presses. The applied force is controlled as the bit is lowered to make a small dent in the surface of the test piece. Then the diameter or depth of the dent is measured. The force applied is correlated with the dent size to provide a measurement of surface hardness. The future usefulness of the test piece is not impaired, except in rare cases when a high degree of surface quality is important. However, because the piece’s contour is altered, the test is rarely considered nondestructive. A nondestructive alternative to this hardness test could be the use of electromagnetic nondestructive testing. NDT is not confined to crack detection. Other discontinuities include porosity, wall thinning from corrosion, and many sorts of disbonds. Nondestructive material characterization is a growing field concerned with material properties including material identification and microstructural characteristics—such as resin


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curing, case hardening and stress—that have a direct influence on the service life of the test object. Nondestructive testing has also been defined by listing or classifying the various methods. This approach is practical in that it typically highlights methods in use by industry. These are the NDT systems in order of most used: ultrasonic testing (UT), radiographic testing (RT), electromagnetic testing (ET) in which eddy current testing (ECT) is well known, and acoustic emission (AE or AET). Besides the main NDT methods, a lot of other NDT techniques are available, such as shearography, holography, microwave and many more, with other new methods being constantly researched and developed. Some of the conventional NDT techniques employed include:

5.3.1

Visual Testing

With regard to visual testing, the most important instrument is the human eye. Like other instruments, the eye can suffer damage and deterioration over time, or it can be inherently defective. Likewise, the lens can become inflexible with age and thus impact the ability to focus. Moreover, visual testing has become much more complicated to solve the more difficult test problems of today. Visual testing is extremely important and often is the only form of nondestructive testing (NDT) used on some specimens. Moreover, in some areas it can account for a significant percentage of the testing conducted. The main point of visual testing is that the field observer or inspector must be able to view the surface being tested. Moreover, the angle of viewing should be within 45 degrees of the normal. The ability to see well rapidly drops off when objects or scenes are viewed from an angle other than straight on or normal to the specimen surface. Some tests may require that specific lines on a card be placed on the surface being evaluated and be visible for the evaluation to be performed. Likewise, testing should not be performed at an angle that brings intense reflected light into the eye. Excessive brightness within the field of view can cause glare which interferes with the ability to see clearly and make critical observations and judgments. A test may therefore require the light to be increased or decreased to achieve optimum results. Sometimes a visual survey of the specimen may not suffice. A number of physical or mechanical aids may be required to ascertain if the specimen is correct. Tape measures, levels and plumb lines, calipers, many different gages, angle measurement devices, and a variety of other items may be needed to assist the field observer in determining the adequacy of a specimen. Without some of these simple aids, the evaluation might prove to be inadequate or incorrect. Besides corrective eyeglasses and lamps for additional illumination, there are various other visual aids that allow the inspector to see what would otherwise be difficult or impossible. These optical aids include such items as reflective mirrors (for changing angles), rigid and flexible borescopes, magnifying devices, image enhancement technologies, remote video devices, and machine vision instruments. All of these aids can assist the inspector or field observer in some manner, often at a price—like reduced coverage, increased performance complexity and/or higher cost. All of these aids facilitate the inspector’s ability to see surfaces for testing that would have otherwise been difficult or impossible to see. New video devices also now allow permanent records of the evaluation to be made, thereby allowing others to observe the test as it was performed. Optical NDT methods have high sensitivity and they allow a full-field analysis of the inspected area without any need for physical contact with the surface. They can sometimes provide additional information where the other techniques fail or can not be applied. For example, in the analysis of building materials it is possible to obtain information about the displacement distribution over the whole surface. Therefore, the strain distribution and crack formation and propagation in structures can be easily observed. The main optical interferometric techniques for measuring deformations are photoelasticity, moiré methods, holographic interferometry and speckle techniques.


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Although visual and optical evaluations continue to increase in complexity to solve today’s more difficult test problems, the basic premise remains: you need to be able to see it.

5.3.2

Ultrasonic Testing

Ultrasonic testing is one of the most commonly used techniques for NDT, and in recent years the ultrasonic inspection equipment represented over 25 percent of the total world NDT equipment market. And as is the case for many other electronic devices, the technology relating to ultrasonic equipment and systems is developing at a rapid pace. Furthermore, as with the use of most equipment, the reliability of ultrasonic examination results depends on the knowledge, training, and experience of the person performing the work. Ultrasonic shear wave testing is used to detect surface flaws such as cracks and internal flaws such as voids or inclusions of foreign material. It is also commonly used to measure wall thickness in tubes and can measure diameters of bars. Two methods are used for flaw detection—the through-transmission and the pulse-echo method. In the through-transmission test method, two transducers are used, one as a transmitter and the other as a receiver. The two transducers are located on opposite sides of the test part. Ultrasonic testing uses the transmission of high frequency sound waves into a material to detect imperfections within the material or changes in material properties. The most commonly used ultrasonic testing technique is pulse echo wherein sound is introduced into the test object and reflections (echoes) are returned to a receiver from internal imperfections or from geometrical surfaces of the part. A transducer that is coupled to a test object emits ultrasonic pulses in the frequency range 1 MHz to 20 MHz. The pulses travel though the object and are either reflected, diffracted or refracted by defects or discontinuities in the material. A receiver is used to detect the pulses on the other side of the material or, more typically, the returning echo signal. The loss in signal amplitude is then used to determine the existence of a defect and its size. The advantages of this technique include its ability to detect deep subsurface defects, which cannot be detected by other NDT techniques. However, its disadvantages include complex image analysis and the fact that the ultrasound transducer generally needs to be in direct contact with the test object or must have a suitable coupling medium between it and the object’s surface, e.g., water. For this reason the technique tends not to be versatile and is usually designed with a specific application in mind. Applications of ultrasonics: Ultrasound has been used to determine the integrity of various materials including metal and alloys, welds, forgings, and castings. Ultrasound has also been applied to concrete in an attempt to nondestructively determine in situ concrete features such as compressive strength, surface crack measurement, defect location and corrosion damage (Figure 5.9). There are a number of new generation ultrasonic flaw detectors whose features include an all new high bright, high contrast, true LCD display for optimal viewing in the brightest of sunlight or the darkest of environFigure 5.9 Ultrasonic pulse velocity testing on a specimen (courtesy, Christopher C. Ferraro). ments (Figure 5.10).


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63

Thermal Infrared Testing

Infrared thermography (IRT) is a nondestructive evaluation (NDE) process that characterizes the properties of a material by monitoring its response to thermal loading. The term “thermal loading” is normally used to describe the transfer of energy from a heat source to a solid object. Infrared thermography is therefore a technology that looks at the heat signature of objects to monitor the object’s state or condition, since all objects emit heat (energy) waves. The lowest temperature that the human eye can visually detect is approximately 500 degrees celsius. Infrared thermography uses an infrared radiometer (camera) to see infrared heat waves and measure their temperature. If an object is cold, its molecules vibrate more slowly and energy of longer wavelengths is emitted. When the temperature of the object rises, its molecules vibrate faster and the wavelength becomes shorter. An infrared camera detects temperatures in this lower range and can see the “invisible” light and produces colorized images which enable the inspector to see the temperature variations in the image. These imFigure 5.10 New generation ages can be seen on a television or on the eyepiece of the camera and ultrasonic flaw detector, the can be stored on a flash card for viewing on a computer screen, or on Avenger EZ, with a dual timebase videotape. feature allowing a user to view the Infrared building envelope and electrical-mechanical analysis is a full range of the area under well proven nondestructive method for troubleshooting building heat inspection in one window while loss and moisture problems. Infrared images are examined using simultaneously presenting the user analysis software, and priorities are set as to how soon repairs are with a resizable second window (courtesy, NDT Systems Inc.). needed. This could be a failing motor bearing, a loose electrical connection, or a bad door seal. Each of these produces a heat signature, and when they are out of parameter a problem is indicated. Continuous improvements to infrared technology have made it a workable option for monitoring and diagnosing building conditions in many situations. What was once detectable only through destructive investigation can now be uncovered without disturbing a thing. Field observers and forensic architects use infrared testing to help building owners and facility managers save millions of dollars annually by reducing energy costs, minimizing structural damage, and enhancing occupant comfort and health. A common application for thermal imaging is the evaluation of build-up roofing systems. Leaks in the roof allow moisture to become trapped in the insulation below. Solar loading of the trapped moisture causes the temperature to rise, and the area will retain heat for longer periods than those spots with dry insulation. This inspection, which allows for a very accurate location of the affected areas, should take place shortly after sundown. The defective areas are marked using spray paint or other medium. Often we find that only small portions of the roof are in need of repair which saves the owner considerably. Building exteriors can also be evaluated for energy loss. These inspections are best conducted during the time of year when the inside temperature is quite different from the outside temperature. This creates a greater range between the inside and outside to maximize the results of the inspection. These inspections can reveal energy loss around windows and door seals, insulation voids, and construction defects. Moisture penetrated walls and ceilings can also be identified before damage becomes extensive (Figure 5.11). Heat losses from buildings are accelerated by structural problems, poor construction practices, missing or inadequate insulation, moisture infiltration and air leakage. Escaping heat creates a thermal signature that can be detected with infrared thermography. Building envelope analysis uses thermography to


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pinpoint underlying problems in a building. From the collected data, the forensic architect can produce a report that provides the client with details regarding location, causes and extent of the problems within the building envelope. Performing an infrared thermographic survey provides a safe and fast technique for monitoring the condition of a facility’s equipment. This includes electrical and mechanical systems, roofs, buildings for energy loss, and structural integrity. By examining the images Figure 5.11 An example of thermal infrared imaging highlighting from the infrared camera one can defects in a building structure (courtesy, Edward Cy Yiu). determine the condition of components and discover any exceptional temperatures which might indicate that the component is approaching some stage of failure. Because thermography consists of a non-contact, nondestructive testing method, production need not be interrupted nor is there a need for a costly shutdown. Moreover, infrared detection technology allows accurate detection of thermal anomalies that can threaten the safety and reliability of a facility’s electrical and mechanical systems. In electrical and mechanical systems, excessive heat is a sign of impending problems. High temperatures indicate excessive electrical resistance, worn components, lubrication failure, or other common problems that can lead to expensive failures. These failures often eluded visual and manual inspections in addition to being costly and time-consuming. For those areas where the finishes are in the form of concrete, mosaic tiles, or other detectable surfaces with moisture trapping, water leakage, or debonding shall emit different amounts of infrared radiation. These surfaces will show up on the thermographic image as a different range of temperature transmittance. An ideal infrared program incorporates the proper mix of both: an annual inspection by a certified specialist and follow-up and continuing diagnosis by an in-house person. Infrared systems can be used to detect deficiencies relating to: •

• • • • • •

Electrical panels and systems: helps identify poor connections; corrosion; loose parts; electrical shorts; incoming power supply, power transformation to lower voltages, and power distribution; UPS and lighting performance; load imbalances; etc. Roofing systems: leaks, wet insulation, ponding, etc. Windows/doors: air and water infiltration. Exterior walls: delamination on walls, masonry, and foundation; insulation R-values; weatherization. Mechanical systems: helps examine rotating parts; wear of motors, bearings, and belts; loose parts; insulation voids on chilled-water lines; escalator/elevator rails; plumbing leaks. Steam systems: look at steam traps, insulation on steam lines. General: locate causes of frozen pipes and ice dams.

In terms of capital and operations planning/budgeting, infrared studies can provide a means of prioritizing needed repairs and replacements. The main advantages of thermal infrared testing are that it is non-


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contact, nondestructive, full-field; it is a totally passive technique, requiring no external source of illumination; it is ideal for the detection of hot or cold spots, or areas of different emissivities; thermal radiation can penetrate smoke and mist more readily than visible radiation, allowing visually obscured objects to be detected; and it provides a real time, remote sensing technique and makes post-processing possible. However, infrared has its limitations. For example, it can’t see through metal, barrel tile, or shingles that are in a pitch. In roofing applications, it’s really designed for a traditional, commercial flat roof or a low-slope roof that doesn’t exceed a 2/12 pitch. Likewise, infrared cameras can’t see through foamed-over roofing systems or other highly reflective surfaces.

5.3.4

Acoustic Emission (AE)

Acoustic Emission (AE) is the term used when defects in metals, plastics and other materials rapidly release energy when subjected to mechanical loading. There are basically two types of acoustic emission signals: continuous signals and burst signals. A continuous emission is a sustained signal level, produced by rapidly occurring emission events such as plastic deformation. A burst emission is a discrete signal related to an individual emission event occurring in a material, such as a crack in concrete. The energy propagates in the form of high frequency stress waves. These types of oscillations are picked up by AE sensors on the surface of the specimen and converted to electrical signals, so-called bursts. The AE analysis is the characterization of the bursts according to intensity and frequency content. Analyzing bursts from several sensors at well placed positions on the test object allows for determination of the location of the AE source(s) on the test object. Figure 5.12A,B are schematic diagrams that show the principles and elements of a modern acoustic emission detection system. Acoustic emission testing (AET) methods are currently considered supplementary to other nondestructive testing methods. They have been applied, however, during proof testing, recurrent inspections, service, and fabrication. These tests consist of the detection of acoustic signals produced by plastic deformation or crack formation during loading. These signals are present in a wide frequency spectrum along with ambient noise from many other sources. Transducers, strategically placed on a structure, are activated by arriving signals. By suitable filtering methods, ambient noise in the composite signal is notably reduced. Any source of significant signals is plotted by triangulation based on the arrival times of these signals at the different transducers. Acoustic emission (AE) analysis is an extremely powerful technology that can be deployed within a wide range of usable applications of nondestructive testing: metal pressure vessels, piping systems, reactors, and similar applications. The acoustic emission technique can also generally be used to obtain information about the microstructural changes that are occurring in any mechanical loaded material (e.g., tensile, bending, fatigue, creep). It therefore contributes to a larger and more in depth understanding of the behavior of these materials. There are currently 23 existing AE related ASTM standards in E07.04 and the associated Volume 03.03 Nondestructive Testing, Annual Book of Standards, with two more currently in development. Whereas ultrasonic testing actively probes the structure, acoustic emission analysis listens for emissions from active defects and is very sensitive to defect activity when a structure is loaded beyond its service load in a proof test. AE analysis is a useful method for the investigation of local damage in materials. One of the advantages compared to other NDE techniques is the possibility to observe damage processes during the entire load history without any disturbance to the specimen. Unlike most nondestructive testing techniques, acoustic emission is completely passive in nature. In fact, acoustic emission cannot truly be considered nondestructive, since acoustic signals are only emitted if a permanent, nonreversible deformation occurs inside a material. As such, only nonreversible processes that are often linked to a gradually processing material degradation can be detected (Kaiser & Karbhari


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2002). Acoustic emission is used to monitor cracking, slips between concrete and steel reinforcements, failure of strands in prestressing tendons, and fracture or debonding of fibers in fiber reinforced concrete. An acoustic emission system has the same basic configuration as seen in ultrasonic testing systems. The typical testing apparatus used for acoustic emission consists of the following: •

Transducer

Receiver/amplifier

Signal processors

Transient digitizers

Display

Calibration block

Coupling agent.

A

Applications of acoustic emission: Acoustic emission has been used to determine the integrity of various materials, including metal and alloys, welds, forgings and castings. Acoustic emission has been applied to concrete in an effort to nondestructively evaluate in situ concrete for load testing and structural monitoring. Load testing: The most successful application of acoustic emission is detecting the B presence of discontinuities or cracks and their location in concrete specimens and Figure 5.12A,B A. Principle of the acoustic emission structures. Perhaps the most researched approcess. B. Schematic diagram showing the elements of a plication of acoustic emission testing has modern acoustic emission detection system. been used in the load testing of concrete structures and specimens. The disadvantage of AE is that commercial AE systems can only estimate qualitatively how much damage is in the material and approximately how long the components will last. So, other NDE methods are still needed to do more thorough examinations and provide quantitative results. Nevertheless, because the physical process of acoustic emission occurs in a wide variety of materials and under a large range of loading conditions, the technique offers great potential for use as a continuous monitoring technique.

5.3.5

X-Ray Scanning

X-ray scanning has until recently been more widely known for biological applications than as an NDT technique for materials testing. However, because x-rays have a high penetrating power they are useful for ex-


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amining the majority of structural types. The rays pass through the specimen and are detected at the other side usually by photographic film. As in the biological applications, the developed film shows up areas where attenuation is lowest as darker regions. The differences in intensity will be caused by differences in thickness and density of the object. In this way sub-surface defects are easily recognizable. The obvious disadvantage of this technique is the dangerous effects the radiation can have on biological tissue. The interpretation of the developed film also demands both experience and skill. X-ray test: This is a radiographic test method used to reveal the presence and nature of internal defects in a weld, such as cracks, slag, blowholes, and zones where proper fusion is lacking. In practice, an x-ray tube is placed on one side of the welded plate and an x-ray film, with a special sensitive emulsion, is placed on the other side. When developed, the defects in the metal show up as dark spots and bands, which can be interpreted by an operator experienced in this inspection method. Porosity Figure 5.13 A Fischerscope x-ray 1600 and defective root penetration as disclosed by x-ray inapparatus (courtesy, TPG Industries). spection are shown in (Figure 5.13). Instructions for handling x-ray apparatus to avoid harm to operating personnel are found in the “American Standard Code for the Industrial Use of x-rays.”

5.3.6

Eddy Current (Electromagnetic) Testing

The world eddy current test equipment market segment represents about 20 percent of the total NDT equipment market and is increasing compared to the other product segments. Eddy current testing is a nondestructive test method based on the principle of electromagnetic induction. In standard eddy current testing, a circular coil carrying an AC current is placed in close proximity to an electrically conductive specimen. The alternating current in the coil generates a changing magnetic field which interacts with the test object and induces eddy currents. Variations in the phase and magnitude of these eddy currents can be monitored using a second “search” coil, or by measuring changes to the current flowing in the primary “excitation” coil. Variations in the electrical conductivity or magnetic permeability of the test object, or the presence of any flaws, will cause a change in eddy current flow and a corresponding change in the phase and amplitude of the measured current. This is the basis of standard (flat coil) eddy current inspection, the most widely used eddy current technique. Eddy current testing is used to check welds in magnetic and nonmagnetic materials and is particularly useful in testing bars, fillets, welded pipe, and tubes. The frequency may vary from 50 Hz to 1 MHz, depending on the type and thickness of material current methods. The former pertains to tests where the magnetic permeability of a material is the factor affecting the test results and the latter to tests where electrical conductivity is the factor involved. Nondestructive testing by eddy current methods involves inducing electric currents (eddy or foucault currents) in a test piece and measuring the changes produced in those currents by discontinuities or other physical differences in the test piece. Such tests can be used not only to detect discontinuities, but also to


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measure variations in test piece dimensions and resistivity. Since resistivity is dependent upon such properties as chemical composition (purity and alloying), crystal orientation, heat treatment, and hardness, these properties can also be determined indirectly. Electromagnetic methods are classified as magnetoinductive and eddy current methods. The former pertains to tests where the magnetic permeability of a material is the factor affecting the test results and the latter to tests where electrical conductivity is the factor involved. Eddy currents are induced into the conducting test specimen by alternating electromagnetic induction or transformer action. Eddy currents are electrical in nature and have all the properties associated with electric currents. In generating eddy currents, the test piece, which must be a conductor, is brought into the field of a coil carrying alternating current. The coil may encircle the part, may be in the form of a probe, or in the case of tubular shapes, may be wound to fit inside a tube or pipe. An eddy current in the metal specimen also sets up its own magnetic field which opposes the original magnetic field. The impedance of the exciting coil, or of a second coil coupled to the first, in close proximity to the specimen, is affected by the presence of the induced eddy currents. This second coil is often used as a convenience and is called a sensing or pick up coil. The path of the eddy current is distorted by the presence of a discontinuity. A crack both diverts and crowds eddy currents. In this manner, the apparent impedance of the coil is changed by the presence of the defect. This change can be measured and is used to give an indication of defects or differences in physical, chemical, and metallurgical structure. Subsurface discontinuities may also be detected, but the current falls off with depth. Applications to concrete: Currently, magnetic testing methods have no relevant use in the nondestructive testing of concrete itself. Concrete is nonmagnetic in nature, so the use of magnetic flux leakage for the detection of flaws and anomalies in concrete devoid of reinforcing steel is insignificant. However, the use of magnetic methods for the inspection of ferromagnetic materials embedded within concrete structures has proven to be extremely valuable. Magnetic methods have been applied to detect defects in prestressing tendons and steel rebar within concrete structures. They have proven effective in the detection and location of embedded steel. The detection of flaws such as seams, cracks, pits, slivers, weld-line defects and internal discontinuities in metallic materials can be done conveniently by using an encircling coil eddy current system. This type of inspection system is most frequently used to locate surface defects in bar stock or wire products, and to detect both ID and OD defects in tubing. The test is usually conducted at production speed. The basic principles of operation in encircling or through coil systems are simple. The test coil is excited by an alternating current of a given frequency which induces a flow of eddy currents around the material that is passing through the coil. When a flaw in the material passes through the coil, it causes a change in the flow of eddy currents. It is this change that is detected by the electronics (Figure 5.14). Surface seams and cracks in metallic materials can be reliably detected by using eddy current technology. Eddy currents are induced by one or more test probes which traverse the surface of the material under test. To conduct Figure 5.14 Eddy current flow is interrupted by holes, etc. a test using probe type eddy current instru-


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ments, the probes are excited by an alternating current of a given frequency which induces a flow of eddy currents in the metal beneath them (Figure 5.15). As the test probes pass over a flaw, the flaw causes a change in the flow of eddy currents, and it is this change which is detected by the instrument’s electronics. The change in the flow of eddy currents as the probes pass over the defect is generally proportional to the depth of the defect. It is therefore possible to estimate the depth with proper electronic calibration. Testing magnetic materials: When testing materials such as carbon steel, austenitic stainless, and alloy steels having a permeability higher than one, it is often necFigure 5.15 Multi-test eddy current and ultrasonic test essary to saturate the material with a magsystem. netic field. The effect of this magnetic saturation is to even out the permeability variations in the material, thereby making the material appear to the test coil system as though it were non-magnetic. The material can be saturated by using a permanent magnet or a saturating coil in which D.C. current is flowing. In either case, the eddy current test coil is placed within the saturating field and performs the test.

5.3.7

Penetrant Testing

Dye penetrant inspection (DPI), also known as liquid penetrant examination (LPE), is a type of nondestructive testing used generally in the detection of surface flaws in non-ferrous alloys. Liquid penetrant inspection testing is a widely used NDT method. This method employs a penetrating liquid, applied to the surface of the component and enters the flaw, crack, or seam. After the excess penetrant has been cleared from the surface, the penetrant is drawn back out and the crack is observed using a white light or UV light. Dye penetrant inspection (DPI) is also used to inspect ferrous materials where magnetic particle inspection is difficult to apply. In some cases dye penetrant inspection (DPI) can also be used on non-metallic materials. Variations include the use of fluorescent dyes, where a black (UV) light illuminates the residual penetrant. This dye penetrant inspection (DPI) technique has even higher sensitivity than normal LPE but can only be used in the absence of other light sources. Dye penetrant inspection can be applied to any nonporous clean material, metallic or non-metallic material, but is unsuitable for dirty or rough surfaces. Fluorescent penetrant test: Fluorescent penetrant inspection is a variant of the penetrant nondestructive test method by means of which cracks, pores, leaks, and other discontinuities can be located in solid materials (Figure 5.16). It is particularly useful for locating surface defects in nonmagnetic materials such as aluminum, magnesium, and austenitic steel welds and for locating leaks in all types of welds. This method makes use of a water washable, highly fluorescent material that has exceptional penetration qualities. This material is applied to the clean dry surface of the metal to be inspected by brushing, spraying, or dipping. The excess material is removed by rinsing, wiping with clean water-soaked cloths, or by sandblasting. A wet or dry type developer is then applied. Discontinuities in surfaces which have been properly cleaned, treated with the penetrant, rinsed, and treated with developer show brilliant fluorescent indications under black light.


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Some advantages of fluorescent penetrant testing are that it is a practical and effective investigative technique, and it is economical, sensitive, versatile, nondestructive, easy to operate, and requires less high technology. However, there are also a number of problematic issues with this test, such as: •

When insufficient flushing water is used the dye does not reach the damp zone

Possible absorption of dye solutions within other parts of the structure

Insufficient elapsed time between addition and sampling

Sometimes when powder dye is used the dye fails to dissolve completely in water

Use of excessively strong solutions, or powder, may produce unsightly staining after the test

Some dyes used for metal crack detection testing, where neutral conditions exist, are not appropriate for use in buildings.

Figure 5.16 Penetrant testing using fluorescent and visible dyes.

Moreover, it should be noted that the test is not always successful and failure to record the presence of the dye at the damp zone cannot be taken as definite evidence against the suspect source, although a positive test confirmed by laboratory testing is firm proof of the source.

5.3.8

Magnetic Particle (Magnetic Flux) Testing

Magnetic particle testing or magnaflux, as it is sometimes called, is an NDT method for detecting discontinuities and subsurface cracks that are primarily linear and located at or near the surface of ferromagnetic components and structures. A magnetic field is applied to the structure to be inspected, bringing the structure to magnetic saturation (i.e., it cannot hold additional magnetic field). The magnetic field can be applied in several different ways—encircling coils, permanent magnets, etc., and each technique has its own advantages and disadvantages depending on the inspection scenario. Magnetic lines of force (MLF) is still relatively underused in many areas of NDT. This is perhaps due in part to the fact that although more common NDT inspection techniques such as ultrasonics can be used to inspect a wide variety of materials, MLF is limited to inspecting ferromagnetic materials. At the same time, MLF overlaps in a sense with magnetic particle inspection (MT), and in many cases MT is used as a faster and easier method of inspection. This testing method is based on the principle that magnetic flux in a magnetized object is locally distorted by the presence of a discontinuity. This distortion causes some of the magnetic field to exit and reenter the test object at the discontinuity. This phenomenon is called magnetic flux leakage. The flux leakage field attracts the added magnetic particles and they will produce a visible indication of the discontinuity. In the presence of a flaw, the structure cannot accommodate as much magnetic field as in its undamaged state, and some of this magnetic field escapes into the surrounding environment—the magnetic field is said to “leak” into the environment. It is this flux leakage that is detected as the indication of a problem with the structure. An illustration of a magnetic field leaking around an air-filled flaw in steel is shown in Figure 5.17A. Generally, the magnitude of the leaking flux is small in comparison to the applied magnetic field, but is easily detectable.


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A wide variety of flaws in steel can be detected with MLF, although it is most often used to find voids, cracks, corrosion, and other loss of material flaws (Figure 5.17B). More subtle forms of damage, such as heat or impact damage or grinder burns and crashes can also be detected by MLF as changes in local stress levels (whether permanent or temporary) change local magnetic properties. Some research also suggests that MLF can distinguish between the stress conditions prevalent at the time of defect formation. In the case of oil and natural gas pipelines for example, MLF could potentially determine if a flaw occurred while the pipe was in service or during the construction phase, which might have significant consequences in terms of liability in the event of a catastrophic pipeline failure. The major difference between MT and MLF is the method of detection. In magnetic particle testing, the detection is visual. In MLF, the field is detected with a magnetic sensor such as a coil, hall probe, or even a SQUID (superconducting quantum interference device). Using a magnetic sensor, MLF eliminates the sometimessubjective nature of visual detection, greatly increases sensitivity, and perhaps most importantly, eliminates the need to have direct access to the steel’s surface and allows the detection of flaws that do not break the surface. Due to this difference, MLF is preferred over MT where direct visual and physical access to the structure is difficult and/or dangerous. As an inspection technique, MLF is perhaps most useful to inspect in situ structures or components that would A otherwise have to be torn down and/or removed from servFigure 5.17A Magnetic lines of force ice for inspection. Besides the standard MLF applications (MLF) interacting with air-filled void (source, for inspecting in-service oil and gas pipelines and storage Chris Coughlin—NTIAC). tanks, MLF is a technique to consider when direct access to the steel component isn’t possible. Unlike many other methods of NDE, MLF does not rely on direct or close contact to the part but can be applied even with significant (an inch or more) separation. In addition, as a magnetic method of inspection, MLF is insensitive to all non-ferromagnetic materials, which include most electroplating, cladding, paint, insulation, and other forms of protection; dirt or other pollutants; and the surrounding environment (air, water, etc.). In effect, MLF “sees” non-ferromagnetic materials only as a distance between the sensor and the steel. In contrast, both ultrasonic and eddy current inspections have to take into consideration most materials between the sensor and the structure’s surface. As is the case with MT, demagnetization should be a routine when it comes to MLF. In most cases the demagB netization procedure can closely follow similar procedures for MT. Heating or tapping the structure is normally Figure 5.17B Magnetic particle inspection enough to remove residual magnetization, although the (MPI) being conducted using a lightweight, preferred method is to apply an AC magnetic field, e.g., usencapsulated magnetic yoke device (source, ing an adjustable yoke. A final residual field measurement Silverwing Ltd.). on the structure is also useful.


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Particles come in many forms, and understanding their morphology and chemistry is cardinal to discerning their origin. Particle detection and analysis encompasses numerous applications in a variety of industries. Magnetic particle testing is done by inducing a magnetic field in a ferro-magnetic material and dusting the surface with iron particles (either dry or suspended in a liquid). Surface imperfections will allow the magnetic field to leak out of the part, distort the magnetic field and concentrate the iron particles near imperfections, thus indicating their presence. Particle detection may require scanning large areas of samples automatically and performing recorded analysis on specific types or simple manual inspection of a specimen to locate a typical example. The leakage flux test method is used for the detection of outer surface, inner surface, and subsurface discontinuities in magnetic steel tubular products of uniform cross sections such as seamless and welded tubing. Properly applied, this method can detect the presence and location of significant longitudinally or transversely oriented discontinuities such as pits, scabs, slivers, gouges, roll-ins, laps, seams, cracks, holes, and improper welds. The amplitude and frequency of the voltage generated by the flux sensor in response to a discontinuity is generally indicative of the severity and location of that discontinuity. The magnetic flux leakage method has been applied to the determination of nonmagnetic coating thickness, the depth of case hardening, and the carbon content of a material. Another major application has been in testing steel bearing raceways and gear teeth. In its most refined form, MLF is one of the most sensitive methods for the detection of surface and near-surface cracks and flaws in ferromagnetic materials.

5.3.9

Radiographic Testing

Radiography involves the use of penetrating x- or gamma radiation to examine parts and products for flaws that could be detrimental to their intended use. An x-ray machine or radioactive isotope is used as a source of radiation. Radiation is directed through a part onto a film or an electronic device (plate). When the film or plate is processed, a negative-like picture is obtained that shows the internal characteristics of a part. Possible imperfections show up as density changes in the film, in much the same way an x-ray can show broken bones. A radiograph is a picture produced on a sensitive surface by a form of radiation other than visible light, typically an x-ray or a gamma ray. Radiography is the NDT technique that employs the use of radiographs for material inspection. X-rays are a form of electromagnetic radiation with a relatively short wavelength, about 1/10,000 the wavelength of visible light. Gamma rays are 1/1,000,000 that of visible light. It is this extremely short wavelength that enables x-rays or gamma rays to penetrate through most materials (Reese 2003). Structural radiography is very similar to the x-ray technique people experience during a doctor’s visit. The method involves a wave source, usually x-rays or radioisotopes, and a detector, which is most commonly photographic film. Radiometry: Often the terms radiometry and radiography are used interchangeably despite the fact that the tests are different. While radiography produces a visible image, radiometry is more quantitative in nature and is used to ascertain material properties. While both NDT techniques implement the use of radiation energy to analyze material properties, some radiometry techniques require only one side of a material to perform testing. The backscatter mode and certain aspects of the direct transmission mode (for both radiometry techniques) can send and receive radiation signals from a single side of the material. The direct transmission mode of radiometry uses the same principles as the radiography test, though the radioisotope source can be oriented in several configurations to enable personnel to perform surface testing of a material. The direct transmission mode of radiometry uses the same theory as radiography, the main difference being that the equipment is configured differently. The direct transmission mode of radiometry usually has one or two probes that penetrate into the test material. A radioisotope source emits pulses


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which are received by the detector. The rate of arrival of the pulses is related to the density of the material. This technique is commonly used in geotechnical engineering for the rapid calculation of soil composition, water content, and density. Applications of radiographic testing include: castings, forgings and extrusions, electronic components, all types of welds, and bridge structures. Radioactive methods have various applications in the nondestructive testing and monitoring of structures. Radiography may be the most powerful qualitative means of NDT since it offers inspectors a view of the internal structural elements unrivaled by any other nondestructive inspection technique. Radiography can be applied to virtually any structural element in which two opposite sides are accessible. The method permits inspectors to assess every component on a visual basis, comparable to a medical doctor’s ability to examine internal organs non-intrusively. Radiometry has been successfully used to quantitatively determine properties of concrete such as density, porosity, water content, and thickness. The techniques used for determining material properties and integrity using radiation waves is comparable to the techniques used in determining material properties via stress waves. However, stress waves are of a lower energy and less versatile for material inspection than radiation waves. Limitations: Although radiation testing is among the most powerful methods used in nondestructive testing today, it has several limitations that prevent it from becoming the most widely used NDT technique. Radiation testing techniques are the most expensive of NDT methods available for the testing of concrete materials. The technique is so much more expensive than the other techniques in service today that many inspectors don’t consider it to be practical from a cost-benefit standpoint. Another limitation of radiography as an NDT technique is that both sides of the material to be tested need to be accessible for inspection. Therefore, structural elements like slabs and foundation walls are not usually suitable for testing with radiography. ASTM has developed a testing standard covering the practices to be employed in the radiographic examination of materials and components. The standard outlines a guide for the production of neutron radiographs that possess consistent quality characteristics, as well as a guide for the applicability of radiography (ASTM E748-02) Radiation testing also presents many safety concerns that are not easily addressed in the field. While it may usually be feasible to protect operating personnel while conducting testing, it is not always practical to use radiographic testing because of public safety concerns. Similar types of problems arise when performing radiographic testing of buildings and building components.

5.4

DESTRUCTIVE TESTING

From time to time, the forensic architect or inspector may find it necessary from a walk-through survey to recommend a more detailed examination of an element or component by actually changing its condition in some manner. When the examination goes beyond mere observation and entails changing the condition or appearance of the element, it is referred to as Destructive Testing. Destructive testing can cover a spectrum of activities ranging from merely changing a product’s position to actually cutting or extracting a sample or component in order to subject it to analysis beyond the visual. While the spectrum of activity is broad, the words “destructive testing” often connote some analysis that subjects a portion of the element or component to stresses, forces, or chemical influences to better reveal the condition or cause of failure. Destructive testing usually provides a more reliable assessment of the state of the test object, but destruction of the test object usually makes this type of test more costly to the test object’s owner than non-


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destructive testing. Destructive testing is also inappropriate in many circumstances, such as forensic investigation. The fact that there is a tradeoff between the cost of the test and its reliability favors a strategy in which most test objects are inspected nondestructively. In destructive testing the part characteristic, such as tensile strength, impact strength or burst pressure of a vessel, is measured as the part is destroyed, and once a measurement is taken for a particular part, that part ceases to be available for additional measurements (Figure 5.8A,B). By its nature, destructive testing done by or on behalf of one litigant is of keen interest to the other. Because spoliation risks (or other accusations) can come back to haunt the tester, the entire episode needs to be well thought out by counsel and safeguards considered. Sometimes, when adversarial tensions are high or where destructive testing can truly affect the quality and integrity of the remaining crown jewels, it may be helpful to seek court supervision or intervention by moving for a protective order that permits the destructive testing and specifies the conditions of such analysis. Some tests, such as tensile and bending tests, are typically destructive, in that the test specimens are loaded until they fail so that the desired information can be gained. The court addressed the first factor: was the testing “reasonable, necessary, and relevant?” By examining case law in which destructive testing was not allowed, the court found that “a party may not use destructive testing merely to bolster an expert opinion or to gain other potentially intriguing, albeit irrelevant, information.” Instead, the evidence sought “must be integral to proving the movant’s case and do more than strengthen an already established claim or defense.” While plaintiffs “must show that the evidence sought through destructive testing is necessary to prove their case,” the burden “is not so high as to require definitive proof that plaintiff’s hypothesis will prove correct.” In other words, “plaintiffs need not prove their case for the opportunity to prove their case.” Guided bend test: These tests are used to determine the quality of the weld metal at the face and root of the welded joint as well as the degree of penetration and fusion to the base metal. Guided bend tests are made in a jig (Figure 5.18A,B,C). These test specimens are machined from welded plates, the thickness of which must be within the capacity of the bending jig. The test specimen is placed across the supports of the die which is the lower portion of the jig. The plunger, operated from above by a hydraulic jack or other device, causes the specimen to be forced into and to assure the shape of the die. To fulfill the requirements of this test, the specimens must bend 180 degrees and, to be accepted as passable, no cracks greater than 1/8 inch (3.2 mm) in any dimension should appear on the surface. The face bend tests are made in the jig with the face of the weld in tension (i.e., on the outside of the bend). The root bend tests are made with the root of the weld in tension (i.e., on outside of the bend). Nick break test: The nick break test has been devised to determine if the weld metal of a welded butt joint has any internal defects, such as slag inclusions, gas pockets, poor fusion, and/or oxidized or burnt metal. The specimen is obtained from a welded butt joint either by machining or by cutting with an oxyacetylene torch. Each edge of the weld at the joint is slotted by means of a saw cut through the center. The piece thus prepared is bridged across two steel blocks and struck with a heavy hammer until the section of the weld between the slots fractures. The metal thus exposed should be completely fused and free from slag inclusions. The size of any gas pocket must not be greater than 1/16 inch (1.6 mm) across the greater dimension and the number of gas pockets or pores per square inch (64.5 sq mm) should not exceed six. Another break test method is used to determine the soundness of fillet welds. This is the fillet weld break test. A force, by means of a press, a testing machine, or blows of a hammer, is applied to the apex of the V-shaped specimen until the fillet weld ruptures. The surfaces of the fracture will then be examined for soundness.


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B Figure 5.18A,B,C

C

A. Guided bend test jig. B. Guided bend test specimens. C. Wrap-around guided bend test machine.

Tensile strength test: This test is used to measure the strength of a welded joint. The width thickness of the test specimen is measured before testing, and the area in square inches is calculated by multiplying these before testing, and the area in square inches is calculated by multiplying these two figures. The tensile test specimen is then mounted in a machine that will exert enough pull on the piece to break the specimen. The testing machine may be either a stationary or a portable type. The tensile strength, which is defined as stress in pounds per square inch, is calculated by dividing the breaking load of the test piece by the original cross section area of the specimen. The usual requirement for the tensile strength of welds is that the specimen shall pull not less than 90 percent of the base metal tensile strength. The shearing strength of transverse and longitudinal fillet welds is determined by tensile stress on the test specimens. The width of the specimen is measured in inches. The specimen is ruptured under tensile load, and the maximum load in pounds is determined. The shearing strength of the weld in pounds per linear inch is determined by dividing the maximum load by the length of fillet weld that ruptured. The shearing strength in pounds per square inch is obtained by dividing the shearing strength in pounds per linear inch by the average throat dimension of the weld in inches. The test specimens are made wider than required and machined down to size.


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5.5

LABORATORY TESTING

Before conducting any laboratory tests, it is necessary for the forensic expert to establish the appropriate test standard to be used. Laboratories are typically organized for exactitude and careful recording of all work, which is also a crucial requirement for legal work. It is best for legal architectural forensic work for laboratories to use recognized testing protocols that are fully recorded. Carefully recorded and documented compliance with recognized and pertinent standards is almost a prerequisite for acceptance in court. Deviations may subject the forensic expert witness to lengthy questioning and greater scrutiny of his/her testimony. Also, prior to testing, legal considerations make it necessary for continuous control of all samples that are to be tested and Figure 5.19 Laboratory testing— which should be maintained and recorded. demonstration of ultrasonic welding of Laboratory testing is typically performed on materials or on aluminum. structural components. For litigation purposes, it is usually required for material specimens to be tested in accredited laboratories. As part of their quality system, laboratories also are required to operate a program for the maintenance and calibration of equipment used (Figure 5.19). Material testing: Testing of material samples that are removed from the site may take numerous forms. Some of the more common laboratory techniques for different materials are shown in Figure 5.20. Component testing: Load testing may be performed on components removed from the site or on mockups made in a laboratory. However, one should bear in mind that component testing is subject to various sources of error, just as are calculations. In architectural forensics applications, laboratory accreditation is important and typically includes the following material areas: concrete and aggregates, cement, soils, bituminous materials, roofing materials, masonry, steel, and nondestructive tests as related to construction. Applications for accreditation may be made for one or more tests in each area. Additional areas may be added upon request. The American Association for Laboratory Accreditation (A2LA) is a nonprofit, public service society founded in 1978 dedicated to providing comprehensive services in laboratory accreditation and laboratoryrelated training. In addition it is dedicated to providing formal recognition of competent testing and calibration laboratories, inspection bodies, proficiency testing providers, and reference material producers. A laboratory may also obtain accreditation for one or more of the following construction materials engineering standards: ASTM E329 ASTM C1077 ASTM D3666 ASTM D3740 ASTM C1093

Specification for Agencies Engaged in the Testing and/or Inspection of Materials Used in Construction Practice for Laboratories Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Laboratory Evaluation Specification for Minimum Requirements for Agencies Testing and Inspecting Bituminous Paving Materials Practice for Evaluation of Agencies Engaged in Testing and/or Inspection of Soils and Rock as Used in Engineering Design and Construction Practice for Accreditation of Testing Agencies for Unit Masonry


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Figure 5.20 Table showing common laboratory testing techniques (source, G. R. Bell).

ASTM E1212 ASTM E543 ASTM A880

Practice for Establishment and Maintenance of Quality Control Systems for Nondestructive Testing Agencies Practice for Evaluating Agencies that Perform Nondestructive Testing Practice for Criteria for Use in Evaluation of Testing Laboratories and Organizations for Examination and Inspection of Steel, Stainless Steel and Related Alloys.


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When accredited for one of these engineering standards, the laboratory’s scope of accreditation shall indicate “Construction Materials Engineering.” At the time that any inspection is carried out, the forensic expert should normally make a record of the following: (a) (b) (c) (d) (e) (f) (g) (h) (i)

5.6

Contract identification or job number Date of inspection Procedure being used Traceability identifying each inspection test site Surface condition, e.g., surface preparation Any aids used during inspection Any observed imperfections/indications Name(s) of person(s) executing the project Any other relevant information or limitations that may affect the test result

STANDARDS, CODES, AND SPECIFICATIONS

A common source for material specifications is the American Society for Testing and Material (ASTM) standards. The annual ASTM standards currently fill over 80 volumes and are divided into 16 sections as outlined below. ASTM Sections and Volumes Section 01 - Iron and Steel Products Section 02 - Nonferrous Metal Products Section 03 - Metals Test Methods and Analytical Procedures Section 04 - Construction Section 05 - Petroleum Products, Lubricants, and Fossil Fuels Section 06 - Paints, Related Coatings, and Aromatics Section 07 - Textiles Section 08 - Plastics Section 09 - Rubber Section 10 - Electrical Insulation and Electronics Section 11 - Water and Environmental Technology Section 12 - Nuclear, Solar, and Geothermal Energy Section 13 - Medical Devices and Services Section 14 - General Methods and Instrumentation Section 15 - General Products, Chemical Specialties, and End Use Products Section 00 - Index An ASTM standard represents a common viewpoint of producers, users, consumers, and general interest groups intended to aid industry, government agencies, and the general public. These standards provide guidance on the material conditions that must exist in order to be considered satisfactory for use.


CHAPTER

6 Forensic Photogrammetry 6.1

GENERAL

Photogrammetry is the technique of acquiring measurements from photographic images. The American Society for Photogrammetry and Remote Sensing (ASPRS) defines photogrammetry as “the art, science, and technology of obtaining reliable information about physical objects and the environment through the processes of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant energy and other phenomena.” The term “art” here refers to an advanced level of skill achieved through significant practical experience. In forensic photogrammetry or photograph reconstruction, specialized cameras and related equipment, targets, and software are used to determine certain measurements. The scene can then be diagrammed to scale with the accurate placement of evidence. As William Hyzer, a forensic photogrammetry expert, aptly states, “It is difficult to imagine any civil or criminal case requiring the services of an engineering expert that does not include the use of photographs in development of the case in support of testimony.” In most instances, the use of photogrammetry is more efficient, less labor-intensive, and more cost-effective than field collection. The term photogrammetry was first used by the Prussian architect Albrecht Meydenbauer in 1867; he produced some of the earliest topographic plans and elevation drawings. Although photogrammetric techniques in topographic mapping have been well established for some time, it is only in recent years that the technique has begun to be widely applied in fields such as architecture, engineering, forensics, geology, and others for the production of accurate 3-D survey data. Data acquired by photogrammetric methods is an integral part of the data input to both geographical information systems (GIS) and computer aided design (CAD), and plays an important role in areas where accurate spatial data is required. As a discipline, the field of photogrammetry is currently undergoing profound changes, with new technologies and protocols continuously being developed. One of these developments is the rapid shifting in recent years of the practice of photogrammetry from the analog world to digital. Previous conventional prac-

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tice has been to use aerial photography, manually process the negatives, diapositives, contacts and prints, and laboriously view stereoscopic pairs to capture features and topography. Recent advances in computer technology, digital cameras, and ever-more high resolution remote sensing satellite images have encouraged photogrammetric firms and equipment manufacturers to develop new technologies and techniques for data acquisition (CCD cameras, photoscanners), data processing (computer vision), structuring and representation (CAD, simulation, animation, visualization) and archiving, retrieval and analysis (spatial information Figure 6.1 Image acquisition and image processing systems). As working with 3-D computer systems in architectural photogrammetry (source, Klaus models is becoming a standard in architec- Hanke & Pierre Grussenmeyer). tural practice, architectural photogrammetry and CAAD are becoming natural partners (Figure 6.1). Defining photogrammetry: Photogrammetry can be defined as the science and technology of generating 3-D information from 2-D measurements on photos, nowadays mostly digital images. It requires a camera, PC-based software, and a few other inexpensive tools. Basically any complex three-dimensional object can usually be measured and modeled more efficiently by using photogrammetric techniques than using conventional surveying or manual measurement methods. Photogrammetry is a technique of measuring objects (2-D or 3-D) from photographs or imagery stored electronically on tape or disk taken by video or CCD cameras or radiation sensors such as scanners. Photogrammetry’s most important feature is the fact that objects are measured without being touched. This has invited the term remote sensing to be used by some authors instead of “photogrammetry.” Remote sensing is a rather young term that was originally confined to working with aerial photographs and satellite images. Today, it also includes photogrammetry, although it is still associated more with “image interpretation.”

6.2

PRINCIPLES OF PHOTOGRAMMETRY

Photogrammetrists are skilled at using photographs to obtain reliable measurements. As used in forensic science, photogrammetry involves applying scientific and mathematical techniques to two-dimensional images in order to accurately measure two- or three-dimensional objects or to create three-dimensional models or reconstructions from the two-dimensional images. As its name implies, photogrammetry, or mensuration as it is sometimes called, is a three-dimensional coordinate measuring technique that uses photographs as the basic medium for measurement. The main principle used by photogrammetry is triangulation. By taking photographs from a minimum of two different locations, so-called “lines of sight” can be developed from the individual cameras to points on the object. These lines of sight are mathematically intersected to produce the three-dimensional coordinates of the points of interest. Triangulation is also the way our two eyes work together to gauge distance or depth of field.


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Photogrammetry can be broadly divided into two main categories: 1. Photography which describes the photographic principles involved in photogrammetry, and 2. Metrology which describes the techniques for producing three-dimensional coordinates from two-dimensional photographs. 1. Photography: Taking photographs is, of course, essential for making a photogrammetric measurement. They are required to achieve the highest accuracy, reliability, and quality possible. The three main factors for good photography are: •

Field of view

Focus

Exposure

Field of view: When you look through the viewfinder of an SLR you should see as near as possible what will appear in your image, but because of the design, position and size of the camera’s mirror/pentaprism, etc., this is not always possible and you often see less than 100 percent. The higher this figure is, the more accurate the final results will be. A camera’s field of view therefore defines how much it sees and is a function of the focal length of the lens and the size (often called the format) of the digital sensor (Figure 6.2). For a given lens, a larger format sensor has a larger field of view. Similarly, for a given sensor size, a shorter focal length lens has a wider field of view. The wider the field of view, the more you see from a given location. For a medium angle lens, a convenient rule of thumb is that you will normally need to step back as far from the object as the size of the object. Thus, you need to step about three meters (10 feet) back to see a three-meter (10 foot) object. Generally for greater accuracy, the longest focal length lens possible should be used as there is a tradeoff between the field of view of a lens and accuracy. Thus, while a wider-angle lens needs less room around the object, it also tends to be less accurate. Focusing: One consideration for normal photography is focusing the lens so that the image is at its sharpest. A camera’s depth of focus refers to the range over which the image plane can be moved while an acceptable amount of sharpness is maintained. A lens’s depth of focus is a function of several factors,

Figure 6.2 Diagram illustrating field of view (courtesy, Geodetic Systems).


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including: its focal length, the f-number of the lens, format size, the distance from the camera to the object, and the size of the object. Fixing the focus effectively eliminates the depth of focus problem. Exposure: For photogrammetry purposes, it is desirable to brighten the targets and dim the background. When retro-reflective targeting is used, the target and background exposures are almost completely independent of each other. The target exposure is completely determined by the flash power while the background exposure is determined by the ambient illumination. The amount of background exposure is typically controlled by the shutter time. Eliminating the background exposure makes the targets easier to find and measure. However, if there is no background image whatsoever, trying to figure out which target is which can be confusing. A compromise is usually reached allowing the background exposure to be set so that the object is dim enough to not interfere with target measurement, but still bright enough to be observed when enhanced. Most professional cameras like the Inca3 have an auto exposure feature that can be used to automatically set the shutter speed. If auto exposure is selected, the shutter exposure is set automatically the first time you take a picture on a job. For a target exposure the flash power setting is determined by both the distance from the camera to the target and the target’s size. 2. Metrology: As mentioned earlier, photography in its broadest sense is a process that converts the real three-dimensional world into flat two-dimensional images. The camera is the device that makes this transformation or mapping from three dimensions to two dimensions. Unfortunately, we cannot completely map the three-dimensional world onto two dimensions, so some information (primarily the depth) is lost. Photogrammetry basically reverses the photographic process described above. It converts or maps the flat two-dimensional image back into the real three-dimensional reality. However, since information is lost in the photographic process, we cannot reconstruct the three-dimensional world completely with a single photograph. As a minimum, two different photographs are required to reconstruct the three-dimensional reality. If this process was perfect, the two photographs would provide more than enough information to perfectly reconstruct the three-dimensional world they represent. But as the photography and measuring process is imperfect, the reconstruction of the three-dimensional world is also necessarily flawed. Triangulation: Triangulation is the principle used by photogrammetry to produce three-dimensional point measurements. Photogrammetry uses the basic principle of triangulation and by taking photographs from at least two different locations, lines of sight can be developed from each camera to points on the object. These lines of sight, sometimes called rays because of their optical nature, are mathematically intersected to produce three-dimensional coordinates of the points of interest (Figure 6.3A). However, in order to triangulate a set of points one must also know the camera position and aiming angles or orientation for all the pictures in the set. A process called resection does this. Since the camera is a precision measuring instrument, it must be calibrated so its errors can be defined and removed. Although each of these techniques is best described separately, they are actually all performed simultaneously in a process called the bundle adjustment (Figure 6.3B). Of note, photogrammetry can measure multiple points at a time with virtually no limit on the number of simultaneously triangulated points. In photogrammetry, it is the two-dimensional (x, y) location of the target on the image that is measured to produce this line. By taking pictures from at least two different locations and measuring the same target in each picture, a “line of sight� is developed from each camera location to the target. By knowing the camera location and aiming direction, the lines can be mathematically intersected to produce the XYZ coordinates of each targeted point. Resection: Resection is the procedure used to determine the orientation or final position and aiming of the camera when a picture is taken. Typically, all the points that are seen and known in XYZ in the image are used to determine this orientation. For a strong resection, at least 12 well-distributed points are re-


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Figure 6.3A A schematic diagram showing the principle of triangulation (courtesy, Geodetic Systems).

Figure 6.3B Examples of different configurations for bundle solutions (source, Klaus Hanke & Pierre Grussenmeyer).

quired in each photograph. If a measurement lacks this number of points, or if the points are not well distributed, it is recommended to add points. When points are added to strengthen the solution these points are called fill-in points. Knowing the XYZ coordinates of the points on the object allows the camera’s orientation to be computed. To achieve this, both the position and aiming direction of the camera are required. It is insufficient to know only the camera’s position since the camera may be located in the same place but be aimed in any direction. Consequently, it is vital to know both the camera’s position, which is defined by three coordinates, and where it is aimed, which is defined by three angles. Thus, although three values are needed to define a target point (three coordinates for its position), we need six values to define a picture (three coordinates for position and three angles for the aiming direction).


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Architectural and engineering applications: As the term “photogrammetry” was devised by an architect, it is not surprising that the greatest use of the technique, outside of mapping, has been in the arena of architectural recording and is now established as a standard technique for the survey of building elevations. The technique is also applied in the recording of historic buildings and monuments to produce elevation drawings and sections normally at scales of 1:20, 1:50 and 1:100 (Figure 6.4A,B). Imagery can be obtained from a variety of cameras ranging from large format metric cameras, where high accuracy and archival value are important, to smaller digital cameras (these can also be metric), which are useful where access is restricted. Use is often made of aerial platforms and scaffolding to obtain the most economic coverage of a façade. Architects are becoming increasingly aware of the benefits of accurate photogrammetric surveys, particularly the advantage of using a totally remote measurement system with superb archival qualities. The products available range from rectified images, orthophotos, or precise 3-D data formatted for use in a CAD package.

Figure 6.4A,B A. A stereopair from CIPA-testfield “Otto Wagner Pavillion Karlsplatz, Vienna.” B. A façade plan derived from above stereo pair of images (source, Klaus Hanke & Pierre Grussenmeyer).


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PhotoModeler is one of several software packages widely used by professionals as a 3-D measurement and modeling tool in architectural applications, preservation, forensic and conservation (Figure 6.5A,B). Using photographs or video images taken at the scene, PhotoModeler helps extract accurate 3-D measurements and models, allowing you to analyze and measure failures and accident scenes long after the incident has taken place. These programs can be used for: •

Documenting and measuring different types of buildings and structures for conservation and preservation

Generating 3-D models for visualization purposes and view studies

Generating elevation drawings of existing structures and new construction

Generating rectified photographs of facades from single and multiple photo projects

Producing photo-textured 3-D models for realistic walk-bys

Surveying and recording existing structures and objects

Various forensic applications.

Other applications: The remote measurement aspect of photogrammetry makes it ideal for many other applications which are out of the scope of this book.

6.3

PHOTOGRAPHIC TECHNIQUES

Depending on the available material (metric camera or not, stereopairs, shape of recorded object, control information, etc.) and the required results (2-D or 3-D, accuracy, etc.), different photogrammetric techniques can be applied. Depending on the number of photographs, three main categories can be distinguished. Mapping from a single photograph: Only useful for plane (2-D) objects. Obliquely photographed plane objects show perspective deformations which have to be rectified. For rectification there exists a broad range of techniques. Some of them are very simple. However, there are some limitations. To get good results even with the simple techniques, the object should be plane (for example, a wall), and since only a single photograph is used, the mappings can only be done in 2-D. The rectification can be neglected only if the object is flat and the picture is made from a vertical position toward the object. In this case, the photograph will have a unique scale factor which can be determined if the length of at least one distance at the object is known. Digital rectification: Digital rectification is a rather new technique. It is somehow similar to “monoplotting”. But here, the scanned image is transformed pixel by pixel into the 3-D real-world coordinate system. The result is an orthophoto, a rectified photograph that has a unique scale. Stereophotogrammetry: As the term implies, stereopairs are the basic requirement here. These can be produced using stereometric cameras. If only a single camera is available, two photographs can be made from different positions, trying to match the conditions of the “normal case.” Vertical aerial photographs come closest to the “normal case.” They are made using special metric cameras that are built into an airplane looking straight downward. While taking the photographs, the airplane flies over a certain area in a meandric way, so that the whole area is covered by overlapping photographs. The overlapping part of each stereopair can be viewed in 3-D and consequently mapped in 3-D using one of the following techniques: •

Analogue: The analogue method was mainly used until the 1970s. The method consists of two projectors, with the same geometric properties as the camera used, that project the negatives of


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Figure 6.5A,B A. Use of PhotoModeler as a 3-D measurement and modeling tool. In this illustration, the 3-D surface model on the left shows the detail that can be achieved with PhotoModeler. Compare this to the photo of the Merlion on the right. B. PhotoModeler Pro 5 was used to create this model of the Bank of China Tower in central Hong Kong which is a 368 meter skyscraper. The project was completed using 25 photos taken with a 2.1 Mega Pixel Canon Powershot digital camera (source, Eos Systems, Inc.).


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the stereopair. Their positions then have to be exactly rotated into the same relationship toward each other as at the moment of exposure. After this step, the projected bundle of light rays from both photographs intersect with each other forming a three-dimensional optical “model.” The optical model is viewed by means of a stereoscope. The intersection of rays can then be measured point by point using a measuring mark. This consists of two marks, one on each photograph. When viewing the model, the two marks fuse into a 3-D object, which can be moved and raised until the desired point of the 3-D object is met. The movements of the mark are mechanically transmitted to a drawing device which creates the maps. Analytical: The first analytical plotters were introduced in 1957 and from the 1970s on they became commonly available on the market. The idea is still the same as with analogue instruments. But here, a computer manages the relationship between image- and real-world coordinates. The restitution of the stereopair is done within three steps: 1. After restoration of the “inner orientation,” where the computer may now also correct for the distortion of the film, both pictures are relatively oriented. After this step, the pictures will be viewed in 3-D. Then, the absolute orientation is performed, where the 3-D model is transferred to the real-world coordinate system. Therefore, at least three control points are required. 2. After the orientation, any detail can be measured out of the stereomodel in 3-D. Like in the analogue instrument, the model and a corresponding measuring mark are seen in 3-D. The movements of the mark are under the photogrammetrist’s control. The main difference to the former analogue plotting process is that the plotter no longer plots directly onto the map but onto the monitor’s screen or into the database of the computer. 3. The analytical plotter uses the computer to calculate the real-world coordinates which can be stored as an ASCII file or transferred on-line into CAD programs. In that way, 3-D drawings are created, and can be stored digitally, combined with other data, and plotted later at any scale. Digital: The digital photography revolution continues to progress by leaps and bounds. Digital techniques have now become widely available. Here, the images are not on film but digitally stored on tape or disc. Each picture element (pixel) has its known position and measured intensity value, only one for black/white, several such values for color or multispectral images.

Mapping from several photographs: This kind of restitution, which can be done in 3-D has only become possible by analytical and digital photogrammetry. Since the required hardware and software are steadily getting cheaper, it’s application fields grow from day to day. Here, mostly more than two photographs are used. Three-dimensional objects are photographed from several positions located around the object, where any object-point should be visible on at least two, or better yet three photographs. The photographs can be taken with different cameras and at different times (if the object does not move). Technique: As mentioned above, only analytical or digital techniques can be used. During all methods, first a bundle adjustment has to be calculated. Using control points and triangulation points the geometry of the whole block of photographs is reconstructed with high precision. Then the image coordinates of any desired object-point measured in at least two photographs can be intersected. The results are the coordinates of the required points. In that way, the whole 3-D object is digitally reconstructed. Photographing devices: A wide variety of cameras have application in forensic photography, and while traditionally the 35-mm single-lens reflex (SLR) has been found to be the most versatile and widely used, today the digital camera has taken over because of its ability to provide instant image access. Current photogrammetric practice includes a combination of analytical and digital photogrammetry. The advantages of the 35-mm SLR camera is that it offers accurate framing, easy focusing, interchangeable


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lenses, portability, a wide choice of films, and versatility in use. It is also capable of producing transparencies for projection and high quality prints for direct viewing. However, the main disadvantage is that of wetprocessing photography which does not allow you to view the image within a reasonable time after exposure. This disadvantage has been resolved with the availability of the digital camera. A photographic image is a “central perspective.” This implies, that every light ray which reached the film surface during exposure passed through the camera lens (which is mathematically considered as a single point, the so called “perspective center”). In order to take measurements of objects from photographs, the ray bundle must be reconstructed. Therefore, the internal geometry of the used camera (which is defined by the focal length, the position of the principal point and the lens distortion) has to be precisely known. The focal length is called “principal distance,” which is the distance of the projection center from the image plane’s principal point. Depending on the availability of this knowledge, the photogrammetrist divides photographing devices into three categories: 1. Metric cameras: They have stable and precisely known internal geometries and very low lens distortions. Therefore, they are very expensive devices. The principal distance is constant, which means that the lens cannot be sharpened when taking photographs. As a result, metric cameras are only usable within a limited range of distances toward the object. The image coordinate system is defined by a series of fiducial or index marks, usually four or eight, which are fixed in the focal plane of the camera. Figure 6.6A shows an analogue metric camera (Leica R5 Elcovision) and Figure 6.6B shows a digital metric camera (Fuji FinePix S3 Pro). 2. Non-metric and stereometric cameras: Off-the-shelf digital cameras have to be regarded as nonmetric cameras although there are currently a number of more expensive high quality metric digital cameras. The non-metric cameras have been developed primarily to meet mass market demand but they are not in accordance with photogrammetric stability demands. Nevertheless, there is often mounting pressure to use such cameras because they are typically significantly cheaper than their metric counterparts. However, these cameras have limited applications because they lack a fiducial reference system, which means that the precision will not reach that of metric cameras, and their use is restricted to instances where high accuracy is not a prerequisite.

Figure 6.6A,B A. An analogue metric camera—Leica R5 Elcovision. B. A digital metric camera—Fuji FinePix S3 Pro.


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A stereometric camera in principle consists of two metric cameras mounted at both ends of a bar, which has a precisely measured length (mostly 40 or 120 cm). This bar is functioning as the base. Both cameras have the same geometric properties. Since they are adjusted to the normal case, stereopairs are created easily. If an object is photographed from two different positions, the line between the two projection centers is called “base.” If both photographs have viewing directions which are parallel to each other and in a right angle to the base (the so called “normal case”), then they have similar properties as the two images of our retinas. Therefore, the overlapping area of these two photographs (which is called a “stereopair”) can be seen in 3-D, simulating man’s stereoscopic vision. In practice, a stereopair can be produced with a single camera from two positions or using a stereometric camera. 3. Digital cameras: Since their introduction, the use of digital cameras has increased dramatically. These are cameras in which the conventional photographic material has been replaced by an electronic light sensitive sensor. Digital photogrammetry (softcopy photogrammetry) is well over a decade old now, and has matured and superseded the analytical photogrammetry in terms of accuracy, production, efficiency, and multiple usages. But for digital cameras to be of use in photogrammetry, their resolution has to be of sufficient quality to produce a high resolution image. There are now a large number of high resolution digital cameras and systems available that have been developed specifically for photogrammetric use. For example, Geodetic Services, Inc. of Melbourne, Florida, USA produces the Inca3 digital camera (Figure 6.7A) and the V-Star System which is a photogrammetric coordinate measurement system that uses single or multiple digital cameras to take photographs that are subsequently processed to obtain spatial three-dimensional coordinates (Figure 6.7B). The V-Stars/M standard configuration essentially consists of

Figure 6.7A,B A. The Inca3 digital camera. B. The Nikon ex.2 digital camera used in V-Stars/M standard configuration (source, Geodetic Services, Inc.).


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a notebook computer, two cameras and some accessories and is highly portable. Additionally, the system can be operated off-line or on-line. Imetric of Porrentruy, Switzerland also offers excellent system packages like the ICam Photogrammetry systems. These are high-accuracy portable coordinate measuring machines (CMMs) which can be used to determine the 3-D coordinates of targets, of points materialized with adapters, as well as of features. The ICam system is extremely portable, consisting of a camera, coded and un-coded targets, scale bars, and for certain applications, various adapters. Other useful cameras include the Nikon D80 SLR calibrated digital camera (Figure 6.8A) that is often used with the PhotoModeler 3-D modeling and measurement package, and the Nikon D300 (Figure 6.8B) with its 12.3 megapixel DX-format CMOS sensor. Kodak, Canon, Olympus and other camera manufacturers have also produced high quality digital cameras that can be used successfully in architectural photogrammetry. RolleiMetric also markets a range of state-of-the-art photogrammetric survey cameras and evaluating systems which are used in the field of architecture, facility management, cultural heritage, and other applications (Figure 6.8C,D). Factors affecting measuring accuracy in photogrammetry: The most important factor to consider in determining project requirements is deciding the level of accuracy required to achieve the desired result (Figure 6.9). Accuracy, photographic scale, and project size are all directly related. Typically, the higher the level of accuracy required, the larger the scale of photography necessary, which in turn increases the mag-

Figure 6.8A,B,C,D A. The Nikon D80 SLR calibrated digital camera, often used with the PhotoModeler 3-D modeling software package. B. The Nikon D300, 12.3 megapixel DX-format CMOS sensor. C. Rollei d7 metric digital single-lens reflex (SLR) camera. D. Rolleiflex 6008 metric single-lens reflex camera system.


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nitude of the job. Once the accuracy requirement is determined, the process of designing a project to achieve the desired results can begin. However, the accuracy standard of a photogrammetric measurement can vary significantly depending on several interrelated factors. The main factors that affect accuracy include: Camera calibration: This is the process of finding the true parameters of the camera being used. These parameters include focal length, format size, principal point, and lens distortion. Even where the cameras and lenses used are of the highest quality, they still need to be precisely calibrated to remove errors that may be present within the system. When the camera is calibrated at the time of measurement, and under the environmental conditions that exist (temperature, humidity, etc.) at the time of measurement, it is termed self-calibration. Self-calibration is a powerful technique in which the camera is calibrated as a by-product of the measurement. This is much more preferable to relying on laboratory calibration that may have been done under significantly different conditions than existed at the time of measurement. In order to self-calibrate the camera a minimum of six photographs are needed if the object is essentially flat and a minimum of four photographs if the object isn’t flat. There are certain other requirements that must be met in order to self-calibrate a camera, but these are outside the scope of this chapter. Photo resolution: The higher the resolution of the images, the better chance of achieving high accuracy because items can be more precisely located. Image resolution is defined by the quality and capabilities of the digital camera or film scanner being used.

Figure 6.9 Some of the main factors that affect the level of accuracy in photogrammetry.


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Angles between photos: Points and objects that appear only on photographs with very low subtended angles (for example a point appears in only two photographs that were taken very close to each other) have much lower accuracy than objects on photos that are closer to 90 degrees apart. Camera positions with good spread provide the best results. Photo orientation quality: One factor that greatly contributes to the accuracy of projects is an accurate orientation for every camera position. The orientation quality improves as the number of well-positioned points increases and also as the points cover a greater percentage of the photograph area. Some software packages like PhotoModeler compute the location and angle of the camera for each photo during processing—this is called orientation. Size of object: The size of the object being measured also impacts accuracy. Photo redundancy: A point’s position or object’s position is generally more accurately computed when it appears on several photographs—rather than the minimum two photographs. Targeting the object: A three-dimensional point’s accuracy is essentially tied to the precision of its location in the images. This image positioning can be improved by using targets. The photogrammetry accuracy scale in Figure 6.10 illustrates the effects of some of the main factors that influence accuracy. The diagram represents a pyramid with the four factors at the base of the pyramid and high accuracy at the top of the pyramid. To get higher accuracy (a higher pyramid) you need more of the items shown on the lines of the pyramid (higher resolution, smaller size, more photos, and wider, but not too wide, geometry). Instruments and camera accessories: A stereoplotter is an instrument used in photogrammetry to compile spatial data by using stereoscopic models and ground coordinates. The more traditional, analytical stereoplotter utilizes diapositives (film transparencies) of the photography. The diapositives are then placed on glass platens in the carriage of the stereoplotter and the photos are oriented. Information is supplied to the computer plotter resulting in a series of mathematical calculations and optical observations which enable the photogrammetrist, through sophisticated optics, to view the photography in a 3-D environment. Photogrammetry is rapidly evolving into a digital environment referred to as softcopy photogrammetry. Softcopy photogrammetry utilizes the same photogrammetry principles as the analytical stereoplotter, but

Figure 6.10 Photogrammetry accuracy scale—four accuracy factors of photogrammetric measurement (source, Geodetic Systems Inc.).


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using digital files of the imagery. These files can be supplied either directly from a digital sensor or by scanning the film. Film scanning is typically performed with an extremely accurate (micron accuracy-level) scanner which results in a digital representation of the film. The digital files are then displayed on a computer monitor in a manner allowing the operator, equipped with a pair of specially designed glasses, to view the digital files in a 3-D environment. Both approaches (analytical stereoplotter or softcopy photogrammetry) allow the photogrammetrist, with the aid of sophisticated software, to interpret the imagery and collect the data necessary to produce a reliable image. The professional photogrammetric investigator typically needs an assortment of lenses and other photographic accessories to meet project requirements. A 35- to 105-mm zoom lens fulfills most focal length requirements. The short focal length is used mainly in scenes where the working distance is restricted. The long focal length on the other hand allows distant objects to be recorded that cannot otherwise be easily accessible for close examination. It should be noted that image distortion is greater in most zoom lenses compared with an equivalent fixed-focal length lens (e.g., 50-mm lens). Another zoom lens disadvantage is the problem of determining the exact focal length used in recording a scene. Where the focal-length settings on the zoom lens are engraved on the lens barrel, the value selected should be recorded in field notes. Unfortunately, the majority of zoom lenses lack precise focallength gradations, and focal length settings are easily overlooked when jotting down field data. These omissions can gravely affect the validity of an expert’s testimony when photographic evidence is involved. Figure 6.11 shows a list of useful photographic accessories recommended by William G. Hyzer, a forensic photogrammetry expert. Hyzer considers a stable tripod, cable release, electronic flash unit, tape measure, and appropriate in-scene reference scales as absolute requirements. The importance of the remaining items depends on the project Figure 6.11 Useful photographic accessories (source, William G. Hyzer). and the expert’s field of specialty.

6.4

MEASUREMENTS FROM PHOTOGRAPHS

Photogrammetry is a flexible and powerful measuring technology. Measurements have been done on land, sea, underwater, as well as in the air, and outer space. Three-dimensional photo-based measurements are accomplished by extracting two-dimensional information from multiple photographs or digital images. Reference scales: One of the most important non-photographic accessories in the forensic expert’s photographic kit is a selection of in-scene reference scales or scale bars. The actual need for making measurements from photographs may not be immediately apparent, but when the physical evidence is removed and the photograph is the only remaining source of spatial information regarding a critical measurement that was overlooked or possibly recorded in error, the need becomes significant. Scale bars are generally used to provide precise distance information which allows the measurements to be correctly scaled. However, not all measurements need to use scale bars. For example, scale data may be acquired by using the known distances between some stable points on the object. Or, the nature of the application may not require scaled measurements.


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The scale bars should be secured on or near the object to avoid movement with respect to the object during measurement. Scale bar points, like any other points, need to be seen from at least two different locations. However, since these points are used to scale the measurement, it is advisable to try and see them from as many locations as possible. Likewise, they should be placed in a manner that does not block other targets. For best results, scale bar targets should be at least as large as the other targets. Scaling photogrammetry: Photogrammetric measurements are inherently dimensionless. To scale a photogrammetric measurement, at least one known distance is required. If the actual coordinates of some targeted points are known beforehand, the distances between these points can be computed and used to scale the measurement. Another possibility is to use a fixture with targets on it and measure this along with the object. As the distance between the targets on the bar is known, this information can be used to scale the measurement. Multiple scale distances: Whenever possible, more than one distance should be used to scale the measurement. A good system combines the individual scale measurements to provide higher scale accuracy. This also facilitates the finding of scale errors which is important because when a reference scale is used and it is in error, the entire measurement will be incorrectly scaled. On the other hand, if you have multiple scale distances, scale errors can be detected and removed. Three known scale distances are typically needed to detect an error and remove it. Long scale distances: The scale distance(s) should be as long as practical as any inaccuracy in the scale distance(s) is magnified by the proportion of the size of the object to the scale distance. This means that if a 40 inch (one meter) scale distance is used on a 400 inch (10 meter) object, and the scale distance gives an error of 0.004 inch (0.1 mm), then the object will display ten times this error, or 0.040 inch (1 mm). Measuring steps: Proper measuring usually consists of several steps such as: planning the measurement, targeting the object, taking pictures, measuring pictures, processing pictures, and analyzing the results. These steps are only a general guide, and each measurement project is different. The order of the measuring steps may also vary. For example, on some projects, it may be prudent to take all pictures first (to minimize time spent on site) and then measure them, while on other projects, each picture will be taken and then measured. On the other hand, some projects may require the taking and measuring of some pictures, and then processing them to get preliminary results to make measuring the remaining pictures easier. Planning summary and checklist: Below is a planning checklist to assist with project planning. It can be added to or modified to suit individual project needs: 1. Triangulation requirements a. Need two different sightings of every point (prefer four as a minimum) b. Need good intersection angles between points (60–120 degrees is good) 2. Resection requirements a. Need to see the autobar or four known points in every picture (points cannot be in a line) b. Need at least 12 well-distributed points on every photo (but 20 is better) 3. Self-calibration requirements a. Need to roll camera by 90 degrees (at least once, more is better) b. Need at least four to six photographs (four if not flat, six if flat) c. Need photographs from at least three different locations d. Need at least 20 well-distributed points in the entire measurement (but 40 is better) 4. Overlap requirements (only necessary if entire object is not seen at once) a. Need at least three common points for adjacent sections (but more is better) b. Common points cannot be in a line (triangle or better)


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5. Scale requirements (only needed if accurate scaling is needed) a. At least one known distance is available (prefer at least three) b. Scale distance is as long as practical. Number of points needed for a good measurement: To get a good solution, we recommend measuring a minimum of 12 well-distributed points (and preferably 15 to 20) in each photograph. Also, the entire measurement should have at least 20 (preferably 30) well-distributed points. When in doubt, add more points. It’s quick and easy to do, so go ahead and do it. Of course, measuring more points will lead to a better solution, but you quickly reach a point of diminishing returns. In most cases, measuring more than 40 well-distributed points in each photograph, and more than 60 well distributed points overall will not significantly improve the solution. Notice we always qualify the number of points with the term well distributed. The distribution of the points can often be much more important than the number of points. It is better, for example, to have 20 points which are spread out over the entire area being measured than to have 50 clustered in one small area and 50 more clustered in another small area. Points which are added only to improve the distribution of points are usually called “fill-in” points.

6.5

RECONSTRUCTION METHODS

Realistic image synthesis continues to gain importance in such areas as design, architecture, entertainment, and more. A common trend in all these areas is the quest for more realistic images of increasingly complex models. However, until recently, cost has been a major inhibiting issue in achieving the desired results. Indeed, one of the main drawbacks of photogrammetric reconstruction methodology has been the need for costly medium to high-end hardware and software. This traditional impediment is rapidly disappearing with the widespread use of digital cameras and enormous advances in computer technology and electronics. This is partly because: •

Digital systems are based on computer technology (in contrast to analogue and analytical instrumentation, which were based on optical-mechanical parts) and the costs of these technologies have rapidly declined.

Off-the-shelf “amateur” digital cameras are increasingly being used and these are becoming less expensive, while their resolution has increased dramatically over the past few years. Even though these cameras are non-metric, extensive literature shows that metric content is recoverable to a high degree from non-metric imagery, the quality of the recovery depending on the knowledge of the internal geometry of the camera (through camera calibration).

Many affordable software packages have become available during the last decade (Figure 6.12).

There are several traditional methods used in reconstruction, but these have limited applicability due to their now outdated and tediousness analogue approaches. Nevertheless, they are discussed briefly below: A. Two-dimensional reconstruction: There are two basic traditional approaches to two-dimensional reconstruction from a single image containing an appropriate scale or four known points of reference, and they are: 1. Algebraic: This method requires the solution of eight simultaneous equations to achieve the determination of eight calibration constants in the two equations below:


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X and Y are object-plane coordinates, x and y are corresponding image plane coordinates, and C1, C2, C3, etc. are calibration constants that must be determined for each particular combination of photograph and scene. The solution requires four points in the object and image planes for which the X, Y, x, and y values are known. Once the calibration constants have been determined from these four known points, any point in the object plane can be located from the x and y coordinates of that same point in the image. The solution of eight simultaneous equations is a tedious operation to perform manually. Computer software is available and is recommended as the only practical approach to computing the calibration constants. 2. Graphical: This method is based on adding grids to a photograph that includes a perspective grid. However, care must be taken when using this method as it is vulnerable to cumulative errors in laying out the transversal grid lines. However, one can achieve improved results by combining the two methods, but this is outside the scope of this book. B. Three-dimensional reconstruction: Traditionally, the three-dimensional reconstruction of a scene usually requires a matched pair of images taken from two vantage points. The heights of objects that stand normal to flat surfaces can be determined from single images where there is sufficient three-dimensional information available for calibration purposes. The height of an object can be scaled if the film and object planes are mutually perpendicular. This can be done by simply transferring its height (e.g., with di-

Figure 6.12 Commonly available 3-D software systems.


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viders) to the transversal grid line intersecting its base, and then measuring the distance between two orthogonal grid lines in the gridded photograph. If the film plane is oblique to the object plane and the focal distance is not known, sufficient information for height measurements is provided by four known points, or a perspective grid template plus two scales of known heights that intersect the plane at right angles. Height of the object in question can be determined by locating the points at the base of the object of unknown height and the two scales of known height using the traditional methods above. The unknown height can be calculated relative to the two known heights. C. Reverse projection: This is another technique, also referred to as inverse photogrammetry, and is used in obtaining measurements from photographs that depict information that no longer exists at the scene and do not include sufficient calibration data for performing the two-dimensional or three-dimensional reconstruction procedures. Reverse projection is a fairly old technique that is rather seldom used today, largely because of its limited applicability and the tediousness of earlier analogue approaches, although today’s digital processing techniques offer tools making its application both easier and more flexible. This method requires making a copy transparency of the original photograph and returning to the original scene with an SLR camera equipped with a zoom lens. The transparency can be used in one of two ways. It either is placed in contact with the focusing screen in a 35-mm SLR camera in which the screen is accessible, or is sandwiched with a piece of frosted plastic film and taped into the camera’s focal plane.

6.6

LABORATORY TESTING

Photogrammetry has been widely used to measure the results of load testing in laboratories. Object sizes can vary from small samples of materials or models up to full sized structures. The number of photographs required per epoch can vary from one to ten or more photographs. It is possible to use a single photograph if movement in only one plane is anticipated. For example, if a beam is being loaded from above it is often reasonable to expect that all deformation in the beam will occur in the vertical plane. However, the use of at least two photographs would uncover any unexpected horizontal deflection of the beam. If complex 3-D deformation is expected then highly convergent multistation photography should be used.

6.7

GENERAL GUIDELINES FOR EFFECTIVE FORENSIC PHOTOGRAPHY

The main objective of the forensic photographer is to produce images that reflect the photographer’s best efforts in depicting reality, and include adequate information to allow complete and accurate analysis. The photographic and reporting guidelines outlined below are offered to assist in achieving these objectives: •

Establish measurement objectives and accuracy requirements. A good estimate of the required measurement accuracy for each photogrammetry project is important, avoiding both under- and over-estimating the requirements. This should be followed by the selection and calibration of the cameras and lenses to be used. Accurate photogrammetry requires precise knowledge of the optical characteristics of each camera, referred to as the internal camera parameters. Whenever possible, anticipate how each photograph will be used, and then decide upon the most appropriate camera position and photographic technique accordingly.


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Decide whether to use film or a digital camera. If film is being used, select the most appropriate film for the situation in hand, e.g., 35-mm negative film or direct reversal film. Of note, close-range photogrammetry today (as opposed to aerial photogrammetry) has shifted dramatically so that it now uses digital cameras almost exclusively rather than traditional film or analog (for video) equipment due to its many advantages, which include: 1. Images are immediately available for computer analysis (using removable storage media or cable connection). 2. Photogrammetrists can take numerous extra pictures at the test site using different camera and lighting settings. The photogrammetrist can then select the best images for the analysis, without incurring any additional cost. 3. The measurement accuracy can be higher than for standard 35-mm film, which can shift relative to the camera lens. Also, image transmissions (for video) are higher quality using digital data lines. Plan your photographs carefully and logically to allow you to completely cover the scene. You may not get a second chance. Good field notes and record keeping are essential.

Process, scale, and rotate the data. Identify each photograph and complement it with annotations on a separate sheet. Record all relevant information including time, date, scene details, pertinent photographic and camera data, etc.

Select type, size, and distribution of targets. Ensure that important scenes or objects are photographed from different vantage points to fully portray and explain the situation. Photogrammetry achieves the greatest accuracy using high-contrast, solid-colored circles as targets.

In the absence of statistical criteria, use a graded scale and/or take appropriate measurements in all photographs which are expected to be used for quantitative purposes at a later date. Ensure that the scale does not obstruct or obscure possible critical evidence.

If a digital camera is used, copy all images onto a CD, DVD or other storage device and keep on file (a period of 10 years is good practice). If film is used, keep original negatives and transparencies on file. Also maintain a file for receipts, film processing, printing, shipping and other miscellaneous items.

If camera originals or CD/DVD of digital photos are given to an attorney or another expert, obtain a written receipt for your files.

Select data analysis software and import the images. Some conclusions can be made using statistical criteria, whereas other conclusions rely on subjective criteria. When a statistical basis for a conclusion can be made, this conclusion should be quantitatively reported.

Decisions derived from photogrammetric analyses can often be reported in terms of statistical criteria. In contrast, conclusions derived from image-content analyses are frequently based on subjective criteria. Any ambiguity or incomplete data in the final conclusion should be explained and reflected in the reporting. Also any lessons learned and how to improve the methods should be stated.

The report format and contents of a photogrammetric analysis should typically follow industry standards.

Photogrammetrists are obviously skilled at using photographs to obtain reliable measurements which is why close-range photogrammetry is used in many areas of litigation. Experts in disciplines outside of im-


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aging science however, should refrain from trying to apply any of the reconstruction methods cited. The intricacies of defending the scientific validity of these techniques under cross examination require the expertise of a specialist in imaging science who is qualified to testify in matters pertaining to light, optics, physics and chemistry of imaging, photogrammetry, and the psychophysics of human visual perception in the interpretation of images. Asserting such qualification is an open invitation to the opposing attorney to inquire into the expert’s knowledge of highly technical areas of photographic science. In photogrammetry, analog photographs can be digitally scanned, or today’s “amateur” digital camera images are directly imported into specialized PC-based photogrammetry software programs that are able to give us accurate 3-D models and measurements displayed in court-ready diagrams for demonstrative evidence. But there remain many deficiencies of photography in accurately trying to portray an object or scene, such as limited tonal range and imperfect color reproduction, in addition to the possible manipulation or “doctoring” of the image. This is particularly true with modern digital processing methods, especially digitally recorded images. Importance of experience in photogrammetry: In most cases, photogrammetry is more than scanning photographs or importing digital camera images into a software program and creating “instant, accurate 2-D or 3-D measurements.” Lee DeChant, of DeChant Consulting Services—DCS Inc., and co-developer of the iWitness close-range photogrammetry software system, says, “A photogrammetry expert can determine if your case pictures and requested data can be extracted from the image to meet your objectives. Typically, working with bystander pictures from an unknown camera source, or even the client’s camera, can present many technical problems that must be overcome by an experienced photogrammetrist. A photogrammetry expert will typically review the analog pictures or digital images to determine if the attorney’s requested measurements are in fact doable from the case pictures. The amount of time to generate the photogrammetric 3-D model/measurements is a function of knowledge of the camera specifics, the complexity of the scene, the picture geometry, what is important to extract from the pictures, as well as accuracy expectations.” What to look for in a photogrammetry expert: As stated above, experience is a prime consideration, and the photogrammetrist should show a proven record of image-based measurements and reconstructions to support litigation cases—particularly in the interpretation of attorney-provided photos/images. In addition to having an attractive and persuasive personality, the expert should be able to complete the photogrammetry, prove the accuracy of the work, and put the data into a layman’s format that is easy for the attorney, judge, and the jury to understand. A competent photogrammetrist should be well versed in forensic measurements and reconstructions, be it from academic studies or from non-academic use, with several years of practical field experience. It would also be helpful to have published papers or articles on the subject of photogrammetry. It all adds to the credibility of the photogrammetrist.


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CHAPTER

7 The Building Site 7.1

GENERAL

Many site components, including soil, topography, paving, landscaping, and drainage, can be significant budget issues and should be reviewed carefully. The diversity of the site components is clearly illustrated in Figure 7.1. The trees, groundcover, and lawns of a facility site directly impact both the value and aesthetics of a property. Common deficiencies in the natural environment of the site include irrigation and drainage problems and dead or missing vegetation. It is usually prudent for a prospective purchaser of a property to have an environmental impact assessment conducted, the general objective of which is to ensure that the effects of the project over its projected life do not unacceptably degrade the environment and that no residual effects are anticipated that would contribute to long-term environmental deterioration. It is surprising that environmental assessments are typically required by lenders, but not necessarily requested by the client. Nevertheless, the forensic architect may feel it appropriate to recommend that the owner bring in environmental specialists to undertake any number of studies. But because parties and properties differ, the level of inquiry that is appropriate will differ. Possible recommendations could include: •

Phase I Environmental Site Assessments and Compliance Audits

Phase II Analytical Testing

Phase III Remediation Design and Contractor Solicitation

Phase IV Monitoring and Remediation

Asbestos Surveys and Abatement Management

Lead-Based Paint Surveys and Abatement Management

Site structures should also be evaluated when considering site issues. These structures include retaining and dividing walls, shacks, fountains, and other building structures. Common deficiencies include general damage, deterioration, and poor maintenance.

101 Copyright © 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.


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Identify the extent of the site systems and visually observe each system. Site assets not reportable as ‘constructed assets’ are considered to be land elements. Adjoining assets—if part of building or within the boundary, should also be included in the report. Provide an evaluation of the visual character of the site. This may include view boundaries, special visual features, vegetative character, microclimate conditions, or sensory information. When walking the site the forensic architect should indicate the condition of landscaping, lighting, parking surfaces, curbs, walks, drainage, retaining walls, etc. Note any unusual site features such as wells, retention ponds, etc. The site infrastructure, which includes the irrigation system, lighting system, and traffic circulation patterns, should be considered when evaluating the quality and performance of the site. Infrastructure deficiencies include insufficient coverage, deterioration, and inconsistent usage. Also, within the past few years, underground storage tank (UST) evaluation, and soil and groundwater contamination evaluation have been added more and more frequently to the scope of work of a typical facility evaluation. In the past, both above and below ground storage tanks were conFigure 7.1 Typical components to be surveyed during a site evaluation. structed using a single wall containment. As a result, many older tanks have become damaged or deteriorated to the point of leaking a variety of chemicals, from oil to chlorinated hydrocarbons. The leaking tanks can contaminate both the soil and the groundwater at the property. As is typical in the Level I assessment, in addition to a review of the existing conditions at the site, a thorough review of the past and present public records of the property is performed to determine the historical uses of the site. If the site was used for operations extensively employing chemicals, such as a plating factory or a gasoline situation, the property should be reviewed carefully. The forensic consultant should be given timely access, which is complete, supervised, and safe, to the subject property’s improvements (including roofs) or failure in question. In addition, access to the subject property’s staff, vendors, and appropriate documents should be provided by the owner, the owner’s representative, or made available by the user, or a combination thereof. In no event should the forensic expert seek access to any particular portion of the property, interview property management staff, vendors, or tenants, or review documents, if the owner, user, or occupant objects to such access or attempts to restrict the expert from conducting any portion of the inspection, research or interviews, or taking of photographs. Any conditions that significantly impede or restrict the expert’s ability to inspect or research, or the failure of the owner, the owner’s representative, or occupant to provide timely access, information, or requested documentation, should be timely communicated by the consultant to the owner or the owner’s representative. If such conditions are not remedied, the consultant is obligated to state within the consultant’s report all such material impediments that interfered with the conducting of the inspection.


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Finally, the EPA issued the standards and practices for conducting all appropriate inquiry (AAI) on November 1, 2005, and this rule went into effect on November 1, 2006. The rule applies to any party claiming protection from liability as an innocent landowner, a contiguous property owner, or a bona fide prospective purchaser. In conjunction with the development of this rule, ASTM International updated the E1527 standard to ASTM E1527-05 which is consistent and compliant with the AAI rule. The rule and ASTM standard requirements are designed to identify hazardous substances at, on, in or to the property that would cause the incurrence of response costs for which the purchaser would be liable. It is strongly advised that users of Phase I assessments modify their standard Phase I Request for Proposal to require that the Phase I comply in all respects with the AAI rule and ASTM E1527-05.

7.2

COMPONENTS TO BE EVALUATED

Environmental conditions and hazards: Conditions of environmental concern relating to the site should be recorded and documented. This would include: storm drainage patterns indicating watershed boundaries and the direction of flow; storm water management areas; flood plains; wetland areas; wildlife habitats (especially for threatened and endangered species); buried tanks, and other hazards. Sources of air, noise and light pollution should be identified and recorded and their environmental impact on the site evaluated. The need and potential for achieving mitigation should be assessed and non-point sources of pollution entering or leaving the area evaluated. All existing on-site conditions and future development should be recorded. Topography: More than any other site characteristic, topography will influence the design of a project. In new construction, a project should be designed to fit the topography, and require a minimum of grading, so as to preserve the character of the site and produce a compatible, economical, and efficient composition. Where existing buildings exist, the topography of the site should be observed and any unusual or problematic features or conditions noted. Design of parking areas should be to economize construction by conforming to existing topography and balancing the cut and fill quantities. If there is no alternative to placing the parking on steep slopes, the parking lot should be terraced into the slope and more than one parking level is to be provided. Figure 7.2 shows an example of a topographic site model. Storm water drainage: Storm drains essentially collect the site water and deliver it to the sewer system. The system includes a series of field drains built into paving or landscaping to remove water from the site surface. Identify and observe the condition of the storm water collection and drainage systems and note the presence of on-site surface waters, and retention or detention basins and any other problems with the removal of storm water such as evidence of ponding or clogging. Also note any evidence of poor or buried curbing and gutter systems. Sites with good surface drainage away from the building location would be most desirable, and sites where significant drainage runs through from off-site locations and where adequate vegetated areas are not present to enhance stormwater infiltration should be avoided. Culverts are used for storm water runoff, typically under roads or walkways. They are usually constructed of reinforced concrete pipe, corrugated metal, or plastic. Culverts should be in good condition and well maintained. They should also be checked for sealant or joint deterioration. Trench drains are used to remove surface water, and are typically constructed using a metal grated cover. Access and egress: The main means of ingress and egress from the site should be observed. Building codes require that exit passageways be provided for a building from every section of every floor to a public street or alley. When the rated number of occupants exceeds a certain number, additional exits are required.


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Paving, curbing, and gutters: One of the most significant issues to review in a property is the condition of the paving systems. Paving is important for several reasons. Potential liability conditions can be present if the paving is damaged or deteriorated. Also, due to the large quantities of paving on most properties, the paving quality directly impacts the perceived quality of the entire property. Paving systems include both vehicular surfaces and pedestrian surfaces. Vehicular surfaces include driveways, and parking and loading areas. Pedestrian surfaces include patios, sidewalks, and other walkways. The paving at a site is most often comprised of a variety of materials. The most common of these are concrete, asphaltic concrete, and precast pavers. The existing conditions of the paving system may range from being in a very deteriorated state to being in excellent condition (Figure 7.3). When deteriorated, the paving exhibits several defects as shown in Figures 7.4A,B. Often, the property may have recently undergone repairs. One issue to keep in mind during the survey of paving systems is whether there has been extensive patching and repair work. This could indicate a likelihood of substantial problems in the future. If slurry seal work has been performed, inspection should determine whether the work has addressed and handled system deficiencies or simply consists of a cosmetic improvement. The make-up of the paving section includes the condition and type of the subsoil, base layer, interim layer, and top layer. In properties where significant paving deficiencies are found, the paving section can be identified and analyzed by performing a core test (which is not in the normal scope of a standard PCA). A core between 2 and 4 inches in diameter is taken of various locations around the site. The depth of the test may range from 6 to 60 inches, depending on the paving section and the intended test result. Paving should be evaluated for issues including type, location, and general condition, evidence of cracking, sink holes, or other areas of settlement. The forensic expert will also look for evidence of ponding, extensive remedial patching, spalling, etc. The joint seals should be in good condition. There should also be adequate control joints and drainage. Curbs and gutters: Curbs adjacent to pedestrian or vehicular areas include poured in place or extruded concrete or asphalt. Curbs should be checked for their general condition, and whether cracking or other damage is evident. Similar to curbs, gutters are typically poured in place or extruded concrete or asphalt. Gutters should be in good condition, well maintained, and not clogged or buried. Curbs and gutters are used to control drainage within parking areas. Curbs may be designed to allow runoff into detention catch basins for temporary storage or infiltration. Parking and vehicle access: Onsite parking should be provided to meet current design standards (Figure 7.5A,B). With respect to the disabled, the number of provided spaces for the handicapped should meet ADA and other code requirements as discussed in Chapter 18. Local requirements should be used when they Figure 7.2 Topographic stepped contour site model of C&D are more stringent. Site design to obtain Farms, LLC, Cornwall, CT (source, Howard Models). This type physical security is discussed in Chapter of model is useful for designing security systems, landscaping, etc. 18, Section 18.2.


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Compliance with the criteria and guidelines for determining the design vehicle, turning radii, and circulation should be recorded (Figure 7.6A,B). The guidelines cover access and service drives; and special vehicle-use areas including gateways, drop-offs, delivery, dumpsters, and drive-in facilities. Circulation will promote safe, cost effective, and efficient movement of both vehicles and pedestrians. Safe vehicular circulation systems have a perceivable hierarchy of movement, lead to a clear destination, and do not interrupt other activities. Parking Space Count and Parking Zoning Requirement Review: Using a combination of reviewing site surveys and field counting, the existing number of available parking spaces (including ADA parking) should be identified and recorded. Review zoning requirements and compare to actual. Parking space count:

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Figure 7.3 Typical paving system defects.

A. Compact spaces B. Regular spaces C. Spaces for handicap parking D. Spaces for van accessible handicap parking Parking zoning requirements: The various square footages (from rent rolls or floor plans) of each occupancy type currently built out should be estimated and the required parking calculated and compared

A

B

Figure 7.4A,B A. Pavers should never be installed over a mortar bed if traffic will travel over them. This is just one of many projects (in Bellevue, Washington, USA) where the mortar bed has failed. B. Concrete pavement defects which can prove dangerous, Cole Gardens Apartments, Washington, D.C. (courtesy, IVI International).


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with actual. Consider vacant and occupied space and indicate if parking limitations may impact amount and type of occupancy in the remaining space to be leased. In non-office type zones, check for zoning regulations that might set a maximum percentage of office use vs. warehouse or manufacturing use. Parking Control Equipment: This includes the control gate and arms, ticket dispensers, and attendant booths. The equipment should be evaluated for its type and general condition and whether it is operating satisfactorily. It is also important to ensure that the equipment is well maintained and that adequate and visible signage is in place. Utilities: Site utilities are not often directly observable, and the forensic expert will therefore need to rely more on the questionnaire and interviews to indicate potential issues. Forensic experts should therefore seek to gather information about hidden utilities by performing interviews with site personnel and reviewing relevant available records. Visual observations are generally limited to directly observable components. Examples may include water systems, wastewater treatment systems, power generation systems, telecommunications lines, gas supply pipelines, etc. Utilities that are the responsibility of utility companies should be excluded. Experts should review and note operating costs against the age and use of the systems. However, the forensic architect should not access concealed spaces (i.e., underground services, manholes, or utility pits). Identify and document the type and provider of the utilities provided to each property (water, electricity, natural gas, oil, telephones, steam, and storm and sanitary drainage). Identify the presence of any onsite utility systems such as water or wastewater treatment systems, or special power generation systems. Where applicable and available through document research, identify system type, manufacturer, system size/capacity, age, and maintenance history to determine remaining useful life. Forensic experts shall not perform demolition, non-destructive, or destructive testing or uncovering of any existing finishes, systems, or components to gain access to hidden conditions. Operating any systems or accessing manholes or utility pits either in person or using remote-controlled equipment is not required. Location of all utilities in the immediate vicinity to the site should be surveyed including the size of the lines, capacities of generation, current and projected demand, and proposed expansion. The utilities to be

A

B

Figure 7.5A,B A. Residential reserved parking area (with one handicap parking space) in housing development in Bethesda, Maryland, USA (courtesy, IVI International). B. General parking lot behind a shopping strip in Bethesda, Maryland, USA.


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Figure 7.6A,B A. A table showing general design vehicle dimensions. B. A table indicating general design vehicle minimum turning radii.

included are: water system with locations of fire hydrants; sanitary sewer system; storm drainage system and drainage basin with invert elevations; electrical, gas and steam systems; telephone system; and other types of communication systems or specialized utility systems. The site must be accessible to a public sewer district for sanitary sewage disposal. A desirable feature would be if the site also allowed for future construction of an on-site treatment area for gray water. In areas that are not provided with city sewers, on-site sewage disposal is necessary. Even when a site has access to a sewer, it may be desirable to treat sewage on site in order to return water to the local soil, or to provide irrigation for non-food plants. Cesspools, which combine aerobic and anaerobic treatment in the same chamber and leach directly into the soil, may still be allowed in some rural areas. However, in the majority of cases, a concrete or plastic septic tank is required in which anaerobic bacteria provides primary treatment. The effluent from the septic tank discharges either directly to a leach field, or indirectly through an aerobic treatment unit and then to a leach field.


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Landscaping: The objective of a landscape is to preserve and enhance existing resources; improve the environmental quality of the facility; minimize life-cycle maintenance; and improve visual quality. The landscaping system includes planting and soil conditions. The selective placement of turf, trees and shrubs in randomly selected parking stalls breaks up the visual impact of large areas of vehicles and provides an irregular pattern of planted areas. The forensic architect should look for evidence of overwatering, underwatering, and poor drainage. Likewise, the assessor should check whether the site is well maintained (or if there are dead, dry, or vacant areas), or if the land slopes toward the building. Irrigation systems: The irrigation system includes the components necessary to deliver water to the landscaping. Sprinklers include both automatic and manually controlled systems. Attention should be paid to the condition of the landscaping during the review of the irrigation system. The field observer should check for the presence of a backflow preventer and for evidence of leaks or exposed lines. Stairs and ramps: If a site has a change of topography or if the building is at a different elevation than the surrounding property, stairs and ramps are typically employed. These stairs and ramps should be evaluated for safety, operational efficiency and handicap accessibility. In addition to the general condition of stairs and ramps, one should check for evidence of tread wear or unsafe conditions, railing damage, cracking, or other damage (Figure 7.7A,B). Loading areas: Truck docks and other loading areas should be assessed during the site review. In addition to their general condition, loading areas should be checked for damaged walls, platforms, or doors and missing bumpers and guards (Figure 7.8). Signage and exterior lighting: There are generally four types of exterior lighting fixtures: 1. 2. 3. 4.

Pole-mounted Bollards Surface-mounted Floodlighting.

Figure 7.7A Photo of stairs built into retaining walls

Figure 7.7B Photo of exterior concrete stairs with

inset between sidewalls.

metal balustrades leading to building (courtesy, IVI International).


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Figure 7.8 Photo of a typical loading bay behind a shop.

To provide optimum lighting design, light levels should be uniform, fixtures properly spaced to reduce shadows, glare controlled, and maintenance performed regularly. Parking lots should be illuminated with uniform lighting coverage to meet pedestrian and vehicular safety requirements. A number of states have adopted the International Building Code, which mandates the need for emergency lighting outside of buildings. All businesses, unless they are on a public street, have to provide a safe dispersal area (for the people in the building) that is at least 50 feet out from the building. Building owners are to provide a safe and unobstructed path to the dispersal area. Should a power outage occur during the night, the only way it would be safe is if it were lit. Fluorescent lamps are ideal for these applications because of their instant-start capabilities and their ability to operate on battery packs. Energy management systems are effective in controlling exterior lighting; they can be programmed to turn lights on and off, as well as lower lighting levels, if desired. When possible, it is recommended that all exterior lighting be switched on and off by a control system that combines a photocell and time clock. Exterior lighting should be switched on about 30 minutes before sunset. Lighting for safety and security is usually kept on throughout the evening. Lighting associated with the building façade is generally switched off at 11 p.m. or 12 a.m. Exterior signage, lighting and the accompanying equipment should be reviewed during the site evaluation. The review of signage is especially important in acquisition studies because of its effect on the marketability of a property. Signage should be consistent, well-designed, and have good visibility. The sign and light bases are typically made of wood, metal or concrete. Equipment should be well maintained and evaluated for signs of vandalism, damage, rusting, etc. Hazardous waste: This is a type of waste with properties that make it dangerous or potentially harmful to human health or the environment. The universe of hazardous wastes is large and diverse. Hazardous wastes can be liquids, solids, contained gases, or sludges. They can be the by-products of manufacturing processes or simply discarded commercial products, like cleaning fluids or pesticides. In regulatory terms, a RCRA hazardous waste is a waste that appears on one of the four hazardous wastes lists (F-list, K-list, P-list, or U-list), or exhibits at least one of four characteristics—ignitability, corrosivity, reactivity, or toxicity. Hazardous waste is regulated under the Resource Conservation and Recovery Act (RCRA) Subtitle C.


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The hazardous waste identification (HWID) process is the crucial first step in the hazardous waste management system. Being able to determine whether a waste meets the RCRA definition of hazardous waste is critical to determining how the waste must be managed. The HWID process consists of four basic questions: 1. 2. 3. 4.

Is the material a solid waste? Is the waste specifically excluded from RCRA? Is the waste a listed hazardous waste? Does the waste exhibit a characteristic of hazardous waste?

RCRA provides a process to remove a waste generated at a facility from the list of hazardous wastes. This delisting process needs to be initiated by the person who created the waste who should prepare a petition for delisting the waste. Ponds and reservoirs: Detention ponds, retention ponds, and infiltration basins are drainage devices used to control the quantity and velocity of runoff. The increase in runoff is held within these ponds and gradually released at rates that are equal to or less than the rates that occurred prior to site improvements. The maintenance of runoff rates impedes flooding, erosion, and sedimentation of recipient drainage ways. Ponds and basins can be typically designed to allow collected runoff to stand long enough for heavier sediments to settle to the bottom, thereby reducing sedimentation downstream. Evaluations should include a review of any ponds, reservoirs, or other bodies of water which exist on the site. Location, depth, and approximate surface area square footage should be recorded. Indication should also be made as to the primary function of the water. The pond or reservoir may be in place for cosmetic, water retention, or overflow containment purposes. Notes should be taken on whether the system is natural or manmade and whether there is a PVC or other type of waterproofing or filtering system in place. Railings or other types of pedestrian protection should be in place. Ponds and reservoirs should be checked for evidence of flooding or soil saturation surrounding the area (Figure 7.9).

Figure 7.9 Artificial lake adjoining Trinity Center office complex in Centreville, Virginia.


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7.3

111

DATA COLLECTION

Any visit to the site under inspection should be an intrinsic part of the data collection process. No other task provides as much useful information for understanding overall area impacts. In addition to providing a visual impression assessment of features such as architectural character, significant views, landscape character, and prominent land features, it also provides an opportunity to inspect building systems (in new or existing constructions) and any possible deficiencies. The site visit also provides an opportunity to review the following: • •

Site reconnaissance to evaluate and verify existing information and impressions The compatibility of existing on-site and off-site conditions

Reveal any unknown or unrecorded conditions and factors

Evaluate sustainable design issues and design qualities and recommendations.

The data that needs to be collected will obviously differ from site to site and project to project, but in general, it falls into three broad environmental categories; they are: the natural environment, the built environment, and the socio-cultural environment. Required site data to be collected includes the following: • •

Background data Environmental features such as topography and hydrology (ground water, surface water, drainage ways, wetlands, etc.)

Physical features such as existing buildings, vehicular circulation, parking, pedestrian circulation, and physical barriers and buffers

Property easements and leases

Tree surveys to include the location, common and botanical name, size, and condition of all trees

Significant climatic conditions such as wind, sun and precipitation

Sustainable design issues and recommendations

Proposed modifications or changes that may impact the area

Significant architectural or historical features.

7.4

SYSTEM DIAGNOSTICS

System diagnostics for the building site are very diverse. Unlike some other building systems, the site is comprised of several very different types of subsystems. The site evaluation, including planting, irrigation, paving, and structural amenities, requires a wide range of expertise. In some facilities, the site evaluation will take as long as the building evaluation. The evaluation of the site should be started at one location and thoroughly and systematically conducted. Depending on the size or complexity of the site, it is often more effective to assess the subsystems or components one at a time. For example, it may be more efficient to assess all areas of asphalt vehicular paving and curb areas, then all the concrete walkways and the paved areas. The measurements of damaged areas should be taken using one of any commercially available rolling measuring wheels. After


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the paving, it may be useful to review the landscaping, in conjunction with the irrigation. This approach typically makes the complexity of the site more understandable and the issues for review more digestible. In this way, there is less chance to have an issue in any subsystem omitted. With this methodology, the paperwork for each subsystem can be completed and any system deficiencies diagnosed fully prior to moving to the next component. This is the preferred methodology for complex sites or groups of site subsystems, but is unnecessarily time consuming in sites which are simple and/or in very good condition. The inspector shall document physical deficiencies and repair needs with photographs. Photographs should include examples of each repair need as a minimum. Excessive photographs of typical systems and components that do not help document repair needs should be avoided. With simpler building sites, the components of the property should be evaluated simultaneously during the general field investigation. In less complex sites and sites in good condition with relatively few deficiencies to be addressed, this method will save time. General notes and specific condition and equipment identification can be produced during the walk-through. Visual signs of distress should be noted, and documentation of deficiencies or deterioration of utilities. Deficiencies may include visible physical deterioration, leakage, obvious non-compliance with codes, or other visible evidence that may indicate a hidden condition. Update equipment inventories and estimate take-off quantities using either estimates taken on site or review of available drawings to determine the costs of replacement or repairs that are necessary to correct deficiencies. Identify issues that may require more detailed evaluations or testing.


CHAPTER

8 Structural Systems 8.1

GENERAL

A forensic architect/engineer is typically called in either to investigate a building/system failure or deficiency or by a potential buyer of a property. The structural components are usually the most important considerations for a prospective purchaser. However, in most commercial and residential buildings, structural components are not visible, but are concealed by various finishes or other non-structural components. The precise objectives of structural design may vary from one project to another, but in all cases, the avoidance of collapse and the ability of the building to resist any and all forces placed upon it are probably the most important requirements. It is therefore of paramount importance to incorporate an adequate factor of safety. In this context, the structure should be designed to fulfill both strength and stability requirements. Loads that a building structure must withstand include those of the building equipment and materials, the building users, as well as earthquake and wind forces. A building’s structural system is also intended to assist in the protection of the occupants and contents from the weather (rain, wind and extremes of temperature). It is critical therefore, that the building’s exterior enclosure systems are designed and built to achieve all of these functions. Methods of analyzing structural attributes and behavior have advanced significantly in recent years, particularly as a result of developments in computing and electronics. Yet, many deficiencies and failures continue to appear that are basically the result of inadequate design or construction, and not taking into consideration potential loadings, etc. But structural failure can still occur, even with correct design and construction, if the materials used are unsuitable or subsequently deteriorate. Structural systems today come in many shapes and forms and there are a myriad of materials out of which these systems are made, including masonry, concrete, steel, and wood. Most of today’s tall buildings extend one or several floors below grade level. These below grade areas typically provide functional spaces for uses such as storage, parking, office space, mechanical/electrical rooms, etc. While below grade areas in buildings provide important critical functions for the building, the subject of below grade building enclosure systems is seldom understood or analyzed. Acceptance of poor performance of the below grade building enclosure is typical and historically not questioned. Leaking into

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basement areas is a common problem for building operators and managers. Air quality, such as radon, and conditioning in terms of humidity levels are often a concern. Unlike some other building components that might be designed to be replaced several times within a building’s overall service life, below grade systems need to be durable and built to approximate the overall service life of the building. Below grade systems are often inaccessible for repairs and extremely costly if repairs or modifications are necessary. For below grade enclosure systems design and materials must not focus on the first initial cost but consider the life cycle costs of various design options. Also of great importance is to prevent damage during construction that could go undetected until the building is in service, creating costly repairs or inadequate performance.

8.2

BUILDING STRUCTURAL TYPES

It is said that 90 percent of all building failure occurs during the initial 18 months of construction, mainly as a result of incomplete construction. Principal components of a structural system include, but are not limited to, the foundations, footings, interior and exterior walls, columns, beams, girders, joists, roof rafters, trusses, wind bracing, and special conditions. Any structural or engineering investigation as to the structural condition and integrity of the building should answer certain questions, like: 1. Are the structural elements designed and built to accept the anticipated loads to be placed upon them, and 2. Are they continuing to perform their intended function? The ability to render such an opinion is fundamental to this definition. In many states, like New Jersey, only a registered professional engineer is permitted to render an opinion as to the structural integrity of a building. Steel frame system: Steel is widely used in the construction of multi-story buildings. In fact, most American style skyscrapers have a steel frame, whereas residential tower blocks are normally constructed out of concrete. Figure 8.1A shows an example of an early American steel-framed building built in New York in 1902. Figure 8.1B is an example of a well-known contemporary steel-framed building—the 100story John Hancock Center in Chicago. One of the principal advantages of steelwork is the speed with which execution can proceed. In order to maximize this advantage it is sometimes necessary to adopt structurally less efficient solutions, for instance using the same profile for all members in a floor construction, even though some floor beams are less highly loaded than others. In resisting lateral forces, steel frame systems can be rigid, non-rigid, or ductile. Each system is designed to predictably address, resist, and evenly distribute all forces. Used extensively in high-rise construction, steel frame systems can be erected more quickly than concrete, and over the years various improved systems have been developed. The beams and columns in steel frame construction are fastened together by rivets, bolts, or welds. Decking materials used with steel frame systems typically include either steel or concrete, or a combination of the two. In many buildings, steel members are typically fireproofed through the use of spray-applied material, gypsum materials, or concrete. Steel frame systems should be evaluated for their general condition, including corrosion, bowing, deformation, and any alignment inconsistencies. The system’s ability to resist lateral loads should also be checked, as well as the design strength of the rigid frame. Prefabricated steel wall framing can be used with all types of floor construction. Although framing varies in detail between manufacturers, the general principles are the same for all systems. Steel wall framing is erected in the same sequence as pre-fabricated timber, ensuring squareness and vertical alignment of individual frames. Steel framing must be firmly anchored to the foundation or floor structure. Wherever possible, the walls should be anchored as soon as possible after they have been plumbed and aligned. There are two forces you must account for when attaching walls to the foundation or floor slab. These forces are shear and uplift.


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Figure 8.1A,B A. The New York Flatiron office building is an early example of steel-frame construction (built in 1902). It consists of 22 floors and is covered with a non-load-bearing limestone and terra cotta facade. B. The John Hancock Center (1968–1974) in Chicago, USA. The 100-story building uses large X braces exposed on the exterior of the frame to stiffen the structure against wind loads, and is an example of a contemporary steel-framed building.

Concrete frame system: Concrete frame systems are fairly common in buildings. Reinforced concrete (RC) frames consist of horizontal elements (beams) and vertical elements (columns) connected by rigid joints. The system can be comprised of both pre-cast and cast-in-place members. RC frames provide resistance to both gravity and lateral loads through bending in beams and columns. Concrete frame systems are less expensive than steel frame systems and stronger than wood frame construction, plus concrete is fireproof. The system should be observed for deformation, bowing, alignment inconsistencies, and the condition of expansion joints as well as areas of exposed rebar, spalling, delamination, or discoloration. The assessor should ensure that the members have been designed to adequately resist lateral loads. Wood framing system: Wood framing is considered the predominant form of construction for building homes and apartments in the United States. It is increasingly being used in commercial and industrial buildings as well, mostly in low-rise construction, mainly because it can be constructed more easily than either steel or concrete systems. These framing systems include light wood, heavy timber and glue-laminated members while being very adaptable to traditional and contemporary styles. Plywood is typically used for the horizontal and vertical diaphragms. Dry rot and termite damage should be looked for, as well as possible delamination of members and evidence of cracking or splitting.


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Types of frame construction systems include: 1. The platform frame construction system (Figure 8.2A) is used largely in home building. In platform-frame construction, the first floor joists are totally covered with sub-flooring, thereby creating a platform upon which exterior and interior walls are erected. The platform erection system is simple and readily adaptable to various methods of prefabrication. 2. The balloon frame construction system is characterized by the exterior wall studs that continue through the first and second stories (Figure 8.2B). Both the first floor joists and the exterior wall studs bear on the anchored sill. 3. In the plank and beam framing system, beams designed to support floor and roof loads are used and are spaced up to 8 feet apart. Floors and roofs are covered with 2 inch planks that serve as subflooring and roof sheathing. The ends of floor and roof beams are supported on posts which provide the wall framing. Supplementary framing between posts permits attachment of wall sheathing and exterior sidings. 4. The strength and resilience of truss-framed construction comes from its framework of structural lumber combined with a covering of subflooring, wall and roof sheathing. Wood joists & truss floor construction: Wood joists and trusses are used in smaller buildings and many old buildings, and often are used in conjunction with wood decking systems. There are a number of floor joist systems on the market. New floor joist technology provides extended benefits that standard joists do not. Because of their easy installation, light weight, and open design for accommodating water, sewer, and electric, many builders prefer them to other forms of construction. Such systems are used extensively in warehouses, hangars and supermarkets. The main issues to look for are dry rot and termite damage, evidence of cracking or splitting, evidence of water damage, and evidence of delamination of members. Steel joists & truss floor construction: Today, steel joists are much more versatile and sophisticated than when initially invented. Moreover, the boundary between joists and structural trusses has become less clear cut (Figure 8.3). Joist profiles have been expanded from traditional parallel chords to various geometries, such as scissor, arched chards, bow string, and gable, etc. The maximum span has also

Figure 8.2A,B A. Platform frame construction system. B. Balloon frame construction system (source, American Forest and Paper Association).


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been expanded from an initial 32 feet to 144 feet in SJI load tables. Some joist manufacturers have further extended the standard load tables. Open web steel joists are typically welded to the steel beams and attached to bearing walls using masonry anchors or preset embedded plates. Metal deck systems are then connected to the joists and trusses. Concrete decks are also utilized. The steel deck and open web steel joist combination is a roof and floor framing system widely used in many building types. The most efficient application is in warehouses, distribution centers, and super stores, where the repetitive configuration of bay sizes takes most advantage of the nature of joists—mass production. In North America, this system is very popular in virtually all kinds of commercial, industrial, and institutional buildings. In the residential sector, this system finds its main application in condominium construction. Today, most steel joist fabricators produce steel deck too, and steel joists and deck are often bid and shipped in a single package. A steel deck unit consists of a corrugated panel cold formed from sheet steel. Steel decks are widely used in roof framing systems to support finished roofing materials and to resist wind uplift loads. Steel deck is also widely used in floor framing systems. There are basically two types of floor deck applications: form deck and composite deck. The first deck type serves as a permanent form for concrete slab. The composite deck type serves dual purposes: during the construction stage, the deck serves as a form for wet concrete; after the concrete has hardened, the composite deck is bonded to concrete and becomes positive reinforcement for the concrete slab. In addition to its primary structural function to support gravity loads, steel decks’ secondary function is to provide lateral structural capacities. First, steel decks provide lateral support for the steel joist top chord, eliminating lateral braces needed for compressive stability; and second, steel decks are often designed to act as horizontal shear diaphragms, with the steel decks forming the web, interior steel joists forming the web stiffeners, and the perimeter structural members on all four sides forming the flanges of the diaphragm. This shear diaphragm may be used to transfer wind and seismic loads to lateral load resisting components, replacing part or all of conventional structural bracing systems.

Figure 8.3 Example of joist to frame/wall connection.


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When inspecting this type of system, the forensic expert should check for evidence of buckling, cracking or deteriorated welds, and signs of corrosion. The expert should also look for possible loose, damaged, or missing bolt connections. Concrete slab floor construction: This includes poured-in-place waffle and flat slabs of steel-reinforced concrete as well as precast, pre-stressed members, planking and single and double “T� beams. Figure 8.4 shows a hollow-core precast slab system that is commonly used for floor and roof structures. Castin-place concrete construction can be either post-tensioned or conventionally reinforced. Both of these systems are supported during initial concrete placement, and they will deflect when supporting shores are removed. In typical office environments, the concrete floor slab itself is comprised of 4- to 6-inch thick concrete reinforced with one layer of welded wire fabric at mid depth. Suspended concrete floor systems also come in several types, including: 1. Cast-in-place suspended floors 2. Slabs with removable forms 3. Slabs on metal decking 4. Topping slabs on precast concrete. Design requirements for cast-in-place concrete suspended floor systems are covered by ACI 318 and ACI 421.1R. Slabs on metal decking and topping slabs on precast concrete are hybrid systems that involve design requirements established by ANSI, ASCE, The American Institute of Steel Construction, Precast/ Prestressed Concrete Institute, and tolerances of ACI 117. The levelness of suspended slabs depends largely on the accuracy of formwork and strikeoff, but is also influenced (especially in the case of slabs on metal decking) by the behavior of the structural frame during and after completion of construction. Each type of structural frame behaves somewhat differently; it is important for the contractor to recognize these differences and plan accordingly.

Figure 8.4 Example of a hollow-core precast slab which is commonly used in various types of floor and roof structures (source, WHE Report 33, Kyrgyzstan).


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Construction of slabs on metal decks involves the use of a concrete slab and a supporting platform consisting of structural steel and metal deck. The structural steel can be shored or unshored as required at the time of concrete placement, with the metal deck functioning as a stay-in-place form for the concrete slab. This construction can be composite or noncomposite. One of the advantages of reinforced concrete floor systems is that they can provide economical solutions to a wide variety of situations. Numerous types of nonprestressed and prestressed floor systems are now available that can satisfy most spans and loading conditions. Selecting the most effective system for a given set of constraints is essential to achieving overall economy, especially for low- and mid-rise buildings and for buildings subjected to relatively low lateral forces where the cost of the lateral-force-resisting system is minimal. The main deficiencies to look for include cracks, spalling, or discoloration and whether the expansion joints are in satisfactory condition.

8.3

STRUCTURAL ELEMENTS

This section should be read in conjunction with the relevant sections of Chapter 15. In modern multi-story buildings, concrete walls around cores have often been employed to provide wind and seismic resistance either in concrete or in mixed systems with steel framing. The concrete core braced system offers many opportunities for shaping of the exterior of the building and appears to be sufficiently adaptable to meet the needs of emerging design trends. These trends usually require diversity in exterior shaping involving plan and profile variations to fit the site constraints or reflect various expressions of the building’s aesthetics. In such cases, the simpler non-rigid steel frame can be used and can readily adapt to these variations. Sometimes, local failure of a major structural support occurs and spreads from element to element, resulting in the collapse of the entire structure. This sequence of failure is termed progressive collapse and resembles the “domino effect.” FEMA’s definition of progressive collapse is local failure of a primary structural component which leads to the collapse of adjoining members, which leads to additional collapse. The total resulting damage is disproportionate to the event. Progressive collapse is a chain reaction of structural failures following damage to a relatively small portion of a structure. Progressive collapse can propagate vertically upward or downward from the source of the failure, as well as propagate laterally from bay to bay. Except for specially designed protective systems, it is impractical to design structures to resist this kind of collapse. Nevertheless, minor changes in reinforcement detailing can be made to provide continuity and redundancy, and to increase the ductility of the structure, and thus limit the effects of local damage to help prevent or minimize progressive collapse. The overall capacity of a reinforced concrete structure to withstand such abnormal loads can be substantially increased by instituting relatively minor changes in the detailing of the reinforcement, without significantly impacting the overall economy. The basement can be a challenging environment in which to build useful space. By its very nature, it is the lowest location in the building, and often the coolest, the most humid, and the darkest. It is surrounded by earth that can be dry, moist, wet, or frozen, and at times, all of these simultaneously. As a result, the envelope components are subjected to greater structural, water and moisture loads than the above-grade portions (Figure 8.5). And although it is generally agreed that from a thermal standpoint, the above-grade components are subjected to more extreme loads, the duration of the below-grade heating season can be longer and is out of phase with the rest of the building and the outdoors. Yet many consumers now com-


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Figure 8.5 Waterproofing approach to control groundwater in basements.

monly expect basements to potentially perform as viable functional and livable spaces, offering the same quality environment as the rest of the building. In these conditions, the basement envelope has some difficult and often contradictory functions to perform, and these are generally not well understood.

8.3.1

Below Grade Elements

Many of today’s buildings extend one or several floors below grade level. This is particularly true in urban areas where land prices are at a premium. Below grade areas serve many functions such as storage, office space, mechanical/electrical rooms, parking, tunnels, crawlspaces, etc. But while below grade areas in buildings provide important critical functions for the building, the below grade portion of the building enclosure is seldom analyzed numerically in design. Acceptance of poor performance of these areas is typical and is infrequently questioned. Leaking into basement areas is a common problem for building operators and managers. Air quality, such as radon, and conditioning in terms of humidity levels are often a concern. Below grade enclosures are essentially comprised of three main elements (Figure 8.6): 1. Foundations & foundation walls 2. Floor slabs 3. Plazas/tunnels/vaults 1. Foundations & foundation walls: Foundations are designed to support several different types of loads including the dead and live load of the building, wind loads, earthquake loads, and horizontal forces of soil and water below grade. They are designed to resist the overturning moment forces on the structure. The design and configuration of a foundation is directly related to the load-bearing capacities of the soil. All foundations experience at least minor settlement, but damage to foundations occurs most often when differential settlement is experienced. The foundation wall of a building may be a cast-in-place concrete retaining or basement wall or a structural wall complete with load-bearing pilasters. Materials used may be concrete or reinforced masonry (Figures 8.7, 8.8). The foundation wall system may include an earth retention system of soldier piles and wood


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Figure 8.6 A below grade building systems schematic graphically illustrating the three main elements and the typical loadings for below grade building enclosure systems (courtesy, Tom Smith AIA).

lagging or shotcreted rock requiring consideration of waterproofing applied to the earth retention system. For most portions of the foundation wall, water removal and control is of prime importance. In the upper areas of the foundation wall thermal loading considerations must be addressed. 2. Floor slabs: The base floor within a building may simply be a cast-in-place concrete slab-ongrade with limited design considerations for structural support or environmental control functions. The base floor may also be comprised of a mud or structural foundation slab complete with waterproofing and wearing slab with the overall system designed to carry structural hydrostatic pressure loads and maintain a controlled environment. Floor slabs are often the source of leakage into the building with slab cracking of common concrete materials being a primary cause. Issues of controlling soil gas emissions such as radon may also be of importance. Floor slabs of below grade building enclosures must be capable of carrying downward vertical gravity loadings as well as any upward soil or hydrostatic pressure loadings. Downward vertical gravity loadings are the result of the floor slab’s dead weight plus the presence of occupancy live loads. Floor slabs may also resist upward soil or hydrostatic pressure loadings. Upward soil pressures may be applied to the floor slab in situations where it acts as a matt foundation and the building point loads on the foundation results in an upward pressure on the floor slab.


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Figure 8.7 Typical concrete wall foundation system.

Figure 8.8 Typical concrete block foundation.


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A typical base floor slab where the design criteria include controlling moisture migration and water vapor transmission into the interior space can be referred to as a waterproof system. The components of a waterproof system include a well compacted yet well draining granular drainage system placed directly on unexcavated, undisturbed ground. The granular drainage system provides a collection area for moisture to accumulate and dissipate as well as a firm support for slab loadings. To provide a solid base material on which to apply the waterproofing membrane, a mud slab or compacted earth layer is provided (Figure 8.9). In some instances with significant hydrostatic pressure or to accommodate building loadings, a matt foundation slab is used in lieu of the mud slab. The waterproofing is then applied directly to the matt foundation slab and protected with protection board. In this case a wearing floor slab is poured on top of the protected waterproofing system. 3. Plazas, tunnels, vaults: Buildings frequently have plazas, vaults, tunnels or extensions below grade. The planning, development, detailing, and construction of waterproofing for such features are significant. Although much more complex and far more maintenance intensive, these features are generally not treated with the same detailing attention that roof assemblies receive. In all such areas, regardless of membrane detailing, protection, drainage and isolation, along with thermal considerations, must be incorporated into the design. Plaza decks, tunnels and vaults are often subject to deterioration and distress more rapidly than other structural systems due mainly to poor design, poor construction, and abnormal or excessive loading. Other common causes of plaza deterioration or failure are: severe exposure including freeze-thaw, moisture, thermal effects, chemical applications, overload and/or improper materials selection and application. Structural systems for tunnels/vaults and plazas are typically cast-in-place concrete systems, either conventionally reinforced or post-tensioned. The use of precast concrete elements for these areas should be avoided due the difficulties in obtaining effective joint and surface waterproofing.

Figure 8.9 Below grade slab floor detail showing waterproofing membrane.


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Below are some of the relevant issues to below grade building enclosure systems: 1. System monitoring during service should include: •

Waterproofing

Leak detection systems

Water transmission rates

Drainage layer effectiveness

Elastomeric properties

Protection layer breakdown

Soil permeability when used with various backfills

2. Planning for long term system maintenance •

Injection grout systems for post construction leaks

Wall weep ports to discharge impounded water

Internal contained leak collection system at wall floor interface

Interior positive side water proofing protection/membrane systems

External secondary perimeter drain fields

3. Service life prediction from below grade waterproofing •

Getting the maximum service life from exterior systems

4. Integration of existing systems with new adjacent (newly constructed) facilities •

Solving continuity problems

5. Enhancing systems in place •

Extend the existing system with targeted maintenance

Available options

Adapting to existing constructed systems

Data utilization considerations

8.3.2

Wall Systems

There are several classification methods for exterior wall systems that are commonly associated with above-grade, commercial building enclosure design and construction. This section should be read in conjunction with Chapter 15. Following is a summary of one classification method used. Structural masonry walls: Structural masonry load-bearing walls can be single or double-staggered with or without reinforcing. They are essentially self-supporting and transfer roof and other loads directly to foundation systems. The simplest form of this construction consists of a single thickness of hollow core, concrete block. When reinforced, the reinforcement consists of vertical steel reinforcing bars inserted into the cores for the full height of the wall and the block cores are then filled with mortar. Horizontal steel joint


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reinforcement is imbedded within the horizontal mortar joints of every other course of block. Masonry buildings require verification as to whether they are unreinforced. Unreinforced masonry buildings are susceptible to severe damage in areas of seismic activity or if blast is a threat, and such buildings are required to be upgraded in California. To mitigate blast and seismic activity effects, the designer should: •

Use 8-inch concrete block masonry walls fully grouted with vertical centered reinforcing bars placed in each cell and horizontal reinforcement at each layer because masonry is a brittle material that can generate highly hazardous flying debris in blast or seismic situations.

For increased protection, 12-inch blocks with two layers of reinforcement should be used.

When blast is a perceivable threat the use of unreinforced masonry should be avoided, as masonry walls break up easily and become secondary fragments during blasts.

Grout (mass) and reinforcement (ductility) are recommended for blast resistance.

Use reinforced concrete wall systems in lieu of masonry or curtain walls to minimize flying debris in a blast.

For detailed code requirements, refer to the relevant applicable building codes and standards such as the International Building Code (IBC), the IBC-based California Building Code, the Masonry Standards Joint Committee’s (MSJC) Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TM 402), Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602), and the American Society for Testing and Materials (ASTM). For masonry materials, freeze-thaw damage and damage from the action of soluble salts are considered the two most common brick deterioration mechanisms. Others include acid damage from pollutants and structural damage caused by overstress conditions, foundation movements, and corrosion of embedded metals. Concrete walls: Reinforced concrete walls are employed not only for both bearing and non-structural walls but also for shear walls for lateral resistance. They can be precast or poured-in-place. Cast-in-place concrete wall systems consist of exposed structural systems that also serve as the façade. Openings or penetrations in the structural system are generally infilled with windows, masonry, or some other cladding material. Concrete tilt-up buildings constructed prior to 1972 were often constructed with inadequate anchorage between the tilt-up wall and the roof. These buildings should be investigated thoroughly, and in most cases additional ties should be installed. In tilt-up buildings, concrete walls can be used as shear walls, designed to resist lateral forces. This type of construction involves precasting horizontally, erecting (tilting up) and joining of exterior concrete walls at the building site. Wall panels are custom made (in a wide variety of finishes) using the floor slab as the form for the exterior panel face. Panels range in thickness from 6 to 8 inches and are formed as close to their final position as possible. Concrete structures designed and constructed in the United States are governed by the minimum provisions of the ACI Building Code. Certain factors which influence the design of the structural system also impact the exterior wall. These factors include deflection, cracking, concrete cover, and corrosion protection. Wooden-stud-framed load-bearing walls: This system is a form of sandwich construction used extensively in residential construction. The cross-sectional configuration typically consists of a number of elements including: an exterior facing component known as cladding, a water-resistant sheet membrane (vapor barrier), a layer of sheathing, vertically aligned lumber framing members (called studs), wall insulation between the studs (e.g., fiberglass batting), a gypsum panel of wallboard constituting the interior wall. The vertical stud bottom sits on a horizontal wooden member (sole plate) that is at least 8 inches above


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exposed earth, and the tops are capped by another horizontal wooden member (top plate). A single top plate may be used where roof rafters or trusses bear directly above wall studs, in which case adequate corner ties are required. Otherwise, the top plates are doubled and lapped at corners and at bearing partition intersections to tie the building into a strong structural unit. Exterior wall framing must be of adequate size and strength to support floor and roof loads. Walls must also resist lateral wind loads and, in some locations, earthquake forces. Figure 8.10 is a typical example of wooden-stud load-bearing walls. Retaining walls: Retaining walls are structures that hold back soil or rock from a building, structure or area, and prevent downslope movement or erosion as well as provide support for vertical or near-vertical grade changes. Retaining walls are constructed of a number of materials including masonry, concrete, stone, metal, and treated wood. Retaining wall failure consists typically of cracking or other fracturing, overturning, sliding or undermining by ground water. Common deficiencies in concrete retaining walls include cracking, poor alignment and bowing. Common deficiencies in timber retaining walls include rotted wood, deterioration, and poor alignment and bowing due to insufficient tie-back members. Segmental retaining walls are gaining favor over poured-in-place concrete walls or treated-timber walls, mainly because they are more economical, easier to install and more environmentally sound. There are several types of retaining walls (Figure 8.11) including: Gravity: Gravity walls depend on the weight of their mass (stone, concrete or other heavy material) to resist pressures from behind and will often have a slight ‘batter’ setback to improve stability by leaning back into the retained soil. For short landscaping walls, they are often made from dry-stacked mortarless stone or segmental concrete masonry units. Sheet piling: Sheet pile walls are often used in soft soils and tight spaces. Sheet pile walls are made out of steel, vinyl, fiberglass, or plastic sheet piles or wood planks driven into the ground. Structural design methods for this type of wall exist but these methods are more complex than for a gravity wall. As a rule of thumb; 1/3 third above ground, 2/3 below ground. Taller sheet pile walls usually require a tie-back anchor which must be placed behind the potential failure plane in the soil. Cantilevered: Until the introduction of modern reinforced-soil gravity walls, cantilevered walls were the most common type of taller retaining wall. They are constructed from a relatively thin stem of steelreinforced, cast-in-place concrete or mortared masonry (often in the shape of an inverted T). In this system loads are cantilevered (like a beam) to a large, structural footing, converting horizontal pressures from behind the wall to vertical pressures on the ground below. Cantilevered walls require rigid concrete footings below seasonal frost depth. Anchored: This type of wall uses cables or other stays anchored in the rock or soil behind it. Usually driven into the material with boring, anchors are then expanded at the end of the cable, either by mechanical means or often by injecting pressurized concrete, which expands to form a bulb in the soil. Technically complex, this method is very useful where high loads are expected, or where the wall itself has to be slender and would otherwise be too weak. Proper drainage behind retaining walls is critical to their performance. Drainage materials will generally reduce or eliminate the hydrostatic pressure and increase the stability of the fill material behind the wall. Hybrid exterior wall systems and emerging technologies: In recent years, technological advancements in the design and manufacture of building enclosure materials, components, and systems have lead to the development of several hybrid and sustainable exterior wall systems, some of which include: •

Trombe wall systems

Double-skinned façade systems

LEED and green buildings


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Figure 8.10 Example of two story exterior timber load-bearing wall system.

Figure 8.11 Schematic diagram of various types of retaining walls.

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Mechanically ventilated wall systems and dynamic buffer zones

Passively ventilated wall systems

Radiant heating and cooling systems using thermal mass

Passive heating and cooling systems

Integrated photovoltaics systems.

These systems typically include design features and individual building elements that are designed to improve the long-term durability and performance of the building enclosure, and are often adapted in response to issues and concerns that are unique to a particular geographic area and/or climatic region in which a project is to be designed and constructed. Employing and integrating such wall systems should be given careful consideration by the designer during the schematic design phase of a project and should be discussed in detail with the owner/end-user.

8.4

TYPICAL DEFICIENCIES

The most common deficiencies in structural components are stress-related. Thus, the evaluation of the structural system should concentrate on the areas where the stress level is the highest in the structural members. In beams, the mid-span is usually the portion of the component where the flexural stress is the highest. Connections and fasteners for both beams and columns should be investigated to determine any areas of questionable integrity. Evidence of deterioration in concrete can take several forms including, cracking, spalling and discoloration. Steel systems deficiencies can include rotation and deformation from inadequate sizing or connection details. Wood structural systems can experience problems such as decay, dry rot, insect infestation, moisture deterioration and overstress resulting in cracking or shearing. Figure 8.12 illustrates some of the types of damage and deterioration that structural members can experience. Cracking over reinforcement may be due to many things, such as inadequate consolidation of concrete, inadequate concrete cover over the reinforcement, use of large diameter bars, higher temperature of reinforcing bars exposed to direct sunlight, a higher-than-required slump in concrete, revibration of the concrete, inadequate curing of the concrete, or a combination of the above items. In evaluating the structural system, the forensic expert should pay particular attention to Figure 8.12 Types of damage and deterioration that the susceptibility of water ponding on the roof. structural systems can experience. Flat or nearly flat roofs, in combination with long


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structural spans and clogged drains, can provide an opportunity for extensive ponding to occur. This ponding greatly increases the loading of the structural members and the potential for failure. Ponding on the roof may also be a contributing factor to the occurrence of leaks (Figure 8.13). Persistent ponding on bitumen covered flat roofs at the same location will eventually lead to a deterioration of the felt, especially if it is old, causing it to leak. Slab moisture: Many moisture-related problems can be traced to floor slabs which have been finished when floors were not dry. This moisture content of any floor slab should be measured before any finish floor application is applied. Again, this requires experience and the proper testing equipment. There are a few acceptable ways to test the moisture content of a slab.

8.5

SYSTEM DIAGNOSTICS

The scope and level of depth in diagnosing the structural system can vary widely but generally consists of a visual survey subject to limitations affecting accessibility and safety. The system’s components can be reviewed superficially during a general walk-through of the interior and exterior of a building. This level of review will typically identify the most obvious of deficiencies (Figure 8.14). For example, the deflecting of a cracked structural member will be discovered during this level of review. Unless directed otherwise, observations of the building’s structure are generally limited to vantage points that are on-grade or from readily accessible balconies or rooftops. In order to adequately understand the structure, where drawings are available, assessments should include a detailed drawing review. An assessment should not include a review of original design assumptions or calculations or structural design analyses. The entering of crawl or confined spaces should be excluded unless it is stipulated in the contract. The consultant should nevertheless observe conditions to the extent easily visible from the point of access to the crawl or confined space areas. Any determination of previous substructure flooding or water penetration should be based on easily visible evidence or from information provided.

Figure 8.13 Photos showing clear evidence of ponding on flat roofs which increases potential for water penetration.


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Figure 8.14 Examples of various types of deficiencies that may be observed during an investigation or survey.

Identify and observe the condition of the structure for each constructed asset. Observe the substructure, including the foundation system, superstructure or structural frame (floor and roof framing systems). Observe the structural elements for visible signs of distress (wall cracking, displacement, etc.). Perform seismic evaluations (probable maximum loss (PML) studies) in high earthquake risk areas that have been identified according to NEHRP guidelines (discussed in Chapter 17). The structural system can also be reviewed in greater depth than almost any other building system. Complete structural calculations and three-dimensional modeling can determine design and actual load capacities for any given member in a building. This type of detailed analysis is most easily done if the original construction drawings are available. The structural system’s components will have been designed with an adequate factor of safety and, with the exception of lateral design, significant deficiencies are unusual. Also, the majority of the system’s components are concealed behind building finishes, both exterior and interior, thus in most cases in-depth observation is cost-prohibitive. The system’s horizontal components and connections can usually be inves-


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tigated by accessing a ceiling or floor cavity. Often, a representative number of members and connections are accessible for review to provide a sufficient indication of the system’s condition. In some instances, destructive testing is warranted to verify structural connections. When inspecting walls, attention should be paid to the joints and grouting between units or panels. If a wall is leaning to the extent that a plumb line, if hung down the center of the wall, falls outside the middle one-third of the base of the wall, it is generally considered unsafe. Basement water problems are often diagnosed during surveys for the prospective buyer. These are usually diagnosed using some form of moisture detection equipment by a building inspector. The use of electronic moisture detection equipment is valuable for detecting moisture problems, but should not be used as the sole source of information in making decisions about the problem. For example, a moisture meter will not identify the source of the problem. When relying on moisture meters to make a diagnosis, using the wrong meter could lead to false, positive, or negative readings. It is important that the inspector knows how to correctly diagnose building pressures, condensation issues, dew-points, humidity, construction materials and practices, etc. While the most direct and common investigation of the structural system is through visual observation, various building diagnostic instruments have been developed to assist in the investigation. These are discussed in greater detail in Chapter 5. Pachometers, fiber-optic borescopes and other instruments are available which enable investigators to test material capabilities and view concealed spaces during an evaluation. The most common of these include: •

Cover meters and pachometers

Borescopes & fiberscopes

Moisture meter

Stereoscope

Wood probe test

Masonry hammer test

Acoustic impact test

Schmidt rebound hammer test.

There are other tests from the American Society of Testing and Materials (ASTM) and the American Concrete Institute (ACI) for the structural system components including the following: •

ASTM C803, “Standard Test for Penetration Resistance of Hardened Concrete”

ASTM C805, “Test for Rebound Number of Hardened Concrete”

ASTM E447, “Test Method for Compressive Strength of Masonry Prisms”

ASTM E518, “Test Method for Flexural Bond Strength in Masonry”

ASTM E519, “Test Method for Diagonal Tension in Masonry Assemblages”

ACI 201.R, “Guide for Making a Condition Survey of Concrete in Service.”

Limitations & exclusions: The forensic architect is not required to survey and report on building systems and components other than what is provided in the scope of works in the protocol agreement with the client. Also excluded from the PCA survey would be systems and components which are not readily accessible to view or which may present a potential safety hazard.


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When an issue arises that is outside the expertise of the forensic architect, it is important to recommend and select an expert that has both the knowledge and experience required to supplement your own. If the failure or deficiency is structural related, then it would be prudent to bring in a qualified structural engineer that is able to identify the problem as well as any other potential deficiencies. Based upon his/her review, a verbal or written report is prepared. At the forensic architect’s request, the engineer can develop drawings outlining the repairs and retrofit measures required or recommended. These construction documents should be submitted to the local building department for review and approval.


CHAPTER

9 Roofing Systems 9.1

GENERAL

Prior to the late 1970s, the majority of low-slope roofs were asphalt or coal tar built-up roofs. During the last couple of decades however, a number of other types of low-slope roof systems began to appear and compete with traditional built-up roofs (BUR). These newer systems included modified bitumens, single-plies, sprayed polyurethane foam, and metal panels. While the modified bitumen systems are related to BUR, the other low-slope alternatives are radically different. The abundance of materials from which to choose has greatly complicated roof system design. A roofing system provides a building and its contents protection from the elements. It also provides drainage of storm water to the various drainage systems (roof drains, scuppers and gutters) and directs it to the ground, retention ponds, or to a storm sewer. In addition, the roof structure is designed to transfer the combined weight of live and dead loads to the support members. Live load considerations include snow, rain, wind, moving installation equipment, etc. Dead loads include HVAC units, roof drains, roofing systems, and the deck itself. There are varying opinions regarding roof areas that can be effectively drained by one drain, but as a very general rule of thumb for minimized ponding with adequate drainage, two roof drains are required for roof areas of 10,000 square feet or less, and at least one drain is required per 10,000 square feet of area for larger roofs. In the replacement of drains, uniform distribution is generally desirable to achieve proper roof drainage. Likewise, careful consideration of roof structural members, dividers, expansion joints, and other projections including rooftop equipment is essential in planning the roof drainage system for adequate drainage of each area of the roof (Figure 9.1). System longevity is one of the most critical aspects of smart building management. Moreover, due to the common occurrence of deficiencies in roofing design, construction, materials and maintenance, and the importance of system integrity to the building and its contents, the roofing system is one of the most frequently evaluated. More money is wasted on roofing repair, maintenance and replacement than on any other building system. The roofing system, in coordination with the exterior closure system, is the first line of defense against the intrusion of water into a building.

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The roofing system consists of two basic components: the waterproofing members and the structural members. The waterproofing members, which typically include rolled or liquid-applied membranes as well as shingles, are intended to prohibit moisture from entering the structure. The structural members typically are constructed of concrete to wood to steel, and include elements such as beams, rafters and decking surfaces. The role of the strucFigure 9.1 Typical considerations when evaluating a built-up tural members is to hold the memroofing system. brane in place and support any additional rooftop loads which may exist, such as equipment or pedestrian traffic. Future developments: It is likely that as the industry moves through the early part of this century, there will be relatively minor, but important changes to products due to environmental, health, and laborsaving issues. The introduction of significantly different types of roofing materials is unlikely, but the trend toward more sustainable roof design and construction will likely continue. The use of advanced roof design technologies, such as expert systems, may develop, but this is not likely to occur in the very near future. However, it is likely that we will see an increased use of computer programs to evaluate performance issues, such as moisture gain within roof systems. The design of very robust roof systems may also become more common place on some buildings. Past experience has shown us that introducing new materials and system designs is not easy and typically it takes several years for unexpected problems to be identified and successfully resolved. Minor modifications to materials and system designs have also resulted in problems, but these have generally been less serious and more quickly resolved. It would therefore be prudent for designers and contractors to be cautious when specifying or installing new and untried products and systems. Should an emphasis on sustainable roof design be desired, then sustainable design criteria would become major factors in the selection process, depending upon the degree to which sustainability is pursued. At the very least, the selected system should be thermally efficient, with consideration given to both Rvalue, reflectivity and emissivity. And for those buildings that are intended to have a service life in excess of 20 years, a system with enhanced durability should be chosen to reasonably maximize the life of the roof to the extent that the budget allows.

9.2

ROOFING SYSTEM TYPES

The majority of roofing system types normally consists of built-up or single-ply roofing, shingles, tiles, or panelized systems.

9.2.1

Shingles and Tile Roofing

Constructed of wood, asphalt, slate or clay, shingles and tiles are typically used on roofs with slopes greater


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than 3 ½ inches per foot. Usually one or more layers of felt are placed between the structure and the shingles or tiles. Most manufacturers currently produce shingles that meet ASTM D3462, and this standard is increasingly being referenced by model code agencies, although some manufacturers, responding to requests for inexpensive products, are manufacturing “commodity” 20- and 30-year shingles that do not meet this standard. Recent developments in shingle manufacture include the increasing use of larger-sized “metric” shingles, longer “multitabbed” shingles, and distinctly-styled, non-rectangular, diamond and hexagonal (scalloped) shingles. Asphalt shingles: The Asphalt Roofing Manufacturing Association (ARMA) estimates that asphalt shingles represent 80 to 85 percent of the total residential roofing market in the United States. They consist of a fiberglass mat impregnated with asphalt, covered with mineral surface granules. They are formed into one foot by three foot sheets and nailed in a checkerboard pattern, overlapping to provide double coverage (two layers of thickness). Shingles were until recently categorized by weight (e.g., 240, 250, 280 pounds, etc.). The weight was generally related to service life. The life expectancy is between 15 years for standard weight to 25 years for heavy weight. Today, shingles are classified by warranty duration, such as 20, 25, 30, or 40-year. The organic core felt in the shingles is gradually being replaced with glass fiber felt. Glass fiber shingles are lighter than organic mat, do not absorb moisture, and are more resistant to wear. Also, they are incombustible and do not rot, mold, or mildew. Although fiberglass mat doesn’t necessarily perform better, it does allow shingles to meet Class A fire resistance ratings, while organic mat only meets Class C. The proliferation of different asphalt roofing shingle types and styles has made the selection of these materials difficult (Figure 9.2). If asphalt shingle roofs are being installed in hurricane-prone regions, most manufacturers tend not to warrant their products for wind speeds greater than 80 mph. Asphalt shingles have frequently performed poorly in high winds, and can be a significant source (along with other roofing products) of windblown debris. Wood shingle and shake roofing share the disadvantages of other wood products—namely, insufficient fire resistance and vulnerability to drying, curing, splitting, mold and mildew. Many codes in many jurisdictions prohibit the use of shakes and shingles due to the risk of fire. Both wood shingles and wood shakes are available in pressuretreated wood to meet U.L.790 firerated standards for Class A roofs. When properly installed and with the correct slopes, wood shingle roofs can last up to 20 years. Slate tile roofing is rarely used today due largely to its exorbitant cost. Slates should only be used where the slope exceeds 6 inches Figure 9.2 An example of a grey asphalt shingle pitched roof— Certainteed Roofing Collection. per foot. Copper nails are the only


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nails suitable to be used with slate. Properly installed, slate roofs can last up to 100 years. If slate is specified, a very durable underlayment is recommended to avoid premature degrading. Also, synthetic materials are often marketed as slate, some of which are made from slate particles, while others are made from polymers or other materials. Tile roofing consists largely of molded clay and precast concrete products and is a very versatile and durable roofing material. Tiles typically can be expected to offer a longer service life than asphalt shingles, but they are heavy and more costly than shingles. Tiles come in a variety of shapes, patterns and colors. Today clay tile roofing can be seen throughout much of the United States, particularly in commercial and retail facilities, garden offices, restaurants and residences (Figure 9.3). Because clay tile is a heavy material, clay tile roofing requires appropriate structural allowances if used. Critical to tile roofs are the attachment nails and wires. Galvanized or copper products should be used or corrosion will cause tile loosening and damage. Tiles will often shift and crack underfoot and are also vulnerable to significant breakage in transit. They have a high useful life expectancy but their high cost limits their widespread application.

9.2.2

Built-up (Multi-ply) Roofing

Built-up roofs (BUR) are the most common flat roofing type and consist essentially of three elements: felts, bitumen, and surfacing. In construction of a BUR, the felts, usually in two to four plies, and which are usually made of vegetable or glass fibers (polyester felts are also available), act as reinforcement for the thin layers of bitumen. The felts are necessary as tensile reinforcement to resist the extreme pulling force in the roofing material. Built-up roofs thus offer additional layers of protection against moisture penetration. This feature, together with the bitumen’s ability to seal itself during warm weather, makes BUR a good waterproofing system. The bitumen, whether asphalt or coal-tar-pitch, is what holds the felts together (Figure 9.4). While coal tar is still used, the vast majority of BURs are constructed with asphalt. The asphalt is typically hot-applied, although cold-applied asphalt constitutes a viable alternative that is gaining popularity (cold-applied asphalt incorporates solvent). And while both built-up roofing and modified bitumen systems can be applied with cold adhesives, the real growth in this application method is expected to come in modified bitumen systems which are less labor-intensive.

Figure 9.3 Examples of concrete tile roofing systems.


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Cold-applied systems are particularly effective on roofing projects that have difficult access, or in areas where odor can be of concern such as schools, hospitals, or hotels. Another advantage of cold-applied systems is that with specialized equipment they can be applied year-round and are particularly effective in cold weather. Exposed asphalt is susceptible to relatively rapid weathering. To mitigate this, BURs are surfaced with aggregate such as gravel or slag, mineral granules, a field-applied coating, or a mineralcoated cap sheet. If aggregate is specified, wind blow-off should be considered. The gravel, slag and mineral granules may be embedded into the still fluid flood coat. The purpose of the surfacing material is to protect the felts from direct sunlight, severe Figure 9.4 Example of conventional built-up (multiweather, fire, and impacts, and to act as a ballast. ply) roofing with asphalt bitumen surfacing being Surfacing materials also provide reflectivity, thereby applied. lowering surface temperatures and ensuring longer membrane life. The BUR is attached to a structural roof deck either by mechanical means such as nails, or adhered by non-mechanical means such as hot-mopping bitumen. BURs are usually applied to roofs with slopes of up to ½ inch per foot. When assessing a BUR system the following need to be taken into account: 1. Weathering: ultraviolet deterioration of asphalt, 2. Heat: deterioration and oxidation of asphalt, 3. Moisture: water penetration into plies and insulation, and 4. Movement: tension and stress on components. BUR roofs can have a useful life of 20 years or more when correctly constructed and maintained. ASTM standard D 312 is the product specification for asphalt. There are four types of asphalt. Type I is much more susceptible to flow than Type IV. ASTM D 6510 provides guidance for selection of asphalt type in BURs.

9.2.3

Single-Ply Roofing

The single-ply family of roof membranes is composed of thermoplastic and thermoset products. Single-ply membranes or elastomeric roofing systems are factory-fabricated and installed in a single thickness (Figure 9.5). These systems are relatively easy to install on steep or complex roof slopes. In comparison to BUR or Modified Bitumen (MB) membranes, they are also very lightweight (except for ballasted systems). However, they do not offer the same resistance to abuse as do BUR and MB membranes. Primary methods for securing the membrane to the roof deck or other substrate include: • • •

The fully adhered method, e.g., using a continuous layer of adhesive. This method is particularly suitable for high-rise buildings. The partially adhered method, using a series of strips or plate fasteners and no ballast to attach the membrane to the supporting structure. Loose laid over the substrate and ballasted to resist wind uplift (with fused or glued end laps to form a continuous sheet and covered with ¼ to ½ inch of stone). Ballasted systems are limited to a maximum slope of 2:12.


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• •

It can be mechanically attached where the membrane is loose-laid except for discrete rows of fasteners. There are a variety of fastening and seam fabrication with this method. The thermoplastic single-plies method in which field-fabricated seams are welded by robotic hotair welders. Hand-held hot-air welders are used to weld seams at flashings and penetrations.

There are four categories of single-ply systems: 1. Thermosetting (vulcanized or “cured” elastomers) types include EPDM (ethylene, propylene), neoprene (synthetic rubber), and PIB (polyisobutylene). 2. Thermoplastic (non-vulcanized or “uncured” elastomers) types include PVC (polyvinyl chloride), CPE (chlorinated polyethylene). 3. Chlorosulfonated polyethylene (CSPE) is neither a thermosetting nor thermoplastic material. 4. Composite types include glass-reinforced EPDM and neoprene, various modified bitumen and polyethylene combinations, and nylon or polyester-reinforced PVC. EPDM is a lightweight, synthetic elastomer material that currently enjoys the largest market share of single-ply roofing in America (Figure 9.6). Reasons for this include EPDM’s properties of resilience, tensile strength, elongation, greater flexibility to accommodate wide ranges of movement, moisture resistance (provided it is not torn or punctured), ease of repair, and generally a cleaner installation process. It also offers superior resistance to heat, ozone, ultraviolet light, ponding water, and weathering in general. However, EPDM punctures easily, and should not be used on high traffic roofs unless adequate precautions are taken (e.g., use of extensive walk pads.). EPDM is also susceptible to swelling when exposed to aromatic, halogenated and aliphatic solvents, and animal and vegetable oils such as those exhausted from kitchens. Polyvinyl chloride (PVC) membranes are among the oldest single-plies currently on the market. If in contact with polystyrene insulation, the polystyrene will cause the plasticizers in the membrane to leach out. When used with polystyrene, a separator sheet needs to be installed between the membrane and the polystyrene to avoid membrane embrittlement. To avoid membrane damage, a separator is also needed to isolate PVC from asphalt and coal tar products. PVC membranes are available in a wide variety of colors. This type of membrane is often selected for steep-slope roofs where a strong or unique color is desired.

Figure 9.5 Example of mechanically fixed single-ply roofing (SPR) system.


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Figure 9.6 Drawing of an EPDM single-ply membrane roofing system with expansion joints (courtesy, John Maniville).

Thermoplastic polyolefin (TPO) is the latest thermoplastic membrane introduced into the marketplace. It is made from polypropylene, polyethylene, or other olefinic materials. TPO membranes do not rely upon plasticizers for flexibility (unlike PVC and PVC blends), and therefore embrittlement due to plasticizer loss is of no concern. Thermoplastic materials do not cross-link, or cure, during manufacturing or during their service life. Field-fabricated seams are typically welded with robotic hot-air welders. Thermoplastic membrane seams are typically extremely reliable, resulting in a very low incidence of seam failures. These sheets are normally around 5 to 12 feet wide (1.5 to 3.6 m).

9.2.4

Modified Bitumen (MB)

Modified Bitumen (MB) roof systems are hybrid built-up roofs initially developed in Europe. The term modified refers to the addition of plastic or rubber-based polymeric binders to asphalt to improve its performance. MB membranes are characterized by increased toughness and resistance to abuse. They are typically composed of pre-fabricated polymer-modified asphalt sheets. Polymers are added to bitumen to enhance various properties of the bitumen. The quality of MB products is highly dependent on the quality and compatibility of the bitumen and polymers, and the recipe used during the blending process.


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MB roof systems have the benefits of the built in redundancy of the BUR, along with the added strength, flexibility and UV resistance of a modified membrane. The membrane consists of an asphalt and polymer blend which allows the asphalt to take on characteristics of the polymer. There are several surfacing options for this system which include a factory applied mineral surface, a gravel surface laid in bitumen, or a liquid applied coating that is typically reflective in nature. Modified bitumen membranes are typically applied like a traditional BUR, but because there is only one “ply,” the labor cost is reduced. The idea behind modified bitumen roofing is a simple one: By pre-manufacturing the cap sheet component of BUR systems in controlled factory environments, material suppliers could add polymer modifiers that improve the performance of multi-ply roofs, which had traditionally been fabricated in the field. Today’s high-performance polymer modifier technology is selectively targeted at enhancing increasingly specific performance attributes, such as low-temperature flexibility or ultraviolet-radiation resistance. Similarly, yesterday’s cotton felts have given way to high-strength alternatives such as fiber glass and polyester. Durability is the most significant performance advantage of modified bitumen roofing. Not only do the modifiers improve the roof’s ability to withstand foot traffic and other abuses, they help roofs age more gracefully. Unlike other less resilient commercial roofing options, modified bitumen roofs lend themselves to restorative alternatives as they age, delaying the need for tear-off and re-roofing. With consistent monitoring and proactive maintenance, modified bitumen roofs remain watertight for decades. MB membranes are typically composed of pre-fabricated polymer-modified asphalt sheets. Polymers are added to bitumen to enhance various properties of the bitumen. The three most popular primary types of MB sheets, as well as field-applied modified mopping asphalt are: Atactic polypropylene (APP), styrene butadiene styrene copolymer (SBS) and styrene butadiene rubber (SBR). Atactic polypropylene (APP) polymer is blended with asphalt and fillers. The mixture is then factoryfabricated into rolls that are about a yard wide. The prefabricated sheet, commonly referred to as a cap sheet, is typically reinforced with fiberglass, polyester or a combination of both. The sheets are available smooth (i.e., unsurfaced); embedded with mineral granules in a variety of colors; or factory-surfaced with metal foil such as aluminum, copper, or stainless steel. The aluminum foil is available in colored finishes. APP MB membranes are generally resistant to high-temperature flow. APP MB membranes are typically composed of a base sheet and an APP cap sheet. The cap sheet is either heat-welded (i.e., torched) to the base sheet, or it is adhered in cold adhesive. Mechanically attached systems are also available. To minimize potential surface cracking, a field-applied coating (such as aluminum-pigmented asphalt, asphalt emulsion, or acrylic), factory-applied surfacing (granules or metal foil), or a sheet with protective reinforcement near the top should be used. Styrene-butadiene-styrene (SBS) is blended with asphalt and fillers. The mixture is then factoryfabricated into rolls with reinforcement and surfacing similar to APP MB sheets. SBS sheets generally have good low-temperature flexibility, but they are susceptible to premature deterioration when exposed to UV radiation. Styrene butadiene rubber (SBR) is a random polymer made from butadiene and styrene monomers. It possesses good mechanical property and processing behavior, and can be used like natural rubber. There are two main types of SBR, Emulsion SBR (E-SBR) and solution SBR (S-SBR), based on the different manufacturing process. The styrene-isoprene-styrene (SIS) roofing system consists of self-adhering sheets that are blended with SIS polymer, asphalt, and fillers. The mixture is then factory fabricated into either 3 feet or 1 meter wide rolls. The top of the prefabricated sheet is available with embedded mineral granules or a factorylaminated UV-protective surfacing, such as aluminum foil.


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Styrene-ethylene-butylene-styrene (SEBS) is a polymer that is generally blended with asphalt in the factory. The SEBS modified asphalt is then reheated at the job site in specially-designed tankers or kettles. The hot modified asphalt is applied in a manner that is very similar to BUR systems. The membrane is typically surfaced with aggregate. Sprayed polyurethane foam (SPF) is a very unusual type of roof system in that the membrane is constructed by spraying a two-part liquid onto a substrate. The mixture expands and solidifies to form closedcell polyurethane foam. The substrate can either be the roof deck, an existing roof membrane (provided the existing roof is suitable for re-covering), gypsum board, or rigid insulation. The foam is applied with hand-held sprayers or by robotic sprayers. Each pass of foam is typically between ½ to 1 ½ inches (13 to 38 mm) thick. If a greater total thickness is desired, two or more passes would normally be required. The total thickness of the foam can easily be adjusted to provide adequate slope for drainage (Figure 9.7). The foam needs protection from UV radiation as it will break down and fail if exposed. This is normally achieved by using one of the following coatings which should, if possible, be applied on the same day as the SPF, or at least within 24 hours. Acrylic Latex coating: This is the least expensive of the coatings, but normally offers the shortest service life (re-coating is required about every 10 to 15 years although the best acrylics can last longer than some of the polyurethane coatings). Polyurethane coating: Properly formulated, this coating offers long service life and can be the toughest coating available in terms of impact and tear resistance. Also, a wide range of physical properties is available in this product category. Silicone coating: Silicone coatings offer exceptionally good weather resistance and long service life. More than other coatings, silicone coatings are prone to being pecked by birds. To avoid the pecking, granules are commonly set into the coating while it is wet. Mineral granules: Mineral granules (similar to those used to surface asphalt shingles) can increase the durability of a coating and provide greater slip-resistance. Course sand can also be used for this purpose. Granules or sand are placed into the coating while it is wet. Aggregate surfacing: Properly formulated and installed SPF is quite resistant to liquid water. Therefore, aggregate of the size used on BUR systems can be applied directly over the foam. As with aggregate-surfaced BUR, consideration should be given to aggregate blow off. Other types of coating include Neoprene (Hypalon), butyl rubber, epoxies and modified asphalts. Whichever coating is applied, it is important that the coating used is compatible with the SPF product, and approved by the SPF manufacturer. Some coatings, such as acrylic latex, asphalts, and vinyls, reFigure 9.7 Photo showing a worker applying sprayed polyurethane foam (SPF) on existing single-ply membrane roof quire that the SPF be sprayed first with a (courtesy, Servcor International, Inc.). primer for good adhesion.


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SPF systems have several important attributes. Besides readily lending themselves to complex roof shapes, SPF roofs are exceptionally thermally efficient, since they do not have mechanical fasteners or insulation board joints which create thermal bridges. And notably, an SPF roof is not in imminent danger of leaking if the coating is weathered away or ruptured or the aggregate surface is displaced, provided that the penetration does not extend all of the way through the foam.

9.2.5

Metal Panels Roofing

Metal roofing is relatively lightweight, has strong architectural appeal and durability, and is relatively easy and quick to install. Prefabricated metal panels may be made of copper, terneplate, galvanized steel, or aluminum. Various seam configurations allow for metal roofing on both flat and pitched roofs. Various custom panel sizes, profiles, colors and finished coatings are available for commercial applications. Metal roofing’s attributes are impressive, offering long-term weatherability, low maintenance and aesthetic value (Figure 9.8). Metal panels are not often considered for use on low-slope roofs, although some metal panel systems can be used on very low slopes. Some manufacturers even tout their systems as being suitable for slopes as low as ¼:12 (2 percent), NRCA recommends a minimum slope of ½:12 (4 percent). Basically, with metal panel roofing the greater the slope, the more reliable the leakage protection. The popular standing seam metal roof is constructed of interlocking panels that run vertically from the roof’s ridge (the top of the roof) to the eave. The interlocking seam where two panels join together is raised above the roof’s flat surface, allowing water to run off without seeping between panels. Some panels have snap-together seams, while others are mechanically seamed with an electrically powered mechanical seaming tool. On slopes of ½:12 (4 percent) or less, it is recommended that mechanically seamed panels be specified. Two methods are commonly used to secure the panels to the roof sheathing. The first (and better) system consists of concealed fastener clips that are secured to the raised portion of each interlocking panel, and subsequently covered by the next adjoining panel during installation. The second (simpler and less costly) method utilizes exposed fasteners that are driven through each metal panel into the roof sheathing. One of the chief concerns presented by metal roofing is movement caused by thermal expansion. This continuous movement resulting from expansion and contraction sometimes causes the fasteners to loosen, thereby affecting the system’s integrity of water Figure 9.8 Example of metal panel roofing—Knightsbridge Financial Center, New Jersey (courtesy, Englert, Inc.). tightness.


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Figure 9.9 Drawing of roll roofing application parallel to the rake using concealed nail method.

9.2.6

Other Roofing Systems

Asphalt roll roofing is manufactured in 36-inch-wide sheets in a variety of weights, surfacings and colors. It is used both as a primary roof covering and a flashing material. Roll roofing has a useful life expectancy of about 10 years. It is not suitable for applications where slopes are less than 1 inch per foot. Roll roofing consists of a reinforcing felt covered with coating asphalt; organic felts are impregnated with a saturant asphalt. Roll roofing contains a surfacing material, usually coarse or fine mineral, and is installed using mechanical fasteners or cold-applied adhesives; it does not require hot mopping asphalt. In addition, roll roofing is typically installed over an underlayment felt that has been impregnated with coating asphalt during manufacture, and is affixed to the roof substrate by mechanical means or cold adhesives. It is applied either parallel to the eaves or parallel to the rakes (Figure 9.9). There are numerous variations of asphalt roll roofing such as the Modified Bitumen Roll Roofing MSR which complies with ASTM D-3462 Tear Strength SBS Modified. This is essentially an asphalt roll roofing system with glass mat reinforcement and is available in a variety of colors. It typically comes in a 36-inch width and 37-foot length and weighs 90 pounds per 1 square coverage. Mineral surfaced roll roofing can also be an economical flashing material for roof valley installations.

9.3

COMPONENTS TO BE EVALUATED

The roof deck (or field): The roof deck supports the waterproofing membrane of the roof. It can be made of various materials including steel, concrete, wood and formboard. Office buildings typically have steel or concrete decks, although plywood or OSB decks are also used on smaller buildings. The deck can have significant influence on the roof system. Of the deck types, steel is the most common.


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In some cases this can be inspected from below to identify any splits or damage to the deck. A corrugated deck is typically covered by rigid insulating boards or insulated with vermiculite, perlite, or cellular types of roof fill, on top of which is the roofing material. A concrete deck can be a waffle slab or pan joist and can be pre-cast or poured in place. A formboard deck is a dense composite board, usually made from wood fibers, cement, and occasionally urethane foam. When evaluating or inspecting existing roof decks, the following issues should be noted and addressed: • • • • • • • • •

The type and general condition of the roof. That there is adequate drainage (no ponding) and that the roof drains are clean. That the slope of the roof is adequate for the roofing system used. There are no exposed areas of felt or areas missing aggregate. Have the materials been sampled and analyzed for asbestos? That the adhesion of the felt membranes is adequate. Is there evidence of bowing or sagging? No evidence of punctures or openings at the edge wrinkle of a felt lap (in BURs). Check for evidence of alligatoring, ridging, splitting, or raised blisters.

Roof flashing: Flashing forms the intersections and terminations of roofing systems and surfaces to thwart water penetration. The most common locations for roof flashing are at valleys, chimneys, roof penetrations, eaves, rakes, skylights, ridges, and at roof-to-wall intersections. Roof flashing materials can be classified into two primary groups: membrane and sheet metal. Ice and water barriers and roll roofing are membranes. The most typical sheet metal flashing materials are aluminum, copper, lead-coated copper, lead, stainless steel, galvanized steel, zinc, and GALVALUME®. Both sheet metal and membrane flashing are available unformed or, for some particular applications, in pre-formed configurations. Flashing must be configured to resist the three mechanisms of water penetration: gravity, surface tension, and wind pressure. To achieve this, flashing can be lapped shingle style, soldered, or sealed to function as a continuous surface, or can be configured with a noncontinuous profile to defeat water surface tension. Flashing materials must be durable, low in maintenance requirements, weather resistant, able to accommodate movement and be compatible with adjacent materials. Common modes of failure include exposure to salt air, excessive heat, acid rain, heavy snows, and scouring winds. Base flashing: Each type of roofing material requires a flashing material with similar characteristics to achieve a good seal. Base flashing is used to seal the roof field membrane at upturned edges and is typically found at parapets, penthouse walls and equipment penetrations (Figures 9.10). Flashing materials typically include asbestos, organic, or glass fibers in combination with bitumen, various types of rubber and PVC, and metals including aluminum, copper, lead, and steel. The Environmental Protection Agency (EPA) has now effectively eliminated the use of asphalt-saturated asbestos felts which were used extensively as base flashing or as support for base flashing in BURs. Counter flashing: Covering the exposed edges or joints of the base flashing, counter flashing is made of materials similar to base flashing. Counter flashing should be evaluated for issues similar to those of base flashing. Parapet: The parapet is the wall around the roof, typically 2 ½ to 5 feet high, which usually is an extension of the exterior wall of the building (Figure 9.11). The field observer should check that the parapet’s general condition is satisfactory, the mortar joints are in good condition, the scuppers are adequately sealed and there is no evidence of cracking or spalling.


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Figure 9.10 EPDM base flashing detail (courtesy, John Maniville).

Coping: Coping is a flashing, typically metal, masonry or wood, located at the top of a wall, pier or chimney (Figure 9.12). The basic function of coping is to act as a protective cap and should be waterproof, weather resistant, and sloped to shed water. The joints and caulking should be examined to make sure they are in satisfactory condition and there are no signs of corrosion or discoloration of adjacent surfaces due to water run-off. Gravel stops: Gravel stops are installed to prevent gravel from washing off the roof, as a counterflashing, or to provide a decorative edge finish detail to roofs not using parapets. Gravel stops are typically constructed of aluminum, copper, lead-coated copper, PVC, galvanized or stainless steel. Gravel stops should be examined for their type and general condition and for evidence of deterioration of material, joints, or caulking in addition to evidence of corrosion or discoloration of adjacent surfaces due to water run-off. Likewise, attachment and fastening to the building should be examined for adequacy. Gutters, downspouts and drains: This equipment is installed to collect, distribute and convey rainwater from the roof area. Gutters are constructed of various materials including metals, plastic, and vinyl. Downspout materials also include black steel or cast iron. Roof drains are typically constructed of cast iron, brass, galvanized steel, copper, lead or PVC, and usually discharge water into a drainage system (Figure 9.13A,B). PVC drains are compatible with elastoplastic systems, but are not suitable for torching or hot-


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Figure 9.11 Mechanically attached parapet wall—single-ply roof (courtesy, IB Roof Systems).

Figure 9.12 Example of bullnose parapet wall coping (courtesy, W.P. Hickman Co.).


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Figure 9.13A Examples of different drain types (courtesy, Smith Drainage Systems).

Figure 9.13B Drawing of roof drain detail.

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mop applications because they melt under high temperatures. Gutters should not have leaks and should contain basket strainers at downspouts to capture any debris. Downspouts should be plumb and be installed away from wood products to prevent moisture accumulation and rot. In addition, an adequate overflow back-up system should be in place. Equipment penetrations and supports: Every penetration in a roof membrane threatens the roof’s integrity. Ducts, pipe vents and other mechanical components, equipment penetrations and supports, are common avenues for water infiltration and should be given special examination. Included in this category are pitch pans, which are metal containers surrounding equipment supports, structural columns, or any other roof penetration. Some of the issues to check when surveying equipment penetrations and supports include: general condition, adequacy of flashing methods and conditions, evidence of thermal movement of penetrations or supports, signs of excessive field wear from maintenance operations around equipment, pitch pan fill material shrinkage evidence and sufficient attachment. Expansion joints: Expansion joints are installed to allow full-depth separation of roofing materials which allows relative thermal or structural movement to take place without causing damage to the roofing system (Figure 9.14A,B,C,D). Expansion joint construction at the roof typically consists of a blocking material to raise the joint above the roof, a prefabricated protective covering of rubber, neoprene or metal to prevent water penetration, and a compressible filler of felt, rubber, or neoprene to keep the joint clean. Expansion joints for built-up applications are required at 150 feet intervals.

Figure 9.14A Typical roof to roof expansion joint detail (courtesy, W.P. Hickman Co.).


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Figure 9.14B Roof to wall expansion joint detail (courtesy, W.P. Hickman Co.).

Figure 9.14C Roof expansion joint detail (courtesy, John Maniville).

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Figure 9.14D Flashing to drain (courtesy, John Maniville).

The inspector should check that the expansion joints are in good condition and look for evidence of deterioration, rusting or other signs of corrosion. He should also look for evidence of punctures or splits in the joint or cover material or any open joints where covers have been removed or omitted and ensure that the attachment and fasteners are in good condition. Rooftop projections and fixtures: Flag poles, antennas, satellite dishes, access hatches, skylights, rooftop projections and fixtures should be included in an evaluation of the roofing system. Basically, their general condition should be evaluated and whether they are adequately fastened or braced. They should also be monitored for evidence of damaged or deteriorated flashing or waterproofing. Insulation: Roof insulation is used to reduce heat transfer through the roof. It can be installed above or below the roofing membrane. There are two categories of roof insulation, rigid and non-rigid. Rigid boards are typically used in low-slope assemblies. Non-rigid insulations are typically used in attic spaces and in pre-engineered buildings. The insulation is made of various materials including mineral fiberboard, fiberglass boards, perlite sheets, polystyrene, urethane, various composite sheets, and poured-in-place lightweight concrete. Rigid board insulation has sufficient compressive resistance to support the roof membrane. The following common types of rigid insulation boards are available: Perlite: This is a low R-value insulation (R-2.78 per inch). It is commonly used as a cover board. It has good fire resistance, but when exposed to water it loses compressive resistance, turns to mush, and can be easily compressed. Polyisocyanurate: This is a high R-value insulation (R-5.6 per inch) and is one of the plastic foam insulations that is widely used in low-slope roof systems. Polystyrene: There are two types of polystyrene insulation, molded expanded and extruded expanded. The two types have distinctly different properties. Polystyrene is one of the plastic foam insula-


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tions. Polystyrene boards should not be in direct contact with PVC membranes, otherwise the polystyrene will leach plasticizers out of the PVC. A suitable separator needs to occur between polystyrene and PVC. Wood fiberboard: This is a low R-value insulation (R-2.78 per inch), and is commonly used as a cover board. This board has good compressive resistance, but when exposed to water it loses compressive resistance and can be easily compressed. Composite boards: Composite boards typically consist of two layers of different types of insulation that are laminated together in a factory. The primary insulation is typically polyisocyanurate or MEPS. The secondary layer is typically perlite, wood fiberboard, oriented strand board (OSB), plywood, or gypsum board. Batt, blanket or blow-in insulation: Batt insulation is insulation that is factory pre-cut into lengths of approximately 4, 8, or 9 feet and bundled without rolling. Blanket insulation is insulation that is supplied in a roll. This is commonly used to insulate attic spaces. Blanket insulation is commonly used to insulate roofs of pre-engineered metal buildings. Fiberglass insulation is the most common batt/blanket insulation, and it is also available as a blow-in product. Cellulose is also a common blow-in insulation. If cellulose is specified, specify a product that has been treated for mold and fire resistance. Warranty considerations: A warranty is not a maintenance contract, nor is it an insurance policy. Furthermore, it does not ensure that leakage, damage caused by hail or wind, or another type of damage will not occur. Rather, a warranty defines specific legal rights and obligations of the building owner and warrantor. It includes remedies and exclusions. If the warrantor is out of business when a problem covered by the warranty is experienced, the warranty often becomes a useless piece of paper. A warranty may have some merit if it means that the manufacturer will take steps to minimize the potential for future problems (such as reviewing the architect’s specification and details and providing meaningful inspection during application). A warranty may also enhance the likelihood that a roof will be installed by a professional contractor. However, rather than relying on a warranty to obtain a qualified contractor, architects should specify contractor qualification requirements as discussed in the next section. If a problem that is covered by the warranty occurs, and the warrantor is still in business, the presence of the warranty may lead to a quick resolution of the problem. Virtually every warranty issued by a manufacturer covers repair of leaks caused by defective materials and workmanship (if the warranty is not for materials-only) provided that the cause(s) of the leakage is covered under the terms of the warranty. Without a warranty, the building owner might have to pursue legal action to obtain relief. Pursuing legal action may be too costly if the problem is small. Also, the presence of a warranty provides a direct avenue for the building owner to pursue a claim with the manufacturer if the manufacturer does not respond to a problem covered under the warranty. Warranties are normally prepared to limit the manufacturer’s liability to a narrow scope of provisions rather than to provide protection for the building owner. Warranties typically preclude claims based on other theories of liability, including negligence and breach of contract. In addition, warranties typically exclude the implied and express warranties established by the Uniform Commercial Code (UCC). In any case, a roofing system should be selected for its suitability to the project and not on the basis of a warranty.

9.4

TYPICAL DEFICIENCIES

In general, the performance deficiencies in the roofing system fall into two categories: initial application and maintenance-related. Deficiencies in the roofing system typically consist of breaches in the system’s waterproofing capabilities. Most deficiencies can be detected from visual observation. Water stains on


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walls for example, may indicate fascia problems. Wet spots on the walls, or wall cracks, can indicate a separation of the building, probably at a structural beam. Bare spots on bituminous roofs may be due to wind sweeping, flow of flood-coat, blistering, etc. Unlike some building systems where there may be graduating levels of effective and adequate performance, the roofing system is performing adequately only if the integrity of the waterproofing barrier is intact. In asphalt shingle roofs, isolated small holes or cracks in shingles can be temporarily repaired by troweling on plastic roofing cement. Curled shingles can often be cemented back in place, whereas individual shingles that are badly damaged can be replaced. However, where a large number of shingles exhibit excessive drying out, curling, cracking, or other deterioration, or if there is evidence of significant leaks that are not due to faulty flashing, then a complete shingle replacement may be necessary. Roofing failures can be due to a number of causes including: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Moisture penetration Improper flashing Improper equipment supports & penetrations Poor maintenance Thermal movement High roof drains Inadequate inspection Improper flashing Improper material selection EPDM membrane shrinkage Inadequate surfacing Improper patching

Application: The majority of roofing deficiencies are caused by application-related problems. There are numerous problems which can arise due to errors in application methodology or judgment. The most common error in BUR systems is installing the materials at an improper temperature, thereby causing inadequate or defective adherence and waterproofing integrity. Maintenance: The most important reason for establishing a program of regular roof maintenance inspection is to protect the owner’s investment. A well executed maintenance program not only adds years to the life of the roof, but it also allows detection of roofing problems before damage becomes widespread, so that the internal functions of the building are not interrupted. Inadequate maintenance plays a significant role in the deterioration of a roofing system’s integrity. Often taking corrective measures soon enough—basic repairs—can pay substantial dividends to the owner. Roof penetrations are typically the single most common source of roof leakage which is why surveys should carefully include individual rooftop equipment, including metal work, to see if there is evidence of moisture entry into the roofing system.

9.5

SYSTEM DIAGNOSTICS

In most roofing systems, it is not unusual to find at least some level of material deterioration and signs of insufficient maintenance, such as leaves and other debris clogging the drains. It is therefore wise to con-


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duct periodic roof maintenance surveys as part of a facility’s preventive maintenance program. This alone will lengthen the service life of a roofing system. Before performing the physical maintenance inspection, the roof’s historical and repair records should be examined (e.g., to determine whether the roof is still under warranty). Upon completing the initial research, it is useful to inspect the ceiling of the upper floor of the building for any signs of water penetration or damage indicative of a deficient roofing system (Figure 9.15). Indicative signs of water entry include stained ceiling tiles, dry rot in a wood deck, and rust in a steel deck or efflorescence in a concrete deck. All deteriorated areas and their location should be noted. The next step would include a walk around the perimeter of the building checking for cracks and/or other signs of structural movement. Evidence of water entry into walls such as efflorescence of masonry buildings; rusting fasteners, lintels, shelf angles, etc. should be looked for. The inspector should also look for evidence of open expansion joints and sealant joints at wall penetrations. Drainage accessories (downspouts, scupper heads, and gutters) should be examined for signs of leakage, rusting or loose attachments. Identify and observe the condition the roof systems, accessories, and details (exposed membrane and flashings around the perimeter of the roof), including parapets, slope, drainage, etc. followed by an evaluation of the roof deck (field). Drains and the flashing surrounding the drains should be checked for the presence of upward movement caused by pipe expansion. Identify previous repairs, evidence of significant ponding, or roof leaks. Downspouts should be inspected to ensure that the straps securing them are in place. Evidence of ponding should be noted, and in the absence of standing water, check for other symptoms such as discoloration of the roof membrane, growth areas of algae or other vegetation, and accumulations of dirt. Areas of heavy foot traffic should also be checked for punctures, deterioration and bare spots in the surfacing. Assessors should not walk on pitched roofs, or any roof areas that appear to be unsafe, or roofs with no built-in access. Assessments should exclude determining roofing design criteria.

Figure 9.15 Photograph showing stained ceiling tile which indicates a leaking roof.


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Observe penetration details for condition and conformance with standard accepted industry practices. The age of the roof should be determined and whether there is a valid roof warranty in effect. Upon identifying the apparent or reported ages of roof systems and, combined with visual observations, identify the roof systems’ remaining useful life (RUL). There are many causes for a roof to deteriorate before its natural useful life. Workmanship problems lead the list of causes, followed by poor designs, material failures, and poor maintenance. Once a roof begins to leak water it is absorbed into the roof assembly, especially the insulation. Once wet, for all practical purposes, insulation never dries. In fact, the trapped moisture can quickly cause further serious degradation to the roof, including the rusting of metal decks and fasteners, reduction in insulating value, and decay of the membrane. When maintenance or repair no longer can effectively prevent leakage or extend useful roof system service life, consideration must be given to roof system re-cover or replacement when one or more of the following occurs: • • • •

Repair expenditures become excessive Leakage becomes intolerable Damage is occurring to the structural components Damage is occurring to building interior finishes and/or contents

Unlike some of the other building systems, various diagnostic tools are readily available to evaluate the roofing system. Although these diagnostic tools go beyond the scope of a baseline review or inspection, the forensic architect should nevertheless be familiar with them. These tools and methods can monitor to what extent moisture has entered the system and include: Roof cut: One of the standard tests of a roofing system is the roof cut. The purpose of this test is to determine the existing construction and conditions of the roof. Once the cut is removed, the sample can be evaluated to determine the condition and the moisture content of the materials. This test should not be conducted where a warranty exists as this may be jeopardized. Moisture meters: Moisture detection in a roofing system is greatly aided by the use of instrumentation. The presence of moisture in roofing and structural members can be detected by several portable diagnostic tools, with moisture meters being the most common. Infrared thermography: Infrared thermography identifies radiation wavelengths within building materials and components. By using infrared thermography to spot thermal anomalies in the roof, many leaks can be tracked, verified and repaired. Since the moisture is usually of a lower or higher temperature than the surrounding materials, the scanner registers the areas of differential temperature. Infrared can quickly let you see the true condition of the roof’s insulation and by applying infrared thermography it is possible to save money by replacing only the moist areas of insulation. Moreover, when the roof develops a leak infrared surveys can locate the trapped water (Figure 9.16). Because the leak is typically found to be within the boundary of the wet insulation, the wet area is marked for removal and repair. That keeps the roof in a dry condition, minimizing roof degradation, and extending the life of the roof. Nuclear moisture detector: Another type of moisture detection instrument is the nuclear moisture detector. It works by emitting a cone of high velocity neutrons into the roof. As the neutrons are reflected back, a reading is taken to determine the speed of their return. Neutrons which have come in contact with the hydrogen in the water return more slowly. In this way, areas of moisture can be identified. Unlike the infrared meter, the nuclear meter can be used during the day. A license to operate the equipment is required by the U.S. Nuclear Regulatory Commission.


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The Troxler Roof Reader™ is an example of a commercial roof nuclear moisture detector (Figure 9.17A). It essentially maps the hydrogen concentrations within the roofing structure, permitting repair or replacement of only saturated areas (Figure 9.17B). As part of a preventative maintenance program, the RoofReader can quickly pinpoint problem areas, saving time and minimizing capital outlay.

Figure 9.16 Three components of an aerial survey: photo, infrared, autocad.


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Figure 9.17A,B A. Applying a nuclear roof moisture detector (courtesy, Troxler Labs), B. Mapping of moisture data levels on a nuclear moisture gauge (courtesy, Troxler Labs).


CHAPTER

10 Heating, Ventilating & Air Conditioning (HVAC) Systems 10.1 GENERAL Today, millions of Americans work in buildings with mechanical heating, ventilation, and air-conditioning (HVAC) systems. These systems are designed to provide air at comfortable temperature and humidity levels, free of harmful concentrations of air pollutants. And the continuous development of air conditioning systems has brought about fundamental changes in the way we design projects because it allows investors to build larger, higher, and more efficient buildings than before. But even as buildings today are being designed with increasingly sophisticated energy management and control systems (EMCS) for monitoring and controlling the conditions of a building’s interior space, we still often discover that a building’s heating, ventilating, and air-conditioning (HVAC) equipment routinely fails to satisfy the performance expectations of its designers and owners. But even more troubling is that such failures often go unnoticed for extended periods of time. Developments in computers and electronics equipment have made HVAC systems smarter, smaller, and more efficient. They have reshaped how the systems are installed, how they are maintained, and how they operate. Other important recent developments in HVAC equipment design include the introduction of variable air volume (VAV). With these systems, persons who have conditioned air circulating in, on, or around them can control the temperature in their own particular personal space. For example, if two persons are on the same system and one wants to increase the temperature, the system can heat that person’s space and cool the other’s. It can also change the volume of air delivered to the space. Moreover, with variable air volume systems, it is possible to damper off a space that is unused or unoccupied, increasing efficiency.

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Figure 10.2 A drawing illustrating the attributes of good indoor air quality (illustration, Johannes Knesl).

Buildings in the United States annually consume approximately 42 percent of America’s energy and 68 percent of its electricity. A significant percentage of this is consumed by HVAC systems. The energy source that provides power to an HVAC system is usually gas, solid fuels, oil, or electricity. The conducting medium is typically water, steam, or gas. The heating and cooling source equipment consists of components that use the energy source to heat or cool the conducting medium. The heating and cooling units (such as air conditioners and air handling units) are the components of the system that modify the air temperatures for the interior environment. The assessment of the HVAC system is one of the main components of a general baseline evaluation. This is in large part due to the cost of operations and maintenance typically associated with HVAC systems. It has been known for many years that physical comfort is critical to work effectiveness, satisfaction, and physical and mental well-being. Empirical evidence shows that uncomfortable conditions in the work-


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place such as noise, inadequate lighting, uncomfortable temperature, high humidity, ergonomics, and other physiological stressors invariably restrict the ability of workers to function to their full capacity, leading in many cases to lower job satisfaction and increases in building related illness symptoms. And since humans generally spend about 90 percent of their time indoors, health, well-being, and comfort in buildings are crucial issues (Figure 10.1).

10.2 REFRIGERANTS A refrigerant is a compound used in a heat cycle that undergoes a phase change from a gas to a liquid and back. The main uses of refrigerants are in refrigerators/freezers and air conditioners. The two refrigerant families most often used in air conditioning systems are hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs). The Environmental Protection Agency, in accordance with the Montreal Protocol, is now obligated to phase out hydrochlorofluorocarbon (HCFC) refrigerants used in heat pump and air conditioning systems because of their impact on ozone depletion. Chlorofluorocarbon (CFC) refrigerants manufacture has been banned in the United States since 1995. To date, the main alternatives are hydrofluorocarbons (HFCs) and HFC blends, although there are several potential non-HFC alternatives as well. Dupont has produced a complete family of easy-to-use, non-ozone-depleting HFC retrofit refrigerants for CFC and HCFC equipment. But while (HFCs) may be suitable as short- to medium-term replacements, they may not be suitable for long-term use due to their high global warming potential (GWP). On September 21, 2007, parties to the Montreal Protocol overwhelmingly agreed to accelerate the phase out of hydrochlorofluorocarbons (HCFCs) to protect the ozone and combat climate change with adjustments beginning in 2010 to production and consumption allowances for developed and developing countries. This refrigerant phase out of CFCs and HCFCs will have a significant impact on proposed real estate purchases that still utilize this equipment. This means that owners and administrators need to take the long view when making decisions about their capital investments. This should all be documented in the forensic architect’s report, which would also include a review of capitalization requirements associated with the phase-out of CFC/HCFC-containing refrigerants.

10.3 TYPES OF HVAC SYSTEMS There are a number of different classifications for HVAC systems (e.g., single zone/multiple zone, constant volume/variable air volume), but the most common classification is by the carrying mediums used to heat or cool the building. The two main transfer mediums for this purpose are air and water, which take them to emitters. On smaller projects, electricity is often used for heating although some systems now use a combination of transfer media. And while there are a wide variety of HVAC systems in use today, no system is right for every application. HVAC systems range in complexity from stand-alone units that serve individual rooms or zones to large, centrally controlled systems serving multiple zones in a building. Heating systems: Most modern structures in colder regions in the world and in countries with temperate climates typically install some form of heating system. This mechanism is used to regulate the temperature in public offices, residential homes, and other facilities. Heating systems can be either central or local. The most commonly used setup is the central heating system where the heating is concentrated in a single area—central—and is then circulated for various heating processes and applications. Some of the more common heating systems include:


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Electric heating: Here, an electrical heater is used. This is a device that transforms electrical energy into heat. Every electric heater contains an electric resistor, which acts as its heating element. The practice of using electricity for heating is increasing in both residences and public buildings. Electric heating generally costs more than energy obtained from combustion of a fuel, but the convenience, cleanliness, and reduced space needs of electric heat can often justify its use. The heat can be provided from electric coils or strips used in varying patterns, such as convectors in or on the walls, under windows, or as baseboard radiation in part or all of a room. The overall cost of electric heating can be substantially reduced through the incorporation of a heat-pump system. Electric baseboard heaters: Baseboard heaters are a fairly common heat source, heating the room by using a process call electric resistance. These types of heaters are zonal heaters controlled by thermostats located within each room. Inside baseboard heaters are electric cables that warm the air that passes through them. Electric baseboard heaters are typically installed along the lower part of outside walls to provide perimeter heating. Room air heated by the resistance element rises and is replaced by cooler room air, establishing a continuous convective flow of warm air while in operation. Baseboard heaters are typically controlled by an electric thermostat, which may be in an adjacent or remote location. Central heating: There are many different types of central heating systems available, most of which are comprised of a central boiler or furnace to heat water, pipes to distribute the heated water, and heat exchangers or radiators to conduct this heat to the air. In large systems, steam or hot water is usually employed to distribute the heat. The vast majority of modern commercial buildings including office buildings, high-rise residential, hotels, and shopping malls are today provided with central heat. Most modern systems have a pump to circulate the water and ensure an equal supply of heat to all the radiators. The heated water is often fed through another heat exchanger inside a storage cylinder to provide hot running water. Forced air systems send air through ductwork, which can be reused for air conditioning, and the air can be filtered or put through air cleaners. The heating elements (radiators or vents) are ideally located in the coldest part of the room, typically next to the windows. Furnace: This is a heating system component designed to heat air for distribution to various building spaces. Furnaces can be used for residential and small commercial heating systems. Furnaces use natural gas, fuel oil, and electricity for the heat source as well as on-site energy collection (solar energy), and heat transfer (heat pumps). Natural gas furnaces are available in condensing and non-condensing models. The cooling can be packaged within the system, or a cooling coil can be added. Radiant heating is provided in part by radiation in all forms of direct heating, but the term is usually applied to systems in which floors, walls, or ceilings are used as the radiating units. Steam or hot water pipes are placed in the walls or floors during the construction process. If electricity is used for heating, the panels containing heating elements are mounted on a wall, baseboard, or the ceiling of the room. Radiant heating provides uniform heat and is both efficient and relatively inexpensive to operate. Warm air systems: The simplest warm air heating system consists of a firebox and waste-gas passage set within a sheet metal casing, and ducts leading to the various rooms. To ensure natural circulation of the warm air, which tends to rise, the furnace is usually situated below the first floor of the facility. Cold air, either from within the building or from outdoors, is admitted between the firebox and the casing and is heated by contact with the hot surfaces of the furnace. Often the furnace is arranged so the warm air passes over a water pan in the furnace for humidification before circulating through the building. As the air is heated, it passes through the ducts to individual grills or registers in each room of the upper floors. The grills or registers can be opened or closed to control the temperature of the rooms. Forced-circulation systems have a fan or blower placed in the furnace casing which blows air through an evaporator coil, which cools the air (Figure 10.2). This cool air is routed throughout the intended space by means of a series of air ducts thus ensuring the circulation of a large amount of air even under unfavor-


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able conditions. When combined with cooling, humidifying, and dehumidifying units, forced-circulation systems may be used effectively for heating and cooling. Forced-circulation warm air systems are popular for residential installations, primarily because the same equipment can provide air conditioning throughout the year. Modern hot water systems typically employ a central boiler, in which water is heated to a temperature of from 140 to 180 degrees F (60 to 83 degrees C). The water is then circulated by means of pipes to some type of coil units, such as radiators, located in the various rooms. Circulation of the hot water can be accomplished by pressure and gravity, but forced circulation using a pump is more efficient because it provides flexibility and control. In the rooms, the emitters give out the heat from their surfaces by radiation Figure 10.2 A diagram describing components of a forced and convection. The cooled water is then rewarm air system (source, warmair.cominc). turned to the boiler. In addition, there are combination systems that use ducts for supplying air from the central air handling unit, and water to heat the air before it is transferred into the conditioned space. Combination boiler heating systems are the most commonly used in central heating systems. Running on mains, pressure water eliminates both the need for tanks to be placed in the loft and the need for a hot water cylinder as the water is instantly heated when required. Hot water systems use either one-pipe or two-pipe systems to circulate the heated water. In a one-pipe system, water enters each radiator from the supply side of the main pipe, circulates through the radiator, and flows back into the same pipe. Most modern layouts use a two-pipe layout in which radiators are all supplied with hot water at the same temperature from a single supply pipe, and the water from these radiators flows back to the furnace to be reheated through a common return pipe. Although the two-pipe system requires more pipe work, it is more efficient and easier to control than the one-pipe system. In both systems an expansion tank is required to compensate for variations in the volume of water in the system. Another system that is sometimes used is the sealed hot water system. This is basically a closed system that does not need water tanks because the hot water is supplied direct from the mains. Steam systems: Steam is often used to carry heat from a boiler to consumers as heat exchangers, process equipment, etc. Sometimes steam is also used for heating purposes in buildings. These systems closely resemble hot water systems except that steam rather than hot water is circulated through the pipes to the radiators. The steam condenses in the radiators, giving up its latent heat. Both one-pipe and twopipe arrangements are employed for circulating the steam and for returning to the boiler the water formed by condensation. In a one-pipe, gravity-flow system, each heating unit has a single pipe connection through which it receives steam and releases condensate at the same time. All heating units and the end of the supply main are sufficiently above the boiler water line so that condensate flows back to the boiler by gravity. In a twopipe system, steam supplied to the heating units and condensate returned from heating units are through


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separate pipes. Air accumulation in piping and heating units discharges from the system through the open vent on the condensate pump receiver. Piping and heating units must be installed with proper pitch to provide gravity flow of all condensate to the pump receiver. The three main types of steam systems generally employed are: air-vent systems, vapor systems, and vacuum or mechanical-pump systems. Heat pumps are actually air conditioners that run in reverse to bring heat from outdoors into the interior. However, to achieve the required space heating more economically, it is best to use the heat pump in conjunction with the central furnace. In certain weather conditions they are extremely efficient, especially when the outside temperature is around 50 degrees Fahrenheit. However, as the outdoor temperature begins to drop, the heat loss of a space becomes greater, requiring the heat pump to operate for longer stretches of time for it to be able to maintain a constant indoor temperature. During the heating season, a liquid refrigerant is pumped through a coil that is outside the area to be heated. The refrigerant is cold, and thus absorbs heat from the outside air, the ground, well water, or some other source. It then flows to a compressor, which raises its temperature and pressure so that it becomes vapor, after which it flows to an indoor coil. There the warmth is radiated or blown into the room or other space to be heated. The refrigerant, having given up much of its heat, then flows through a valve where its pressure and temperature are lowered further before it liquefies and is pumped into the outdoor coil to continue the cycle. To air condition a space, valves reverse the flow so that the refrigerant picks up heat from inside and discharges it outside. As with furnaces, heat pumps are usually controlled by thermostats. Figure 10.3 illustrates a typical residential application of a heat pump system. The geothermal heat pump (GHP) is a relatively new technology that is gaining wide acceptance for both residential and commercial buildings. This system utilizes the relatively constant temperature of the ground or water several feet below the earth’s surface as a source of heating and cooling. Geothermal heat pumps are appropriate for retrofit or new facilities where both heating and cooling are desired, and business owners around the United States are now installing geothermal heat pumps to heat and cool their buildings. In addition to providing increased comfort for employees, customers, and tenants, this technology offers significant dollar savings in energy and operation and maintenance costs. Conventional ductwork is generally used to distribute heated or cooled air from the geothermal heat pump throughout the building. GHPs should not be confused with airsource heat pumps that rely on heated air (Figure 10.4). Figure 10.3 The Vitocal 200-G brine/water heat pump offers all of the functions required for using a heat pump for residential Efficiency is measured by the applications (courtesy, Viessmann Werke). amount of heat a system can pro-


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duce or remove using a given amount of electricity. A common measurement of this performance is the Seasonal Energy Efficiency Ratio (SEER). The new Federal Appliance Standards, which took effect on January 23, 2006, will require the new standards for central air conditioners be a minimum of 13 SEER. Most manufacturers now offer SEER 10, 11, 12 and 13 models, and some offer SEER 14. This translates into five separate efficiency options, with model numbers usually keyed to the SEER numbers, so they are easy to recognize. The development of new technologies and innovations is improving the performance of heat pumps. The introduction of two-speed compressors allows heat pumps to operate close to the heating or cooling capacity that is needed at any particular moment. This saves large amounts of electrical energy and reduces compressor wear. Two-speed heat pumps also work well with zone control systems. Some Figure 10.4 A commercial-size geothermal heat pump heat pumps are equipped with variable-speed used to circulate water through ground-source heat or dual-speed motors on their indoor fans, outexchangers to provide space heating/cooling and hot door fans, or both. The variable-speed controls water on the Georgia Tech University campus (courtesy, for these fans attempt to keep the air moving at Craig Miller, U.S. Department of Energy). a comfortable velocity, minimizing cool drafts and maximizing electrical savings. Another advance in heat pump technology is the scroll compressor, which consists of two spiral-shaped scrolls. One remains stationary, while the other orbits around it, compressing the refrigerant by forcing it into increasingly smaller areas. Vapor compression refrigeration unit: This is the most widely used approach for air-conditioning of large public buildings, private residences, hotels, hospitals, theaters, and restaurants. It involves the operation of a vapor compression refrigeration cycle to induce heat to travel in a direction contrary to gross environmental temperature differences. During the overheated period, the outside air temperature is usually not only above the balance point temperature, but also above the indoor air temperature. Under such conditions, heat flow will be from higher to lower temperature (from outside to inside). Maintaining thermal comfort during the overheated period requires that heat be removed from a building, not added to it. Through a series of artificially maintained temperature and pressure conditions in a heat transfer fluid (refrigerant), a refrigeration system can induce heat to flow from inside a cooler building to a warmer outside environment. All such systems have four components: a compressor, a condenser, an expansion or throttle valve, and an evaporator. A solar thermal collector is a solar collector specifically intended to collect heat: that is, to absorb sunlight to provide heat, and may be used to heat air or water for building heating purposes. Water-heating collectors may replace or supplement a boiler in a water-based heating system. Air-heating collectors may replace or supplement a furnace. Solar systems can be either active or passive. The terms passive and active in solar thermal systems refer to whether the systems rely on pumps or only thermodynamics to circulate water through the systems. As solar energy in an active solar system is typically collected at a location re-


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mote from the spaces requiring heat, solar collectors are normally associated with central systems. Solar water-heating collectors may also provide heated water that can be used for space cooling in conjunction with an absorption refrigeration system. Solar water heating systems are generally used in hotels and homes in sunny climates such as those found in southern Europe. Figure 10.5 illustrates an example of an indirect active solar system. Active solar water heaters use pumps to circulate water or an antifreeze solution through heatabsorbing solar thermal collectors. In an indirect system, also known as “closed loop,” a simple pump moves the antifreeze solution through a Figure 10.5 A diagram of an indirect active solar system which is loop into the solar collector, through preferred in climates with extended periods of below-freezing temperatures (courtesy, Southface Energy Institute). the collector’s pipes, and out of the solar collector. Then, the sunwarmed antifreeze solution flows into a heat-transfer unit where it warms the cool water heading into a conventional hot water tank. The antifreeze solution then returns to the pump and again flows into the solar collector without ever mixing with the building’s water. Ventilation: While many of us tend to think of ventilation as either air movement within a building or the introduction of outdoor air, ventilation is actually a combination of processes which results in the supply and removal of air from inside a building. These processes typically include exchange of air to the outside as well as circulation of air within the building. Buildings in which people live and work must be ventilated to replenish oxygen, dilute the concentration of carbon dioxide and water vapor, minimize unpleasant odors, and remove contaminants from the air of the occupied space. Ventilation can be accomplished passively through natural ventilation, or forced ventilation through mechanical distribution systems powered by fans. In general, increasing the rate at which outdoor air is supplied to the building decreases indoor air problems. In cold climates natural ventilation is often just a matter of opening a window, but in hot climates it is an important consideration in the design of buildings. Buildings with excessive ventilation rates may suffer indoor air problems due to an uneven distribution of air, or insufficient exhaust ventilation. Forced ventilation may be used to control humidity or odors, and kitchens and bathrooms typically have mechanical ventilation to control both. Heat recovery ventilation systems, on the other hand, employ heat exchangers to bring the fresh air temperature to room temperature. Factory ventilation systems must remove hazardous airborne contaminants from the workplace. Nearly all chemical processes generate hazardous waste gases and vapors, and these must be removed from the workplace environment in a cost-effective manner. It’s in the building owner’s best interest to adhere to the ASHRAE standards and local building codes. Engineers estimate that for adequate ventilation the air in a room should be changed completely from one and a half to three times each hour, or that about 10 to 30 cubic feet (about 280 to 850 liters) of outside air


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per minute should be supplied for each occupant. Providing this amount of ventilation usually requires mechanical devices to augment the natural air flow. Ventilating systems may be combined with heaters, filters, humidity controls, or cooling devices. Many systems include heat exchangers. Air conditioning: ASHRAE’s definition of an air-conditioning system is a system that accomplishes four specific objectives simultaneously. These are to: 1. Control air temperature, 2. Control air humidity, 3. Control air circulation, and 4. Control air quality. In fact, air-conditioning systems typically provide heating, cooling, ventilation, and humidity control for a building or facility. Systems are usually installed in modern offices and public buildings, but it is difficult to retrofit because of the bulky air ducts required. Moreover, systems must be carefully maintained to prevent the growth of pathogenic bacteria in the ducts and to ensure efficient operation. Essentially, an air conditioning system cools a facility by a cold indoor coil called the blower coil or evaporator. The condenser, the hot outdoor coil, releases the collected heat outside. The evaporator and condenser are both comprised of tubing, usually copper, surrounded by aluminum fins. A pump called the compressor transfers the fluid between the evaporator and condenser. This pushes the refrigerant through the tubing and fins of the coils. The refrigerant evaporates in the indoor evaporator coils and draws the heat out of the air and cools the facility. Finally, the hot refrigerant gas is pumped into the outdoor condenser unit where it returns to liquid form. Some of the types of systems available include: Exterior wall or window air-conditioning units: Wall or window electric air-conditioning units are often used in single zone applications such as small buildings and trailers. They are also used in retrofit situations in conjunction with an existing system. Basically, they are small ductless units with casings extending through the wall. The units are generally noisy, and being ductless, are only practical for cooling small areas. If you take the cover off of an unplugged window unit, you will find that it contains a compressor, an expansion valve, a hot coil (on the outside), a chilled coil (on the inside), two fans, and a control unit (Figure 10.6). The fans blow air over the coils to improve their ability to dissipate heat (to the outside air) and cold (to the room being cooled). Some of the newer units display significant innovations such as electronic touchpad controls, energy saver settings, and digital temperature readouts. A timer is another improvement now available on new air conditioning units as it allows you to set the AC to cycle on and off at certain times of the day (i.e. the air conditioner might stay Figure 10.6 Components of a basic window AC unit off all day and turn on an hour before you (courtesy, HowStuffWorks.com). are scheduled to come home from work).


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Central air-conditioning systems: A central HVAC system may serve one or more thermal zones and its main components are located outside of the zone or zones being served—usually at a convenient central location in, on, or near the building. Central air conditioning systems are extensively installed in offices, public buildings, theaters, stores, restaurants, and other building types. Although centralized air-conditioning systems provide fully controlled heating, cooling, and ventilation, they need to be installed during construction and are difficult to retrofit (install in a building that was not designed to receive it) because of the need for bulky air ducts. In recent years, these systems have increasingly been automated by computer technology for purposes of energy conservation. In older buildings, indoor spaces may be equipped with a refrigerating unit, blowers, air ducts, and a plenum chamber in which air from the interior of the building is mixed with air from the exterior. Such installations are used for cooling and dehumidifying during the summer months, and the regular heating system is used during the winter. Figure 10.7 shows the general components of a central air-conditioning system. There are three main components to central air-conditioning systems: the outdoor unit (condenser and compressor), the indoor unit (blower coil or evaporator), and the indoor thermostat to regulate the temperature. The success of a central air system is dependent upon these three systems functioning together. Likewise, the design of an air-conditioning system depends largely on the type of structure in which the system is to be placed, the amount of space to be cooled, the function of that space, and the number of occupants using it. For example, a room or building with large windows exposed to the sun, or an indoor office space with many heat-producing lights and fixtures, requires a system with a larger cooling capacity than a space with few windows in which cool fluorescent lighting is used. Also, a space in which the occupants are allowed to smoke will require greater air circulation than a space of equal capacity in which smoking is prohibited. Split system: With a split-system central air conditioner, the compressor and condenser are contained in an outdoor cabinet and the evaporator is stored in an indoor cabinet. With many split-system air conditioners, the indoor cabinet also houses a furnace or a part of the heat pump. The cabinet or main supply duct of this furnace or heat pump also houses the air conditioner’s evaporator coil. For reverse cycle applications, the heat exchangers can swap roles, with the heat exchanger exposed to outside air becoming the evaporator and the inside heat exchanger becoming the condenser (Figure 10.8). Split systems may have a variety of configurations. The four basic components of the vapor compression refrigeration cycle— compressor, condenser, refrigerant metering device, and evaporator—can be grouped in several ways. The grouping of components is Figure 10.7 Domestic central air conditioners are made based on practical considerations, such as up of two basic components: the condenser unit, located available space, ease of installation, keeping outside the house on a concrete slab, and the evaporator noise outside occupied spaces, etc. coil above the furnace. These components in turn also In businesses, malls, department stores, are comprised of several elements (courtesy, warehouses, etc., the condensing unit is norHowStuffWorks.com).


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mally located on the roof and can be quite massive. Alternatively, there may be many smaller units on the roof, each attached inside to a small air handler that cools a specific zone in the building. In larger buildings and particularly in multi-story buildings, the split-system approach begins to run into problems such as the distance between the condenser and the air handler exceeds pipe distance limitations, or the amount of duct work and the length of ducts becomes unmanageable. Figure 10.8 A drawing illustrating how a split system works Packaged systems: The differ(courtesy, Southface Energy Institute). ence between a package unit and a split-system is that a split system uses indoor and outdoor components to provide a complete comfort system whereas a package unit or self-contained unit requires no external coils, air handlers, or heating units. Packaged units commonly use electricity to cool and gas to heat. Packaged systems have all their components located in a single outdoor unit located on the ground or roof. A packaged rooftop unit is a self-contained air handling unit (AHU), typically used in low-rise buildings, and mounted directly onto roof curbs, discharging conditioned air into the building’s air duct distribution system. AHUs come in many capacities, from units of just over one ton to systems of several hundred tons that contain multiple compressors and designed for single or multiplezone application. In the process of assessing packaged rooftop units the inspector should essentially confirm that the condensate line and pan are watertight and free of leaks and that there is no evidence of rust or corrosion. Filters should also be checked to see if replacement is required. All-air systems represent the majority of systems currently in operation. These systems transfer cooled or heated air from a central plant via ducting, distributing air through a series of grilles or diffusers to the room or rooms being served. The overall energy used to cool buildings with all-air systems includes the energy necessary to power the fans that transport cool air through the ducts. Because the fans are usually placed in the air stream, fan movement heats the conditioned air, thus adding to the thermal cooling peak load (Figure 10.9A). All-water systems: In all-water systems, conditioning effect is distributed from a central plant to conditioned spaces via heated or cooled water. Water is an effective heat transfer medium, thus distribution pipes are often of relatively small volume (compared to air ducts). On the other hand, water can not be directly dumped into a space through a diffuser, but requires a more sophisticated delivery device. All-water heating-only systems employ a variety of delivery devices, such as baseboard radiators, convectors, unit heaters, and radiant floors. All-water cooling-only systems are rare with valance units being the most common delivery device for such systems. When full air conditioning is contemplated, the most appropriate delivery device may be the fan-coil unit. All-water systems are generally the most expensive to install and own, and are classed as the least energy efficient in terms of transfer of energy (Figure 10.9B). Air-water systems: A category of central HVAC systems that distributes conditioning effect by means of heated or chilled water and heated or cooled air (Figure 10.9C). Larger buildings in the United States generally incorporate one of several variations of primary system types, including central chilled water plant with floor-by-floor air handling units and variable air volume dis-


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Figure 10.9 A diagram illustrating three basic HVAC systems: A. All-air system, B. All-water system, C. Air-water system. (after N. Lechner).

tribution, central condenser water with floor-by-floor self-contained air units, variable air volume distribution systems, and central condenser water systems with console heat pumps and constant volume on the interior zones. High-velocity dual duct and multi-zone systems are also used for small buildings and outside the U.S. Multi-zone systems are typically used in large multistory buildings where it is not practical or efficient to use many AHUs, each serving a single zone. Instead, several zones are served, each with its own thermostat control.


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10.4 HVAC SYSTEM REQUIREMENTS To understand HVAC requirements, the forensic expert should have a proper understanding of HVAC equipment and equipment components relating to operation, uses, control parameters, and maintenance. Building spaces such as cavities between walls can support platforms for air handlers, and plenums defined or constructed with materials other than sealed sheet metal, duct board, or flexible duct must not be used for conveying conditioned air including return air and supply air. Ducts installed in cavities and support platforms must not be compressed to cause reductions in the cross sectional area of the ducts. Connections between metal ducts and the inner core of flexible ducts must be mechanically fastened and openings must be sealed with mastic, tape, or other duct closure systems that meet local codes and standards. In most jurisdictions, building codes stipulate that access be provided to certain components of mechanical and electrical systems. This is usually for maintenance and repair, and includes such elements as valves, fire dampers, heating coils, mechanical equipment, and electrical junction boxes. Commercial construction usually takes advantage of ceiling plenums to run horizontal ducts while vertical ducts are contained within their own chases. Depending on the type of structure and depth of the plenum, large ducts may occupy much of this depth, leaving little or no space for recessed light fixtures. Where the plenum is used as a return air space, most local and national building codes prohibit the use of combustible materials such as wood or exposed wire within the space in commercial construction. Occasionally, commercial construction uses access flooring (typically in computer room applications), which consists of a false floor of individual panels raised by pedestals above the structural floor. This is designed to provide sufficient space to run electrical and communication wiring as well as HVAC ductwork. Sometimes small pipes are designed to run within a wall system, whereas larger pipes may need deeper walls or even chase walls to accommodate the pipes. Fan systems that exhaust air from the building to the outside must be provided with back draft or automatic dampers. Gravity ventilating systems must have an automatic or readily accessible, manually-operated damper in all openings to the outside, except combustion inlet and outlet air openings and elevator shaft vents. This includes clothes dryer exhaust vents when installed in conditioned space.

10.5 COMMON DEFICIENCIES The chief cause of HVAC deficiencies is usually maintenance related. When maintenance of the equipment is deferred or performed by unqualified personnel, the system will increasingly experience problems. When properly maintained, a building’s HVAC system can enjoy a life span of up to 60 years. HVAC deficiencies fall into two main categories: issues that are fairly simple to address, such as filter or belt replacement, and complex issues requiring the attention of specialized personnel, such as pump or boiler replacement. Another deficiency often encountered is inadequacy of the system for the size of the facility. Most designers of mechanical systems now utilize computer analysis software to determine heating and cooling loads, but a general rule of thumb in an assessment is to compare the actual tonnage of the unit to the standard design tonnage using the formulas below: BTU of unit ⫼ 12,000 ⫽ actual tonnage of the unit Square footage of the building ⫹ 350 ⫽ design tonnage When assessing a facility’s heating systems, the forensic architect should observe the heating and distribution equipment in place with regard to its installation and working condition. The report should include


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any readily accessible component found to be in need of immediate or major repair. In the building survey report it should be clearly stated that the survey method will be largely visual. Readily accessible service doors or access panels will be removed as provided by the equipment manufacturer for routine servicing and maintenance. Upon getting permission from the client, the inspector may then operate the equipment using normal operating controls. Deficiencies and other issues requiring to be checked for conformance when conducting HVAC evaluations include: 1. Evidence of abnormal component vibrations or excessive noise 2. Insufficient air movement to reach all parts of the room or space being cooled or alternatively, the presence of drafts in the room or space being cooled 3. Return air at the return registers is not at least 10 to 15 degrees Fahrenheit warmer than the supply air 4. Identify the location of the thermostats 5. Evidence of leaking caused by inadequate seals 6. Evidence of fan alignment deficiencies, deterioration, corrosion, or scaling 7. Evidence of unsafe equipment conditions, including instability or absence of safety equipment (guards, grills, or signage) 8. Does the building have an exhaust system and are the toilets vented independently or mixed with the common area venting system? 9. Is there a fresh air make up system in the building? The following are normally excluded from typical HVAC baseline evaluations: 1. Observation of or reporting on heating/cooling system components not readily accessible 2. Operation of equipment that does not comply with building codes or when doing so would compromise the safety of the inspector or the building occupants, or the operation or testing of safety controls and devices installed by the equipment manufacturer 3. Equipment not otherwise known or able to be determined from information received prior to the inspection as normally provided by the client or his representative, unless mutually agreed upon prior to the inspection 4. Evaluation of the working condition of heating/cooling equipment that has been disused or shut down for any length of time 5. Disassembly of any HVAC equipment in order to observe system components or parts thereof not otherwise readily accessible to view upon removal of service access panels 6. Equipment not included in the building inspection proposal as submitted and agreed to before conducting a commercial property inspection 7. Determination or evaluation of the efficiency of the heating/cooling system. Defect recognition is an important aspect of any commercial survey. A field observer is required to observe and report on the following issues during an HVAC systems evaluation: 1. Equipment type and size: chiller, water-cooled, air-cooled, single- or multi-zone 2. Equipment location: roof, basement, attic, or on grade


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3. Types of thermostat controls: low-voltage, high-voltage, pneumatic or interior duct controls 4. Installation issues: roof curbs, vibration eliminators, air distribution, etc. 5. Recording of water temperature for cooling towers and circulating water temperature for each chiller convector 6. Refrigeration circuit: leaks, piping and arrangements, condensate discharge 7. Ventilation and fresh air requirements.

10.6 HVAC COMPONENTS AND SYSTEMS HVAC systems generally include a variety of active mechanical/electrical systems employed to provide thermal control in buildings. Control of the thermal environment is one of the key objectives of virtually all occupied buildings. Numerous systems and components are used in combination to provide fresh air, as well as temperature and humidity control in commercial real estate (Figure 10.10). HVAC system components are often grouped into three functional categories: • • •

Source components provide or remove heat or moisture. Distribution components convey a heating or cooling medium from a source location to portions of a building that require conditioning. Delivery components serve as an interface between the distribution system and occupied spaces.

Compact systems that only serve a single zone of a building often incorporate all three functions in a single piece of equipment. Systems that are intended to condition multiple spaces in a building (central systems) usually have distinctly different equipment elements for each function. Also, for each commercial property type, some systems will perform better than others. From a lender’s perspective, performance is judged by how well the needs of tenants and owners are met regarding comfort, operating costs, reliability, flexibility, and aesthetics. Ductwork: The major goal in duct design is to provide a distribution network of conditioned air to the various building spaces. In order to achieve this in an energy-efficient manner, the ducts must be designed to facilitate air flow and minimize friction, turbulence, and heat loss and gain. The optimal air distribution system has correctly sized ducts with minimal runs, smooth interior surfaces, and the least amount of direction and size changes. Moreover, ducts that are not properly designed and installed can result in poor air distribution, bad indoor air quality (IAQ), occupant discomfort, additional heat losses or gains, increased noise levels, and higher energy bills. The overall design and construction of the building envelope can also significantly impact the design of the duct system. The overall performance of duct stems can be impacted by the materials used. Fiberglass insulation products are currently used in the majority of duct systems installed in the United States, and serve as key components of well-designed, well-operated, and well-maintained HVAC systems that provide both thermal and acoustical benefits for the life of the building. Other materials commonly used for duct construction include galvanized steel, black carbon steel, aluminum, stainless steel, copper, fiberglass reinforced plastic, polyvinyl steel, and concrete. A regular preventive maintenance inspection program will reveal system breaches, which are typically more prevalent at duct intersections and flexible connections. Both supply air and return air may utilize ductwork that may be located in the ceiling cavity or below the floor slab, depending on the configuration of the system. There are single-duct systems, with both cool air and hot air utilizing the same ducts, or dou-


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Figure 10.10 A drawing showing typical HVAC system components that deliver conditioned air to a building or space to maintain thermal comfort and indoor air quality (courtesy, Terry Brennan, Camroden Associates). ble-duct systems, with separate ducts for cooling and heating. Fire dampers are required where ducts penetrate a fire wall. Modern fire dampers contain a fusible link that melts and separates when a particular temperature is reached, causing it to slam shut in the event of a fire. Acoustic consideration is another major factor impacting the fabrication and design of duct systems, and unless properly designed and constructed, ducts can act as large speaker tubes transmitting noise throughout the building. Grills, registers, and diffusers are employed in conjunction with ductwork, and assist in controlling the return, collection, and supply of conditioned air in HVAC systems. A grille is basically a covering for an opening through which air passes that does not have an attached damper and, in most cases, has no moving parts. However, a grille can be used for both supply air and return air. The same is not true for a register or diffuser. A diffuser is an air flow device designed to discharge air in a spreading pattern, specific path, or particular direction. The location of supply air diffusers and return air grills should be integrated with other ceiling elements, including lights, sprinkler heads, smoke detectors, speakers, and the like, so that the ceiling is aesthetically pleasing and well planned. To assist in this integration, these components are usually connected to the main ductwork with flexible ducting to allow some adjustability in their placement. The terms register and diffuser are often interchanged, even by professionals. Registers are adjustable grill-like devices that cover the opening of a duct in a heating or cooling system, providing an outlet for heated or cooled air to be released into a room. Supply air registers are in essence grills equipped with double deflection adjustable vanes at the face and a damper behind the face for balance and to control the


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direction of flow and/or flow rate. A diffuser performs the task of diffusing the gas. The grills, registers, and diffusers introduce and blend the fresh air with the air of another environment or location. When fitted together, the grills take in fresh air, the registers blow the air out, and the diffusers scatter the air in the surroundings. Thermostats: All boilers and heating systems use thermostats to prevent overheating and also control the temperature of the circulating water. Thermostats are fitted to hot water cylinders, boilers, radiators, and in rooms. In addition to providing the basic function of maintaining comfortable indoor temperatures, modern programmable thermostats are capable of being programmed to automatically raise or lower the temperature of a facility according to predefined schedules. Most programmable thermostats allow input of weekday and weekend schedules. More sophisticated thermostats will allow humidity control, outdoor air ventilation, and can signal when the system filters need changing. Some modern thermostats can also include a communications link and demand management features that can be used to reduce air conditioning system energy use during periods of peak electrical demand or high electricity costs. Thermostats are typically placed 48 to 60 inches above the floor and away from exterior walls and heat sources. Their location should be coordinated with light switches, dimmers, and other visible control devices. Zoning represents just one of several actions that are designed to improve HVAC performance and which give the occupants personal climate control throughout their work environment. An HVAC system can have single-zone or multi-zone capabilities. In a single-zone system, the entire building is considered one area, whereas in a multi-zone system, the building is divided into various zones, allowing specific control of each area. In fact, most of today’s newest HVAC systems are designed to incorporate many individually controlled temperature zones to improve occupant comfort and provide the ability to manage the heating or cooling of individual rooms or spaces by use, to adjust individual room temperatures for individual preferences, or to close off airflow in rarely-used rooms. Also, by using zone dampers zoning can also save on the installation cost of multiple-unit systems. Lastly, whether zoning with one HVAC unit using zone dampers or using multiple HVAC units, zoning can save on maintenance costs and utility bills. Boilers: A boiler is a heating system component designed to heat water for distribution to various building spaces. As water can not be used to directly heat a space, boilers are only used in central systems where hot water is circulated to delivery devices (such as baseboard radiators, unit heaters, convectors, or air-handling units). Once the delivery device is heated with the hot water, the water is returned back to the boiler to be re-heated and the water circulation loop continues. Depending upon design intent, a boiler may produce either hot water or steam. An on-site solar energy collection system may serve in lieu of a boiler. Heat transfer systems (heat pumps) likewise may serve as a substitute for a boiler. Constructed of cast iron or steel, and occasionally copper, there are several types of boilers including: • • • •

Gas-fired, steam or hot water, cast iron or steel construction (Figure 10.11) Electric, steam or hot water, steel construction Oil-fired, steam or hot water, cast iron or steel construction Gas/Oil combination, steam or hot water, cast iron or steel construction

Chillers are cooling systems that remove heat from one element (water) and move that heat into another element (ambient air or water). A chiller is similar to an air conditioning system in that it is compressor-based, but a chiller cools liquid while an air conditioning system cools air. Other components are a reservoir, re-circulating pump, evaporator, condenser, and a temperature controller. Chillers vary in terms of condenser cooling method, cooling specifications, and process pump specifications. The cooling fluid used is usually a mix of ethylene glycol and water. Chillers can be either air-cooled or water-cooled. Aircooled chillers are usually located outside and consist of condenser coils cooled by fan-driven air. Water-


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cooled chillers are typically located inside a building, and the heat from these chillers is carried by recirculating water to outdoor cooling towers. Air-cooled chillers are used in many small to medium chiller plants with aircooled screw chillers in the 150 to 400-ton range being the most common. Air-cooled screw chillers offer very good performance particularly at part load (Figure 10.12). The compressors are modulating rather than stepped, which provides more accurate control. Air-cooled chillers avoid the need for cooling towers, condenser pumps, and condenser piping which can offer substantial capital savings. MoreFigure 10.11 A drawing of a gas-fired hot water boiler over, they do not require mechanical showing the main components (courtesy, Home-Cost.com). room space, which offers additional savings. Another advantage of air-cooled chillers is that they do not consume water like water-cooled chillers. Since an aircooled chiller transfers the heat from the process to its surroundings in the form of air, the environment in which the chiller will be used must be suitable. For example, to avoid overheating, air-cooled chillers must be located in an open, wellventilated space. Larger air-cooled systems use a remote condenser connected to the chiller by refrigerant piping. One of the main disadvantages of this system is that it requires additional duct clearance which can reduce the usable floor space. Sometimes an air-cooled chiller is the only solution available in the absence of an existing cooling tower or the absence of 85-degree F plant water to use for the Figure 10.12 Illustration of a McQuay air-cooled screw condenser. compressor chiller. These chillers must be located in an open, Water-cooled chillers absorb heat well-ventilated space to avoid overheating. In a typical plant from process water and transfer it to a layout, the evaporator and condenser are located inside the separate water source such as a cooling chiller unit (source, McQuay International). tower, river, or pond. They are generally used for large capacity applications, where the heat generated by an air-cooled chiller creates a problem. They are also considered when a cooling tower is already in place, or where the customer requires optimum efficiency of power consumption. Water-cooled chillers require condenser water treatment to eliminate mineral buildup, as mineral de-


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posits create poor heat transfer situations, reducing the efficiency of the unit. In a typical plant layout, the evaporator and condenser are located inside the chiller unit, while the cooling tower is located on the outside. For chilled water cooling systems, water chillers come in three basic designs. The reciprocating compressor, direct-expansion type is usually powered by an electric motor. The centrifugal compressor, directexpansion type is typically powered by an electric motor or sometimes a steam-turbine drive. The absorption type uses approximately 10 percent of the electrical power of the other two types, and uses water as a refrigerant and lithium bromide or other salts as an absorbent. One of the chief factors impacting the choice of a water-cooled chiller or an air-cooled unit depends on the availability of a cooling tower. The water chiller option is often preferred over the air-cooled unit because it costs less, has a higher cooling capacity per horsepower, and consumes less energy per horsepower. Compared to water, air is a poor conductor of heat, making the air-cooled chiller much larger and less efficient. Evaporatively-cooled chillers are basically water-cooled chillers in a box. These packaged units cool the air by humidifying it and then evaporating the moisture. Thus, the hot gaseous refrigerant is condensed by water flowing over the condenser tubes and evaporating. This ties the condensing temperature to ambient wet bulb, like a water-cooled chiller. The condenser, water sump and pump, etc., are all integral to the chiller. Whereas a water-cooled chiller will require a cooling tower, condenser pump, and field erected piping, the evaporatively-cooled chiller comes as a complete package from the factory. Evaporativelycooled chillers offer the ease and savings of air-cooled chiller installation while providing performance comparable to water-cooled chillers. Evaporatively-cooled chillers will require makeup water, water treatment, and drains, and have similar limitations as air-cooled chillers. The equipment is most effective in dry climates. It can significantly reduce the peak electric demand when compared to electric chillers. Dual-compressor chillers have two compressors operating in parallel between a common evaporator and condenser. By utilizing two compressors on a common refrigeration circuit, it is possible to greatly improve the part load efficiency of a centrifugal chiller. This is a major benefit of a dual compressor chiller as opposed to conventional chillers. Also, in terms of performance, dual compressor chillers offer a superior performance profile. Single compressor chillers are most efficient at or near 100 percent capacity where as dual compressor chillers are most efficient at 50 to 60 percent capacity. This matches the typical building load profile very well, offering optimum efficiency where there are the most run hours (Figure 10.13). Variable frequency drive chillers (VFDs) replace the compressor motor starter. They can be unit or remote mounted and in most cases have to be water-cooled. Chillers with VFDs still have inlet guide vanes. The chiller controller monitors the operating conditions using a combination of inlet guide vanes and speed control. Compressor speed is typically only lowered to about 60 percent of the design speed. Both dual compressor and VFD chillers operate much more efficiently at part load, whereas conventional chillers operate most efficiently at or near full load. However, harmonics generated by the VFD can disrupt computer and communications equipment and a careful harmonic analysis should be conducted whenever a VFD chiller is applied. The VFD can only be used when the lift on the compressor is reduced, and performance savings obtained when the VFD is used rather than the inlet guide vanes. The most effective way to take advantage of a VFD chiller is to reduce the condenser water temperature as much as possible. With the right operating conditions, VFDs can offer significant energy savings. A careful economical analysis using realistic load profiles and ambient wet bulb is recommended if considering using VFDs. Climates with reasonable annual changes in wet bulb are prime candidates for VFD chillers. Heat recovery chillers come in two forms: single condenser and split condenser. A single condenser heat recovery chiller can produce 105 degree F to 110 degrees F hot water, which can be used for heating the building, or for preheating domestic hot water. A split condenser heat recovery chiller does not re-


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Figure 10.13 Dual-compressor centrifugal chillers have many advantages over conventional chillers. A VFD, which is used to change the speed of the compressor, may be added by the manufacturer (courtesy, McQuay International).

quire a heat exchanger and is more common than single condenser chillers. Heat recovery can take place only when there is a source (a cooling load in the building) and a requirement (a heating load in the building). Different HVAC system types and building functions will dictate the viability of condenser heat recovery. Typically, a heat exchanger is used to transfer the heat from the condenser loop into the hot water loop to avoid contamination from the open tower condenser loop entering the hot water loop. The second type has an additional condenser shell that allows the rejected heat to be rejected to a separate heat recovery water loop. Cooling towers are evaporative coolers used for cooling water or other working medium to near the ambient wet-bulb air temperature. Their main function therefore is removing heat from the water discharged from the condenser so that the water can be discharged to the environment or recirculated and reused. Cooling towers are used in conjunction only with water-cooled chillers and vary in size from small roof-top units to very large hyperboloid structures. Cooling towers are also characterized by the means by which air is moved. Mechanical draft cooling towers are the most widely used in buildings, and rely on power-driven fans to draw or force the air through the tower. They are normally located outside the building and typically on the roof. There are currently two common types of mechanical draft towers used in the HVAC industry: induced draft and forced draft. Induced draft towers have a large propeller fan at the top of the tower (discharge end) to draw air upward through the tower while warm condenser water spills down. They require much smaller fan motors for the same capacity than forced draft towers (Figure 10.14A,B). Forced draft towers utilize a fan at the bottom or side of the structure. Air is forced through the water spill area and discharged out the top of the structure. After the water has been cooled in the cooling tower, it is pumped to a heat exchanger or condenser in the refrigeration unit where it picks up heat again and is returned to the tower. The piping system is called the condenser water system. Natural-draft cooling towers utilize the buoyancy of the exhaust air rising in a tall chimney to provide the draft. A fan-assisted natural-draft cooling tower employs mechanical draft to augment the buoyancy effect. Many early cooling towers relied only on prevailing wind to generate the draft of air.


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Figure 10.14A,B A. Forced draft towers with fans on the air inlet to push air either counterflow or cross-flow to the movement of the water. B. Induced draft towers have a large propeller fan at the top of the tower to draw air counterflow to the water. Induced draft towers are considered to be less susceptible to recirculation, which can result in reduced performance (courtesy, McQuay International).

With respect to the heat transfer mechanism employed, there are three primary types: •

Wet-cooling towers operate on the principle of evaporation. In a wet-cooling tower, the warm water can be cooled to a temperature lower than the ambient air dry-bulb temperature when the air is relatively dry. As air is drawn past a flow of water, the two flows attempt to equalize. If the air is not saturated it will absorb additional water vapor, leaving less heat in the remaining water flow. Dry coolers operate by heat transmission through a surface that divides the working fluid from ambient air. They thus rely mainly on convection heat transfer to reject heat from the working fluid, rather than evaporation. Fluid coolers are hybrids that pass the working fluid through a tube bundle, upon which clean water is sprayed and a fan-induced draft is applied. The heat transfer performance that results is much closer to that of a wet-cooling tower, with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure.

Cooling tower controls and energy efficiency: Given today’s developing technology, remote access via the computer and the controller may provide the best scenario of cost, results and documentation. Among other functions, cooling tower controls provide condenser water at the correct temperature to the chillers. Defining correct water temperature is very important because lowering the condenser supply water temperature (to the chiller) increases the effort by the cooling tower and more fan work would be expected. Cooling towers consume power to operate the fans. Induced draft towers should be selected since they typically use half the fan horsepower that forced draft towers use. Some form of fan speed control is also recommended, such as piggyback motors, multi-speed motors or variable speed drives (VSDs). Cooling towers required to work in freezing winter environments require additional care. The condenser water must not be allowed to freeze, particularly when the tower is idle. Common solutions include electric or steam injection heaters or a remote sump within the building envelope.


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Condensers: Condensers are used in air-conditioning systems to cool and condense the refrigerant gas that has become hot during the evaporation stage of the cooling process. The cooling process is accomplished using air, water, or both. Condenser types include air-cooled and cooling tower. Air-cooled condensers are the most basic and the most common way to condense the refrigerant in a refrigeration system. In air-cooled condensers, the installation of variable speed drives (VSDs) to control pumps and fans will deliver significant energy reductions in many commercial and industrial applications. The primary reason is that there is a cube relationship between power and speed (Figure 10.15). In an aircooled system, this will normally consist of a multi-fan condenser with the fans sequenced individually from a step control to maintain the required pressure. Water-cooled condensers use water that is cooled directly from the evaporative condenser or indirectly via a cooling tower. The lower temperature achieved by evaporating water allows chillers served by watercooled condensers to operate more efficiently. The capacity of the water-cooled condenser is affected by the temperature of the water, quantity of water circulated, and the temperature of the refrigerant gas. The capacity varies whenever the temperature difference between the refrigerant gas and the water is changed. The device used to adjust the water flow through the condenser is called a condenser water-regulating valve. This is a self-contained valve with pressure from the high side of the refrigeration system. An increased temperature difference or greater flow of water increases the capacity of the condenser. The three most popular configurations for water-cooled condensers are shell and tube, shell and coil, and tube within a tube. The main advantage water-cooled condensers have over air-cooled condensers is they create a lower head pressure. And except for small air-conditioning installations, heat rejection via cooling towers is more efficient, takes up less space, and has an overall lower lifecycle cost than dry coolers. Evaporative systems are both smaller and quieter than air-cooled condensers, and also offer much lower life-cycle costs. Large

Figure 10.15 Liebert Quiet-Line air-cooled condensers (courtesy, Liebert Corp).


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chilled-water air-conditioning systems have traditionally utilized large constant-speed pumps to circulate the chilled water, with throttle valves to control the flow. Pumps are normally used to circulate the water around the central heating system and are also used to convey, raise, or otherwise change the pressure of fluids. In some cases pumps are not needed, as gravity will allow the water to circulate. Pumps are utilized in many applications, including increasing water pressure in fire sprinkler systems and conveying hot and chilled water throughout the building. The pumps most commonly used are centrifugal, driven by an electrical motor and constructed of cast iron or bronze. When evaluating pumps, their type, capacity, general condition, and location should be noted. In addition, the expert should check that the motor is operating satisfactorily, the strainer is in satisfactory condition and the valves are all operable and free of damage. Sometimes an inspector might discover that the pump is not working. This may be due to it being seized or frozen, or due to a faulty pressure switch, worn bearings, or the motor simply being burned out. If the pump short-cycles or runs continuously, this may be an indication that the foot valve is leaking, the pressure tank is waterlogged, there is a leak in the piping system, or it may be due to a pressure switch. Where there is evidence of excessive noise or vibration, this may be caused by poor alignment or worn bearings. Fans usually consist of an electric motor and a belt or direct motor drive, blades, and a wheel or propeller. There are several different types of fans including centrifugal and belt drive models. Fans require periodic maintenance to calibrate and make ongoing adjustments. Roof ventilators are designed to remove air from or deliver air to a building through natural convection or wind force. Roof ventilators are designed to provide ventilation in a building without the use of a fan. They are normally constructed of galvanized steel or aluminum and should be adequately secured to the roof. Air filters are a critical component of the air conditioning system. Their primary function is to remove particles from the air. Without filters, air conditioning systems would become dirty and the interior environment would be filled with pollutants. In order to maintain clean air in occupied spaces, filters must also remove bacteria, pollens, insects, soot, dust, and dirt with an efficiency suited to the use of the building. The filter’s type and design determine the efficiency at removing particles of a given size and the amount of energy needed to pull or push air through the filter. Filters are rated by different standards and test methods, such as dust spot and arrestance, which measure different aspects of performance. There are a variety of air conditioning filters. The most common types are: conventional fiberglass disposable filters (1 and 2 inch), pleated fiberglass disposable filters (1 and 2 inch), electrostatic filters, electronic filters, and carbon filters. Most air conditioning filters are sized 1½ to 2 square feet for each ton of capacity for a home or commercial property. However a filter’s efficiency and ability to clean can be judged by using MERV ratings—minimum efficiency reporting value—which are from 1 to 12. The higher the rating the more efficient the filter is. Filters should be selected for their ability to protect both the HVAC system components and general indoor air quality. The main issues to look for when inspecting the filters, in addition to their general condition, is whether they are sized properly and are correctly installed. Tanks are used in many applications, including hot water or oil storage, expansion tanks for forced hot water heating systems, and water storage for fire extinguishing systems. They are typically constructed of steel or fiberglass.

10.7 SYSTEM DIAGNOSTICS The term building diagnostics as it relates to HVAC can be used to describe investigations and analyses of issues and deficiencies with systems and equipment that are performed during commissioning and/or during everyday operations and monitoring. Commissioning diagnostics generally use active test signals


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to force valves, dampers, fans, etc. to a condition where the expected operation of the component or system is well understood. One method of determining whether the HVAC system is doing its job is the degree to which the building users are healthy and comfortable. When a building’s HVAC system fails to perform satisfactorily, indoor air quality can suffer, bacteria can grow in cooling towers, and occupant health can deteriorate, leaving companies at risk for low productivity, excessive sick time, degraded system performance, and possible liability claims. Having the capability to quickly diagnose operational problems in HVAC equipment means that equipment will operate as intended for a greater percentage of the total run time. Changes to standards and evolutions in equipment continue to shape the future of HVAC systems. As a result, two of ASHRAE’s standards affecting HVAC systems in commercial facilities underwent recent changes. ASHRAE 90.1 was updated as of 2004. The standard now offers more stringent energyefficiency requirements for controls and equipment, as well as for building construction and operation. The equivalent International Energy Conservation Code (IECC) also underwent similar updates in its most recent release published in 2001. The ASHRAE 62.1 standard for ventilation has also been updated and includes new requirements for ventilation. Some of the changes include the need to base ventilation rates in multi-room buildings on the ventilation requirements of each room and on requirements of spaces and the recirculation of air. An evaluation of the HVAC system should normally begin with a review of all construction documents to determine the layout, components, and design of the system. During an evaluation, the consultant should identify potential problem areas where possible, and present reasoned recommendations for correction. This should be followed by interviews with building staff and maintenance personnel as they can usually provide important information regarding the condition, operation, and capabilities of the HVAC system. If the building superintendent or maintenance manager is attentive to the trends and conditions of the system, the deficiencies will be much easier to pinpoint and correct. After reviewing the construction documents, reports, interviews, etc., the expert can commence conducting the physical inspection which starts at the main equipment area. This could be a mechanical room or at the rooftop package units. After reviewing the energy source equipment, the distribution system should be reviewed. This may be the ductwork, a ceiling plenum, or a combination of the two. The registers, grills, and outlets should be observed and reviewed during the physical survey of the interiors of the facility. The expert should also review the building interior, including the adequacy of service and general performance of the system. Verification should be made as to whether the heat source for each room is functioning. In kitchen areas, vented range hoods should be operated and surveyed, and restroom exhaust fan operation should be evaluated. Buildings are insulated to control conductive losses or gains of thermal energy. Air-conditioning equipment deficiencies: During the HVAC evaluation, the consultant should look for critical defects in the HVAC equipment and components. Critical defects are those defects which form an immediate, significant safety hazard as well as defects that are quite likely to involve significant repair or replacement costs, and/or which involve components or systems that are necessary to occupy and use the building. While several diagnostic tools and instruments can be used in the diagnosis of specific conditions in the HVAC system, the interviews with building personnel and observation during the physical survey will be the methods most typically employed. This methodology will discover most of the significant issues at a given facility. Infrared sensors, thermometers, and humidity testing equipment are typically outside the scope of standard surveys, but can still be used in a follow-up investigation to quantify and analyze the existing conditions of the system.


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Drafts in a space or room are often an indication of poor duct design; but one must also check for blocked off registers or diffusers. In office environments, women are frequently colder than their male counterparts, and therefore may prefer to close off the register in their areas. This can create problems in other areas because the balance will have been altered, creating drafts in these areas. Even when registers and diffusers are closed, they will still allow about 10 percent of the air in the system to escape. The correct location of return grills can greatly impact the efficiency of a system. If the returns are positioned too close to the supplies, the result will be very little air circulation into the space. Hot spots will appear in the space because the air cannot reach the specified area due to short cycling between the supply and return air. Closing the registers can also create noise. This is due to duct systems that have no volume dampers. Volume dampers are designed to close off the air supply at the trunk line and reduce the noise at the register, and are also better for balancing the system. However, when too many registers or diffusers are closed, the cooling system cycles on and off; it then freezes up, delivering no cooling at all. Thermostats must be able to adequately regulate the temperature in all parts of the space in order to maintain a balanced system of heating or cooling, which is why location of the thermostat is of prime importance. Blower fans should be run continuously to ensure total circulation within the space to achieve a well-balanced system. High noise levels may be due to worn bearings, failed vibration eliminators, failed pads or curbs. Mechanical equipment creates noise because of vibrations from moving components, which require vibration isolation elements to rectify. Chillers are also noisy by nature and should be placed in locations removed from the general working area. To help reduce noise levels chillers and compressors should, whenever possible, incorporate sophisticated vibration eliminators. Rooftop equipment, towers, condensers, fans, and other HVAC equipment should all be located to allow easy access and servicing. Relative humidity testing devices: Relative humidity is the percentage of saturation of air by moisture. The higher the relative humidity, the more likely deterioration of components and building material will occur. A number of testing instruments and methods are available for use by inspectors. With humidity indicator cards like the Cobaltous Chloride Humidity Indicator, the chemical is applied to a blotting paper attached to a portable wand. As the paper is exposed to the atmosphere, the color begins to change. Other tools include use of a hygrometer which is used to determine relative humidity, and the Sling psychrometer (also called a whirling psychrometer) which provides a more accurate relative humidity reading than a stationary hygrometer. Infrared thermography is a relatively new technology that allows us to see thermal energy or heat, and infrared thermography (IR) cameras produce images of invisible infrared or “heat” radiation and provide precise non-contact temperature measurement capabilities. Nearly everything gets hot before it fails, making infrared cameras extremely cost effective, valuable diagnostic tools in many diverse applications. Thermography can therefore be used in any circumstance where the identification of thermal patterns can be applied to find something or diagnose a condition (Figure 10.16). Thermal imaging is a type of infrared imaging. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 micrometers) and produce images of that radiation. Since infrared radiation is emitted by all objects based on their temperatures, thermography makes it possible to “see” one’s environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature, so thermography allows one to see variations in temperature. When viewed by a thermographic camera, warm objects stand out well against cooler backgrounds. For example, where thermal insulation becomes faulty, building maintenance technicians can see heat leaks to improve the efficiencies of cooling or heating. Moreover, thermography allows you to find deteriorating components prior to failure and measurement can be taken in areas inaccessible or hazardous for other methods.


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Figure 10.16 An infrared thermal image of a heat exchanger displaying uneven cooling deficiency (source, Infrared Thermal Imaging Inc).

A draft gauge is used to measure air velocity and whether there is an adequate supply of air flow in a given location. Draft gauges can be used to monitor the performance of air-conditioning systems. Velometers are used for HVAC balancing, static pressure measurements, energy audits, and more. Since these instruments use a swinging vane measuring technique they do not require a power source or batteries.


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11 Electrical & Lighting Systems 11.1 GENERAL Although electrical power does not directly impact the shape or form of buildings, it remains a cardinal element in a building’s function and operation. A modern building facility requires electricity to run many of its vital systems such as lighting, heating, hot water, appliances, elevators, and air-conditioning. Because so many of today’s appliances require electric power, some existing buildings do not have enough circuits to support the demands of modern electrical usage. Buildings with insufficient electric service need not be very old. Even buildings built only 10 years ago may not have the electric wiring to support tasks in today’s business environment. Perhaps more important, without electricity the modern office building would be unable to function and would cease to exist. The most common form of electric service is delivered into buildings through overhead wires. This is known as the “service drop.” Most electrical power systems are prone to slight variations in voltage due to demand or other factors. Most frequently, distribution line voltage carried at utility poles is 2,400/4,160 volts. Transformers step down this voltage for use within buildings. Many former 220V countries have converted or are in the process of converting to the EU standard of 230V. Generally, this difference is inconsequential, as most appliances are built to tolerate current a certain percentage above or below the rated voltage. However, severe variations in current can damage electrical equipment. Electrical inspections will vary from one installation to another, as will the equipment and wiring methods. The electrical needs of a commercial facility can be simple, with only a few lights, or complex, with transformers and heavy industrial equipment. Before operating a switch or device the forensic expert should perform a visual inspection for damage, looseness, burning or arcing, or heat. Devices missing cover plates are unsafe and risk both shock and fire. Metal cover plates also add shock risks. Care should be taken when turning on switches found off in the service panel. It is prudent to leave them off and record the finding. The property owner should be consulted for permission before turning on any electrical device

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which has been found shut down. Care should also be taken when turning off switches found in the on position, as this may cause unforeseen damage to electronic or medical equipment, resetting an alarm system, or turning off a marginal switch for the heat that leaves the property with no heat in freezing weather. Electrical and lighting system deficiencies are often subtle, but measurable. These deficiencies include power surges, tripped circuit breakers, noisy ballasts, and other more obvious conditions such as inoperative electrical receptacles or Figure 11.1 Typical deficiencies found in electrical systems. lighting fixtures that are often discovered or observed during a system review. Figures 11.1 and 11.2 illustrate some of the more common deficiencies found in both the electrical and lighting systems. The lighting system is an integral component of any electrical system in a facility, and the major load placed on a given electrical system typically comes from the lighting requirements; therefore, the distribution and management of electrical and lighting loads must also be considered in a comprehensive evaluation. Lighting management should be checked periodically, for as time passes, building space uses change and users relocate within the building. Figure 11.2 Typical deficiencies found in lighting systems. There are a number of electrical codes in existence and enforced in various jurisdictions throughout the U.S. Many larger cities, such as New York and Los Angeles, have created and adopted their own electrical codes. The National Electrical Code (NEC) and the National Fire Protection Code (NFPC), published by the National Fire Protection Association (NFPA), cover the majority of electrical system components. The NEC is commonly adopted in whole or in part by municipalities. Should the forensic expert consider that unsafe conditions exist at a property to be inspected, it is imperative that all concerned parties be notified, including building occupants, owners, management, and other appropriate authorities. Where a code compliance inspection of the electrical and lighting system is required by the client, it should be conducted by an electrical engineer specialist as it is outside the scope of a normal forensic architect’s survey. The depth of the electrical inspection is affected by the use and occupancy of the building. Very large facilities with complex electrical equipment may be operated under engineering supervision, or there may be a full-time facilities manager.


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11.2 UNDERSTANDING CURRENTS, AMPS, VOLTS & WATTS Electrical service is normally brought into a building at either 240V or 120V. These numbers are termed “nominal,� meaning that the actual voltage may vary. The majority of modern buildings currently receive 240V service, a total achieved by the provision of two individual 120V incoming power lines. Older buildings and electrical services often delivered only 120V. Knowing which voltage level is available is important, but knowing the voltage alone does not indicate the amount of electrical power available inside a building. For that we need to know both the service voltage at a building, and the service amperage. Before proceeding it is important to have a basic understanding of some electrical terms that apply to electrical systems. Direct current (DC) is an electric current which flows in one direction only, with constant voltage. The associated direct voltages, in contrast to alternating voltages, are of unchanging polarity. Direct currents and voltages may be of constant magnitude or may vary with time. Direct current typically is not widely distributed for general use by electric utility customers. Instead, DC power is obtained at the site where it is needed by the rectification of commercially available alternating-current (AC) power to DC power. Moreover, direct current installations usually have different types of sockets, switches, and fixtures, mostly due to the low voltages used, from those suitable for alternating current. DC is commonly found in many low-voltage applications, especially where these are powered by batteries, which can produce only DC, or solar power systems, since solar cells can produce only DC. Most automotive applications use DC, although the alternator is an AC device which uses a rectifier to produce DC. A DC power supply is required for certain industrial applications, such as electroplating and electrometallurgical processes and for most electronic devices. Also applications using fuel cells (mixing hydrogen and oxygen together with a catalyst to produce electricity and water as byproducts) also produce only DC. Likewise, telephone exchange communication equipment, such as DSLAM, uses standard 48V DC power supply. The negative polarity is achieved by grounding the positive terminal of power supply system and the battery bank. This is done to prevent electrolysis depositions. For many applications either type of current is suitable, but alternating current (AC) is most widely available because of the greater efficiency with which it can be generated and distributed. Alternate current (AC) is electric current that reverses direction periodically, usually many times per second. Electrical energy is ordinarily generated by a public or a private utility organization and provided to a customer, whether industrial or domestic, as alternating current. Alternating current is based on the concept that electricity has nearly no inertia, and therefore the direction of the flow can be reversed very rapidly by reversing the voltage. The current flow may lag behind the voltage reversal, and therefore the amount of power is not as simple to calculate as with a DC circuit. One complete period, with current flow first in one direction and then in the other, is called a cycle, and 60 cycles per second (60 hertz) is the customary frequency of alternation in the United States and in all of North America. In Europe and in many other parts of the world, 50 Hz is the standard frequency. On aircraft a higher frequency, often 400 Hz, is used to make lighter electrical machines possible. There is also a three-phase version of alternating current; this system is essentially the same as three ordinary single-phase systems and consists of three different single-phase circuits, each out of phase with each other by one-third of a cycle (120 degrees) and one neutral or ground circuit. Three-phase systems are the standard form of electricity from power plant to home/office. However, small domestic customers are usually supplied with single-phase power. Three-phase is commonly used for generation, transmission, and distribution of electric power.


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Amperage or amps provided by an electrical service is the flow rate of “electrical current” that is available. Speaking practically, the voltage level provided by an electrical service, combined with the ampacity rating of the service panel determines the electrical load or capacity. Branch circuit wire sizes and fusing or circuit breakers used set the limit on the total electrical load or the number of electrical devices that can be run at once on a given circuit. If you have a 100A current flow rate available, you could, speaking roughly, run 10 10-amp electric heaters simultaneously. If you have only 60A available, you won’t be able to run more than six such heaters without risk of overheating wiring, causing a fire, tripping a circuit breaker or blowing a fuse. To determine the amount of electrical service provided to a facility, the service ampacity and voltage is required. In the U.S. and Canada service voltages are commonly 240 volts (nominally) at the electrical panel, a system which supports both 120V and 240V circuits in the building. Typically, two 120V hot wires entering the building provide 120V for circuits connected from an individual entering wire and the neutral bus, and 240V for circuits connected between the two incoming individual 120V circuits. The safe and proper service amperage available at a property is set by the smallest of: the service conductors, the main disconnect fuse or switch, or the rated capacity of the electric panel itself. The forensic architect should consider all three of these and report any inconsistencies among them. The main fuse/circuit breaker (CB) is the only component which actively limits amperage at a property by shutting off loads drawing more than the main fuse rating. Volts are the unit of measure of electrical potential and can be defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power. This definition may not be very helpful to consumers. A 10-amp 240V electrical service is capable of delivering approximately twice the energy to the end-user as a 10-amp 120V electrical service. Volts are thus a measure of the strength of an electrical source at a given current or amperage level. Of note, if the current rating of a wire is exceeded, it will get hot, risking a fire which is why fuse devices are used—to limit the current flow on electrical conductors to a safe level to avoid risks of overheating and fires. Most modern electrical equipment is designed to handle small voltage variations and differences, but sensitive electronic equipment may require that a voltage stabilizer be installed. One can usually determine electrical service voltage by visual examination of overhead electrical wires at the service entry that is made at the point of connection of the service drop to the service conductors but which does not include underground conduit. The service conductors are also called the service entry cable or SEC, and underground wiring up to the building is called a service lateral. A 240V electrical service will include three wires connected to the building—the two 120V “hot” legs which together provide 240V, and a third grounded conductor. A 120V service will have only two wires, a 120V power line and a grounded line or neutral. Services provided through underground conduit do not allow visual inspection of the service conductor prior to the electric meter and actual conductors are visible only in the service panel. A watt is a unit of measure of electric power and is equal to current (in amperes) multiplied by voltage (in volts). The formula watts = volts x amps basically describes this relationship. In buildings, the unit of electricity consumption measure is the watt hour, which is usually in thousands, called kilowatt hours (kwh). In larger buildings, not only is the total consumption rate measured, but the peak demand is as well.

11.3 COMPONENTS TO BE EVALUATED Service connection: Electric service is essential to all residential and commercial buildings. Yet, it is usually one of the last components to be installed during the construction process. Even so, planning the de-


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sign, construction, and timing of installation of electric service to a construction project should be contemplated from the very start. The service connection equipment provides a connection between the power company service and the facility. The connection can be located either overhead or underground. The service connection should be checked for type (i.e., voltage, amperage), general condition, and whether the total power adequately serves the facility’s requirements. The equipment should be clean and free from overgrown planting or debris. A detailed discussion of installation requirements of electric service connection is outside the scope of this book. Switchgear and switchboards: This consists of the wires from the main line, a transformer, a meter, and a disconnect switch. The switching equipment controls the power supply in the facility and all the services arriving on the site are called the service drop. The main service switch is the system disconnect for the entire electrical service. To avoid excessive voltage drop and flicker, the distance from the transformer to the meter should not exceed 150 feet. In commercial construction the panel and disconnect is preferably located outside the building but may be located inside if it is directly accessible from an exterior door. Switchgear and switchboards should be readily accessible, in good condition, and have protective panels and doors. They should also be checked for signs of overloading or burn marks. Switchboard covers should not normally be removed. Meters: In normal domestic applications, only the total electric consumption is measured (using “feedthrough� type), whereas in larger buildings both the total consumption and peak rate demand are measured. This is because large peaks require the utility company to build more power generating capacity to meet the peak. Commercial services up to 200 amps single-phase may have service panels similar to those found in residences although larger services may require stand-alone switchboards with one or more meters. In a multiple occupancy building there may be separate meters for each tenant or common metering. Panelboards: A panelboard is a set of fuses or circuit breakers which control the circuit loading in a building. It provides a central distributing point for branch circuits for a building, a floor, or part of a floor. Panelboards control and protect the branch circuits. Each breaker serves a single circuit, and the overload protection is based on the size and current-carrying capacity of the wiring in that circuit. A building may have a number of panelboards and a main panel, with a disconnect switch for the entire building (Figure 11.3). Panelboards should be checked for their general condition and for evidence of wear or disrepair. Annually inspect the inside of the panel for signs of rust, water penetration, and scorched wires. Trip the circuit breakers once a year and the ground fault breakers once a month. If fuses are used, be sure they are screwed in tightly. The equipment should be accessible and protective covers and doors should be in place. The forensic expert should also check for evidence of blown or replaced circuits. Lighting panel types include: 1. Bolt-on circuit breakers (1-pole, 2-pole, 3-pole), 2. Plug-in circuit breakers (1-pole), and 3. Fusible switch. To determine the electric service panel ampacity, look for a tag (normally of paper) or embossed rating on fuse pull outs on the panel itself which often includes the amperage rating of the panel. This information is usually present in newer panels on a panel side or on the panel cover. Actual dimensions of an electric panel are not a reliable determinant of ampacity. For example, many larger panels can be fitted with a variety of bus-bar and main switch assemblies of varying ampacity. Aluminum wiring may have been used in residences and buildings built between 1965 and 1973, but this application has been largely discontinued because it proved to be a potential fire hazard. The connections can become hot enough to start a fire without ever tripping the circuit breaker. Aluminum wiring has a tendency to loosen from connections. When this occurs, the potential for arcing is increased. Where aluminum contacts or wiring are present, a program should be established for inspecting and tightening connections at the source of the electrical system and at utilization units.


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To identify aluminum wiring, look for the word “aluminum” on the wiring. Without opening any electrical panels or other devices, a building inspector can still look for printed or embossed letters on the plastic wire jacket where wiring is visible at the electric panel. Some aluminum wire has the word “aluminum” or a specific brand name such as “Kaiser,” “Alcan,” or “AL/2” plainly marked on the plastic wire jacket (Figure 11.4). Of note, the fact that no aluminum wiring is visible in the panel does not necessarily mean that none is present. Service outlets: Service outlets include convenience receptacles, motors, lights and appliances. They should be checked for general condition as well as satisfactory operation and whether any outlets display evidence of power surges or shorts. Receptacles: These are commonly known as outlets. Outlets should preferably be three-pronged where the third prong is grounded. In large spaces outlets should not all be on the same circuit so that when a fuse or circuit breaker trips due to an overload the space will not be plunged into complete darkness. Important specifications for electrical receptacles include number of Figure 11.3A,B,C,D A. A typical circuit breaker panel B. A circuit breaker panel with missing cover C. An electric poles and grounding method. Electrical reswitch box/fuse panel D. Old and outdated electric service. ceptacles are available with a variety of features. Some devices include surge protection against mild to moderate spikes or peaks in the electrical supply. Others include a locking mechanism or a power light. Grounding is connecting one or more conductive objects directly to the earth using ground rods, cold water copper pipes, or building steel. Grounding of services to earth is a basic safety precaution and is necessary mainly to dissipate any electric current with little or no resistance, and averting possible damage or injury including protection against lightning strikes and other high-voltage line strikes. Earth grounding in a commercial building may be to a grounding rod inside a switchboard, to a plumbing system’s steel cold water pipe, or to a building’s steel frame, depending on the equipment or system to be grounded. Grounding also drains the static charges away as quickly as they are produced. Ground wires are covered with green insulation or may even be bare. Motors: A motor is essentially a machine which converts electrical energy into mechanical energy. The converse is a generator, a machine that converts mechanical energy into electrical energy. Basically, there are four types of motors in general use. The DC motor is used for small scale applications and for elevators, where continuous and smooth acceleration to a high speed is important. Single-phase AC motors


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Figure 11.4 Examples of aluminum wiring (source, Daniel Friedman).

Figure 11.5 A typical electrical room in a Chicago, Illinois hotel.

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are used in various sizes and shapes, typically ¾ horsepower or less. Larger motors are typically three-phase induction motors and are characterized by extreme reliability, remaining constant in rpm, unless heavily overloaded. The fourth type of motor in general use is the universal motor, which runs on either DC or AC current, and which varies in speed based on the load. The universal motor is usually found in mixers, hand drills, and similar appliances. Motors should always be protected against overload by thermal relays which shut off the power when any part of the motor or housing overheats. Switches and controls: The switches and controls direct the flow of power service to the electrical equipment. Safety switches are installed in locations where service cut-off is available in case of emergencies. These include toggle switches, dials and levers. Switches and controls should be checked for general condition and whether they operate satisfactory and are safely and readily accessible (Figure 11.5). It may be appropriate for the forensic expert to recommend thermographic scanning of the electrical switchgear and transformers, especially in larger facilities that are supplied with 600 volt threephase power. Electrical rooms are necessary for housing a building’s electrical, climate control, and security infrastructure. Electrical rooms are built to very specific code regulations designed to maximize the building’s safety. To increase personal safety, National Electric Code (NEC) changes now require more space around the equipment in the electrical room. Emergency power & emergency lighting: Most large facilities have standby power with which to ensure continued electrical service despite the shutdown of the standard power service. Emergency power is required for life support systems, fire and life safety circuits, elevators, exit and emergency lighting. Facilities which require full operation during emergencies or disasters, such as hospitals and shelters, always have back up power. Computer facilities, to ensure continued storage and survival of the data, also com-


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monly have emergency power. For major equipment, a diesel engine generator with an automatic starting switch and an automatic transfer switch is often provided for emergency power (Figure 11.6), while for lighting, battery units are installed. The emergency power should be checked that its condition and operation are satisfactory. Emergency lighting is needed in the event of a power failure; emergency lighting in a facility enables the occupants to exit safely. Emergency lighting can consist of individual battery units located in all corridors and areas which would require sufficient lighting for exiting, in interior and some exterior exitways. These batteries are continuously recharged while power is on, and take Figure 11.6 Photo of an Amtrak generator for over when power is lost. Alternatively, the lightemergency back-up power inside a building. ing can be powered by a central battery unit. Transformers: A transformer is a device that changes the voltage of an AC circuit to a higher or lower value. While a transformer changes the voltage in a circuit, it has practically no effect on the total power in the circuit. Transformers are used to step up voltage (called step up transformers) in order to transmit power over long distances without excessive losses, and subsequently step down voltage (called step down transformers) to more useable levels. Transformers are of two distinct types: Liquid insulated and cooled (liquid-filled type) and non-liquid insulated, air or air/gas cooled (dry type). Also, there are subcategories of each main type. Lower voltage types are dry, and typically noise generating, with minimal requirements for insulation and avenues for ventilation of heat generated by voltage changes. Dry-type transformers account for a large range of capacities and applications. However, they do not have the heat capacity of liquid-filled transformers, and so can’t withstand momentary overloads nearly as well. Dry-type transformers come in enclosures that have louvers or are sealed. In wet-type high voltage transformers, fluids which are often toxic serve as part of the insulation system and also as a medium to remove the heat generated in the transformer due to the change in current. Wet-type transformers typically contain a type of fire-resistive fluid or mineral oil such as PCBs. Liquid-filled transformers are normally more efficient than dry-types, and they usually have a longer life expectancy. Also, liquid is a more efficient cooling medium in reducing hot spot temperatures in the coils. In addition, liquid-filled units have a better overload capability. The Environmental Protection Agency (EPA) requires liquid-filled transformers containing more than 660 gallons to have some type of containment to control possible leaks of Figure 11.7 Illustration of a transformer outside a building protected by bollards. the liquid.


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There should be clear access surrounding exterior transformers and adequate ventilation and access for interior transformers which should be inside a fireproof vault. On-site transformers in parking lots may require bollards or other protection (Figure 11.7). Transformers should be analyzed for PCBs and their registration number noted. Additional components: There are a number of other systems that may be assessed for operations and existing conditions during the review of the electrical systems. These include: •

Telephone systems: Telephone and communication systems are low-voltage systems, which makes the requirements for conduit and other protection less stringent than for high-voltage power. As with all telecommunications wiring, good insulation and separation from the main electrical wiring is necessary. Often, an outlet box is provided at the connection in the wall, and the wire is run within the walls and ceiling spaces without conduit. However, in some commercial construction all cable is required to be protected in conduit to avoid having it catch fire or release toxic fumes in case of a fire.

Security systems (see Chapter 18).

Conduit and wiring of central computer systems: Wiring in commercial buildings differs from that in residential buildings. Commercial wiring methods normally utilize rigid or intermediate metal conduit, EMT, PVC and MC cable. Wires must be physically protected in addition to being insulated. In commercial applications this is accomplished by housing them in a conduit such as rigid conduit, intermediate metallic conduit (IMC), electrical metallic tubing (EMT), flexible metal conduit, or interlocked armored cable. Industrial buildings may also have other wiring methods, such as busways and cable trays.

Fire alarm systems (see Chapter 18).

11.4 BUILDING AUTOMATION & INTELLIGENT BUILDINGS An intelligent building automation system enables a facilities manager to better manage resources, improve building safety, and reduce energy costs. With modern device networking technology, an intelligent building can be created that allows managers to control virtually every system from a central location. While building controls/automation continues to increase in complexity, at the very least an intelligent building is one that minimizes environmental disruption, degradation, or depletion associated with the building, while ensuring a long-term useful functional capacity for the building. The majority of architects and engineers today understand an intelligent building to be a building that incorporates computer programs to coordinate many building subsystems to regulate the interior temperatures, HVAC and providing power. The goal is usually to reduce the operating cost of the building while maintaining the desired environment for the occupants (Figure 11.8). What is not realized is that it is really about the use of advanced technologies to significantly improve the comfort, environment, and performance of its occupants while minimizing the external environmental impact of its structure and systems. The concept of intelligent building systems is well advanced in the United States compared to the rest of the world. And most facility and building managers recognize the potential value of building automation systems (BASs) as a powerful energy saving tool, but the initial cost sometimes makes them hesitate. Commercial-off-the-shelf BAS systems are now readily available. For example, a readily available basic BAS saves energy by widening temperature ranges and reducing lighting in unoccupied spaces. A BAS also reduces costs for electricity by shedding loads when electricity is higher-priced. A building can even


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Figure 11.8 A venetian-blind system at a Berkeley Lab office building is equipped with a "virtual instrument" panel for IBECS control of blinds settings (courtesy, HPCBS).

be designed so that air-conditioning and refrigeration are deferred. Figure 11.9 illustrates an integrated approach to the design of a building’s many systems with a full complement of sustainable design techniques as applied to Integrated Design Associates’ new headquarters in San Jose, California. Subsystems typically contribute to the costs of operating a building which is why customized building automation is usually complex, depending on the needs of the client. Some intelligent buildings have the capability to: •

Manage thermal transmissions through windows or walls

Anticipate forecasted weather, utility costs, or electrical demand

Learn and adapt to building occupants

Track individual occupants to adapt building systems to the individual’s wants and needs (e.g., setting a room’s temperature and lighting levels automatically when a homeowner enters)

Detect and report faults in mechanical and electrical systems, especially critical systems.

Many other non-energy uses for automation in a building abound such as security, rent, or consumables charges based on actual usage, giving directions within the building, scheduling preventive maintenance, and customized lighting to meet different needs or set moods. Some of the more common elements and components of building automation include: Controller: Modern controllers allow users to take advantage of networking and gain real-time access to information from multiple resource segments in a building’s network, creating an “intelligent building.” Application specific controllers come in a wide range of sizes and capabilities to control devices that are common in buildings. Usually the primary and secondary buses are chosen based on what the controllers provide.


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Figure 11.9 A schematic drawing illustrating an integrated approach to the design of a building's various systems in the new IDeAs headquarters (courtesy, Integrated Design Associates, Inc.).

Occupancy sensors: There are various types of occupancy sensors including infrared, ultrasonic, and dual tech sensors that are designed to meet a wide range of applications. Occupancy is usually based on time of day schedules. Override is possible through different means. Some buildings can sense occupancy in their internal spaces by an override switch or sensor. Sensors can be ceiling- or wall-mounted. Lighting: Lighting can be turned on and off with a building automation system based on time of day, or the occupancy sensors and timers. One typical example is to turn the lights in a space on for a half hour since the last motion was sensed. A photocell placed outside a building can sense darkness, and the time of day, and modulate lights in outer offices and the parking lot. This is discussed in greater detail in the lighting section. Air handlers: Most air handlers mix return and outside air so less temperature change is needed. This can save money by using less chilled or heated water (not all AHUs use chilled/hot water circuits). Some external air is necessary to keep the building’s air healthy. Analog or digital temperature sensors may be placed in the space or room, the return and supply air ducts, and sometimes the external air. Actuators are placed on the hot and chilled water valves, the outside air and return air dampers. The supply fan (and return if applicable) is started and stopped based on either time of day, temperatures, building pressures, or a combination of these. Constant volume air-handling units (CAV): This type of unit is a less efficient type of air-handler. The fans in CAVs do not have variable-speed controls. Instead, CAVs open and close dampers and water-supply valves to maintain temperatures in the building’s spaces. They heat or cool the spaces by opening or closing chilled or hot water valves that feed their internal heat exchangers. Variable volume air-handling units (VAV): This is a more efficient unit type. VAVs supply pressurized air to VAV boxes, usually one box per room or area. A VAV air handler can change the pressure to the VAV boxes by changing the speed of a fan or blower with a variable frequency drive or by moving inlet guide vanes to a fixed-speed fan. The amount of air is determined by the needs of the spaces served by the VAV boxes. VAV boxes supply air to a space, like an office. Each box has a damper that is opened or closed based on how much heating or cooling is required in its space. The more boxes are open, the more air is required, and a greater amount of air is supplied by the VAV air-handling unit. Some VAV boxes also have hot water valves and an internal heat exchanger. The valves for hot and cold water are opened


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or closed based on the heat demand for the spaces it is supplying. A minimum and maximum CFM must be set on VAV boxes to assure adequate ventilation and proper air balance. VAV hybrid systems are another variation of a hybrid between VAV and CAV systems. In this system, the interior zones operate as in a VAV system. The outer zones differ in that the heating is supplied by a heating fan in a central location usually with a heating coil fed by the building’s boiler. The heated air is ducted to the exterior dual duct mixing boxes and dampers controlled by the zone thermostat calling for either cooled or heated air as needed. Central plants are required to supply the air-handling units with water. A central plant may supply a chilled water system, hot water system and a condenser water system, as well as transformers and auxiliary power unit for emergency power. If well managed, these can often help each other. For example, some plants generate electric power at periods with peak demand using a gas turbine, and then use the turbine’s hot exhaust to heat water or power an absorptive chiller. Chilled water systems are often used to cool a building’s air and equipment. The chilled water system will have chiller(s) and pumps. Analog temperature sensors measure the chilled water supply and return lines. The chiller(s) are sequenced on and off to chill the chilled water supply. There is a wide range of both air and water-cooled liquid chillers on the market. Condenser water system: Cooling tower(s) and pumps are used to supply cool condenser water to the chillers. The condenser water supply to the chillers has to be constant, so speed drives are commonly used on the cooling tower fans to control temperature. Proper cooling tower temperature assures the proper refrigerant head pressure in the chiller. Analog temperature sensors measure the condenser water supply and return lines. Hot water system: The hot water system supplies heat to the building’s air-handling units or VAV boxes. The hot water system will have a boiler(s) and pumps. Analog temperature sensors are placed in the hot water supply and return lines. Some type of mixing valve is usually used to control the heating water loop temperature. The boiler(s) and pumps are sequenced on and off to maintain supply. Alarms and security: Many building automation systems have alarm capabilities. If an alarm is detected, it can be programmed to notify someone. Notification can be through a computer, pager, cellular phone, or audible alarm. Security systems can be interlocked to a building automation system. If occupancy sensors are present, they can also be used as burglar alarms. This is discussed in greater detail in Chapter 18 (life safety/fire protection). Fire and smoke alarm systems can be hard-wired to override building automation, so that if the smoke alarm is activated, all the outside air dampers close to prevent air from coming into the building, and an exhaust system can isolate the alarmed area and activate an exhaust fan to move smoke out of the area. At sites with several buildings, momentary power failures can cause hundreds or thousands of alarms from equipment that has shut down. Some sites are programmed so that critical alarms are automatically re-sent at varying intervals. There are various propriety protocols and industry standards on the market, including: ASHRAE, BACnet, DALI, DSI, Dynet, Energy Star, KNX standard, LonTalk, and ZigBee. Details of these systems are outside the scope of this book.

11.5 INTERIOR AND EXTERIOR LIGHTING SYSTEMS Light, whether natural or artificial, allows us to see so that we can perform our tasks, and in that respect, light makes a space useable. Different artificial sources produce different kinds of light, and vary signifi-


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cantly in their efficiency, which is the calculated lumen output per watt input. Unfortunately, U.S. lighting design does not translate easily overseas—not when each region has its own voltage, product standards, construction methods, and conceptions about what light is supposed to accomplish. Interior lighting: Standards and guidelines are used in many countries for the illuminance levels that are recommended for different spaces. These recommended values depend on many factors including the type of lighting systems and the activities expected in the space (Figure 11.10). Interior lighting Figure 11.10 A table showing recommended illumination levels. should meet minimum illumination levels. Typically, the light needed for visibility and perception increases as the size of details decreases, as contrast between details and their backgrounds is reduced, and as task reflectance is reduced. Thus for example, the illuminance levels required for task lighting with high accuracy activities are higher than those for ambient lighting. There are four general categories of interior lighting systems: •

Incandescent: Incandescent lamps or bulbs come in numerous shapes with different characteristics (Figure 11.11).

Fluorescent: This type of lighting is far more efficient and lasts 10–20 times longer (fluorescent lamps last up to 20,000 hours of use); it is based on passing a current through gases inside a glass tube. A fluorescent fixture typically consists of the lamp and an associated ballast which controls the voltage and the current to the lamp.

High intensity discharge (HID): This type of lamp consists of a lamp within a lamp, which is run at a very high voltage. There are basically four types of HID lamps: 1. High pressure sodium (HPS) lamps, 2. Mercury lamps, 3. Metal halide gas lamps, and 4. Low pressure sodium lamps.

Fiber optics: This is a relatively new technology, providing an alternative that is superior to conventional interior and exterior lighting systems. A typical fiber optic lighting system can be broken down into two basic components: a light source, which generates the light, and the fiber optics, which deliver the light.

Although it is important for the client to determine how much light is required for the activity that will take place in a space, this is typically outside the scope of a baseline survey and should be determined by a lighting consultant. Interior lighting includes all permanently installed general and task lighting shown on the plans but does not include specialized lighting for medical, dental, or research purposes and display lighting for exhibits in galleries, museums, and monuments. The useful life of a lighting installation progressively decreases in its efficiency due to dirt accumulation on the surface and aging of the equipment. The rate of reduction is influenced by the equipment choice and the environmental and operating conditions. In lighting scheme design the consultant must take into account this decrease by the use of a maintenance factor and plan suitable maintenance schedules to limit the decay.


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Figure 11.11 Types of incandescent lamps.

Exterior lighting systems: Commercial outdoor lighting requires attention to detail and knowledge of architectural and landscaping elements. There are three main areas that require special emphasis in any commercial outdoor lighting project: perimeter, natural landscape, and architecture. If any one of these areas is neglected or overemphasized, the resulting aesthetic communicates an unconscious, disturbing sense of imbalance. Some of the lighting systems commonly used in exterior applications on and near commercial, institutional, industrial, and storage buildings, include: •

Pole mounted floodlights, area lights, and spot lights

Above ground mounted floodlights and spot lights

In ground floodlights and spot lights


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Illuminated bollards and landscape lighting

Wall mounted sconces, wall bracket lights, and wall pack lights

Canopy and soffit mounted surface lights

Step lights and other lights recessed into exterior walls and surfaces.

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Facility evaluations often identify inadequate exterior lighting conditions of which incandescent and high intensity discharge are the most common types. Exterior lighting illumination levels should be adequate and in good condition. Full cut-off lighting fixtures are required for all outdoor walkway, parking lot, canopy, and building/wall mounted lighting, and all lighting fixtures located within those portions of opensided parking structures that are above ground. Automatic controls are required for all exterior lighting. The control may be a directional photocell, an astronomical time switch, or a building automation system with astronomical time switch capabilities. The control should automatically turn off exterior lighting when daylight is available. Lights in parking garages, tunnels, and other large covered areas that are required to be on during daylight hours are exempt from this requirement. In addition, most building codes require special emergency lighting at exits and for certain critical functions. Emergency lighting may be provided by a separate generator within the building or by battery packs and small lights that would provide enough illumination to evacuate the building. This is discussed in Chapter 18.

11.6 SOLAR ENERGY ELECTRIC SYSTEMS Solar technologies use the sun’s energy and light to provide heat, light, hot water, electricity, and even cooling, for homes, businesses, and industry. Types of renewable technologies available for a particular facility depend largely on the type of energy required, as well as building design and access to the renewable energy source. Building facilities can use renewable energy for space heating, water heating, air conditioning, lighting, and refrigeration. Commercial facilities include assembly and meeting spaces, educational facilities, food sales, food service, health care, lodging, stores and service businesses, offices, and warehouses.

11.6.1

Solar Electric System Basics

Configuration: There are two main components in a grid-connected system: the solar electric panels, and the inverter, which converts DC to AC power. Other components include the wiring, the disconnect switch, and conduit. Panels are usually mounted on either a stationary rack or a tracking rack that follows the movement of the sun. Life expectancy of a typical system is 40 to 50 years. Panels are generally warranted for 20 to 25 years and inverters for 5 to 10 years. Also, as they have no moving parts, solar electric panels operate silently. Siting: Panels like full sun, facing within 30 degrees of south and tilting within 30 degrees of the site’s latitude. A one-kilowatt system requires about 80 square feet of solar electric panels. Stationary racks can be roof or pole-mounted (Figure 11.12). Tracking racks are pole-mounted. Energy production: Each kilowatt of unshaded stationary solar electric panels generates about 1,200 kilowatt-hours of electricity per year. A one-kilowatt, dual axis tracking system will generate about 1,600


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kilowatt hours per year. Power is generated during peak daylight hours. Solar power exhibits a very good peak coincidence with commercial building electrical loads. Dual axis tracking systems, where the panels follow the sun, will require periodic maintenance. Solar electric systems are environmentally friendly because they do not generate emissions of greenhouse gasses or other pollutants, thereby reducing global climate impacts. Solar panels provide a visible demonstration of concern for the environment, community education, and proactive forward thinking.

11.6.2

Types of Solar Energy Systems

Grid-tied solar system (alternating current): This type of system does not require storage equipment (i.e., batteries). The crucial issue relative to the photovoltaic panels (PV) system discussed below is the technical aspect of tying into the electricity grid. In these applications, grid-tied inverters must be used that meet the requirements of the utilities. They must not emit “noise� which can interfere with the reception of equipment (e.g., televisions), switch off in the case of a grid failure, and retain acceptable levels of harmonic distortion (i.e., quality of voltage and current output waveforms). This type of system tends to be an optimum configuration from an economic viewpoint because all the electricity is utilized by the owner during the day and any surplus is exported to the grid. Meanwhile, the cost of storage to meet night-time needs is avoided, because the owner simply draws on the grid in the usual way. Also, with access to the grid, the system does not need to be sized to meet peak loads. Stand-alone grid-tied solar system (alternating current): This type of solar energy system is the same as the grid-tied system above except that battery storage is added to enable power to be generated even when the electricity grid fails. The additional cost to the customer can be quantified against the value of knowing that their power supply will not be interrupted.

Figure 11.12 Camp Ramah, in the heart of the Ojai Valley in California, is a 270kW solar power energy system which is the largest private non-profit solar power generator system in the state.


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Stand-alone off-grid solar system without energy storage (direct current): In this configuration (i.e., without any energy storage device), the PV system output is dependent upon the intensity of the sun. In this simple system, the electricity generated is used immediately. Therefore, the application must be capable of working on both direct current (DC) and variable power output. To meet the largest power requirements in an off grid location, the PV system is sometimes best configured with a small diesel generator. This means that the PV system no longer has to be sized to cope with the worst sunlight conditions available during the year. The diesel generator can provide the back-up power, but its use is minimized during the rest of the year in order to minimize fuel and maintenance costs. For any module with a defined peak power, the actual amount of electricity in kilowatt hours (kWh) that you will get from it depends mainly on how much sunlight it receives. The electrical power output of a PV module is the current that it generates (dependent on its surface area) multiplied by the voltage at which it operates (a function of the active material in the PV cell). The bigger the module, or the solar array (an array is simply a number of modules connected together), the more power is generated. A linear current booster can be added which converts excess voltage into amperage in order to keep a pump running in low light conditions. An LCB can boost pump output by 40 percent or more. For safety considerations, PV arrays are normally earthed (grounded).

11.7 HARMONICS DISTORTION Until recently, most electrical equipment operated on an ideal voltage and current waveform. However, in the last few decades we have experienced a dramatic increase in the use of solid-state electronic technology. This new, highly efficient electronic technology provides improved product quality with increased productivity by the use of smaller and lighter electrical components. Savings in providing state-of-the-art electrical building control devices along with the implementation of a comprehensive lighting retrofit can generate significant savings on a typical electric bill. In today’s competitive marketplace, understanding the issues and embracing winning power management strategies has become a necessity. While the topic of harmonic distortion is outside the scope of normal building surveys, it remains vitally important for forensic architects to understand it. Loads connected to electricity supply systems may be broadly categorized as either linear or nonlinear. Until quite recently, the vast majority of loads have been linear. Typical examples include induction motors and incandescent lamps. Linear loads may exhibit high or low power factor, but in either case they draw current only at the powerline fundamental frequency. In contrast, nonlinear loads such as rectifiers or switchmode power converters also draw significant current at harmonic frequencies. Harmonic currents flowing through electric power supply systems cause voltage distortion. This voltage distortion is caused by a growing penetration of nonlinear loads and is often accommodated without serious consequences, but in other cases mitigation steps have had to be instigated to avoid compromised power quality. Problems in electric supply systems can surface through the presence of nonlinear loads of sufficient size and quantity. The severity of problems depends upon the local and regional supply characteristics, the size of the loads, the quantity of these loads, and how the loads interact with each other. Utility companies are clearly concerned about emerging problems caused by increasing concentrations of nonlinear loads resulting from the growing proliferation of electronic equipment. Equipment that can create harmonic distortion: While the majority of loads connected to the electricity supply system draw power that is a linear (or near linear) function of the voltage and current supplied to it, these linear loads do not normally cause disturbance to other users of the system. Some types of loads however cause a distortion of the supply voltage/current waveform due to their non-linear impedance.


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The largest contributors of reflective harmonic currents for commercial buildings that are causing these problems are personal computers and their AC to DC power supply converters, and electronic controllers. Some types of fluorescent lighting or the controllers for such lighting can also cause these effects. Problems occur when such activity causes interference or permanent damage to equipment that is connected adjacent to the disturbing load. In addition, there are many other contributors too such as recorders, battery chargers, copiers, computer power units (CPU), telecommunication equipment, variable speed drives (VSD), discharge lighting (fluorescent, mercury, sodium, etc.), electronic dimmers, electronic ballasts, elevators, fax machines, rectifiers, uninterrupted power supplies (UPS), video recorders, video display units, and welders. Repeated power quality problems will negatively impact the tenant’s environment, ability to conduct business and affect overall satisfaction. Cause and effect of harmonic distortion: The negative impact that any building encounters from harmonic distortion will vary and depend on the types and number of installed harmonic producing loads. Most buildings can withstand nonlinear loads of up to 15 percent of the total electrical system capacity without major concern. However, when the nonlinear loads exceed 15 percent some non-apparent negative consequences can be expected, and for buildings that have nonlinear loading in excess of 25 percent, particular problems can become apparent. Although the results can be unpredictable, they can have legal and financial ramifications. Furthermore, the heating impact of harmonic currents can cause equipment failure, demise of conductors, and fires. Harmonic currents and voltage distortion is rapidly becoming one of the most severe and complex electrical challenges facing the electrical industry. Problems associated with nonlinear loads were previously limited to isolated devices and computer rooms, but today these problems often appear unexpectedly throughout the building and utility system. Harmonics reduction: There are several basic methods for reducing harmonic voltage and current distortion from non-linear distribution loads such as adjustable frequency drives (AFDs). However, in the presence of excessive harmonic distortion, it is highly recommended to bring in a specialized consultant. Some of the methods used by harmonic specialists to reduce harmonic distortion may include the use of a DC choke, line reactors, 12-pulse converters, 12-pulse distribution, harmonic trap filters, broadband filters, and active filters. Of note, these reduction methods must meet the guidelines of the Institute of Electrical and Electronics Engineers, Inc. (IEEE). It may also be possible to request from the equipment supplier a design of lower harmonic current, or in the case of a large installation, request that the supplier consider modification of the supply system to reduce the system impedance.

11.8 SYSTEM DIAGNOSTICS Detailed electrical inspections should only be performed by qualified persons as such inspections can pose some danger to the inspector, as well as to the users of the system. Moreover, if during a baseline survey a forensic architect/engineer encounters situations or equipment that is unfamiliar, it would again be advisable to recommend follow-up inspections by specialists. Often system deficiencies are experienced by building users while not necessarily being observable at the equipment. It is possible that the system is on the brink of failure with no immediate visual indications, particularly as much of the equipment is also inaccessible. It is important for the forensic expert to interview the building users and maintenance staff to assist in determining some of the existing and potential problems. Because of the very nature and configuration of the electrical system, determining ongoing performance trends is as important as one-time field investigation observation. There are several conditions which may occur in the electrical system components which may indicate significant deficiencies or insufficient capacity. For example, are there frequent overheating


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problems or the tripping of protective relays in the primary or secondary equipment? A simple check is to put a hand on the various circuit breakers and switch panels. If any are hot to the touch it is an indication that overheating may be occurring and this should be checked immediately. Also, some components may require more preventive maintenance than others. These are the types of issues about which the maintenance staff generally is knowledgeable and which might not be evident during a typical field survey. Prior to conducting the field survey the forensic architect should review the components and configuration delineated in the construction drawings and specifications. The physical evaluation should then follow, beginning at the main electrical vault which contains the main connection and transformer. Each electrical equipment room should be reviewed, as well as circuit breaker panels located throughout the building. The inspector shall record the amperage and voltage ratings of the service. Transformers should also be checked to ensure air intake grills are clean and that there are no objects stored around the transformers that can block the cooling air supply. Transformers generate heat and this heat must be removed or the insulation will break down, causing eventual failure of the transformer. During the physical inspection of the interior, the inspector should systematically review the lighting and electrical components, such as receptacles and switches. Switches should be operated during the survey to identify any dimmed or flickering lighting which may indicate electrical deficiencies within the circuit. All electrical equipment in a given zone or area should be operated simultaneously to determine that the circuit capacity is adequate. In an occupied building the forensic expert should never pull a fuse or shut off any component. A review of the exterior lighting should be performed, both after dark to determine actual nighttime illumination, and during the daylight to review the condition of the fixtures. To summarize, a forensic expert’s survey/inspection should include identifying and observing the condition of the electrical service and electrical distribution system including distribution panels, transformers, meters, emergency generators, security systems, telecommunications systems, lighting systems, and other such asset-related equipment or systems. The forensic expert should also observe types of wiring, energy management systems, emergency power, lighting protection, etc., and identify the apparent or reported ages of electrical systems and, combined with visual observations, identify the RUL of the electrical components. All electrical rooms in a facility should be locked and entry restricted to maintenance staff or other authorized persons. There are various measuring instruments being deployed in electrical inspections. An ammeter measures current, a voltmeter measures the potential difference (voltage) between two points, and an ohmmeter measures resistance. A multi meter combines these functions into one piece of equipment, and a light meter measures the amount of light. Also, infrared thermography is often employed to inspect electrical and lighting systems. The infrared scanner can determine which circuits and connections are overheated, and therefore overloaded, before they are obvious to the naked eye. The electrical distribution system, including the lighting panels, should be inspected semi-annually to minimize the risk of overloading. Limitations & exclusions: These should be clearly stated in the protocol agreement. Normally, assessments should exclude the removal of electrical panel and device covers, electrical testing, EMF issues, or operating of any electrical devices. Process-related equipment is also excluded from the assessment scope. Inspection of the following processes should also be excluded: 1. Remove or dismantle any electrical device or component other than to remove dead front covers of the electrical equipment 2. Test or operate any overcurrent electrical device other than ground fault circuit (GFCI) and arc fault circuit interrupters (AFCI) when present 3. Power shutdown, major dismantling or disassembly in order to permit opening of larger service or high voltage electrical equipment for inspection thereof


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4. Inspect and evaluate indoor/outdoor power transformers other than observe the compatibility of rated ampacities and voltages with regard to the supply thereto 5. Testing or evaluation of the resistance of the electrical wiring system 6. Testing or evaluation of the electrical grounding system 7. Observe and report on electrical equipment according to these parameters if: a) the equipment is not readily accessible, b) the inspection thereof serves to compromise the safety of the inspector, c) the equipment is owned and maintained by the utility company or some other designated or authorized personnel, d) the inspection thereof is objected to by the building’s owner or authorized representative, e) the equipment is not stated in the building inspection proposal as submitted and agreed to prior to inspection of a commercial property 8. Observe and report on sound, security and alarm systems 9. Observe and report on low voltage or ancillary wiring, systems and components that are not part of the primary electrical power and distribution system 10. Observe and report on electrical equipment other than listed in the building inspection report.


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12 Plumbing Systems 12.1 GENERAL Generally speaking, a plumbing system consists of pipes and fixtures installed in a building for the distribution of potable water and the removal of waterborne wastes. Metal or plastic pipes are joined by a variety of fittings designed to couple lengths in a straight line, turn corners, reduce or enlarge pipe size, or connect to some type of fixture. Plumbing systems generally refer to indoor piping systems—which do not include piping associated with the operation of an HVAC system. Plumbing is further distinguished from water and sewage systems in that a plumbing system serves one building, while water and sewage systems serve a group of buildings or a city. Any facility’s plumbing system constitutes a long-term investment and its design should reflect this fact. A system should not become redundant and require replacement while its major components are still serviceable. This requires a careful analysis of present and future needs so that the correct capacity can be specified. The capacity and dimensions of component parts in a plumbing installation should be capable of meeting both immediate needs and anticipated future use. Current-day water-supply systems use a network of high-pressure pumps and pipes made of copper, brass, plastic, steel, or other nontoxic material. Drain and vent lines are typically made of plastic, steel, castiron, and lead. Lead is not used in modern water-supply piping due to its toxicity. But the complexity and number of subsystems within the plumbing system vary greatly with the size, type, and function of a building. As illustrated in Figure 12.1, there are several possible subsystems and components which may be evaluated in any review or inspection of a plumbing system. In simple buildings, the plumbing may consist of hot and cold water systems, a storm drain system and a natural gas distribution system. More complex buildings such as hospitals may be comprised of several unique plumbing systems including a variety of temperatures of hot water as well as oxygen, nitrogen, nitrous oxide, and other gas systems. Sometimes a building is constructed below sewer lines and sewage ejectors need to be installed to pump the sewage up into the sewer system. Industrial facilities for example may contain cryogenic or other low temperature systems in the process piping which could be included in the plumbing evaluation. All of these components may vary according to the type of facility and therefore

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the evaluation of the plumbing system in each facility is unique. Plumbing systems normally consist of water being provided by a public system (or sometimes a private well for residences or small structures), and entering the building through the floor slab. The water service delivers water to a meter (by which it measures the amount of water consumed) through a large pipe called a main that is often parallel to the street. Once the water passes through the main and meter, it goes into distribution piping, which runs throughout the building and is controlled at different Figure 12.1 Typical components to be evaluated in the locations within the building through the plumbing system. use of various types of valves. Between the water supply and the waste collection systems are fixtures which may be an appliance such as a water heater, washing machine, or dishwasher. Or it may be a lavatory, shower, tub, or toilet. The fixture is where the water distribution and the waste collection systems join. Waste collection systems are an important aspect of any plumbing system. Liquid wastes should be disposed of promptly and hygienically. At each lavatory, sink, tub, shower, and toilet there will be a connection to waste collection piping. Waste water is channeled down and out of the building. When a public sewer exists within reasonable distance of the premises the building waste system should drain to that sewer. Where no such sewer exists, disposal should be through an approved method of treatment, such as a septic tank, where soils and population densities permit, that is located so as to cause no nuisance to the occupants of the building or to those of neighboring properties. Waste collection piping should have vents to get sewer gas into the atmosphere, and provide air into the system to help it work. Those vents should go through the attic and out the roof so that sewer gasses are vented into the atmosphere. Where chemical closets are used, adequate arrangements must be made for sanitary disposal of wastewater (such as the wastewater from other fixtures, sinks, or baths), as well as the residue from the chemical closet. In many facilities the piping consists of several different materials and often is concealed in walls and ceiling cavities. In other facilities, the piping is exposed and readily accessible. The deficiencies in the piping system are frequently associated with the fittings which connect sections of piping. The forensic architect should keep in mind that many multi-family buildings have either polybutylene or CPVC plastic water supply piping within the walls, which is not visible. From the wall etrucheons, the valving and the fixture’s connection tubing may be copper. This may lead one to believe that all supply piping is copper. Installation procedures for plastic piping materials will be in accordance with the Plastic Pipe Institute (PPI) Handbook of Polyethylene Pipe. Plumbing plan reviews: In the United States, most jurisdictions require plans and specifications to be submitted to the local inspection department for review and approval prior to modification or installation of any plumbing systems that serve the public or a considerable number of people (such as a public or commercial building). The review includes not only all interior plumbing, but also building sewer and water service connections and storm water drainage systems within the property line. The purpose of a plan review is to ensure that the design complies with all relevant state plumbing codes and that no plumbing system is installed that may endanger the public health. Normally, plans and


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specifications need to be submitted and approved prior to installation of a plumbing system other than for a single-family dwelling with independent plumbing service. Plans and specifications will not be approved without adequate information to verify compliance with the local codes. Plumbing plan submittals are usually to be accompanied by an application form that is signed by a mechanical engineer or a licensed master plumber that will be installing the plumbing, and the plan review fee. Plumbing submittals should typically include the following: •

Utility Site Plan: This should show the building, service lines, well, and septic system locations on the property.

Floor plan: To show all fixture locations, all horizontal drainage pipe locations, and all pipe sizes for new plumbing.

Roof plan: Show the location of roof drains and the roof area served by each roof drain. If no internally piped roof drain will be installed, a statement should be included.

Water riser diagrams: Include isometric drawings of the water supply system showing all pipe sizes and all fixtures.

Soil, waste and vent riser diagrams: Include isometric drawings of the waste and vent system showing pipe sizes and fixtures.

Plumbing specifications: This should include a list of the manufacturer and model numbers of the plumbing fixtures, a list of pipe materials including the quality standard (ANSI, ASTM, etc.), testing and disinfection procedures.

As with many systems, the final assessment of the condition of the plumbing system is the adequacy of service provided to the users of the building. While the system may include a few or several components, the evaluation of the plumbing components of a building is fairly straightforward. Since the design of the system is such that many of the components are concealed and inaccessible for review, an evaluation will typically concentrate on the adequacy of service and condition of accessible equipment.

12.2 COLD WATER DISTRIBUTION Much of the plumbing work in urban areas is regulated by government or quasi-government agencies due to the direct impact on the public’s health, safety, and welfare. And most modern western water systems are directly fed from a municipal water system by a high-pressure pipe, usually located under the road or street. Houses in rural areas may be forced to use a cistern or a well where convenient water supply is not available; a pump and pressure tanks are used to create and maintain system pressure needed for operating the plumbing fixtures. A water pressure gauge can be used to measure water pressure at each fixture by attachment to the fixture outlet. As a rule of thumb, most fixtures should have a minimum flow pressure of eight psi. Water service pipes should not be of less than 0.75 inch (20 millimeters) diameter and all water service pipes should be laid so as to avoid high points where air may become trapped. Usually the water service pipe between the public main and the curb cock (the water authority’s main water shut-off valve) at the boundary of the property belongs to the water authority, which assumes responsibility for its future maintenance, and the remainder of the service pipe is the responsibility of the owner of the property (in many cases, the responsibility of the water authority is extended up to the meter).


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The typical cold water system distributes water to the plumbing fixtures that require cold water. The largest users of cold water are water closets (toilets), outdoor hose bibbs, and the irrigation system, but cold potable water is needed at lavatories, sinks, bathtubs, showers, water fountains, humidifiers, and icemakers too, for example. Cold water is also supplied to water heaters, if a building is so equipped. The cold water supply system may include filter or water softener appliances. It basically comprises the piping and accessories that connect the building to the water main of the water supply utility, and includes the underground piping and shut-off valves between the building and the water main in the street. Buildings with fire standpipes may require one or more additional, independent water services to be provided to serve the fire protection system. Water supplied for human consumption should be safe at all times. Plumbing systems in domestic or commercial premises should not be permitted to degrade the main water in any way. The drinking-water supply must be protected from cross-connections with unsafe sources or with wastewater plumbing systems. It must be able to cope with the hazards of backpressure or back-siphonage, and the water should not be in contact with plumbing materials that might impart contamination. Those materials should meet quality and performance specifications determined by the authorities, or by an accepted certification organization.

12.3 HOT WATER DISTRIBUTION The majority of modern buildings have a central hot water system. In larger buildings, as well as apartment buildings, a circulating pump is also installed. Commercial buildings with kitchen facilities are designed with an additional hot water system for the dishwashers, which require much higher temperatures than restrooms. The temperature and pressure relief valve on the hot water heater should be checked to ensure the lever is functioning. Domestic hot water is provided by means of water heater appliances, or through district heating. The hot water from these units is then piped to the various fixtures and appliances that require hot water, such as lavatories, sinks, bathtubs, showers, washing machines, and dishwashers. Equipment for heating and storing heated water should be designed and installed in ventilated areas to guard against dangers from explosion or overheating. Pipes used for the conveyance of hot water should be made of materials suitable to withstand the temperature of their contents, and water temperatures should be maintained at the specified level. Basically, the same issues that apply to the cold water systems would apply here.

12.4 PLUMBING FIXTURES The appropriate evaluation of plumbing fixtures is an important part of any facility inspection because they constitute an integral component of a plumbing system. They include a wide variety of fixtures including lavatories (sinks), water closets (toilets), urinals, showers, sinks, spas, bathtubs, showers, dishwashers, water heaters, and drinking fountains. Figure 12.2A shows the piping system of a typical domestic bathroom. Figure 12.2B shows a section of a contemporary residential bathroom that is not ADA compliant. In commercial buildings, the minimum number of each type of fixture that is required is regulated by the locally adopted plumbing code. The most widely applied plumbing code is the Uniform Plumbing Code which states that the number of occupants served determines the quantity of fixtures.


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The main water supply shutoff valve should be periodically closed and opened to ensure that it has not stuck in the open position. Fixture shutoff valves should also be periodically checked. Both the main valve and fixture valves need to be operable so that water can be turned off in an emergency or when plumbing repairs are necessary. Buildings and properties of public accommodation are required by law to comply with the Title III provisions of the Americans with Disabilities Act: Accommodations and Commercial Facilities (ADA). This stipulates that new construction and new areas of public accommodation within commercial buildings must include accessible accommodations for persons with disabilities and includes provision of accessible toilets and toilet fixtures (see Chapter 18, section 18.4). In modern commercial structures, most plumbing is concentrated in a single area near the core where it serves the toilet rooms, drinking fountains, and similar facilities. To provide service to sinks, private toilets, and the like, wet columns are sometimes included in the building. These are usually positioned at structural columns, where hot and cold supply and drainage and vent risers are located. They are designed to allow individual tenants to easily tap into them without having to connect to more remote plumbing at the core of the building. Each fixture or group of fixtures should be connected to the drainage system and should be equipped with a liquid seal trap. The depth of liquid in each seal must be adequate to prevent the emission of odors and gases, and must prevent access by insects or rodents from the sewer to the premises. Self-sealing waste valves are a possible alFigure 12.2A A schematic diagram of a residential ternative to liquid seal traps in some situabathroom showing a typical plumbing piping system. tions. Tank water heaters: Water heaters supply hot water for bathing, cooking, and cleaning, and are classified by fuel (e.g., gas, oil, electricity), size, and recovery rate (Figure 12.3). The recovery rate is how fast the water heater can bring cold water up to the desired temperature. Oil-fired water heaters are the fastest to recover, and usually have the smallest tanks. Gas-fired water heaters rank second in recovery rate, and electric water heaters have a much slower recovery rate. Electric heaters may be located anywhere in the building, while gas and oil heaters must be in a well-ventilated area and require an exhaust flue. Water heaters typically will experience one or more of several different deficiencies. Typically, Figure 12.2B Photo of a non-compliant ADA residential water heaters fail because of rusting. To debathroom. Piping is concealed behind the wall systems.


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lay this process, manufacturers insert anode rods—usually made of magnesium. This element attracts the rust and corrosion that might otherwise affect the tank itself. The useful life and condition of the equipment can be ascertained by the speed with which the water heats. To prevent a malfunctioning water heater from overheating and exploding, water heaters should be equipped with temperature and pressure relief valves (TPR). The TPR valve is usually located at the top or on the side of the water heater. This valve should have a drainpipe that extends to the exterior of the building, even though some jurisdictions allow this pipe to drain on the garage floor. TPR valve leakage is common and the discharge pipe should terminate where any drips or water flow at the pipe are easily noticed. Leaking TPR valves should be replaced. Exhaust stacks on gas and oil-fired water heaters should be annually inspected to ensure that all pipe connections are secure and free of rust, corrosion, and obstructions. It is essential that fuelfired water heaters vent their gasses to the exterior; escape of gasses to the interior could be lethal and pose a fire hazard. The bottom portion of this vent, termed the draft diverter, is typically located at the top of the water heater. The diverter and vent piping can get very hot and thus it is important to avoid storing items on or near the water heater. The best systems use double wall “Type B” vents that extend Figure 12.3 Schematic diagram showing the major through the roof. Type B vents require 1-inch clearcomponents of a gas-fired water heater. ance to combustibles while single wall vent pipes need at least six inches clearance. Gas-fired water heaters require a source of fresh air to provide oxygen to the flame. A water heater in a closet, or a confined space such as a laundry room, requires ducts or openings to the outside to assure an adequate air supply. Exhaust fans in laundry rooms can also cause flue gas spillage and an insufficient supply of oxygen can cause the water heater to produce carbon monoxide. As most water heaters eventually fail and leak, new water heaters are now frequently required to have a catch pan and drain beneath them when installed in areas where leakage could cause damage. During a survey of tank waste heaters the general condition of the heater should be checked, whether there is evidence of leakage around the tank, and whether its valves, dials and controls operate satisfactorily. The piping connections and bracing should be checked, as well as evidence of rust or corrosion. Lavatories & sinks: In all places of employment, lavatories will be made available according to the requirements for lavatories specified in Figure 12.4. In a multiple-use lavatory, 24 linear inches (610 mm) of wash sink or 20 inches (60 mm) of a circular basin, when provided with water outlets for each space, may be considered equivalent to one lavatory.


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Figure 12.4 Generally recommended lavatory allowances for offices and public buildings. Actual code requirements will depend on the actual jurisdiction in which the property is located. Aerators on faucets should be periodically cleaned (every three or four months), depending upon water hardness. Leaking faucets should be noted and recommendations to repair as needed. If washer type, faucet washer should be replaced and if washerless type, faucet needs to be replaced. For other types of employment, at least one lavatory for three required water closets will be provided. For “High hazard” occupancies involving exposure to skin contamination with poisonous, infectious, or irritating materials, lavatories at one per five persons are recommended. Drinking fountains: One drinking fountain for each 75 employees or fraction and at least one fountain per floor will be provided. Toilets (water closets): Toilets sometimes continue to run water in the tank after they are filled. If water still runs, the situation can usually be corrected by adjusting the ball float or flapper valve inside the tank. Alternatively, the inner mechanisms of the tank need to be replaced. Where the toilet itself rocks, the bolts may have loosened and/or the seal beneath the toilet has dried and broken and requires replacing. The seal is there to prevent water leaks under the toilet and to prevent leakage of sewer gas. Additionally, each plumbing fixture drain pipe should incorporate a “P” trap to provide a water filled seal that keeps sewer gases from rising into the building interior. Within buildings, short horizontal runs of drain piping are typically connected to vertical stacks which in turn are vented up through the roof to provide a suitable escape for the gases. Figure 12.5 indicates general recommendations for water closet allowances in commercial and public buildings. Toilet fixtures and fittings include levers and other parts that control the flush and water inlet valves. The ballcock assembly is the primary mechanism that controls water supply in the tank and toilet. Automated controls for faucets, toilets, and urinals help address occupants’ concerns about disease transmission via contact with bathroom surfaces and fixtures; they can also reduce water consumption. Figure 12.6 shows a schematic drawing of an ADA compliant water closet detail. Where toilet rooms will not be used by women, urinals may be substituted for some water closets, except that the number of water closets in such cases will not be reduced to less than one-half to two-thirds of the minimum specified. Tubs and showers—grout and caulk: Tubs and showers are typically surrounded by special water resistant material to keep the water from penetrating the walls and floor. Joints between ceramic tiles are filled with grout which is designed to seal the joint. However, like all masonry products, it is still porous and


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Figure 12.5 Recommended water closet allowance. Note that these are "rule of thumb" recommendations. Actual code compliance depends on the jurisdiction of the property in question.

Figure 12.6 Schematic drawing of an ADA-compliant water closet detail.


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water can still penetrate it, albeit, in minute amounts. The Inspector should check the caulking around the rim of the tub where it joins the wall, and at the joint between the tub and the floor. Unlike grout, caulk sealers stay pliable. Clothes washers and dishwashers: Washing machines and dishwashers have hoses that connect the washer to the hot and cold water supply, and these can rupture or leak. Look for evidence of leaking as a constant leak can cause rotting of the sub-floor underneath.

12.5 NATURAL GAS & FUEL OIL DISTRIBUTION SYSTEMS Gas and oil heating systems use combustion—i.e., they burn a fuel—to produce heat. The heat can then be transferred to air, as is the case with a furnace, and the heated air is then circulated through the building in a system of box-like enclosures called ducts. Alternatively, the heat can be transferred to water; in this case, the system is referred to as a boiler. The heated water is then circulated through the building in pipes, which feed into a device in each heated room that spreads the heat, typically radiators or baseboard convectors, or circulates beneath the floor or ceiling as a radiant heat system. Gas piping should be schedule 40 black steel with screw fittings for piping 1½ inches or less and welded fittings for piping 2 inches or greater. The maximum gas pressure into the building shall be as established by the local gas company. The designer should provide the gas company with the gas load for each appliance, and the minimum and maximum operating pressures for each appliance early in the design process. Liquid propane (LP) gas piping shall not be concealed. Like all building systems, combustion heating appliances and exhaust flues deteriorate with age, and if the gas or oil heating system is 15 years or older, it may contain cracks or pinhole leaks which could allow exhaust gases to escape. Should this happen, it is possible for the gases to mix with the air stream going throughout the building. Exhaust gases from combustion can contain carbon monoxide, an odorless, colorless, and poisonous gas that when inhaled depletes the oxygen in the blood, and with enough exposure is lethal. The threat of carbon monoxide is increased when the system is not operating efficiently. A gas regulator should be provided to maintain the correct inlet pressure to each gas appliance. Likewise, gas piping in plenums should not contain valves or unions. Natural gas piping to island sinks shall be in an accessible trench in the floor with a removable cover. Fuel oil distribution systems are installed mainly in the eastern U.S. as a source of energy in HVAC systems. In some applications, including many navy installations, both natural gas and fuel oil systems are installed. Basically these subsystems should be evaluated for the general condition of the piping and connections, evidence of leakage, evidence of rust or corrosion and whether the piping is accessible for necessary repair. The clean-outs, vents, and drains should be installed as per consultant’s drawings. All exposed pipes should not be susceptible to impact or damage and supports and braces should be secure.

12.6 SANITARY SEWER SYSTEM The building’s waste-disposal system consists of two basic elements: the drainage system and the venting system. The drainage system (also called traps and drains), is designed to collect waste water from the indoor plumbing fixtures. The waste water from the various appliances, fixtures, and taps is transferred to the waste and sewage removal system via the sewage drain system which is outdoors. The building sewer


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is then connected to a municipal sanitary sewage disposal system. Where connection to a municipal sewage system is not possible, a local, private, code-approved septic system is required. Cesspools and outhouses do not normally meet health codes. This system consists of larger diameter piping, water traps, and is well vented to prevent toxic gases from entering the living/working space of a building. Drains should be adequately ventilated. The venting system typically consists of pipes leading from fixtures to the outdoors, usually via the roof. Vents provide for relief of sewer gases, admission of oxygen for aerobic sewage digestion, and maintenance of the trap water seals which prevent sewer gases from entering the building. All fixtures are required to have an internal or external trap; double trapping is prohibited by plumbing codes. With some exceptions, all plumbing fixtures must have an attached vent. The top of stacks must be vented too, via a stack vent. Plumbing drainage and venting systems maintain neutral air pressure in the drains, allowing flow of water and sewage down drains and through waste pipes by gravity. As such, it is critical that a downward slope be maintained throughout. In relatively rare situations, a downward slope out of a building to the sewer cannot be created, and a special collection pit and grinding lift ‘sewage ejector’ pump are needed. By comparison, potable water supply systems operate under pressure to distribute water up through buildings. Piping should be sloped to permit the wastewater to flow by gravity through the building and out to the underground public sewer system. The piping material used for sanitary sewer systems is usually cast iron or plastic (copper is rarely used because of its prohibitive cost). Cast iron piping consists of either hub and spigot type or is hubless. Joints for hub and spigot fittings usually consist of lead and oakum caulked joints or neoprene push-on compression gaskets. For hubless piping joints, a neoprene tube gasket is usually used. This is banded tight around the piping by incorporating stainless steel multi-band couplings. Although internal and external drains are often referred to as “horizontal,” they should never be laid level, but at a constant gradient that will ensure satisfactory drainage. A minimum velocity of 2 feet (0.6 meters) per second will prevent solids from building up to block the pipe, and if the maximum velocity is limited to 10 feet (3 meters) per second this will prevent scouring and damage to the pipes. Plastic piping consists mainly of either PVC (polyvinyl chloride) or ABS (acrylonitrile-butadiene-styrene). For underground piping, asbestos-cement (AC), vitrified clay, and concrete types may be employed. Plastic piping types utilize push-on, bell and spigot ends (joints). AC and clay piping ends use rubber gasket seals while concrete ends are plastered with mortar.

12.7 STORM DRAIN SYSTEM (RAINWATER SEWER) Storm drainage will include roof drains, leaders, and conductors within the building and to a point 5 feet (1.5 m) outside the building. Rainwater sewers are installed in a building to drain water off the roof; the storm drain system is typically evaluated within the plumbing system. Rainwater falling on the roof can be managed in two ways: 1. It can be collected and channeled directly into the public stormwater drainage system (codes prohibit stormwater from being channeled into sanitary sewer). 2. It can be directed to the ground surface and sheet flow along with all other site runoff to on-site drainage systems. To prevent condensation, horizontal piping runs and roof drains inside the building should be insulated with a minimum of 1-inch (25 mm) thick insulation. Systems are normally installed with an overflow backup system of drainage, and the drain pipes may be located adjacent to columns or in furred wall construction. Issues affecting this system are similar to other piping systems including general condition, evidence of leakage, etc.


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When a combined drainage system is to be used (combining storm with sanitary drainage), the systems should be maintained as separate systems within the building. Systems should be combined outside of the building and preferably at a manhole.

12.8 FITTINGS & VALVES Potable water supply systems require not only pipe, but also many fittings and valves which add considerably to their functionality as well as cost. While there are hundreds of specialized fittings manufactured, some fittings are used extensively in piping and plumbing systems. Some of the more common components are summarized below: •

Elbow: A pipe fitting installed between two lengths of pipe or tube allowing a change of direction, usually 90 degrees or 45 degrees. The ends may be machined for butt welding, threaded (usually female), or socketed, etc. When the two ends differ in size, it is called a reducing or reducer elbow.

Tee: A tee is used to either combine or split a fluid flow. Most common are tees with the same inlet and outlet sizes, but ‘reducing’ tees are available as well.

Cross: A cross has one inlet and three outlets, or vice versa. Crosses are common in fire sprinkler systems, but not in plumbing due to their extra cost as compared to using two tees.

Coupling: A coupling connects two pipes to each other. If the material and size of the pipe are not the same, it may be called a “reducing coupling” or reducer, or an adapter.

Cap: A type of pipe fitting, often liquid or gas tight, which covers the end of a pipe.

Union: A union is similar to a coupling except that it is designed to allow quick and convenient disconnection of pipes for maintenance or fixture replacement. While a coupling would require either solvent welding or being able to rotate all the adjacent pipes as with a threaded coupling, a union provides a simple nut transition, allowing easy release at any time.

Nipple: A nipple is defined as being a short stub of pipe which has two male ends. A nipple can usually be replaced by use of a street elbow.

Closet flange: The closet flange is the drain pipe flange to which a water closet (toilet) is attached.

Clean-outs: Clean-outs are fittings that access drains without removing plumbing fixtures. They are used for allowing an ‘auger’ or ‘plumber’s snake’ to ‘clean out’ a plugged drain. Clean-outs should be placed in accessible locations throughout a drainage system, and outside the building because these augers have limited length. Clean-outs normally come with screwed-on caps (Figure 12.7).

Trap primers: Trap primers regularly inject water into traps so that water seals are maintained. This seal is necessary to keep sewer gases out of buildings.

Valves are devices that regulate the flow of substances (gases, fluidized solids, slurries, or liquids) by opening, closing, or partially obstructing various passageways (Figure 12.8). Although valves are technically pipe fittings, they are usually discussed separately. A large variety of valves are available on the market. Valves have many applications with sizes ranging from tiny to huge; the more common valves used in plumbing include:


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Figure 12.7 Drawing of a typical wall cleanout detail.

Figure 12.8 Example of valves (hot water and cold water) below lavatory basin.


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Angle valve: has metering or flow restriction capability.

Ball cock: often used as a water level controller (cistern).

Ball valve: is used for on/off control.

Bibcock: provides a connection to a flexible hosepipe.

• •

Butterfly valve: is used particularly in large pipes. Check valve or Non-return valve: allows the fluid to pass in one direction only. It is essentially a backflow preventer and is critical in avoiding contamination of the community supply.

Faucet (American English) Tap (British English): is the name for a valve used to regulate water flow.

Foot valve: a check valve on the foot of a suction line to prevent backflow.

Gate valve: mainly used for on/off control.

Globe valve: is used for on/off control and for regulating flow.

Needle valve: is used for gently releasing high pressures.

Plug valve: is used for on/off control.

Pressure reducing valve (PRV): also called pressure regulator, reduces pressure to a preset level downstream of the valve.

Pressure sustaining valve: also called back-pressure regulator, maintains pressure at a preset level upstream of the valve.

Regulator: is used in gas cooking equipment to reduce the high pressure gas supply to a lower working pressure.

Safety valve or relief valve: operates automatically at a set differential pressure to correct a potentially dangerous situation, typically over-pressure.

Stopcocks: restrict or isolate the flow of a liquid or gas through a pipe.

Thermostatic mixing valve (TMV): blends hot water (stored at temperatures high enough to kill bacteria) with cold water to ensure constant, safe outlet temperatures preventing scolding.

Three-way valve: routes fluid from one direction to another.

Vacuum breaker valve: prevents the back-siphonage of contaminated water into pressurized drinkable water supplies.

12.9 BACKFLOW ISSUES All municipal domestic water entering the building should pass through a reduced pressure backflow preventer to protect the outside water source from contamination in the building. Thus, where water or waterusing appliances are used with fluids or materials which could contaminate the water, there must be adequate protection to prevent backflow of potentially contaminated water into other parts of the system, especially drinking water. Whenever possible, the backflow device shall be located inside the building. A main pressure-reducing valve is required if the incoming water pressure exceeds 75 psi. Recent regulations introduced a new specification of five fluid risk categories describing types of contaminant, and detailing the appropriate type of prevention device that must be fitted to guard against back-


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flow of contaminated water. A backflow preventer should be included on all incoming systems. In addition, drainage systems should be properly designed and constructed so that sewage cannot enter buildings connected to the sewage system in the event of backflow from the public sewers due to flood, blockage or any other means.

12.10 SYSTEM DIAGNOSTICS The evaluation of the plumbing system is typically carried out at selected access points, much like the electrical system. The majority of the plumbing equipment and piping is often out of sight and inaccessible (e.g., behind walls), so leaks are not normally visible when they occur. However, the consequences of most significant deficiencies in the system will be observable, either at the fixtures or equipment itself, or in damaged building materials and finishes which surround the plumbing system deficiency. Most plumbing system evaluations will require the forensic architect to: 1. Describe the type of water supply and distribution piping materials. 2. Observe the interior water supply and distribution system including water faucets and plumbing fixtures. 3. Describe the type of drain, waste and vent piping materials and observe the interior drain, waste and vent system. 4. Observe domestic hot water equipment with regard to installation and working condition. 5. Identify the presence or absence of plumbing leaks and cross connections as observed at the time of inspection. 6. Observe and report on water and drainage flow with regard to plumbing fixtures inspected. 7. Report any signs of significant rust or corrosion on readily accessible plumbing system components open to view. 8. Report the observed working condition of domestic hot water equipment including any readily accessible component found to be in need of immediate or major repair. 9. Inspect for proper sizing of fuel gas piping, combustion air requirements, and required venting. 10. Fixtures should be evaluated for adequacy of operation, ADA compliance, and general condition. Necessary precautions need to be taken against damage to the property, or danger to the health of its occupants, in the event of malfunctioning of the system. Fixtures should be provided with adequate overflow capacity. Roof tanks and other hidden elements of the system should be similarly provided with overflows that discharge in a manner as to act as a warning before causing damage. Pressure vessels that are part of the system should be equipped with a temperature and pressure relief valve. Food preparation and storage rooms within the building should be located so that any leakage or backflow in the drainage system cannot contaminate their area or contents. In the case of industrial or commercial premises where food is processed or prepared, or where sterile goods or similarly susceptible materials are stored or handled, additional precautions should be taken by indirect connections of the internal fixtures to the plumbing system. The evaluation of the system should typically commence with a review of the construction drawings to determine the location and design of the system’s main components and equipment. Piping and other equipment concealed in wall or ceiling cavities can be located and kept in mind during the field survey. It


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is not uncommon to discover that drains, vents, or clean-outs which were originally designed or installed have been omitted, removed, or plugged. Regular users of the system should be interviewed to get additional information on the normal ongoing conditions. The physical survey can start at the connection to the water main once the construction drawings are reviewed. This is followed by reviewing the system’s components from the water heatFigure 12.9 Typical deficiencies found in plumbing systems. ing and storage source of the fixtures and outlet areas. During the physical survey of the interior spaces of the building, wall and ceiling finishes should be investigated for any evidence of damage or stains caused by defects in concealed plumbing system components, such as leaking or broken piping. The apparent or reported ages of plumbing systems should be identified where available and, combined with visual observations, determine the RUL. Periodic inspection of key plumbing components can help avoid costly water damage and even more costly loss of building operations due to tenant down-time, temporary office relocations, and other resulting expenses. Key connections, especially at water main supply lines; key circulating pumps; rooftop water elements; janitors’ closets and other areas such as sprinkler systems, should be inspected, tested and maintained according to National Fire Protection Association (NFPA) standards. Check all water supply pipes and primary system joints and public bathroom and kitchen supply lines and drain systems on a regular basis and promptly replace leaking fittings or drains. Basement flood control and sump systems should be tested monthly. Loud vibrating noises (water hammer) are common in plumbing supply lines. The condition occurs when faucets are rapidly opened and closed and can often be corrected by anchoring or fastening pipes more securely. Air chambers can be added at the end of long pipe runs to solve this problem. Figure 12.9 illustrates some of the usual deficiencies found in plumbing systems evaluations. More often than not, when problems occur with the plumbing system they usually relate to leaks and should be dealt with promptly. Because the water system is under pressure, any rupture in the system—even a minor leak—may cause water to continue spilling into the building. If a building has experienced extensive leaking of pipes in the past, it may be useful to verify whether other buildings in the area also experience this problem. If so, the water may be the source of the deficiency. In some cases, a source of carbon dioxide may be present in the water and may attack the copper piping. If the piping in the building being evaluated is the only one in the area experiencing leaking, it is likely that the piping has been undersized. During the evaluation of supply and drain lines for leakage, faucets should be turned on and off several times. Each sink should be filled and allowed to drain to determine whether drainage is adequate. The fixtures in a given area, a kitchen or restroom for example, should be operated simultaneously to confirm the adequacy of water flow. A small amount of water should be drained from the water heater tank and inspected for sediment and rust. The inspector should be conversant with the location of all major shut-off valves, from where the water service pipe enters the building to the various fixtures. Most plumbing fixtures have shut-off valves mounted on them which can be used to isolate the fixture from the water system in case of leaking or pipe breaks. Typically they are below the fixture, except those on clothes washers.


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Unless specifically requested to do so, the forensic architect should exclude the following: 1. Determining adequate gas pressure and flow rate, fixture quantities, or pipe size verification. 2. Observe or report on any supply, drain, waste, or vent piping not readily accessible or open to view such as that concealed from view inside floor, wall or ceiling cavities. 3. Determine or verify the existence of prior or reoccurring plumbing leaks inside the building that were not readily apparent at the time of inspection. 4. Remove ceiling tiles in order to access and observe all plumbing system components located above a grid tile ceiling. 5. Operate any valve except for water closet and urinal flush valves, indoor water faucets, and outdoor hose bibs—weather permitting. 6. Report on the working condition of water heating equipment that has been shut down, abandoned, or unused for any length of time. 7. Inspect or evaluate the working condition of private well and septic systems. 8. Operate, test or evaluate lawn irrigation or fire protection sprinkler systems.


CHAPTER

13 Vertical Transportation Systems 13.1 GENERAL The skyscraper was an American creation, and as modern buildings continued to rise to ever-greater heights, elevator technology had to rise to meet these new demands and challenges with ongoing innovations. Modern elevators are the crucial element that makes it practical to live and work dozens of stories above ground. In fact, without elevators high-rise buildings would not be possible, and the contemporary city as we know it would not exist. The advent of the elevator and escalator into standard construction design vocabulary at the turn of the century brought about an efficient, convenient and safe form of transportation between building floors. Today, there are a wide variety of vertical transportation system types available for use in buildings, and with space at a premium, facilities professionals find themselves challenged to make buildings safer, more intelligent, reliable, and efficient—all while maximizing the amount of useable space. Most people have come to accept elevators, escalators, and moving walks as an integral and indispensable ritual of daily life as populations continue to increase, along with the number of people living and working in high-rise buildings. This growth is being fueled by new elevator and escalator system installations, and the resurgence of modernization programs to upgrade buildings built during the 1970s and 1980s construction boom. As elevators continue to develop, their development has been more evolutionary than revolutionary as is the case of the improvement of electronic controls. Control systems are being developed that will learn from past traffic patterns and use this information to predict future needs to help reduce waiting times. Laser controls are also coming into use, both to gauge car speed and distance, as well as to scan building floors for potential passengers. In assessing a building’s transport systems the forensic expert should include both the equipment components and the associated service areas such as machine rooms and elevator pits where applicable. Safety, convenience and quality of maintenance and testing are the main issues to be reviewed in vertical

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transportation systems. Each mode of transportation includes several safety features including emergency devices, alarm bells, and miscellaneous safety equipment. Moreover, any machinery that gets constant use needs constant care. For elevators, that means regular inspection, adjustment and lubrication. Preventive maintenance keeps elevators operating at their best, it helps avoid major replacements, and it prolongs their useful life.

13.2 ELEVATOR SYSTEMS Elevators are the heart of the building, and according to Rod Hoyng of Millar Elevator, “Elevators are in the top three most important components to a facility’s operations, along with HVAC and security services.” Most facility executives measure elevator performance by evaluating parameters such as safety, reliability, uptime, car wait period, and overall trip time. Elevators are usually installed in a building during construction. Modernizations and renovations may consist of replacements for hoistway (floor landing) doors, car doors, interior cab finishes, controls, all hoistway wiring and cab wiring, hoist machines, governors, hydraulic pistons, hall fixtures, and even replacing the entire cab. Often an upgrading may require additional code compliance. The cost of an elevator system is a significant part of a building’s total cost, and taking care of it is a means to protecting one’s investment. The way these elevators look, how smoothly they run, how fast they answer calls, and how often they’re out of service are all facts which impact a building’s reputation and marketability potential. The most popular design for the placement of elevators is in the center or core of a building. This leaves more space for windows and makes it easiest for the greatest number of people to access the elevators. The elevator systems designed for today’s buildings and for the future typically divide the building into sections. These sections of elevator shafts are usually connected by main service elevators that would bring passengers to a sky lobby or transaction floor where they board another elevator to get to their destination. The fact that modern passenger lift reflects a simple means of transport within a building belies the apparent simplicity of a complex and sophisticated mechanical, electrical, and microelectronic system. Recent developments in electronics and technology have, for example, allowed elevator relay control systems to go to solid state. Other recent developments are destination-oriented elevators which eliminate control buttons in elevator cars; instead, passengers enter the elevator-lobby area and select a floor. Based upon the floor they’re visiting, they’re assigned an elevator car. In addition, we also now have the express elevator which does not serve all floors. For example, it moves from the ground floor or a skylobby to a range of floors, skipping floors in between. An innovative concept, namely the machine-room-less elevator (MLR) was introduced into the United States from Europe. This revolutionary elevator system represents the first major breakthrough in lifting technology for many years and was initially designed for buildings up to 20 stories. The MLR system employs a smaller sheave than conventional geared and gearless elevators. The reduced sheave size, together with a redesigned motor, allows the machine to be mounted within the hoistway itself, eliminating the need for a bulky standalone machine and equipment room on the roof (Figure 13.1). Otis’s MRL elevator features unique, flat polyurethane-coated steel belts instead of the heavy woven steel cables that have been the industry standard since the 1800s. The belts are about 1 inch (30 mm) wide and only 0.1 inch (3 mm) thick, yet they are as strong as woven steel cables while being far more durable and flexible. Also, the thinness of the belts makes for a smaller winding sheave, reducing the space required for the machine in the hoistway. Other benefits of continuous elevator technology advances include quicker floor-to-floor operations, improved reliability, smoother and faster acceleration/deceleration, reduced waiting times, as well as im-


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proved leveling so passengers do not trip as they enter and exit the elevator cars. The majority of gains have come in the form of microprocessor-based control systems that supersede the electromechanical relay-based controllers and silicon control (SCR) drives that replace the motor generator sets. The computerized control systems monitor cars and calls to determine which car can answer the call most effectively. The SCR drives also provide better speed control and ensure that the elevators operate at their optimum speed, which saves on wear and tear as the equipment gets older. “With microprocessor control, you can pick up (at least) 15 percent efficiency in response to a call. On a six-car group, that’s like adding another car,” says John Van Deusen of Van Deusen & Associates in Livingston, New Jersey. As a general rule of thumb one elevator is to be provided per 35,000 SF of rentable space minimum above the first floor. This rule does not apply to buildings over 20 stories or whose floor area is less than 10,000 SF. Another applicable rule is that one elevator minimum is needed for every 225 to 250 occupants. Types of elevators: The main types of elevators are: 1. Drum elevators (residential applications), 2. Hydraulic elevators (for applications up to six stories), and 3. Traction elevators (for medium and high-rise applications). 1. Drum elevators: The winding drum machine is the oldest type of elevator system used in the United States and is found primarily in older, lower rise building. It is no longer permitted in the United States for new elevators except for residential applications and freight cars with a maximum speed of 50 fpm and maximum rise of 40 feet (in most jurisdictions). Figure 13.1 Example of basic The standard residential cable winding drum elevators use configuration of machine-less-room steel cables that wind and unwind on an electric motor. This elevator system (source, Kone, Inc.). type of elevator normally travels about 30 fpm and has a weight capacity of 500 to 750 pounds. While drum elevators are slightly less expensive than hydraulic elevators, the hydraulic elevator produces a smoother ride with softer starts and stops. The standard size for a home elevator cab is 3 feet x 4 feet but is available up to 3 feet x 6 feet. Should major repairs to the drum be needed, the entire machine must be replaced (Figure 13.2). 2. Hydraulic elevators: There are two major types of power elevators used in new installations: (1) hydraulic-drive elevators, and (2) electric-drive elevators. Hydraulic elevators are power elevators in which the energy is applied by means of an oil-based “hydraulic fluid” under pressure in a cylinder that is equipped with a plunger or piston. There are four major components to the hydraulic system: a tank (fluid reservoir); a pump powered by an electric motor; a valve between the cylinder and the reservoir; and the cylinder. In contrast to geared and gearless systems, hydraulic elevators do not use large overhead hoisting machinery. The car is connected to the top of a long fluid-driven piston that travels up and down inside a cylinder. The car moves up when an electric motor pumps hydraulic fluid into the cylinder from a reservoir, raising the piston. When the valve is opened, the pressurized fluid returns to the fluid reservoir. As the car approaches the correct floor, the control system sends a signal to the electric motor to gradually shut off


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the pump and close the valve. With the pump off, the hydraulic fluid ceases to flow into the cylinder, and the fluid already there cannot escape because the valve is closed. The piston rests on the fluid, and the car remains where it is. To lower the car, the elevator control system sends a signal to the valve to open. When the valve opens, the high-pressure hydraulic fluid that has collected in the cylinder flows out into the low-pressure fluid reservoir. The weight of the car and the cargo pushes down on the piston, which drives the fluid into the lower pressure reservoir, and the car gradually descends. To stop the car at a lower floor, the control system Figure 13.2 Example of a winding drum elevator system closes the valve again (Figure 13.3). in a residential application (source, Elevator Concepts, Ltd.). The main venue for hydraulic elevator systems is in low-rise installations—typically in buildings averaging five or six stories in height, where moderate car speed (usually between 50 and 150 feet per minute) is acceptable. In addition because of their short travel distance at relatively low speeds, hydraulic elevators are widely used for freight in industrial and low-rise commercial buildings, and for passengers in garden apartments, motels, and malls. Hydraulic elevators cost less than electric elevators due mainly to their relative simplicity of operation. Furthermore, since they have no wire cables or overhead machinery, they do not need a penthouse. Hydraulic elevators move by means of extension and contraction of a hydraulic piston which is located below the elevator cab. The main advantage of hydraulic elevators over traction type elevators is that installation and maintenance costs are generally less than those for conventional traction roped systems. The main drawbacks include slower operating speed and performance (therefore not usable in high-rise buildings), high noise levels, and inferior ride quality as compared with other systems. Types of hydraulic elevators: There are three main types of hydraulic elevators known as in-ground, holeless, and roped systems. A. In ground (conventional) hydraulic elevators require a deep hole below the bottom landing because the cylinder goes down into the ground as far as the elevator travels up. They are quite popular for low and medium Figure 13.3 Example of a decorative hydraulic scenic elevator, Lotte World Hotel, Seoul, Korea (courtesy, rise buildings (two to six floors) and use a hyMitsubishi Electric). draulically powered plunger to push the ele-


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vator upwards. Typical in-ground installations use a PVC casing (also known as a caisson) to protect the cylinder from electrolytic and other corrosive chemical actions that could lead to future underground oil leaks. The inspector should check older systems for leaks because they are “single� bottom design and do not have secondary containment. B. Holeless hydraulic elevators are typically used for buildings where it is not possible to drill a cylinder hole. They employ an above ground conventional cylinder piston/casing arrangement and therefore do not require a hole to be dug for the hydraulic cylinder (Figure 13.4). All piping and hydraulic fluid is contained above-ground, and the cab is usually lifted by a pair of hydraulic jacks, located on each side of the elevator. They are used if a limited amount of travel is required. Sometimes the hydraulic piston (plunger) consists of telescoping steel tubes that allow for increased travel. The advantages of holeless versus the in-ground design (conventional) system are: 1. No drilling is required, 2. It is environmentally friendly, using less hydraulic fluid which is contained above-ground, 3. It is easier to install in the majority of cases where drilling is a concern, 4. It offers newer technology. The main disadvantages are: 1. Greater complexity, and 2. Usually involves higher cost. C. Rope hydraulic elevators use a combination of hydraulics and a complex indirect attachment to the cab. The majority of current applications are in existing buildings where drilling a hole for jack assemblies is impractical or more travel is required than would be possible with a holeless direct-acting elevator. 3. Traction elevators: In the field of traction systems, elevator system designers and engineers are pushing their technological creativity to its full potential, and modern traction elevators are combining the latest digital technology to achieve a new level of precision, energy efficiency, safety, and reliability. A traction elevator system basically consists of an elevator car and counterweight connected by ropes and driven by the drive sheave (Figure 13.5A,B). The system is suitable for medium to very high rises and offers low running costs. There are four basic variables that govern an elevator system: elevator type, speed, size, and quantity. Trends over the past 20 years have been a move toward larger car sizes. Office buildings commonly now have elevators with capacities of 3,500 pounds to allow for more passenger room and comfort. Traction elevators can be either geared or gearless. A. Geared traction elevators: These are moved by hoist cables driven by a geared reduction unit, and are generally used in mid-rise, midspeed applications, such as commercial buildings of nine floors or less and residential buildings of 20 floors or less. Geared traction machines are driven by AC or DC electric motors which, along with the gearbox, are in an elevator machine room located above the elevator shaft and the cab. While the lift rates are slower than in a typical gearless elevator, the gear reduction offers the advantage of requiring a less powerful motor to turn the sheave. An electrically controlled brake between the motor and the reduction unit stops the elevator, holding the car at the desired floor level. Geared traction elevators typically operate at speeds from 125–500 fpm (38 to 152 meters per minute) and carry loads of up to 30,000 pounds (13,600 kg). Geared machines are generally the best option for basement or overhead traction use and although they cost less than gearless Figure 13.4 Example of a systems, they generally give a poorer performance in mid- and high-rise holeless hydraulic elevator buildings. system (source, Kone Inc.).


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B. Gearless traction elevators: Gearless elevators have traditionally been used for very tall buildings and to attain high speeds. The cabs are moved by hoist cables driven directly by a large-frame motor and are generally used for high-rise, high-speed applications such as commercial buildings over nine floors and residential buildings over 20 floors. For these, a cab is hung on a counterweighted cable and is driven by a DC motor directly connected to the cable sheave that winds the cable up and down. The motor is in an elevator machine room located above the elevator shaft and the cab. These are capable of attaining the greatest travel speeds and can travel up to about 1,200 fpm. Speeds of at least 700 fpm are often preferred for high-rises and some mid-rises. For the majority of high-rise buildings, the roped elevator (or cable system) is the most widely used elevator system. With this system the car is raised and lowered by traction steel ropes rather than pushed from below. This system is used in both high-rise elevator installations that typically use gearless traction systems and in mid-rise installations that generally use geared traction systems. The elevator has a counterweight that balances the weight of the car, and at the same time ensures that the hoist-rope’s friction grips the driving sheaves (pulleys) so that when you rotate the sheave, the ropes move too. The sheave is connected to an electric motor, and when the motor turns in one direction, the sheave raises the elevator, and when it turns in the opposite direction, the elevator is lowered. The machinery to drive the elevator is typically housed in a machine room usually directly above the elevator hoistway. To feed electricity to the car and receive electrical signals from it, a multi-wire electrical cable connects the machine room to the car. The end is attached to the car and moves with it. Most modern traction elevators now have microprocessor controls that require air conditioning (Figure 13.6). Freight elevators and lifts: A freight elevator (sometimes called “goods lift�) is an elevator designed to carry goods rather than passengers, even though passengers often Figure 13.5A,B A. Typical configuration accompany the freight. Freight elevators are usually exempt of a cable elevator (source, How Stuff from some code and fire service requirements, although new Works). B. Components of an elevator cab installations are likely to be required to comply with most of and surrounds. these requirements. Freight elevators are generally required to display a written notice in the car that the use by passengers is prohibited. Freight elevators are usually larger and capable of carrying heavier pay loads than a passenger elevator, generally from 5,000 to 10,000 pounds (2,300 to 4,500 kg). Doors may be manually operated, and the interior finishes are often rugged to prevent damage while loading and unloading. Freight elevators can be either hydraulic or electric; the latter being more energy efficient for the work of freight lifting.


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The dumb waiter is considered a small freight elevator normally used for moving lighter items between floors. Passengers are not permitted on dumbwaiters. Dumbwaiters and other material lifts are required to conform to the relevant sections of the ASME A17.1 code in most U.S. and Canadian jurisdictions. Another type of specialized freight elevator is the automobile lift, used to move automobiles around a parking garage or other facility. These are material lifts by definition and are exempt from the ASME A17.1 requirements, but may have to comply with the requirements of American National Standard for Automotive Lifts— Safety Requirements for Construction, Testing and Validation (ALIALCTV) if provided for in the local jurisdiction. General elevator controls: Modern eleFigure 13.6 An elevator control system for high-rise vator controls provide more convenient, effibuildings (courtesy, Total Elevators). cient operation for mid- to high-rise buildings. Old, outdated controls consist of electromechanical relays. All new elevator controls are microprocessor-based; elevators are controlled by software that may incorporate algorithms to save energy. This software allows the elevator system to place cars where they are most needed—in the interest of smooth operation with minimal waiting times—and to shut down extra elevators when they are not needed. The algorithms used in such software are based on analyses of elevator usage patterns called “traffic studies.” Traffic studies are conducted by professional elevator consultants who use specialized tools to determine the optimum size, speed, and number of elevators for a building based on its peak use periods. Zoning: In most new high-rise buildings individual elevators are not usually required to service every level, as this would imply a large number of stops during each trip, which would effectively increase the round trip time. This means that passengers have to endure long waiting and journey times. To resolve this, a limit is put on the number of floors served by elevators. A rule of thumb is to serve a maximum of 15 to16 floors with an elevator, or a group of elevators. This introduces the concept of zoning. Zoning is where a building is divided so that an elevator or group of elevators is constrained to only serve a designated set of floors. Many tall buildings are divided into several zones, e.g., low zone, mid zone, high zone, etc. with service direct from the main terminal floor situated at ground level. These are called “local” zones. Zoning can be interleaved or stacked. An interleaved zone is where the whole building is served by lifts, which are arranged to serve either the even floors or the odd floors. So for example in a 20 floor commercial complex one lift may serve G, 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19, while another lift serves G, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20. The goal is to reduce the number of stops an elevator makes because there are fewer floors to be served, and because there are fewer openings and landing doors to install, the capital costs are also reduced. However, this creates less efficient service to passengers. A stacked zone system is where a tall building is divided into horizontal layers, in effect, stacking several buildings on top of each other, with a common “footprint” in order to save ground space. It is a recom-


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Figure 13.7 An elevator using the destination oriented prediction system which allocates passengers to cars depending on destination floors (source, Mitsubishi Electric).

mended practice for office and institutional buildings. Zoning becomes impractical with very tall buildings and shuttle lifts are employed to take passengers from the ground level main lobby to a “sky lobby.� Destination selection control systems: Over the past years a number of elevator manufacturers have initiated the development of advanced elevator control systems that utilize destination-based dispatching. At each floor there is a touch screen keypad where the passenger selects the floor to which they wish to go. Passengers are grouped according to their destinations; in increasing modern applications, the elevator buttons are outside the elevator cabs, not inside. The system then directs the passenger(s) to an elevator that will be stopping at their floor. When the car arrives, the passenger(s) enters and the elevator car takes them to their destination with no further action required by the passenger (Figure 13.7). Because destination elevators are computer controlled, they provide maximum efficiency of the system—avoiding time-consuming stops and helping passengers reach their destinations more quickly. Destination dispatching systems calculate the shortest possible time to the distance instead of the shortest waiting time in front of the elevator. Studies show that these systems realize an average time savings of up to 25 to 30 percent. Some elevator manufacturers like Otis are exploring ways to improve and enhance accessibility and usability for people with disabilities. In this regard, Otis has introduced a number of input devices which interface with the elevator passenger such as a mechanical keypad with an LCD display and speaker that provides voice output for verbal enunciation. In addition, they also introduced a 10.4-inch touch screen which can be utilized by passengers with low vision or who use a wheelchair.


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13.3 ESCALATORS Escalators are power-driven, continuous moving stairways designed to transport passengers up and down short vertical distances. Escalators are used globally to move large numbers of people in a continuous flow in places where elevators would be impractical and with a relatively low cost of operation. Principal areas of usage include shopping centers, airports, transit systems, office complexes, trade centers, hotels, and public buildings. Varying by design and planned usage, an escalator can rise from 4 feet to over 100 feet and may go floor-to-floor or skip floors. Escalators and moving walks have become an indispensable part of our culture (Figures 13.8A,B, 13.9A,B). Typically there are two escalators installed, with one ascending and the other descending. Escalators should be evaluated for the following issues: An escalator consists of a pair of chains that are looped around two pairs of gears that are driven by an electric motor that rotates the chain loops (the motor also moves the handrails). The motor and chain system are housed inside a truss, which is a metal structure extending between two floors. Instead of moving a flat surface, as in a conveyer belt, the chain loops move a series of linked steps up or down on tracks which keep the treads horizontal at both the top and bottom of the escalator, collapsing on each other to create a flat platform to allow persons to get on and off. Escalators and their cousins, moving walkways, are powered by constant speed alternating current motors and move at approximately 1 to 2 feet (0.3–0.6 m) per second. The maximum angle of inclination of an escalator to the horizontal is typically 30 degrees with a standard rise up to about 60 feet (18 m). The vertical transport industry has witnessed several innovations in escalator manufacture in recent years. For example, one company recently developed a spiral staircase escalator. Another has developed an escalator suitable for transporting wheelchairs. These advances are likely to continue as the industry expands to meet the

Figure 13.8A,B A. Diagram of how an escalator works (courtesy, Tom Harris, HowStuffWorks, Inc.). B. Diagram of the Tugela escalator showing major components (courtesy, ThyssenKrupp Elevator).


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Figure 13.9A,B A. Commercial escalator (courtesy, ThyssenKrupp). B. Crisscross escalator in Berjaya Times Square, Malaysia (source, Mitsubishi Electric).

changing needs and challenges of the marketplace. Likewise, many of today’s escalators have greater intelligent capabilities than their predecessors. Modern escalators and moving walks now have a way of sensing how much power is needed and can adjust the energy consumption accordingly. In Europe some escalators and moving walks will idle very slowly and even stop until they “sense” someone approaching.

13.4 MOVING WALKS AND RAMPS (INCLINED MOVING WALKS) These are completely self-contained systems designed to move people quickly and safely in a controlled manner between two points on the same level or between different elevations. For decades, experts have been exploring methods of moving walks for distances of 150 to 1,000 meters that allow passengers to enter and exit at normal speed and accelerate much faster in the central section, allowing greater distances to be covered more quickly and in greater comfort (in venues where passengers are covering lots of ground, such as airports or exhibition centers). The latest moving walks feature entry and exit sections that move at 2 feet per second, while the central section accelerates to up to 6 feet per second—twice the normal walking speed. The basic principles of moving walks are similar to escalators except that the passenger-carrying surface remains parallel to its direction of motion and is uninterrupted. Inclined moving walks or ramps serve a similar function to that of escalators. They are especially developed for shopping malls and provide quiet, comfortable transportation from floor to floor, even with a fully loaded shopping cart. In contrast to escalators, moving ramps have a continuous tread and incline up to 15 degrees. They are also frequently installed in airport terminals, train stations and major department stores, being used in locations requiring the expedient transportation of large numbers of people. They are ideal for use wherever the elimination of long walks is desired (Figure 13.10A,B).


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Figure 13.10A,B A. Moving ramp, Maju Perdana, Malaysia (courtesy, Mitsubishi Electric). B. Shindler 9500 Moving Walk—Munich Fair, Germany (courtesy, Shindler).

13.5 BUILDING CODES AND ADA COMPLIANCE There are several building codes regulating the installation and use of vertical transportation. The National Electrical Manufacturers’ Association (NEMA) Code regulates electrical motors and generators. The National Electrical Code, sponsored by the National Fire Protection Association, regulates electrical controls. A third code is the American National Standards Safety Code for Elevators, Dumbwaiters, Escalators, and Moving Walks, which is sponsored jointly by the American Society of Mechanical Engineers (ASME), the American National Standards Institute (ANSI), and the American Institute of Architects (AIA). In addition passenger elevators may be required to conform to the requirements of the Safety Code A17.3 for existing elevators where referenced by the local jurisdiction. Passenger elevators are tested using the ASME A17.2 Standard. The frequency of these tests is mandated by the local jurisdiction, which may be a town, city, state or provincial standard. This section should be read in conjunction with Chapter 18, Section 18.3 and 18.4. It should be noted here that because of liability issues, consultants do not typically survey for code compliance unless it is specifically agreed upon in the protocol with the client and additional fees are agreed upon.

13.6 BASIC COMPONENT GROUPS TO BE EVALUATED Elevators typically are comprised of a number of essential components. These are: 1. Machine room and equipment, 2. The hoistway, 3. The pit, 4. Cab and equipment, and 5. Floor landings and equipment. Machine room: This room normally houses the elevators, machines, controllers, governors and related electrical components. Traction machine room size is approximately 12 feet x 12 feet for one elevator system including maintenance space requirements, or 20 feet x 12 feet for two systems. Traction elevator machine rooms, while separate from the elevator hoistway, do communicate by multiple openings for


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ropes or cables serving the cars that introduce air flows into the machine room. The machine room is typically located in the overhead or in the basement, although some designs also incorporate it at the side of the hoistway. When located in the basement area, there will be an overhead space (for traction or roped hydraulic elevators). This overhead space will contain the overhead sheaves, the overspeed governor assembly and other needed equipment (Figure 13.11A). The hydraulic elevator machine room is usually 25 to 50 percent smaller than the traction elevator machine room, and with the development of new technologies it is expected that elevator machine rooms will be gradually phased out and replaced by machineroom-less elevator systems. Safe and convenient access to machine rooms must be provided. At least 7 feet (2.1 m) of headroom is to be provided between the machinery platform and the machine room’s roof to allow persons repairing or inspecting elevator hoisting machinery sufficient headroom to work. Elevator machine room cooling design has normally consisted of an exhaust fan to cool the room. However, with the recent introduction and installation of microprocessor controls in new elevators, machine room temperatures are increasing and seriously affecting the operation of the equipment and controls, especially “stop levels.” Rooms should be well ventilated and lighted with not less than 10 footcandles (108 lux) at floor level. Doors are to be kept locked with affixed warning signs to prevent entry by unauthorized persons. Only elevator equipment is allowed in an elevator machine room. A sprinkler head is required in the machine room. There shall be a heat detector mounted within 2 feet of the sprinkler head and there shall be a smoke detector in the machine room. When hoistway and/or machine room sprinklers are provided, then an automatic disconnect for elevator power (shunt trip) must be provided. An ABC fire extinguisher should be provided and mounted on the wall. A dedicated communication line to the elevator controller must be wired in conduit and made operative prior to inspection. Depending on the machine room’s location, traction and drum machines can be located in the overhead or basement. Hydraulic drive systems are typically located in the basement. The typical life expectancy is between 50 and 75 years depending on maintenance, use, etc. When conducting a survey or inspection, the consultant should check for excessive oil leakage or unusual noise. Where a team approach is used for the survey, it is common to include an elevator consultant. Hoistway (elevator shaft): The hoistway or elevator shaft is the space enclosed by fireproof walls and elevator doors for the travel of one or more elevators, dumbwaiters or material lifts. It includes the pit and terminates at the underside of the overhead machinery space floor or grating or at the underside of the roof where the hoistway does not penetrate the roof. The hoistway typically is comprised of: Guard rails: These should be kept clean and properly aligned. Their life expectancy is about 75 years and roped systems contain car and counterweight. Wire rope cables serve the hoist, compensation, and governor cables. In traction and roped systems, the cables provide the connection between the car, machine, and counterweight assembly and have a life expectancy of roughly 10 to 15 years depending on use, maintenance, etc. Often multiple cables are used to increase the safety factor. They should be routinely inspected for wear and/or breaks and should be replaced on a timely basis. Mechanical safety equipment & counterweights: The counterweights provide system balance and are connected to the elevator cab by wire rope cables. Additional counterweights may be required if larger loads are added to the cab (e.g., heavy wall panels, stone floor, etc.). The mechanical car safety is located below the car platform. In emergency cases, safety may activate and stop the elevator by “clamping” onto the rails. The life expectancy is normally 50 to 75 years. Hoistway door equipment: This includes hoist door panels, support tracks and hangers, interlocks, and closers. Tracks, hangers, interlocks, and closers must be routinely inspected and kept clean and free of debris. Interlocks are designed to prevent the opening of the hoistway door from the landing side when the


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car is out of the “landing zone” and to prevent the operation of the driving machine unless the hoistway door is in the closed position. Life expectancy is usually between 25 and 40 years. Most codes for building elevators require that new elevators be installed in two-hour, fire-resistant hoistways. These hoistways should have 1½ hour fire doors that fill the entire opening to prevent the rapid spread of fire from floor to floor. All electrical equipment and wiring shall conform to NFPA 70/ANSI C1, National Electrical Code. Only electrical wiring and equipment used directly in connection with the elevator may be installed in the hoistway. Pit area: The pit consists of the clearance needed to accommodate the components on top of an elevator car. It is the area located at the bottom of the hoistway, and extends from the threshold level of the lowest landing to the hoistway floor. The main components in the pit include the governor tension sheave (or pit sheave), car and counterweight buffer assemblies, pit light and stop switch, and pit sump pump. With hydraulic systems, the cylinder and piston will also be found in the pit. A light switch and “emergency stop” switch must be reachable from the pit’s access door. Adequate lighting should be provided of at least five footcandles (54 lux) at the pit’s floor level (Figure 13.11B). A minimum clearance should be maintained of 2 feet (60 cm) between the lowest projection on the underside of the cab’s platform and any obstruction in the pit (exclusive of compensating devices, buffers, buffer supports, and similar devices). Measurements should be taken when the cab is resting on fully compressed buffers. Enclose counterweight runways from a point not more than 1 feet (30 cm) above the pit floor to a point at least 7 feet (2 m) above the pit floor and adjacent pit floors, except where compensating chains or cables are used. Screen partitions, at least 7 feet (2 m) high between adjacent pits, will protect persons in one pit from cabs and counterweights in adjacent pits. They will also protect employees from hazards when adjacent pits are at different levels.

Figure 13.11A,B A. Drawing of a conventional machine room and controller developed by Ove Arup & Ptns (courtesy, Elevator-World.com). B. Drawing of an elevator pit developed by Ove Arup & Ptns (courtesy, Elevator-World.com).


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Cab and equipment: The main components include the cab enclosure, the door operating equipment, and the top of the car equipment. The cab enclosure essentially includes the interior panels and flooring, the cab panels and the car operating panel (including push buttons, position indicators and signals, intercom/phone system, etc.). Life expectancy is usually about 20 years depending on maintenance. Cab door operating equipment includes the cab door operator that provides for the automatic opening and closing of the cab doors and the door safety edge that provides protection for passengers entering and exiting the cab. This has a life expectancy of about 20 to 30 years. Top of car equipment is to include inspection station for manual operation of the elevator for inspection purposes, an emergency exit hatch and a work light and convenience outlet. Floor landings and equipment: Floor landings will contain elevator system components typically found in the lobby and at the other floor landings (Figure 13.12A,B,C). The life expectancy of equipment in this section will vary but can be expected to be in the 20 to 30 year range. The main components usually include: • • • •

Hall push button fixtures Position indicators that display the position of the elevator in the hoistway Hall lanterns or direction indicators that indicate the direction of elevator travel Lobby intercom station for communications with elevator cab.

Firefighting lifts and entrapment: The 9/11 terrorist attacks brought to light that tall buildings in the United States should be easier to evacuate, less vulnerable to fire, and structurally sturdier. But it goes without saying that an effective elevator or escalator system must be designed to eliminate entrapments, injuries, and shutdowns. Indeed, due to entrapment concerns all elevators are now required to have communication connection to an outside 24-hour emergency service, automatic recall capability in a fire emergency, and special access for firefighters’ use in a fire. Elevators should not be used by the public if there is a fire in or around the building. Numerous building codes require signs near the elevator to state “USE STAIRS IN CASE OF FIRE.” Of note, some countries allow the use of elevators in emergency evacuation.

Figure 13.12A,B,C Examples of hall design. A. Hilton Hotel, Buenos Aires, Argentina. B. St. Martins Court, United Kingdom. C. Emerald Shapery, San Diego, California, U.S.A. (source, Mitsubishi Electric Corporation).


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In general, the requirements for an evacuation lift are the same as those for a firefighting lift, except that the operation and communication arrangements are different. However, although a firefighting lift can be used as an evacuation lift, an evacuation lift cannot be used as a firefighting lift. Evacuation lifts are provided to facilitate the egress of persons with impaired mobility in the event of a fire or other incident. The evacuation is always supervised and persons are not to attempt self rescue. Often when a fire breaks out passengers may be traveling in elevators or elevators may be empty but in motion. The ideal procedure during a fire is for the lift to be sent to a designated floor, open its doors to allow passengers to exit, close its doors and go out of service. The major obstacle to dealing with the elevator behavior in the event of fire is that only a small percentage of buildings have acquired the technological capability to send the necessary signals to the vertical transport system. Another important issue is that of the emergency power for the elevators should the main power fail. Current codes stipulate that at least one elevator that serves every floor must be provided with emergency power. If the power and control wiring is installed within the hoistway the elevator would continue to operate as long as the hoistway was intact.

13.7 SYSTEM DIAGNOSTICS The consultant should review all documents pertaining to the design, construction, operation, and maintenance of the elevator system prior to conducting the physical baseline survey. During the physical assessment, the consultant should interview in-house or third party maintenance staff currently operating the system. The consultant should seek out information on problem areas and areas that need attention. Based on visual observation, the consultant should report on the status of overall car control, monitoring, and individual door controls, along with the necessary recommendations. The elevator maintenance contract should be reviewed and compared to the actual system and all deficiencies and areas for improved enforcement noted. The assessment of elevators usually focuses primarily on safety. In light of the fact that the majority of lawsuits involving elevators are door-related, the quality of door operations and cab leveling should be emphasized in any assessment. System type, capacity, location, and general condition also need to be assessed in any system evaluation. Likewise, the maintenance contract should be checked for adequacy and to ensure that the equipment is well maintained. Building owners usually contract a service and maintenance firm to provide regular preventive maintenance which typically includes monthly inspections and repairs. The evaluation of the system should therefore include a review of both the maintenance agreement and inspection reports. Adequacy of the agreement should be evaluated to ascertain if it includes all necessary items and whether it meets the requirements of the system. The inspection reports should be reviewed to identify any recurring trends or deficiencies. It is useful to interview the maintenance representatives who have been servicing the system. It is likely that they can provide information on the past and present conditions, and future capabilities of the system, information not otherwise available in a one-time evaluation, no matter how thorough. The past and present conditions and quality of maintenance will determine the remaining life of the equipment. Among the most important reasons for a vertical transportation evaluation is the determination of the degree of obsolescence of the equipment. For older systems it can be difficult to find equipment and replacement parts. The potential benefits of modernization should also be reviewed. In some cases, the increased safety, efficiency, and equipment availability provided by new systems warrants replacement or modernization. Elevators should be operated and the controls and equipment checked. Likewise, the escalation or lifts should be operated and current condition and operational capabilities determined.


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Elevator evaluations require access to several areas including the machine room, top of the elevator cab, elevator pit, and the cab itself. Rotating equipment and the controllers should be evaluated for signs of wear or deterioration. The top of the cab should be ridden to determine operational characteristics, the degree of hoist and safety rope wear and the adequacy of seismic safety precautions. It should also be accessed and reviewed for adequacy of maintenance. Following this the elevator pit should be inspected for general cleanliness and the condition of the buffers. The final aspect of an elevator inspection is usually the cab. Signage, fire safety, handicap accessibility, and code requirements are all evaluated. A tachometer and a stopwatch may be used to aid in determining various operational information including acceleration, deceleration, floor-to-floor speeds, and door open and closing speeds. Vertical transportation system evaluation relies mostly on visual observation. In facilities that historically have experienced problems, more in-depth evaluation may be warranted. For example, pressure and load tests may be required in hydraulic elevators which have experienced hydraulic-related deficiencies in the past. A limited review of the vertical transportation system can be performed by anyone with some knowledge of the system and its operations. An in-depth evaluation of the system should be performed by a knowledgeable professional such as an elevator or vertical transportation consultant. Infrared scanning of electrical equipment, vibration testing on motor and hoistway equipment, and other tests on door closures and safety devices may be required. The work scope will be provided in a separate guidance document or shall be submitted by the consultant and pre-approved by the client. Decision to modernize: An elevator is at its peak performance when passengers fail to comment on it. However, if they’re noticing delays, bumpy rides, uneven leveling, noisy equipment, and other inefficient items, it may be time to consider a modernization program. Moreover, elevators generally become candidates for modernization when they approach the end of their efficient lifespan which can vary depending on how well the elevators are maintained and if they are heavily used, such as in hospitals or hotels. The level of modernization should be decided upon only after a complete survey and analysis is performed and an approximate budget is decided upon. A complete equipment evaluation should be included that covers all the equipment in the machine rooms, hoistways, pits, cabs, and lobbies. The evaluation, plus a history of tenant complaints, will help arrive at a determination as to which parts need to be repaired or modernized and which can remain. Likewise, a modernization program should be based on the needs of the specific building which would include “building related� items and must be determined before the owner requests proposals. One of the prime reasons to modernize elevators is to allow older buildings to compete with newer buildings and with existing ones that have been renovated. This goal is advanced by improving reliability, e.g., by reducing system failures due to normal aging or wear, reducing an excessive number of shutdowns and entrapments, and the opportunity to replace obsolescent components. Older, less-efficient elevators suffer from more frequent reliability problems. In addition to reliability, modernization will provide greater elevator efficiency and safety, improved service, lower operating costs, and more satisfied tenants. Speed is important in mid- to high-rise buildings although passengers prefer to ride in elevators that start and stop smoothly and provide a quiet ride. In low-rise buildings, acceleration and deceleration are more important than maximum travel speed. Higher performance can be achieved by reducing passenger waiting times and traffic handling capability caused by inefficient operation. Ride and operation quality can improve by reducing excessive cab vibration, door noise, and harsh stopping. Finally, modernization can improve the aesthetics by replacing outdated or worn cab finishes and aged or outdated fixtures. It also gives an opportunity to upgrade communications. During the modernization process, it is important to stay current with all safety codes. Up-to-date security precautions will also send a message to tenants that management cares about protecting their premises.


CHAPTER

14 Interior Systems 14.1 GENERAL Today’s construction of high and low-rise building interiors is made more complex by the myriad of possibilities for clients to adapt their interior spaces to suit their individual needs and preferences. Interior systems are comprised of many different components including floors, walls, ceilings, finishes, fixtures, and special systems. During the last decade or so, commercial property owners and investors have come to realize that interior environments from both an aesthetic and health standpoint are playing an increasingly pivotal role in influencing major tenant decisions on leasing. Moreover, because the quality of an office space can impact the ability to recruit, as well as impact the satisfaction and productivity of employees, many organizations have started to look carefully at how their space is working for them and are revisiting their space standards and the quality of their environment. It is therefore important that design consultants analyze building systems from a holistic viewpoint and specify environmentally sustainable materials and methods. Some of the factors that impact the evaluation of an interior systems survey are shown in Figure 14.1. It is important for the forensic architect to understand the significance of this on interior systems design and construction.

14.2 COMPONENTS TO BE EVALUATED 14.2.1

Walls

Today, there are three main types of interior wall partitions systems: 1. The traditional wall system which uses plaster, 2. Wall systems that use gypsum drywall, and 3. Modular wall systems that are demountable. In using traditional wall systems, the focus is on gypsum-based plasters. This is a robust but expensive material that resists abuse and gives designers a bit of artistic leverage. Traditional plaster walls provide long-term beauty and performance and can be finished smooth or textured. Many older structures

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have traditional plaster walls. In these systems, plaster was typically installed over a support structure called lath, often thin strips of wood, with the plaster squeezing between, curling around, and locking on. Sometimes plaster was installed over a gypsum board with holes in it which allowed the plaster to enter and grip the board. When light stresses are put on the plaster walls, the plaster cracks, especially at the corners of windows Figure 14.1 Some of the factors that impact the and doors. If the crack is hairline, you can evaluation of an interior system survey. easily patch it and restore it to its original condition. The main concern in using plaster for walls however, is water. Water leaks from plumbing fixtures not only create problems for the plaster, but can also rot wood lath beneath or cause gypsum lath to crumble. Such an occurrence would be a major repair job because the damaged plaster and the rotted wood must both be cut out. This would necessitate bringing in an experienced contractor adept at working with plaster. Most contemporary drywall wall systems are constructed of gypsum board or drywall, sometimes also referred to as wallboard. Gypsum board is generally nailed or screwed to vertical support pieces, usually made of wood, referred to as studs. Where drywall sections join, the joints are covered with a strip of special tape, and with metal pieces at corners. Joints are then finished with a joint compound, sometimes referred to as spackle. Demountable systems essentially consist of modular panels that are typically manufactured in the factory. They come in numerous finishes and colors. They are also typically thinner, more flexible, and can be designed and manufactured to various heights, widths and specifications. Prefabricated wall systems are cost-effective, easy to install and maintain, and offer a wide array of design options. They are increasingly being used in a variety of distinct commercial applications, such as corporate, medical, financial, and hospitality interiors, transportation terminals, schools and universities, restaurants of all types, and grocery and convenience stores. Veneer plasters: A veneer plaster system is an alternative system that can provide a high-quality, conventional plaster look but at a much lower cost. High-strength, one-coat veneer plaster finishes rank a step above drywall, and offer up to 100 times the abrasion resistance of drywall and at least four times more indentation resistance than drywall. Under favorable drying conditions, one-coat plaster systems may be ready for finishing in as little as 48 hours. Drywall joint treatments normally require multiple drying cycles, spanning four or five days. With plaster, work can be completed several days sooner, depending upon the application. Today’s drywall systems have advanced to a point where the systems provide a smooth, serviceable finish at the lowest possible initial installed cost. Gypsum fiber panels have been used as interior walls, as a high-strength flooring underlayment, and as an exterior sheathing worldwide, especially in Europe, for over three decades. The most popular commercial construction application for these panels is in wall systems, where they typically are specified as an abuse-resistant alternative to drywall and plaster systems. Continuous research efforts have resulted in the development of innovative panels made from a unique manufacturing process that combines cellulose fibers and gypsum, which is the primary ingredient in traditional drywall products. Many of these products now also incorporate water-resistant technology, which provides increased resistance to indentation and penetration without the need for a paper face that can tear


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or scratch. Furthermore, the manufacturing process today actually grows gypsum crystals in and around the pores of wood fiber, and thus more fully integrates the two materials. This is contributing to many of the products’ superior performance features, including greater strength-to-weight ratio; better fire and weather resistance; improved fastener holding; consistent dimensional stability; uniform surface smoothness; and full recyclability. Gypsum fiber panels are now routinely specified in hospitals, schools, prisons, and other facilities that are subjected to occasional moist conditions and are likely to experience abrasions, indentations, and other forms of abuse caused by supply carts, gurneys, machinery, or equipment being moved routinely throughout the premises. Among the benefits of gypsum wood fiber panels are that they provide a smooth, flat surface for finished walls that can be painted, and require less cutting, fewer joints, and no transitions between different types of substrates. In addition, gypsum wood fiber panels are, by their composition and design, extremely environmentally friendly. Many are made from 95 percent recycled materials. Several of these products have been awarded the “Green Cross” certificate for their high recycled content from Scientific Certification Systems, a leading independent testing organization. Mold issues have become a major concern of drywall manufacturers and the building industry in recent years. Mold in new construction is an issue for contractors due to the additional cost of remediation, not to mention visibility with owners and investors. For solid materials such as framing members, mold remediation revolves around cleaning and treating, but for drywall, cleaning may not suffice, requiring a more expensive effort of removal and replacement. Some gypsum board manufacturers have developed products with gypsum cores that will not absorb moisture (an essential ingredient for mold to grow) as easily as typical gypsum board. The current standard for mold-resistant characteristics of drywall is ASTM D3273 Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber. This standard measures the ability of the drywall product to resist mold and mildew growth under certain prescribed moisture conditions, and a number of manufacturers quote the performance of their products to this standard when tested.

14.2.2

Floors

In addressing the need to produce high-performance buildings, building owners and investors seem to be leaning toward constructing larger floorplates, slightly smaller spaces for individual knowledge workers, several small to moderately sized enclosed teaming areas, and larger spaces where impromptu meetings can take place. In an office setting, a fully integrated access floor system with underfloor power, voice, data, and HVAC services distribution, allows a building owner to: • • •

Improve indoor air quality, energy efficiency, individual comfort, and flexibility Reuse modular wiring, modular carpet, access flooring, and under-floor air Reduce the cost of change, carpet scrap and attic stock, absenteeism through improved indoor air quality, and taxes through an accelerated depreciation rate.

In typical office environments, the concrete floor slab itself is comprised of 4- to 6-inch thick concrete reinforced with one layer of welded wire fabric at mid depth. Depending on the interior space, the finish floor covering may be the exposed concrete surface itself or various floor coverings such as carpet, tile, wood, or vinyl floors. Many adhesives used in applying floor coverings are sensitive to moisture, requiring the use of a waterproof system or lengthy drying times if a poly vapor retarder is used.


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The exterior environment that a floor slab is subjected to includes environmental control loadings such as thermal, moisture, insects, and soil gas. The interior environment that the floor slab is subjected to includes environmental control loadings such as thermal and moisture. The performance of the floor slab system depends on its ability to control, regulate and/or moderate these environmental control loadings on the interior of the floor slab to desired levels, particularly since floor slabs are often considered to be the source of leakage into the building with slab cracking of common concrete materials being a primary cause. Issues of controlling soil gas emissions such as radon may also be of importance. In light residential construction, wooden floors are generally used. Such flooring generally consists of a finish floor installed on a subfloor of tongue-and-groove planking or plywood, spanning between wooden beams called joists (Figure 14.2). Slabs of reinforced concrete are a common type of floor for heavier loading. The concrete is cast on forms and reinforced with properly placed and shaped steel bars (rebars), so as to span between steel or reinforced concrete beams or between bearing walls. Composite floors are commonly used in modern office building construction. Concrete is cast on, and made structurally integral with corrugated metal deck, which spans between steel joists of either solidbeam or open-web types, generally spaced between about 16–48 in. (40–120 cm) on center. Prestressed concrete is used for long span slabs. Highly prestressed high-tension steel wires within the high-strength concrete slab produce a thin, stiff, and strong floor deck. A lift slab is used for economy and efficiency. A concrete slab is first formed at ground level, reinforced and cured to adequate strength, and then carefully jacked up into its final position on supporting columns. Wood-framed floors normally consist of repetitive joists or trusses at predetermined spacing, sheathed with either boards or wood structural panels attached to the top surface. Finish materials such as gypsum board typically are applied to the bottom surface where they serve as the ceiling for the space below. Blocking between joists or trusses is usually employed at the ends of the floor joists or trusses and where walls occur above or below. Floor systems also incorporate beams, girders, or headers as needed to support the joists.

Figure 14.2 Wooden floor joist system construction.


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Joists can be sawn lumber, end jointed lumber, or a variety of prefabricated (engineered) members. Examples of engineered lumber include wood I-joists, trusses, or solid rectangular structural composite members such as parallel strand lumber (PSL), laminated veneer lumber (LVL), and laminated strand lumber (LSL). Beams, girders, or headers and blocking also can be either sawn lumber or engineered lumber. Elevated floors span between, and are supported by, beams, columns, and bearing walls. A floor is designed to be strong and stiff enough to support its design loading without excessive deflection; to provide for an appropriate degree of fire resistance; and to supply diaphragm strength to maintain the shape of the building as a whole, if necessary. Concrete has over the years acquired a proven record for strength, durability, and cost effectiveness for a variety of applications including floors, walkways, patios, and driveways. Concrete floors are found in a variety of residential and commercial settings, from high-rise buildings, to basements remodeled for extra living space, and to below grade and slab-on-grade construction (Figure 14.3). The floor slab of the below grade building enclosure must be designed to carry downward vertical gravity loadings as well as any upward soil or hydrostatic pressure loadings. Downward vertical gravity loadings exist from the floor slab’s dead weight in addition to any occupancy live loads. In many deeper structures the floor slab may also be a matt foundation slab carrying significant building column and wall loads. Floor slabs may also resist upward soil or hydrostatic pressure loadings. The floor slab may encounter upward soil pressures in situations where it is acting as a matt foundation and the building point loads on the foundation result in an upward pressure on the floor slab. In all cases, detailing of waterproofing at all terminations and penetrations is critical. It is no surprise that the life expectancy of concrete slabs far exceeds that of flooring materials often used to cover them. Interior concrete is commonly covered with carpet, vinyl, or other flooring materials. For exterior surfaces, materials like slate, granite, or brick are preferred to standard concrete when budgets allow. Carpeting and vinyl are subject to tears, staining, damage from flooding, and general wear. Persons with allergies may also have concerns about dust or molds that may harbor in carpet fibers. In addition, many floor coverings need to be replaced every few years.

Figure 14.3 Below grade slab concrete floor and waterproofing detail.


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There are many decorative finishes on the market that are durable, sanitary, and easy to maintain. These finishes can be applied to existing or new slabs and can last the lifetime of the concrete. The treatment may be as simple as coloring walkways to match architectural features or blend into the landscape. If the look of natural materials is preferred, a slab might be stamped to create the appearance of slate or granite, complete with subtle color shifts, surface texture, and real grout placed in the formed joints between pavers. It is also possible to apply thin layers of cementitious material to existing concrete floors. The material may be self-leveling, to flatten an irregular surface or trowelable where pattern stamping is desired. Colored materials can likewise be applied to seal and waterproof concrete surfaces. Manufacturers offer a broad range of products for various applications, ranging from buffing waxes for interior floors to industrial sealers for high traffic exterior settings. Since concrete is relatively inexpensive, the costs for decorative concrete may still be less costly than installing a floor of different material. Concrete flooring lasts longer than most other floors and can withstand much abuse without damaging its look. Concrete flatwork must comply with applicable building code requirements for thickness, composition, and strength. There may be requirements for slip resistance on exterior walkways that preclude very smooth or glossy finishes. Moreover, some contractors will warrant their work against cracking for a period of several years, generally about five to 10. Radiant floor heating is another form of energy-efficient technology that can easily be incorporated into slab floors. A decorative finish on the concrete will allow the system to provide maximum heat transfer with no thermal barriers from added floor coverings. Besides conditioning the space, the floor will also feel comfortably warm underfoot. Prestressed concrete: Concrete with stresses induced in it before use to counteract stresses that will be produced by loads. Prestress is most effective with concrete, which is weak in tension, when the stresses induced are compressive. One way to produce compressive prestress is to place the concrete member between two abutments with jacks between its ends and the abutments, and to apply pressure with the jacks. The most common way is to stretch steel bars or wires, called tendons, and to anchor them to the concrete; when they try to regain their initial length, the concrete resists and is prestressed.

14.2.3

Interior Doors

Doors come in a variety of standard heights, widths, and thicknesses, yet they may also be custom designed, assume a variety of shapes and forms, and be constructed with a variety of materials. The design, specification, and detailing of a door can significantly impact the function and performance of a structure and is a rather complex task. Doors can also be fire-rated or not. Doors classified as fire doors must comply with certain requirements and standards such as the American Society for Testing and Materials (E152-ASTM), National Fire Protection Association (NFPA-252), and British Standards (B.S.476:Part8 and B.S.459:Part3). Figure 14.4 shows the various classifications of fire-rated doors. Fire doors are normally required for all doors leading to staircases from corridors or rooms, cross corridor partition Figure 14.4 Table showing fire-rated door classification. doors, all doors to laboratories, work-


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shops, storerooms, plant rooms, service ducts, kitchens and tea points, and to defined fire compartments. They are also required for certain circulation areas which extend the escape route from the stair to a final exit or to a place of safety. Likewise, fire doors are required at entrances and lobbies, doors leading onto external fire escapes, and doors between basement and upper floors, etc. Corridors that are protected from adjoining accommodation by fire resisting construction also require fire doors. Generally, fire doors on circulation routes should open in the direction of escape and should not be double swing (except for doors forming a mid-corridor smoke break), but should be rebated to ensure intumescent and smoke seals work correctly. Doors are typically set within a frame or jamb (Figure 14.5), but may also be installed within a wall without a frame or jamb. The frame/jamb interface between door and wall partition is another area requiring special attention by the designer. The design of a door includes hardware, hinges, locksets, closers, stops, and thresholds—a few of the hardware elements that a designer must consider. Door panel construction is basically of two types: steel stiffened and laminated core. Hollow metal swing door construction types include: full flush with continuously welded edge seams, full flush with unfilled edge seams, flush stile and rail, and recessed panels. When evaluating the interior systems of a facility, it is prudent to operate and evaluate as many of the doors as possible. When a door is found to be severely sticking, and there are other doors or windows in the same area that are sticking as well, they could be out of rack, which may indicate a serious problem involving the building’s structural system. There are many different interior door types including hollow core, solid core, fiberglass, bi-folding, accordion, operable partitions, de-mountable partitions, and fire doors. Environments that display corrosive or humid conditions may warrant the use of reinforced fiberglass doors and frame systems; these doors have proven to be tough, are lightweight and may be preferred over metal doors where such conditions exist (Figure 14.6). Moreover, they generally last longer, are easy to install, and the colors are molded in,

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Figure 14.5 A typical door frame opening less than 4 feet wide—non-load bearing.

Figure 14.6 Fiberglass door by Fib-R-Dor shows method of construction.


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which means no painting or maintenance is required. Many industries such as food processing, water/waste management, pulp and paper, and pharmaceutical are well aware of the potential cost savings and have started to take advantage of fiberglass doors. Fire rated fiberglass doors are also available such as the Fib-R-Dor door which meets U.L.’s strict “Standard for Fire Tests of Door Assemblies, U.L. 10B,” and U.L. 305 Standard for Safety “Panic Hardware.”

14.2.4

Stairs

This section should be read in conjunction with Chapter 18, sections 18.1, 18.3 and 18.4. Interior stairs are usually more refined than exterior stairs. Moreover, interior stairways may be the showcase of a building and so are often located near the main entrance and used as a major circulation route (Figure 14.7A). In some instances, they provide an opportunity to connect several floors with natural light. Stairways shall not normally be less than 36 inches (914 mm) in clear width at all points above the permitted handrail height and below the required headroom height. Handrails shall not project more than 4.5 inches (114 mm) on either side of the stairway and the minimum clear width of the stairway at and below the handrail height, including treads and landings, shall not be less than 31.5 inches (787 mm) where a handrail is installed on one side and 27 inches (698 mm) where handrails are provided on both sides (Figure 14.7B). The main source of injuries and lost time from work in the United States (and probably other countries) due to staircases, is caused by odd dimensions of stair tread width, height, depth, nose, low or flimsy stair railings, loose stair components, and a host of other stair and railing defects. Treads are the stair component that gets the most wear, which can result in uneven wear, cracks, splitting, or even extensive scratching to the extent that replacing them is the best option. Conversely, risers are probably the least likely to become worn; however, over time they may be subjected to cracks or dents and may need replacing as well. Stock treads are available with integral factory-milled nosings (Figure 14.8). Whether the staircase is open on one or both sides, or located between walls, replacing treads and risers is a relatively simple procedure. Circular stairs pose special problems regarding tread shape, potential walking area, and railing design. The forensic architect should review construction details, structural connections, loose connections, modifications, support, posts, weather exposure/covering, weathering, rot, tread damage, tread nose wear/damage, moss, algae, cupping, splitting, stairway obstructions, tread con-

Figure 14.7A,B A. An example of an interior stairway located near the main entrance. Notice there are no risers to make it appear “lighter” and more “transparent.” B. Internal concrete fire escape stairs.


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nection and support, rail obstructions, rail grip, and permits. Structural conditions to observe include connections, proper number and type of fasteners, spans, and condition of materials. When replacing an existing stair with a prefabricated stair, caution must be taken with the demolition work. Older stairs are sometimes part of the building’s structure and are not always easy to remove. Prefabricated stair construction consists basically of a pair of spaced, parallel stair stringers, either one or both being a free span member between support beams with developed strength of a rigid truss by the joining of stair rails, balusters, and stringer into a single unit. The stringers are joined together by a number of precast treads secured at each end to the stringer by two welded flanges, the treads having a reinforced nose portion and riser to decrease the bending moment of the tread (Figure 14.9A,B). Fiberglass molded stair tread covers are used to cover existing stairs to provide a convenient nonslip surface. Fiberglass stair tread covers can be placed over any type of stair: concrete, metal, fiberFigure 14.8 An example of concrete stair nosing glass, etc. Stair tread covers are typically used for detail with silicon carbide abrasive strips. environments where corrosive or slippery conditions exist. The high resin composition of 65 percent and lower glass composition of 35 percent provides for optimum corrosion resistance. The covers are low maintenance and will never rust or need to be painted. In addition, they can cover up existing stairs that have holes in them which allows for high heeled traffic.

Figure 14.9A,B Stairs—flights with integral top and/or bottom landings.


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14.2.5

Finishes: Floor, Wall & Ceiling

The National Fire Protection Association (NFPA) defines “interior finish” as “the exposed surfaces of walls, ceilings, and floors within buildings,” with the explanation that interior finish should not apply to surfaces that are concealed or inaccessible. Likewise, furnishings that are secured in place for functional reasons should not be considered to be an interior finish. NFPA also considers interior ceiling finishes as “the interior finish of ceilings,” and interior wall finishes as “the interior finish of columns, fixed or movable walls, and fixed or movable partitions” and interior floor finishes as “the interior finish of floors, ramps, stair treads and risers, and other walking surfaces.” Floor finishes: During the investigation of internal failures or facility evaluations, the forensic architect/consultant will usually encounter several types of floor finishes. Floor finishes include carpet, resilient tile, ceramic tile, concrete, wood, brick, and stone. Floor finishes are especially susceptible to damage, wear, and deterioration at heavily trafficked areas. Corridors, entrances, and office areas typically exhibit more pronounced deterioration than low traffic areas. The durability of the existing materials should be considered when an inspection or evaluation is being performed. Pronounced deterioration often results from a material installation in which the type, grade, or weight of material installed is inappropriate for its intended use. Composite flooring systems offer clients and designers a number of benefits which address the social, environmental, and economic dimensions of sustainable construction. Few managers will argue that some flooring types perform better than others in certain applications, and not all floor finishes are ideal for all locations. Proactive managers often partner with industry professionals, such as architects, interior designers, and manufacturers, to determine the right flooring for each location. Numerous factors need to be taken into account when planning to install flooring: • • • • • •

The function of the space—for instance, a cafeteria at an elementary school might prefer to use vinyl composite tile (VCT) over carpet Repair flexibility Traffic levels—high-traffic areas require flooring that can withstand heavy traffic Ease of maintenance—many types of flooring need significant attention (spills on carpets need to be removed as soon as possible, and terrazzo might require regular buffing) Rated service life—this issue relates to a floor type’s life expectancy and relies on external factors such as maintenance Recycling or reusing the flooring.

Moreover, flooring is important because it can set the tone of the interior whether in the home, the office, or the mall (Figure 14.10). Although aesthetics plays an important role in any design solution, flooring must be practical in today’s environment. Flooring can pull a design together or visually fragment it. The use of one continuous material increases the flow and homogeneity and suggests that areas share equal importance and are equally accessible, whereas the introduction of accent flooring suggests that special areas exist. Flooring finishes can often give a clue to the activity of the space, since it is the one material that is always in contact with the users. Thus, rubber flooring and vinyl tile suggests a high traffic area that is expected to take punishment and get dirty, and therefore should not require high maintenance. Wood is a widely used floor material that has maintained its popularity over the centuries. It is practical, both functionally and aesthetically, and works in most environments. It’s warm mellow tone, soft touch, and easy maintenance, makes it a favorite in residential applications. It lasts well, comes in a variety of formats, and makes an excellent base for decorative rugs.


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Hardwood floors are very common in today’s market. They usually come in hardwood strip, block, parquet, or board form. The most common species used are oak, beech, maple, ash, birch, and pine. Most types of strip flooring come tongueand-groove so that the planks fit together without leaving any gaps. Parquet floors are usually high quality floors and consist of small blocks (12 inch x 12 inch x ½ inch thick) of hardwood fitted together in certain patterns. They can be square edge or T&G, and most of the time they are installed with an adhesive. Floors of this type tend to loosen with moisture or conditions with high relative humidity, and in high traffic areas. In older homes, wood floorboards are typical and usually found laid horizontally across the room, resting on the joists that run from the front of the house to the back. Stains are very difficult to remove from wood flooring, whether it is site finished or refinished at the factory. Sanding can remove some of the stains, but deep, oil-penetrating stains are nearly impossible to totally remove from the wood. Carpet denotes a more relaxed, contemplative and higher status area because it is softer underfoot and therefore quieter. Carpet also has low Figure 14.10 Flooring can set the tone for a space. maintenance costs compared with other commerThis is an example of a concrete overlay system used cial floor coverings. Corporations can also incorin a motor lodge corridor (courtesy, Elite Crete porate product colors and company logos in their Systems, Inc.). flooring designs. Likewise, for many rehab applications, carpeting presents a low-cost, easily installed solution to flooring problems. The inherent cushioning and non-slip characteristics of carpet contribute to a comfortable and safe work environment by reducing the likelihood of falls and minimizing potential injuries. Additionally, the insulating properties of carpet keep floors warm in winter and cool in summer, which helps reduce heating and cooling costs. Carpet’s acoustical benefits include absorbing airborne sound, reducing surface noise, and helping to block sound transmission to floors below. Carpet should be checked for proper stretching and securing of the seams, mostly for safety, since loose carpet can pose a tripping hazard. Carpeting can also affect the air circulation of the HVAC system. If the carpet is extremely thick, and the HVAC system doesn’t have individual returns, it could block the space underneath some of the doors and restrict adequate air circulation to those areas. Carpets that are well-maintained can last 15 years or longer, but if it is rarely vacuumed or cleaned, its life expectancy could diminish by up to half. Regular vacuuming of carpeting not only cleans its surface, but it also extends the carpet’s life. Dirt and grit that are ground into the carpet actually cut fibers at the base, causing irreversible damage. So there is a false economy—and only a short-term savings—in cutting cleaning frequencies of floors.


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Vinyl and Linoleum: Vinyl tile and sheet goods are dependable, as long as the installation is performed properly. There is a wide range in quality and variety of colors and patterns, often with designs that simulate other more expensive types of flooring such as wood, tile, and marble. It is a wholly synthetic material and contains a varying percentage of PVC, which adds to its flexibility. It is also inexpensive, and comes in sheet or tile form. Loose tiles are often a sign of moisture or workmanship concerns, particularly in the kitchen and basement areas. Linoleum is likewise available in sheet or tile form and comes in a comprehensive range of colors and patterns. Its recent rediscovery is largely due to its improved performance and because it is composed of entirely natural ingredients. Hard Tiles and Mosaic: Hard tiles including ceramic, terracotta, and quarry tiles are generally machinemade, which gives them a precise size, and are particularly suited to areas where water is often present, like kitchens and bathrooms. Tiles of baked clay, such as the popular quarry tile, are similar to masonry materials and require a sturdy subfloor. Ceramic tile has traditionally been used as a floor and wall finish in damp areas such as bathrooms, kitchens, basements, and entryways, mainly because it is impervious to water. Also, because of its relative durability, low maintenance and decorative qualities, ceramic tile is increasingly used in other spaces as well. Typical installation methods include: wet bed (traditional method, and is sometimes called mud-set), set in ž inch to 1 Ÿ inch of Portland cement paste/mortar laid over a previously set mortar bed or concrete slab; and thin-set that is set in an organic or epoxy adhesive. New products, such as the mastics and waterproof boards, are making wet bed systems extinct. Ceramic tile is divided into glazed and unglazed varieties. Most historic floor tiles were unglazed and were the color of the clay and added oxides or pigments from which they were made (current examples are quarry tiles). Glazed tile is colored with a variety of glossy or mat glazes applied to the tile surface. Glazed tile is subject to scratching and abrasion from extended use and is usually installed in low traffic areas or covered with rugs. The main causes of tile failure include improper maintenance, such as the use of inappropriate cleaning agents, degenerative effects of standing water on the grout, the erosion of grout over time from traffic cleaning, and structural problems. The latter include cracking and loosening of tile from overloading, sudden impacts, or frequent vibrations; defective or deteriorated substrates, such as concrete floors that have cracked, heaved, or settled; wood floor substrates that deflect excessively (too springy), have buckled, swelled or deteriorated; and concrete or wood floors that have improperly mixed or applied tile bonding materials. Loose tile, due to failing and water-damaged substrates, is one of the major concerns. Grouting around the tub and shower should also be kept up, as failure to do so leads to the deterioration of the tile and allows water to seep into the areas and the substrates below. Mosaic tile floors include any tile that is less than 2 inches square, although they could also be round or hexagonal. Mosaic tiles can be either glazed or unglazed, and they’re usually mounted on 12 x 12 inch sheets with a mesh backing. The small scale of mosaic tiles gives them an almost soft appearance. They consist of small cubes of terracotta, marble, ceramic, or stone and are bedded in mortar. Mosaic works best when restricted to small areas like bathrooms. Porcelain mosaic tiles are colorful, extremely durable, frost-proof, and a good choice for most applications, including kitchen countertops. In the case of unglazed tiles, the color goes all the way through the piece, so it will never wear out. Trim pieces are available for many mosaic tile lines. Marble & granite are treasured for their refined, regal, decorative appearance and are more widely used in countries of the Middle East, Greece, and Italy than in the United States. Both materials have prestigious connotations and in the United States are primarily used in banks and foyers of commercial build-


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ings and in some custom dwellings. Granite and marble tile flooring are natural stone products, very durable and stain resistant and are excellent floor materials. Another benefit of marble is that it is viewed as a hypoallergenic choice for flooring, because it has a dense surface upon which antigens and particles which cause allergy symptoms to become inflamed, are less able to reside than they are in say, carpeting. Terrazzo is a relative newcomer to the American scene. It has been popular in Mediterranean countries from early times. Terrazzo is an aggregate of marble or granite chips mixed into a cement mortar and either laid in place or as slabs or tiles. The mix is then ground and polished to a smooth surface after it has set. Both formats are expensive in the United States and require professional installation. Other Materials—Stone, Brick, Concrete, Rubber, Cork, etc.: Stone is a traditional material having been used for thousands of years in many countries around the world. It can bring an unmatched depth of richness and character to the interior or exterior. Natural stone comes in a variety of formats, colors, patterns, and textures. Moreover, the thicker, larger flags or tiles are heavy and need a solid subfloor to bear their weight. Slate and limestone are the most used by designers. Several types of hardwearing brick are available for indoor use. These should be laid on concrete, and should be sealed for a stronger finish and to prevent dust, etc. These bricks are also used for exterior paving and in restaurants and residential patios. Sometimes they are used as an accent or divider in conjunction with other materials. Concrete is basically a structural material and can provoke strong reactions when used in commercial or domestic settings. It can be troweled to a smooth surface and treated in a number of ways to alter its texture and color. It should either be sealed and polished or painted with special floor paint. Although generally regarded as acceptable only in utility areas, the material has considerable machismo when properly used. Studded rubber flooring was introduced to residential applications with the arrival of high tech, and enjoyed a brief spurt of popularity. It has now reemerged and is available in a variety of colors, and in sheet or tile, with either a smooth finish or in relief. Cork is a warm material and the air trapped inside the cellular structure of cork provides a natural shock absorbing feel to the floor in addition to being soft to the touch. It’s ideal for applications where a person stands for long periods as in a kitchen. The same cellular structure that makes the floor comfortable also reduces noise and vibration. Unlike hard materials like tile, wood, or vinyl, cork is quiet and reduces impact noise such as something dropping on the floor. Cork flooring is environmentally friendly and cork is considered a renewable and sustainable natural resource. In addition, cork has natural properties that are anti-allergenic and resistant to insects. A naturally occurring waxy substance in cork called suberin repels insects, mites, and mold and protects cork from rotting when wet for a long time. In addition, suberin is naturally fire resistant and cork doesn’t release any toxic off-gassing when it burns. These natural properties, plus the coatings used to seal cork flooring, make it healthy and safe for adults, pets, and babies. Cork is produced in tile or sheet form and is sealed with polyurethane. It is used more in Europe than in the United States. Wall finishes: Wall finishes are another area of important review during a survey of the interiors. Typical wall finishes include plaster, drywall, paints and coatings, ceramic tile, masonry, concrete, wood, and wall covering of vinyl, paper, or fabric. Wall finishes are frequently damaged by impact from equipment and goods. Common deficiencies include wear, warping, bulging, stretching, insufficient fastening, and normal deterioration and damage. Signs of exterior water penetration should be investigated and appropriately remedied. Walls are important elements of any design scheme because they define spaces, segregate activities, and mark out personal domains within the home or office. Their importance is highlighted by the enormous


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variety of treatments available that draw attention to the walls themselves. A common finish found in many modern houses and building renovations is textured drywall. It usually has a textured finish that looks like bumps or ripples. Paint: Paint and wallpaper are the two most common protective and attractive finishes applied to walls. Color is a key element in most contemporary interiors, and paint is one of the simplest and least expensive ways of providing an acceptable finish to the office, home, or store, which perhaps explains why it is the most widely used finish. Moreover, there are many decorative wall painting techniques that can be applied, such as sponging, ragging, stenciling, or stamping. Paint is either oil (alkyd) or water-based (latex, vinyl, or acrylic). Oil-based paint is less permeable, shows streaks less, is more durable, and usually takes longer to dry than water-based. Because it does not take abrasion as well as oil-based paint, water-based paint was historically less commonly used. Today, latex-based paint is used for most interior paint jobs because it is easy to maintain, quick drying, and does not require thinning agents for clean-up as you can clean up using water. Latex paints also come in a variety of colors. Wallpaper: Wallpaper offers a large variety of textures, patterns, and imagery, often making it a viable alternative to paint. Wallpapers are traditionally made of paper, cloth, or paper-backed PVC. Today, wallpaper coverings commonly contain vinyl and are pre-pasted, applied with water and a sponge. Vinyl coverings are easy to maintain and are more durable than papers. Vinyl papers are water and steam-proof, washable and tougher than normal paper, which makes them suitable for use in kitchens, bathrooms, and utility areas. Wallpaper also remains popular because it is a practical way of hiding surface imperfections. The vinyl type is frequently used in both commercial and residential applications. Marble and stone: Marble is widely used in monumental spaces and prestige locations such as banks. Marbles are available in varied colors and veining patterns. The element components of marble determine the color of the stone. Generally calcite and dolomite marbles are of pure white color. Variations of whiteness of pure marbles are due to the mixture of foreign substances. Such impurities form streaks and clouds. Travertine is a popular type of marble that is used for walls and floors. Travertine is generally filled with grout before it is honed or polished, which produces a uniform surface more like other marbles. Travertine stones result from hot spring water penetrating up through underground limestone. When the water evaporates, it leaves behind layers of dissolved limestone and other minerals, giving it its banded appearance. Travertine stones are generally light-colored beiges and tans. Slate’s unique colors and texture make it appropriate for interior as well as exterior applications. Slate is formed in compressed layers and can easily be split to expose beautifully textured surfaces. The usual colors of slates are earthy browns, beiges, yellows, black, dark-grays, and greenish-gray, pinks, purples and copper are also found. They usually exhibit lots of variations even in the same quarry. Slates are used for flooring, cladding, and landscaping. Brick is frequently used as an interior finish either using normal bricks or as a panel system. The BrickIt™ Panel System for thin brick applications is a typical panel system that uses brick veneer. No footings, foundations, or supports are needed, and no permits are required when used as siding (Figure 14.11). Cladding: Wall cladding or paneling makes practical sense in many situations, and allows the character of raw materials to be explored in the context of contemporary wall decoration. Wood is the classic paneling material, and often reflects a feeling of luxury. Many homes and offices have wood paneling that covers all or part of a wall in a living room, study, or office space. Sometimes paneling is paired with another material on a single wall—it isn’t unusual for the top of a wall to be drywall and the bottom half to be wood paneling or wainscoting, for example. Wood paneling is typically installed as solid, interlocking boards. Sheets of wood are fairly thin, normally ¼- to ¾-inch thick, and are made of different kinds of hardwood that can be given a clear finish or


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less expensive woods meant to be stained or painted. Boards may be milled to overlap or to interlock with tongue-and-groove or shiplap edges. Wood paneling is also sold as a 4 x 8 foot sheet material with a wood-veneered or simulated wood surface. Paneling may be applied to drywall, directly to wall studs, or to furring strips applied over masonry surfaces. In many jurisdictions, building codes require installing wood paneling over a fire-resistant backing of drywall. Tiling is a tried and tested formula for areas of heavy wear or maximum exposure to water and heat, typically kitchens, bathrooms, and areas around pools. The material comes in a multitude of colors, shapes, textures, patterns, and sizes, from the tiny mosaic to the large squares and rectangles of ceramic tile (see floor finishes). Figure 14.11 The Brick-It™ Panel System is a typical Mirror is a material often used in confined panel system using brick veneer. areas where an illusion of increased space is desired. Mirrors are typically used in public spaces, lobbies, and reception areas. They may be either beveled or flat. Lighting can be enhanced with the use of mirrors because mirrors increase reflectivity. Although fabric is traditionally popular as a material for wall covering, and is available in a variety of colors and textures, vinyl and other plastic sheet materials have increased in popularity and are now often preferred as wall covering. Ceiling finishes: One of the recurring problems involving nonstructural materials is that of suspended ceiling failures. Suspended ceiling failures typically occur due to corrosion of the tie wires, deficiencies in the attachments at the ends of the wires (top or bottom), poor workmanship in the installation, or as the result of overload (loads not considered in the system design). To guard against tie-wire corrosion in new construction, the designer should specify stainless steel wire of nonmagnetic type. In existing facilities, small rust stains on the surface of the plaster may indicate complete corrosion of the wires within the plaster. Ceiling finishes are typically designed for both aesthetics and acoustics (Figure 14.12A,B). Typical ceiling finishes include acoustical tiles and panels, plaster, wood gypsum board, or exposed structure. Common deficiencies of ceiling finishes are damage from impact of equipment and improper use. For example, if a building user decides to attach a plant or some sort of hanging equipment on a plaster or acoustical ceiling panel system, it may result in deformation. Attention should be paid to stains or water damage on the upper level, which are often caused by roof leaks. Ceilings somewhat resemble walls. The newer ones are constructed of gypsum board placed over wood supports, while the older ones are plaster over either wood lath or gypsum lath. The same principles apply to them as apply to walls. Maintenance usually is minimal. You may see a hairline crack where the ceiling joins the wall where joint compound has dried out, or because there has been some movement. If the crack is small, resealing with caulk and repainting ought to do the trick. On the other hand, if the separation is larger, it will be difficult to completely hide it. You may want to think about installing crown molding to cover the separation and add beauty in the room.


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Figure 14.12A,B A. Typical floor/ceiling detail and B. Ceiling suspension system detail with aluminum ‘T’ extrusion.

On occasion, ceilings may sag. This may be due to the gypsum drywall panels loosening, or if you have plaster, the plaster coats may be pulling away from the lath underneath. It may also be structural, such as an overloading of a ceiling joist or truss above. Or it could be water—a leak which is working its way behind and under the ceiling material and causing deterioration. If this condition develops, it is time to call for professional help.


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14.3 SYSTEM DIAGNOSTICS The diversity of most interior systems within a facility necessitates a diagnostic approach of a more indepth systematic nature than most other building systems. The interior materials, finishes, and conditions often vary considerably within a given facility. The lobby may have marble and carpeting, the corridors may have wood and resilient sheet flooring, and individual offices may have any of a variety of different materials. The forensic architect should as part of any inspection or survey, identify and observe the condition of floors, walls, ceilings, and door finishes of typical internal areas, including, but not limited to, lobbies, corridors, assembly areas, and restrooms. Lack of adequate maintenance is one of the main deficiencies that is noticed in surveys. The condition of building amenities or other special features that are secured to the building fabric should be noted as well as major components (such as pools, spas, fountains, major kitchen appliances, etc). Portable items (such as furniture or portable kitchen appliances) are typically beyond the scope of typical baseline inspections. The forensic architect is not normally required to activate or operate appliances or fixtures. Evaluations should exclude determining or reporting STC (sound transmission class) ratings and flammability issues/regulations. One of the most frustrating problems a building manager can face is when floor moisture problems are encountered. These are most often associated with concrete slabs-on-grade (floors supported by soil). Problems most often occur with non-breathable floor coverings such as vinyl, resin terrazzo, plasticbacked carpet, or vinyl composition tile. The primary cause of the problem is moisture vapor that emits from the concrete and that can result in debonding, bubbling, or warping of the floor covering from moisture vapor condensing beneath the floor covering. Unfortunately, there are rarely simple solutions to remedy this problem once the floor covering has been installed, and if left untreated, the problem can result in tripping hazards, unsightly floors, and mold growth. However, if a good-quality vapor barrier is used under the slab during construction, floor vapor levels normally remain at acceptable levels after initial drying. In the evaluation of interior systems, several diagnostic methods and tools are employed. The majority of the diagnostics utilized during the evaluation of interior systems is based on straightforward sensory evaluation. System components should be visually reviewed for deterioration or inability to perform the intended tasks. Cosmetics and function both need to be reviewed to make recommendations toward a more pleasing and usable facility. It is also useful for the forensic expert to probe as much as possible behind installed finish materials, in case more serious deficiencies exist that have been concealed. This includes damage and defects existing behind wallpaper, paneling, ceiling tiles and other finishes. To briefly summarize, the forensic architect should evaluate the following during an initial walk-through inspection or survey: 1. Observe the integrity and working condition of interior floors, walls, and ceilings including a representative number of primary doors and windows inside the building 2. Record any evidence of water penetration into the building including evidence of abnormal or harmful condensation on building system components observed inside the building 3. Record any signs of abnormal settlement, damage, or deterioration (other than normal wear and tear) with regard to floors, walls, and ceilings observed inside the building 4. Observe the operation of a representative number of receptacles and permanently installed switch controlled lighting fixtures inside the building and report any receptacle type wall outlets found to exhibit reverse polarity or open ground


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5. Observe the polarity and grounding of a representative number of receptacle wall outlets inside the building including all receptacles located within six feet of interior plumbing fixtures, and all receptacles located just above the finish grade on the exterior of the building The following issues are not normally included in a walk-through survey unless specifically agreed to with the client: 1. The moving of furniture, appliances, personal storage and the like in order to observe interior floors, walls, or ceilings blocked or concealed from view 2. Determination of the exact cause or origin of water penetration or stains as observed at the time of inspection 3. Removal of ceiling tiles, other than at random locations, in order to observe the entire space or structure above 4. Observe or report on the condition of finish treatments such as paint, wallpaper, or carpeting on interior floors, walls, or ceilings with the exception of buildings built before 1979 and characterized by loose or flaking paint


CHAPTER

15 Exterior Closure Systems—Building Envelope 15.1 GENERAL By building envelope we generally refer to those building components that enclose conditioned spaces and through which thermal energy is transferred to or from the outdoor environment. The building envelope consists therefore of all exterior components of a building (roof, walls, windows, below-grade waterproofing, etc.), that separate the exterior environment from the interior environment. The design of the envelope is very complex and many factors have to be evaluated and balanced to ensure that the desired levels of thermal, acoustic, and visual comfort together with safety, accessibility, and aesthetic excellence are achieved. The envelope has the function of responding to both natural forces and human values. The natural forces include rain, snow, wind, and sun. Human concerns include safety, security, and task success. To achieve this, a typical building envelope uses many systems, each consisting of multiple components and complex technologies. These components need to be properly detailed and maintained for the envelope to be effective. The condition of the building envelope is vitally important since failures can result in safety and health problems, as well as structural damage. Proper evaluation of the building envelope’s performance is often a first step toward stabilization and rehabilitation of the building. It is essential for the forensic expert to understand the condition of a structure, as well as its major building systems and components, as this can be critical to determining its economic viability. The building envelope usually represents a significant percentage of a building’s cost and is paramount in the determination of the overall performance of the building, with an emphasis on the thermal environment, lighting, and acoustical characteristics. A building’s performance can be defined in terms of functional qualities such as resistance to weather, load-bearing capabilities, and appearance. But the ultimate success of any energy

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management program requires an accurate assessment of the performance of the building envelope, for without a proper understanding of how well the envelope performs, a true understanding of the interactive relationships of lighting and mechanical systems cannot be obtained. For new buildings, unreliable building envelopes can permit water leakage from the start, requiring significant effort to correct deficient components. For existing buildings, maintenance is often deferred and water infiltration into the wall system can go unnoticed for extended periods of time, with building components continuing to deteriorate. Thus although it can be an expensive process to construct and/or maintain a comprehensive and reliable building envelope, the consequences of not doing so are even higher, and with construction costs increasing annually and the amount and extent of deterioration multiplying, the cost of a comprehensive building envelope restoration project significantly increases. By implementing a periodic maintenance program, the service life of the building envelope can be increased and the cost of deferred maintenance can be decreased. Today’s building envelope is witnessing a number of emerging innovations that are still in their infancy such as the double-skin curtain wall that aims to provide controlled natural ventilation and hybrid systems that aim to achieve substantial energy savings as a hedge against an uncertain energy future.

15.2 EXTERIOR WALL SYSTEMS 15.2.1

Masonry Wall Systems

A masonry wall system is an organized assemblage of interdependent parts that work together to form a building envelope (Figure 15.1). The wall may be comprised of a combination of clay brick, concrete masonry units, stone, calcium silicate units, etc. The backup may consist of various materials including concrete masonry, wood frame construction, steel stud construction, concrete, etc. Masonry is typically site constructed where the units are laid in mortar to various heights, with the strength of the assembly being achieved during curing of the mortar. The forensic architect should be knowledgeable of the properties of each material and the detailing implications these properties may have on the design. Masonry can form structural elements (bearing walls, beams, columns, pilasters, multi-wythe brick walls with grouted collar joints, and hollow brick walls) and/or the finished cladding system. Masonry walls can be single or multi-wythe. A wythe (also called tier) of masonry refers to a thickness of wall equal to the thickness of the individual units. Reinforced brick masonry (RBM) is different from more conventional brick veneer in several ways. Key to those differences is the concept of grouting the brick masonry. Thus, in addition to forming the exterior cladding, masonry walls can serve to increase the fire resistance of the wall system or structural elements. Quality assurance and minimum standards of workmanship are necessary to ensure a high level of consistency and adequate masonry performance. Brick exterior walls are often classified as either barrier walls or drainage walls. Barrier walls are solid masonry walls that lack drainage cavities. They can be constructed of single or multiple wythes, either of brick, or with concrete masonry unit back-up. Multiple wythe brick barrier walls (three wythes or more) are usually capable through mass, to prevent water infiltration to the interior. In a barrier wall constructed with two wythes of brick (or in composite walls), a collar joint (grouted solid with mortar) joins face brick with a masonry back-up. Water that penetrates the face brick follows the collar joint down to flashing where it is either expelled through the bed joint and/or at weeps, or it dissipates through the face of the wall. Drainage walls (e.g., masonry veneer systems) are designed with cavities between outer wythes of face brick and back-up walls of brick, concrete masonry units, metal or wood stud framing. Should water


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penetrate the face brick or enter the cavity, it is collected at flashing where it is expelled through a bed joint and/or at weeps. The materials used to construct RBM elements should be compliant with the applicable ASTM standards. Brick should meet the requirements of ASTM C 62 Specification for Building Brick, C 216 Specification for Facing Brick, or C 652 Specification for Hollow Brick. Mortar should meet the requirements of ASTM C 270 Specification for Mortar for Unit Masonry. Grout should comply with ASTM C 476 Specification for Grout for Masonry. Metal wall ties, bar positioners, and reinforcing bars and wires should meet the applicable ASTM standards stipulated in the Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602)[2], also known as the MSJC Specification. All metal wall ties, positioners, and joint reinforcement should be corrosion resistant or protected from corrosion by appropriate coatings. Masonry materials: Masonry has been Figure 15.1 Basic elements of an exterior wall used in building construction for thousands of system. years. The more common masonry unit types include clay and concrete units. These may be solid or hollow, and glazed or unglazed. Other masonry unit types include cast stone and calcium silicate units. Brick is made of fired clay and is available in an array of colors, textures and shapes. Its color is derived from the clay or from additives. In either case, the color is as permanent as the brick itself. Bricks also come in a variety of sizes and have been called by many different names due partly to regional variations. This proliferation of sizes and names can sometimes be confusing for the design consultant or the forensic architect. This confusion is further compounded by the need to distinguish between nominal, specified and actual dimensions. Efforts by the Brick Industry Association, the National Association of Brick Distributors and others have led to the development of standard nomenclature for brick which represents the majority of sizes currently manufactured. Facing brick is brick that is made or selected to give an attractive appearance when used without rendering or plaster or other surface treatment of the wall and is manufactured by a controlled mixture of clay or shale to produce high quality units in specific sizes, colors and textures (Figure 15.2). It is typically manufactured to SW and MW grades. Facing brick is classified according to criteria affecting its appearance. Hollow brick is also classified by factors affecting its appearance. Hollow brick are used as either building or facing brick but have a greater void area. Most hollow brick are used as facing brick in anchored veneer. Hollow bricks with very large cores are used in reinforced brickwork and contain steel reinforcement and grout. Glazed masonry bricks have a ceramic glaze finish fused to the brick body. The glaze can be applied before or after the firing of the brick body. These bricks may be used as structural or facing components in masonry. They should be manufactured to ASTM C 126 standard (Standard Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units).


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Concrete masonry units (CMUs) are typically made from a mixture of portland cement and aggregates under controlled conditions. Concrete masonry units should meet the requirements of ASTM C 90. The unit’s categorization is based on its weight (lightweight, normal weight, and heavyweight). Standard unit dimensions (nominal) are 8 inches high by 16 inches wide, although the units can be manufactured to custom sizes and face textures. The units are often used along with masonry to form a load-bearing wall or an interior partition between spaces within a building. Mortar joints are typically tooled when they are “thumbprint” hard (pressing the thumb into the mortar leaves an indentation, but no mortar is transferred to the thumb) with a jointer slightly larger Figure 15.2 A custom residence using the two than the joint. Proper tooling of mortar joints is imbasic brick types—facing bricks and pavers. portant because it assists in sealing the wall surface against moisture penetration. If joints are tooled prematurely they often smear and result in rough joints. If too much time elapses before tooling the surface of the joint, it cannot then be properly compressed and sealed to the adjacent brick. It has been found that concave, “V,” and grapevine joints best resist water penetration in exterior brickwork. These joints produce a denser and more weather-tight surface, as the mortar is pressed against the brick. For interior masonry work, other joints such as the weathered, beaded, struck, flush, raked, or extruded joints can also be used (Figure 15.3). Masonry installation: It is important that masonry is installed on a solid, rigid base such as a concrete foundation or structural steel or concrete beam system. There are many anchoring methods but it is often difficult to determine which type of anchor is best suited for the application. In some cases, there may be more than one type of anchor that will work well. Most building codes do not allow the weight of the masonry to be supported by wood framing, due to the strength loss of the wood member when exposed to moisture. Support systems must be designed for small deflections (typically 1/600th of the span) to avoid cracking of the masonry. Installation entails the masonry units being laid in a bed of mortar. Horizontal joints between units are called bed joints while vertical joints are called head joints. Clay brick masonry should include solid (full) head and bed joints. In concrete masonry it is common to lay the units with mortar only on the Figure 15.3 Typical brick mortar joint details used in masonry construction (courtesy, The Brick Industry face shells. Full bedding of CMUs is typically only Association). performed where a portion of the cells will be filled


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with grout. Where grouting is performed, mortar should be kept from falling into the cells to avoid the formation of a weak plane in the grout. Masonry expansion and shrinkage: Upon manufacture, clay masonry units expand when exposed to moisture whereas concrete masonry units typically shrink following manufacturing. These movements, if not accommodated in the design of the masonry elements, can cause cracking, spalling, and displacements in the masonry. Clay and concrete masonry also undergo cyclic thermal movements, expanding in warm temperatures and contracting in cold temperatures. Movement joints must also accommodate these movements. In clay masonry construction this is addressed by the incorporation of expansion joints, particularly in areas exposed to the exterior where the units will encounter moisture. Expansion joints are typically needed at corners, offsets, and other changes in wall plane as well as changes in wall construction. They are normally incorporated at regular intervals of 20 to 30 feet on center maximum, depending on the units. Concrete masonry walls are typically reinforced with joint reinforcement for shrinkage control. The spacing of control joints varies, being determined by the size and spacing of the reinforcement. However, control joints are required in all concrete masonry walls. Guidelines for control joint placement are provided in National Concrete Masonry Association Tech Note 10-A. Wall systems: Building wall systems may be divided into three broad categories depending on the function they serve. These are: 1. Veneer system, 2. Structural/load bearing wall system, and 3. Non-load bearing wall system. A masonry veneer system typically consists of an exterior wythe (or tier) of masonry that forms a cladding material only, which means that lateral support for the masonry veneer is required. This is normally provided by an interior wall. Common interior walls (backup walls) are typically cold-formed steel framed walls with water-resistant sheathing and concrete masonry. Some of the components that constitute a masonry veneer system that are critical to the success of its performance include: •

• • • •

Provide air space/drainage cavity behind veneer wythe to allow water that penetrates the masonry to flow down to the base of the wall, where it can be directed to the exterior. The recommended cavity width behind the masonry veneer is 2 inches minimum. Include a flashing system at the base of the drainage cavity. A flashing system should be installed that consists of a three-sided pan, typically formed by metal and/or membrane materials, to collect water that penetrates into the drainage cavity and direct it to the exterior via drains or weeps. Provide appropriate cavity seals at windows, doors, and other openings to prevent the passage of cavity air (and moisture) to the door/window frames. A lateral tie system to anchor veneer to the structural back-up. A vertical support system to support the weight of masonry veneer. This is typically provided at each floor line. Provisions for expansion/contraction of the wall system. For a brick masonry veneer, provisions must be made at each of the vertical supports to accommodate the masonry’s vertical expansion. This is accomplished by omitting the mortar between the top course of masonry and the underside of the support. This joint should be designed to accommodate the vertical expansion of the masonry, as well as structural deflections of the support. In concrete structures, creep of the concrete frame should also be accommodated.

Metal ties are required to provide the lateral attachment of the veneer to the backup wall. These are typically spaced at 16 inches on center in each direction.


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Mortarless brick veneer siding: Mortarless brick veneer is an exterior siding system which uses interlocking-shaped concrete bricks that require no mortar for installation. The product is supported by the wall, not the foundation of a building (Figure 15.4). In most applications, the existing wall framing structure supports the weight of the bricks, so foundation ledges are not required, and the system is suitable for retrofitting existing walls. Structural masonry walls are typically constructed using concrete masonry. The concrete masonry can be reinforced both vertically and horizontally to achieve the required flexural resistance. Vertical reinforcement that is installed within the cells of the concrete masonry is generally grouted solid. Horizontal reinforcement is typically installed using prefabricated welded wires that are embedded in the Figure 15.4 An example of the Novabrik bed joints. The horizontal reinforcement improves the mortarless brick veneer siding system (courtesy, strength of the masonry, particularly for horizontal WBDG). spans, and also helps control shrinkage cracking. If structural masonry walls are to serve as exterior walls, a second tier of masonry is typically recommended. In this construction, the masonry can be built as a composite wall (both tiers act as one unit to resist loads) or as a non-composite wall (individual tiers act independently to support loads). If single wythe exterior walls are to be used, a barrier should be provided on the exterior surface, such as a fluid-applied, breathable masonry coating or over-cladding (EIFS, metal panels, stucco, or similar) to prevent water penetration into the masonry. Admixtures can be incorporated in the fabrication of concrete masonry units to reduce water penetration through absorption. While these systems can be effective in reducing the amount of water penetration into the masonry; they should not be relied upon to eliminate water penetration. Thermal and acoustic performance: The thermal performance characteristics of the masonry are primarily based on the insulation placed within the wall cavity or within the backup wall. Because of their mass, the acoustic performance of masonry wall systems is superior to lighter wall systems. Performance can be further improved by eliminating the voids in the cores by filling the concrete masonry with insulation. Maintenance: Properly constructed, masonry wall systems require relatively little maintenance as compared to other wall systems. The most frequent element that requires maintenance is the regular replacement of sealants in expansion joints, perimeter of openings (windows, doors, etc.), and at through wall flashings. Repointing of the mortar joints in exterior masonry is typically required every 20 to 30 years after installation. Masonry walls have a service life of 100 years or more, depending on the detailing and maintenance. Testing: On some RBM projects, it may be necessary to conduct various quality control tests to ensure that the masonry has been properly constructed. This may be conducted prior to or during construction on the individual materials, e.g., brick, mortar, and grout. Bricks are typically tested for compressive strength prior to construction. Mortar may be tested in compression prior to construction in order to establish proportions of ingredients to be measured at the jobsite. The same applies to grout, which should also be tested to verify the slump. The Masonry Standards Joint Committee (MSJC) specification stipulates


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the type, method, and frequency of material and assemblage quality control tests required for masonry elements. Research and development in the construction industry is an ongoing process. New developments in masonry wall design include the use of pre-stressed masonry. This consists of building a concrete masonry wall with cables within the cells, similar to a pre-stressed concrete element. After the wall is constructed, the cables are tensioned and anchored to the masonry. This can greatly increase the resistance of the masonry wall to flexural loads and bending. The necessity to make building envelopes more blast-resistant has forced research of reinforced masonry façade design options with respect to water integrity and thermal performance.

15.2.2

Stone Wall Systems

In many prestigious buildings, the building envelope covering material consists of either granite or marble systems. These thin stone wall systems typically consist of stone panels ranging in thickness from 3/4 inches to 2 inches. While most panels are fabricated from granite or marble, other materials such as limestone, travertine, and sandstone are also used to a lesser extent. A common panel thickness is 1 3/16 inch (3 cm). Overall panel dimensions can vary significantly for different buildings, depending on the strength of the stone used and the architectural effect desired (Figure 15.5). However, maximum panel dimensions are usually approximately 3 to 4 feet and usually not more than approximately 6 feet. Typically, each panel is independently supported to the building structure or back up system using an assemblage of metal components and anchors. Types of stone: Granite is the most commonly used stone type in thin stone wall systems. The commercial classification of granite usually refers to a stone that includes any visibly granular igneous rock consisting of mostly feldspar and quartz minerals. This commercial term encompasses a wide variety of geologic stone types rather than only the limited number that fall under the geologic classification of granite. Geologically, marble is a metamorphic rock resulting from the recrystallization of limestone. While less commonly used in this type of application today, marble is also sometimes used in thin stone wall systems. Sedimentary rocks such Figure 15.5 Detail of stone veneer with through-wall flashing (courtesy, WBDG). as limestone and sandstone can also be


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used in thin stone wall systems. However, panels fabricated from these stone types are usually not less than 2 inches in thickness because of the lesser strengths of these stones relative to granite and marble. Anchorage systems: There are many choices for anchoring into concrete, masonry, and other base materials. It is often difficult to determine which type of anchor is best suited for the application. In some cases, there may be more than one type of anchor that will work well, but the appropriate anchorage system is normally selected according to the stone weight, in consideration of the instructions set by the manufacturer. There are three main criteria to be considered when selecting an anchor type: • • •

The type of base material to be anchored to Desired load capacity Type of load: static or dynamic.

The two primary types of stone installation are: the “hand-set” method, in which each stone is individually attached to the building’s primary structural frame or onto a secondary wall framing system, and the panelized installation method, in which the stone panel or multiple panels are preinstalled onto a frame or attached to a precast concrete panel. The frames or panels are transported to the building where the entire assembly is attached to the building’s structural frame or secondary structural members or framing system. In either installation system, anchors must be used to attach and support the stone panels to the building’s primary or secondary framing system, or to the panelized system frame or element. Structural aspects: Stone wall systems are traditionally constructed as a curtain wall or veneer, in which no building loads are transferred to the stone panels. Most typically, the stone wall system must resist lateral loads directly imparted on it, such as from wind and earthquake, as well as vertical loads resulting from the weight of the stone wall system. These loads must be transmitted through the stone wall system and secondary structural elements to the building’s structure. Other loads related to impact, construction, and transportation must also be taken into account in the design. In stone wall systems, the joints between the panels must be wide enough to allow for thermal expansion and differential movements between panels; 3/8 inch wide joints are typically used. Joints between panels are most commonly sealed with sealant and are the primary line of protection against water penetration into the wall cavity. The wall cavity space and the backup wall, which is usually covered with a water resistant membrane, provide a secondary line of protection against water penetration into the building. Through-wall flashing is usually located throughout the height of the wall at regular intervals to divert water that enters the cavity back to the exterior. Thermal and acoustic performance: Thin stone wall systems derive their thermal performance characteristics primarily from the amount of insulation placed in the wall cavity or within the backup wall as the stone and supporting wall elements provide little insulating value. Because of their mass, stone wall systems may provide better sound insulation than lighter wall systems such as metal panels. Moisture protection: The wall cavity drainage system described above is the most common moisture protection system used in conjunction with stone wall systems. Rain screen systems are also used with thin stone wall systems. In these systems, the primary water resistant barrier is located on the surface of the backup wall, joints are left unsealed, and the stone panels provide a rain screen that minimizes the amount of water that can reach the backup wall. Barrier systems are sometimes employed on certain stone wall systems where the stone panels are in direct contact with the backup wall. Types of finish and material durability: Several finishes can be achieved with stone used in wall systems: for granites and marbles, a polished, highly reflective finish is common. Thermal finish is a rough textured finish that is often employed with granite. Most distress observed in stone wall systems can be attributed to anchors used to attach stone panels to the structure. Panel cracking, displacements, or other


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distress conditions can occur at locations where anchors are inadequately or improperly connected to the stone. Maintainability: Properly constructed, stone wall systems require relatively little maintenance as compared to other wall systems. However, periodic review and evaluation of thin stone veneers may be desirable to determine if any evidence of structural distress exists in the panels due to strength loss and/or accumulated stresses at anchor points. Similarly, periodic review and evaluation of exposed stone surfaces may also be desirable, depending upon the location and exposure of the building. The only maintenance that may be required is periodic replacement of sealant in joints between panels; the time frame for this activity depends on the sealant used but usually ranges from every seven to 20 years. Applications: Stone wall systems have been employed to achieve a wide range of architectural styles, aesthetic affects, and appearances. Generally, thin stone wall systems are used in all environments. However certain stone types such as some marbles may not be appropriate for environments with significant thermal cycling. One of the more interesting recent developments regarding traditional thin stone veneers has been the emergence of “ultra-thin” stone panels in commercial construction. These systems have become increasingly popular in recent years for façade applications on larger, more complex multi-story commercial office and retail projects.

15.2.3

Concrete

The word “concrete” has come to symbolize both strength and permanence. Yet, for all its seeming permanence, concrete has come under continuous attack since the time it was first formed and poured. The relative rate of degradation resulting from these assaults depends on a wide variety of factors, not all of which are controllable. Fundamental understanding of these factors provides the foundation for recognizing when a facility is in need of repair. The architect generally selects the cladding material for appearance, provides details for weatherproofing, and specifies performance criteria. The structural engineer designs the structure to hold the cladding, designates connection points, and evaluates the effects of structural movement on the cladding. The precast concrete manufacturer designs the cladding for the specified loads, erection loads, connection details, and provides for the weatherproofing, performance, and durability of the cladding itself. Precast cladding systems are the most common use curtain walls for building envelopes. Precast concrete wall systems come in a variety of shapes, colors, textures, and finishes which is why the assessment of samples is a key component when using precast concrete. This assessment is in addition to the quality control and field testing that takes place during the production phase. These types of precast concrete panels do not transfer vertical loads, but are designed to resist wind, seismic forces generated by their own weight, and forces required to transfer the weight of the panel to the support (Figure 15.6). There are generally four types of precast panels used as part of building envelopes: • •

Cladding or curtain walls Load-bearing wall units: These resist and transfer loads from other elements and cannot be removed without affecting the strength or stability of the building. Common load-bearing wall units include solid wall panels, and window wall and spandrel panels, mullions, and column covers. Shear walls: Precast concrete shear wall panels are used to provide lateral load resisting system when combined with diaphragm action of the floor construction. The effectiveness of precast shear walls is largely dependent upon the panel-to-panel connections. Formwork for cast-in-place concrete.


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Figure 15.6 Architectural precast round penetration flashing detail (courtesy, WBDG).

15.2.4

Structural aspects: Precast concrete wall systems are similar to those of stone wall systems. Most distress and deterioration encountered with precast concrete wall systems can be attributed to problems during erection, anchors used to attach panels to the structure, or corrosion of the embedded reinforcing steel. Panel cracking, displacements, or other distress conditions can occur at locations where anchors are inadequately or improperly connected. The internal damage caused by the corrosion of the embedded reinforcing steel is perhaps the major cause of concrete degradation. In addition to deterioration of the steel itself, the corrosion affects the concrete surrounding it, which results in cracking, delamination, and spalling. Since virtually all of the concrete found in structures is steelreinforced, this is a widespread problem. A concrete repair specialist can also help determine both the underlying cause of the problem and the optimal solution.

Exterior Insulation and Finish System (EIFS)

Exterior insulation and finish system (EIFS) is an exterior wall covering system that is made to look like traditional portland cement stucco and that utilizes rigid insulation boards on the exterior of the wall sheathing with a plaster type exterior skin. The concern that has arisen with EIFS is that if not properly installed or maintained, moisture can penetrate through openings in the cladding and become trapped. In the case of a wood framed structure, the trapped water is absorbed by the wood and wood rot, decay, fungus, and insect infestations become problems, none of which are externally visible. Because of the perilous nature of the problem, detailed visual inspections and moisture analyses by experienced and certified EIFS inspectors are recommended on buildings with this type of cladding system. Inspectors often use electronic moisture scanning instruments with visual inspection to evaluate for problematic areas. Opinions should be rendered as to the acceptability of the moisture levels and remedial recommendations made. With new EIFS installations, the review of drawings and detailed inspections during various application phases can ensure that the system is installed according to the manufacturer’s specifications (Figure 15.7). The main difference between a traditionally hard-coat stucco exterior system and a barrier EIFS system is that the stucco’s facade is meant to be a primary barrier, but a secondary or “concealed” barrier directs any water that gets behind the facade to the exterior, thus creating a dual barrier to wind-driven rain, snow, and ice. By contrast, barrier EIFS uses multi-layer “synthetic” stucco that is much softer than tradi-


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tional stucco, and while it has the appearance of stucco and is installed similarly, barrier EIFS will not allow water to pass back through the coating in vapor form once moisture gets behind the system. EIFS is available in two basic types: 1. A barrier wall system, or 2. A wall drainage system. Barrier EIFS wall systems rely primarily on the base coat portion of the exterior skin to resist water penetration. Therefore, all other components of the exterior wall must either be barrier type systems or be properly sealed and flashed to prevent water from migrating behind the EIFS and into the underlying walls or interiors. Wall drainage EIFS systems are similar to cavity walls; they are installed over a weather barrier behind the insulation that acts as a secondary drainage plane. The weather barrier must be properly flashed and coordinated with all other portions of the exterior wall to prevent water Figure 15.7 EFIS application—foundation with starter from migrating into the underlying walls or track (courtesy, Dryvit). interiors. Thermal performance: The popularity of EIFS comes from its superior insulating qualities to reduce thermal loads on the exterior building wall and the light weight, low cost, and the ability of the system to be sculpted into shapes and patterns to achieve different aesthetic effects. The thermal performance of the exterior insulation is based on the thickness of the insulation selected. The insulation should never be installed or modified to less than ž inch in thickness. Moisture protection: As mentioned earlier, problems observed with in-service EIFS installations are primarily related to moisture intrusion. EIFS provides protection against moisture infiltration at the base coat; however, moisture migration through window openings, flashings, and other items, or holes and cracks in the EIFS itself, have allowed leakage to occur on EIFS clad buildings. With barrier EIFS installations, or where weather barriers and flashing are improperly installed in conjunction with wall drainage EIFS installations, moisture can enter the wall system at these locations and cause damage to the wall sheathing and framing. The extent of these occurrences on wood frame structures has led to many class action lawsuits. Maintainability: Maintenance of the EIFS lamina and sealants at penetrations or terminations is critical to the performance of the water resistive characteristics of the EIFS. Holes and cracks should be repaired as soon as possible. Maintenance of joint sealants is the same as that for other types of wall claddings, except that care must be taken to prevent damaging the EIFS when removing existing sealants.

15.2.5

Curtain Walls

Curtain wall systems have evolved and developed significantly over recent decades, and have grown increasingly popular in building construction. A curtain wall is the facade element that forms the weather bar-


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rier for the building without supporting the structure. This includes heavy wall types such as brick veneer and precast concrete panels. It can have many different appearances, but typically has narrowly spaced vertical and horizontal mullions with glass, stone, metal, or composite panels. When designed properly, it is beautiful and highly functional in keeping the elements out and the temperate environment in. There are various types of curtain wall including the stick system, unit panel system, unit mullion system, column cover and spandrel systems, and point-loaded structural glazing systems. One method of classification is that of fabrication and installation which puts it into two general categories: stick-built systems and modular or unitized systems. The stick-built system is the oldest type of curtain wall. It is a cladding and exterior wall system which is hung on the building structure from floor to floor. It is assembled from various components to include steel or aluminum anchors, mullions (vertical tubes), rails (horizontal mullions), vision glass, spandrel glass, insulation, and metal back pans. In addition, there are various hardware components to include anchors, aluminum connectors, setting blocks, corner blocks, pressure plates, caps, gaskets, and sealants. A unitized (modular) curtain wall system is a glass and aluminum curtain wall fabricated and installed as a panel system. The curtain wall in this system is composed of large units that are assembled and glazed in the factory, shipped to the site, and erected on the building. Vertical and horizontal mullions of the modules mate together. Modules are generally constructed one or two stories tall and may incorporate numerous panels and glazing units. Both the stick-built systems (Figure 15.8A,B) and the modular/unitized (Figure 15.9) are designed as either interior or exterior glazed systems. Interior and exterior glazed systems offer different advantages and disadvantages. Interior glazed systems allow for glass or infill installation in the curtain wall openings from the interior of the building and are typically specified for applications with limited interior obstructions so as to allow access to the interior of the curtain wall. In exterior glazed systems, glass and infill are installed from the exterior and are secured with glazing stops or pressure bar retainers. These systems are typically specified for systems that have obstructions on the interior of the curtain wall or are monolithic systems that cover large structural elements or entire elevations of the building. Some curtain wall systems allow glazing from either the interior or exterior. Typical infill panels include vision glass, spandrel glass, metal panels, thin stone Figure 15.8A Typical elevation stick-built curtain wall (Figure 15.10), and other opaque panel matesystem (courtesy, WBDG). rials, such as FRP (fiber-reinforced plastic).


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Figure 15.8B Curtain wall head detail—stick-built system (courtesy, WBDG).

Building code requirements govern many aspects of curtain wall design, including type and thickness of glass, maximum permitted glass area, design wind loads, and firestopping of wall cavities. Thermal performance: Overall curtain wall thermal performance is a function of the glazing infill panel, the frame, construction behind opaque (spandrel and column cover) areas, and the perimeter details. Some curtain wall systems utilize “pressure bars” that are fastened to the outside of the mullions to retain the glass. These systems frequently include gaskets that are placed between the pressure bar and mullions and function as thermal breaks as well as waterproofing barriers. Opaque curtain wall areas are subject to wide swings in temperature and humidity, and require careful detailing of insulation and air/vapor barriers to minimize condensation. Many curtain wall systems include condensation drainage provisions, such as condensate gutters, that collect and weep condensate from spandrel areas to the exterior. At the curtain wall perimeter, maintaining continuity of the air barrier reduces airflows around the curtain wall. Integration of perimeter flashings helps ensure watertight performance of the curtain wall and its connection to adjacent wall elements. Proper placement of insulation at the curtain wall perimeter reduces energy loss. Furthermore, curtain wall systems should be designed with swing stage tiebacks to stabilize swing stage rigs used by maintenance and cleaning crews.


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Figure 15.9 Vision glass jamb detail—unitized curtain wall system (courtesy, WBDG).

Thermal conductivity of the curtain wall system is important because of heat loss through the wall, which affects the heating and cooling costs of the building. On a poorly performing curtain wall, condensation may form on the interior of the mullions. This could cause damage to adjacent interior trim and walls. Maintainability and repairability: Curtain walls and perimeter sealants require maintenance to maximize their service life. Perimeter sealants, properly designed and installed, typically have a service life of 10 to 15 years, although breaches are likely from day one. Removal and replacement of perimeter sealants requires meticulous surface preparation and detailing. Anodized aluminum frames cannot be “re-anodized” in place, but can be cleaned and protected by proprietary clear coatings to improve appearance and durability. Factory applied fluoropolymer thermoset coatings have good resistance to environmental degradation and require only periodic cleaning. Recoating with an air-dry fluoropolymer coating is possible but requires special surface preparation and is not as durable as the baked-on original coating. Routine curtain wall inspections and evaluations will help identify issues that can compromise curtain wall efficiency. An effective curtain wall maintenance program would include: • •

Following a preventive-maintenance program suggested by the manufacturer. Scheduling regular inspections, cleaning, and prompt repair of minor problems. Inspection reports should be passed on to management for action. Hardware repairs and replacements should be carried out by professionals.


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Update maintenance records to document problems and solutions (this helps maintenance personnel make effective and informed decisions). Many factors affect the performance of curtain walls and can lead to deterioration and failure if not addressed in a proper and timely fashion. Weather (wind and rain) is a leading source of deterioration to the exterior components of a building. Gasket and sealant material selections are critical in preventing air and water infiltration; inferior quality can lead to early disintegration and failure. Proper panel installation is a key factor. Check for leaks in curtain walls, in the form of both air and water, as they can contribute to indoor air quality problems by supplying liquid water and condensation moisture for mold growth. Water or condensation can often remain hidden within the wall system and not become evident until concealed wall components experience significant deterioration and mold growth, requiring costly repairs or replacement. Routine inspections and evaluations help identify issues that can arise and compromise a curtain wall’s efficiency. Thoroughly check the system’s gaskets, seals, system joints, and the thermal insulation capabilities of the vision and insulating panels.

There are a variety of assessments to measure how well your curtain wall system is performing. These tests include measuring air leakage, water resistance, water drainage, wind resistance, ability of the curtain wall to support its own weight, safety, and thermal performance. Recent developments: In recent years we have seen the emergence of “smart” curtain walls that, like smart windows, control visible light transmittance by employing electrochromic or photochromic glass coatings (see the discussion in glazing). Double-skin systems, which employ a ventilated space between the inner and outer walls, are rare in the U.S., but have been used in Europe and Asia where energy costs are much higher. Similar in concept to air-flow windows, the ventilated space is intended to conserve energy by modulating the temperature conditions inboard of the curtain wall. During the heating season, the space acts as a buffer between the exterior and interior, and can be used to temper outdoor supply air. During the cooling season, warm interior air is exhausted into the space. Panelized metal wall systems: A wide variety of panelized metal wall systems are available for installation as a building’s exterior wall cladding. Each system must be specially adapted to its intended building use. Metal wall panels are usually fabricated of aluminum but can also be manufactured from steel, stainless steel, copper, or composite materials. A wide variety of solutions are implemented to prevent water leakage for metal Figure 15.10 Curtain wall with granite spandrel panels. panel systems including face sealed bar-


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rier systems, weeped drainage systems, and rainscreens. Rainscreen metal panel designs can be pressure equalized and back-ventilated. In general, simpler metal panel systems tend to be barrier systems while larger, more complex buildings feature drainage systems with back-up membranes or rainscreen design principles. Anchorage systems: Metal panel systems are engineered to support gravity, seismic and wind loading. The fastening of the panels also needs to accommodate interstory drift requirements in seismic zones. The support system of the panels needs to be able to accommodate tolerance from existing construction and fabrication. The metal panels are typically screwed or bolted on a structural frame which often consists of metal studs. Joints and joint detailing: Since metal is impervious to water, panel joint design is critical to the water tightness of the system. A metal panel building typically has an extensive number of joints. How the joints perform is a factor of the panel design and construction. If the metal panel system is designed based on a barrier system design, the joints between the metal panels are typically face sealed. If the system is a rainscreen or drainage design, the joints between the panels are typically left unsealed. Some designers select a rainscreen or drainage system for both performance characteristics and the aesthetic criteria of unsealed joints. Compared to concrete or masonry cladding elements, metal panel systems have higher coefficients of expansion for thermal movement. Designers of metal panel systems need to calculate the expected movement of metal panels due to changes of temperature. For example, a 20 foot long aluminum extrusion may expand or contract 0.30 inches when subjected to a 100 degree temperature change. Joints between panels must therefore be wide enough to accommodate thermal expansion and differential movements between panels. Thermal and acoustic performance: Metal panel wall systems typically derive their thermal performance characteristics from the amount of insulation placed in the cavity or within the backup wall. As for acoustic performance, metal panel systems do not typically offer much sound insulation (unless insulated). The metal panel back-up wall cavity is typically designed to provide for sound insulation. Maintainability: Properly designed and constructed metal panel systems require little maintenance. However, over the life of the structure cleaning and sealant replacement are required. If the system includes sealant, the time frame for sealant replacement usually ranges from seven to over 20 year periods, depending on the sealant used and the joint design. Nevertheless, there are a number of potential problems associated with the use of metal panel systems which, while not usually impacting their structural performance, are an aesthetic concern as they negatively affect the appearance of the system and include: •

• •

Pitting: Over time, as metal panels are exposed to weather and pollution, their protective coating can be attacked, resulting in a pitted appearance. While the pitting is not a structural concern, the pitting detracts from the appearance of the panel and the building. Oil canning: Oil canning is characterized by pillowing or waviness of the metal panel and can be caused by problems in fabrication, design, or installation. Oil canning detracts from the appearance of the panel, since part of the selection criteria for metal panels is often flatness. Shadowing: Installing welds or stiffeners on the backsides of metal panels can result in shadowing, a condition in which the weld or stiffener is visible on the panel face. Dissimilar metals: The use of dissimilar metals can result in water runoff staining and galvanic corrosion. When water runs off one type of metal onto another, it can stain and corrode the other metal. Galvanic corrosion occurs when one type of metal is in physical contact with another type of metal. The less noble metal will corrode, and this can affect the panel structural strength. When


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dissimilar metals are in close proximity, they should either be physically separated or reviewed for galvanic action potential.

15.2.6

Siding

Siding remains a popular cladding material in residential construction in the United States, and many types of siding are available in today’s market. Although all are subject to wear over time, newer manufactured sidings have been developed to require less maintenance than traditional materials such as wood. The most common siding materials used today include: •

Aluminum: After centuries of using wood clapboards which require sanding and painting to keep them in good condition, aluminum was suggested as a durable, easily maintained alternative. Its main disadvantage is that it dents easily.

Wood clapboard: Wood siding is a very durable material when properly maintained. The woods most often used are cedar, pine, spruce, redwood, cyprus, or douglas fir. Wood siding is installed over studs or exterior wall sheathing with an appropriate weather-resistant barrier (WRB), using galvanized nails or screws that penetrate into wall studs.

Engineered or composite wood: Made with wood products and other materials to look like wood, these engineered materials are less expensive than using wood for siding. Fiber-cement siding is an example of an engineered siding and is composed of cement, sand, and cellulose fiber that has been cured with pressurized steam to increase its strength and dimensional stability. The fiber is added as reinforcement to prevent cracking. Planks come in 5¼-inch to 12-inch widths and 5/16inch and 7/16-inch thicknesses. Fiber-cement siding is termite-resistant, water-resistant, non-combustible, and warranted to last 50 years. Installation is similar to that of wood siding.

Cedar shingles: These shingles look great in natural settings, and are usually stained in earth tones, browns, or grays. They require less upkeep than clapboard that needs periodic painting.

Brick: This material is discussed in earlier sections of this chapter.

Seamless steel: Anything made of steel is going to be durable, and seamless steel siding is no exception. It can be manufactured to resemble wood textures and unlike vinyl, it does not shrink or bulge when the temperature rises and falls.

Stone: Stone is the most enduring of all the various materials that can be used for siding and is discussed in earlier sections of this chapter.

Stucco: Stucco is basically cement combined with water and other ingredients like sand or lime. The rock hard surface cre-

Figure 15.11 An example of insulated vinyl siding cladding.


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•

15.2.7

ated by stucco is solid and keeps moisture out. While there are synthetic stuccos available, they offer less durability. Vinyl: Vinyl siding is a plastic made from PVC, or polyvinyl chloride with the advantage of being water-resistant, termite-resistant and not requiring painting. However, vinyl siding has a tendency to crack, split, and look faded after a few years of exposure to the weather. Manufacturers have made improvements on these problems, but they still exist. Of note, two new products give vinyl siding a competitive edge by increasing its energy efficiency and enhancing its impact resistance. One product is an insulative foam underlayment, custom contoured to fit snugly behind hundreds of different brands and styles of vinyl siding. The other is a line of vinyl siding products fused to a foam backing material, to create an all-in-one siding and insulation system (Figure 15.11).

Exterior Doors, Windows & Glazing

Doors and windows are pivotal elements of the exterior closure system because they provide both physical and visual access between the exterior and interior environments. Moreover, these penetrations provide the elements of greatest potential moisture problems in the façade, being the most common cause of water and air infiltration into buildings. For this reason, special weatherproofing precautions are often installed around the perimeter of exterior doors and windows (Figure 15.12). Doors: Exterior doors include entrance and exit doors, as well as industrial loading dock doors, and require materials that are waterproof and durable. Entrance and exit doors generally serve as building entrances for the general public or as service entrances for building operations personnel. They typically serve double-duty as emergency egress. The International Building Code (IBC), government regulations, including the Americans with Disabilities Act (ADA), and local codes govern many entrance/exit door requirements pertaining to life safety and accessibility which are discussed in Chapter 18 (Life Safety Systems). Commonly used door materials include aluminum, steel, wood, and glass. Doors that are integrated with commercial storefronts are typically aluminum frames with glass in-fills, or all glass. Steel-clad doors are generally utilized for service entrance/exit functions. Wood doors are most commonly employed in low density residential construction. Monumental wood or wood-and-glass doors are sometimes used in commercial or institutional buildings. Industrial doors are used for material handling, not for pedestrian access. Their Figure 15.12 Section of door head detail. main function is to provide security. They


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are, therefore, frequently not designed for building envelope performance. Rolling doors typically consist of a steel frame that is anchored to the perimeter construction to resist wind and operating loads, structural guides for the door edges, and a hood that contains the rolled up “curtain” when the door is in the open position. Larger industrial doors are motorized; smaller units can be operated by manual push-up, chain hoists, or cranks. Motorized doors are often opened and closed with automatic gate operators. Accessibility: The intent of accessibility regulations is to allow persons with physical disabilities to independently enter and use a building. Because non-compliant doors can present obstacles to wheelchairbound individuals, door design must account for accessibility. This is discussed in Chapter 18 (Barrier Free Design—ADA Requirements). Thermal performance: Doors can dramatically impact a building envelope’s thermal performance. Typical issues include heat loss from air movement during operation, heat loss from air movement through the perimeter detail, and radiant heat loss through the door materials themselves. Entrance vestibules with separate inner and outer doors provide improved energy performance over a single entrance door, mainly by limiting loss of conditioned air during door operation. When they are closed, all doors rely on weatherstripping between the operable sash and the door frame to limit air movement. Revolving doors minimize heating and cooling losses from air movement and minimize wind effects on door operability. Windows: Window units can be categorized as fixed, operable, or a combination of the two. Fixed windows generally offer better resistance to air infiltration and water penetration, as well as requiring less maintenance than operable windows. Materials commonly used in window frame construction include aluminum, steel, PVC, and wood. Aluminum frames are the most widely used window frame material, and provide design flexibility because of the wide range of available stock systems and the relative economy of creating custom extrusions. Steel frames on the other hand are less common than aluminum. PVC windows are resistant to water absorption, chemical corrosion, abrasion and rot, and are warp resistant. Wood frames are widely used in the residential market, often with aluminum or vinyl cladding to reduce maintenance. Water leakage has been and continues to be the main complaint relating to building facades, as expressed by building owners and managers. Much of this leakage can be attributed to window systems and their interface with other façade components. Understanding the basic waterproofing principles of window systems, common failure modes, and typical repair strategies can help resolve this issue. Types of window systems: The most common type of modern, non-residential (inoperable) window system is known as a drainage system; also referred to as a rain screen or skin-barrier system. This system has essentially two lines of defense against water leakage: the outer seals and an internal drainage system. The outer seals generally consist of rubber gaskets, preformed pliable tape, or sealants. The internal drainage system utilizes a network of window framing components, internal flashings, and sealant to capture any water that penetrates the outer seals and channel it back to the exterior. A less common type of window system is a barrier system, which relies on the outer seals as the only line of defense against water leakage. Emerging trends & technologies: Smart windows control visible light transmittance by using photochromic or electrochromic coatings. Some high R-value glazing includes the use of evacuated insulating glass units, which limit conductive and convective heat loss compared to conventional interior glass units. Air-flow windows incorporate a separate interior glass of lite and use either supply or exhaust air to modulate the surface temperature of the interior glass unit. Among the most promising switchable window technologies today is the electrochromic (EC) window, which has the ability to change from clear to a colored transparent state without compromising views. The main advantages of EC windows are that they typically only require low-voltage power (0 to 10 volts DC), remain transparent across their switching range, and can be modulated to any intermediate state between


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clear and fully colored. Switching occurs through absorption (similar to tinted glass), although some switchable reflective devices are now in research and development. Glazing: Architectural glass comes in three different strength categories. Annealed glass is the most commonly used architectural glass. Because it is not heat-treated and therefore not subject to distortion typically produced during glass tempering, it has good surface flatness. Heat-strengthened and fullytempered glass is a heat-treated glass product. Heat-strengthened glass has at least twice the strength and resistance to breakage from wind loads or thermal stresses as annealed glass. The necessary heat treatment generally results in some distortion compared to annealed glass. Fully-tempered glass provides at least four times the strength of annealed glass, which gives it superior resistance to breakage. There are several types of glass that are used in today’s building envelope. These include: •

• • •

Laminated glass: This consists of two or more lites of glass adhered together with a plastic interlayer. The plastic interlayer provides protection from ultraviolet rays and attenuates vibration, which gives laminated glass good acoustical characteristics. Because laminated glass has good energy absorption characteristics, it is also a critical component of protective glazing, such as blast- and bullet-resistant glazing assemblies. Coated glass is covered with reflective or low-emissivity (low-E) coatings. In addition to providing aesthetic appeal, the coatings improve the thermal performance of the glass by reflecting visible light and infrared radiation. Tinted glass contains minerals that color the glass uniformly through its thickness and promote absorption of visible light and infrared radiation. Insulating glass units consist of two or more lites of glass with a continuous spacer that encloses a sealed air space. The air space reduces heat gain and loss, as well as sound transmission. Self-cleaning or easy-to-clean glass was recently developed and uses titanium dioxide coatings as a catalyst to break up organic deposits. It requires direct sunlight to sustain the chemical reaction and rainwater to wash off the residue. Photochromic coatings incorporate organic photochromic dyes to produce self-shading glass. Originally developed for sunglasses, these coatings are self-adjusting to ambient light and reduce visible light transmission through the glass. Glass with electrochromic coatings utilizes a small electrical voltage, adjusted with dimmable ballasts, to adjust the shading coefficient and visible light transmission.

15.3 WEATHERPROOFING Since the beginning of time, man has sought shelter as protection from the elements. Likewise, in today’s competitive real estate market, building owners and investors desire a structure that remains aesthetically pleasing and leak free for as many years as possible. In the United States moisture intrusion into buildings annually causes billions of dollars in property damage. Moisture enters buildings in a number of ways. Rainwater penetrates through leaks in walls, floors, roofs, windows, and doors due to improper design, construction, and maintenance. Waterproofing techniques preserve a structure’s integrity and effectiveness through an understanding of natural forces and their effect during life-cycling. Moisture can also enter the building from improperly designed and/or constructed vapor barriers in walls, roofs, and floors. This condition is normally aggravated


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by the use of air conditioning and construction in hot and humid climates. Moisture in buildings is the number one contributor to mold and mildew growth. Mold and mildew should be removed before it contaminates the entire buildings and occupants (Figure 15.13). A building envelope should be designed to prevent the intrusion of nature’s elements (wind, cold, heat, and rain) into interior spaces and protect the building’s structural components from weathering and deterioration. When looking at these components from a weatherproofing perspective, it is essential that each component be taken into consideration to prevent moisture or air from migrating into the building.

15.3.1

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Figure 15.13 Photo showing effects of water penetration contributing to mold growth.

Air Barriers

There are several methods of transporting moisture and air permeability is one of the major ones. It relies on the premise that when hot, humid air contacts colder surfaces/temperatures, condensation occurs and moisture gathers, creating a potentially ideal breeding ground for numerous airborne organisms. Therefore, the control of air leakage improves the indoor air quality of a facility and ensures extended building durability and energy efficiency. It is estimated that air leakage can account for as much as 40 percent of a structure’s heat loss/gain.

15.3.2

Control/Expansion Joints, Sealants & Caulking

Control/expansion joints are designed to allow relative movement of adjacent building components while keeping a seal between the components. Vertical expansion joints are often employed to prevent cracking by accommodating movement of the wall, or of structural elements adjacent to the wall. These joints are vertical separations built into the wall at locations where cracking is likely to occur due to excessive horizontal stress. Control joints relieve horizontal tensile stresses due to shrinkage by reducing restraint and permitting movement to take place, but they should have sufficient shear and flexural strength to resist lateral loads and be weather tight when located in exterior walls. Their size and spacing along the wall length will vary from one project to another and depend upon: 1. Estimated magnitude and direction of potential wall movement(s) or other elements, 2. Resistance of wall to horizontal tensile stress, and 3. Extent and location in the wall of windows, door recesses, chases, and other causes of stress concentration. Caulking & sealants have the function of sealing the spaces between intersecting building components to provide a watertight seal, and are an integral element in a building’s design and construction. Caulking compounds are made up of a combination of oils, resins, plastics, and synthetic rubbers and are usually applied with a caulking gun which emits a consistent quantity of material. Although the chief function of a sealant is to prevent the infiltration of air, water, and other environmental elements from entering or exiting a structure, it should also allow limited movement of the substrates. Specialty sealants are used in special applications, such as for fire stops, electrical, and thermal insulation.


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Relevant codes and standards: ASTM has developed various standards and guide specifications used in the design, manufacture, testing, and installation of joint sealants. Additional information can be attained from the ASTM Web site: www.astm.org.

15.4 TYPICAL DEFICIENCIES Hands-on, close-up inspection is critical to the correct diagnosis of facade problems. Once a problem is detected, it needs to be appropriately addressed. An investigation should be conducted to look at the entire building envelope (i.e., roofs, walls, and basements), the building structural system, and mechanical systems to identify the real cause of the problem. It is important to keep in mind that what works for one building may not work for another. Brick exterior failures: Symptoms of deterioration in brick exterior walls are generally attributable to water infiltration and include staining and efflorescence, cracking, spalling, displacement, and deterioration in mortar joints, among other things. Efflorescence occurs when water washes soluble salts out of mortar and onto the surface of brick. It is apparent in the form of white crystalline particles that develop on brick surfaces as water evaporates (Figure 15.14). Water penetration through exterior masonry elements exposed to rain should be anticipated. Water typically flows through separations between the mortar and the units. This can be due to bond separations, voids, and cracks. Water penetration can also occur, although typically to a lesser degree, due to absorption through the units and mortar. Systems must be provided in exterior masonry construction with means to prevent water penetration into the wall system. Cracks: Building materials typically move in response to temperature and moisture fluctuations and cracks often occur when there is no provision for a material to expand or contract. This displacement of one material vs. another often indicates a lack of necessary control joints to accommodate such expected movements. Some materials, like concrete and stucco, develop fine shrinkage cracks (similar to cracks in dried-out mud); these are normal and nothing to worry about. Signs that may be indicative of more serious problems include wide cracks, vertical cracks running up concrete or masonry columns, and cracks near a building’s corners. After an earthquake, x-shaped cracks sometimes appear in piers between windows, as well as where towers and lower portions of buildings come together and pound against each other. All cracking should be evaluated by a trained engineer who can differentiate between normal cracks and those which repreFigure 15.14 A masonry brick wall showing signs of efflorescence. sent serious underlying problems.


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Building materials need periodic maintenance. The forensic architect/engineer should look for hardened or cracked sealant joints, shrinkage of window gaskets, cracks and erosion in mortar joints, and blistered or peeling paint. Particular attention should be paid to window sills, ledges, and tops of parapets. Windows can leak through the window parts themselves (less likely) or around the windows (more likely). Through-the-window leaks generally result from frame corners that were once sealed in the factory but have become unsealed, or from external gaskets that have lost their ability to seal between frames and glass. Window-perimeter leaks generally result from inadequate design and/or construction of the joint between the window and the façade. It is critical to determine the cause of the leak before undertaking a repair. Steel in buildings is usually hidden beneath the surface as reinforcement in concrete buildings, and anchors and ties in brick, stone, and terra cotta-clad buildings. When this steel rusts, the rust product expands with enough force to crack and cause the surrounding concrete or masonry to fall off. Early indications are orange rust stains and cracks in locations where steel is likely to be found (over windows and at steel columns in masonry-clad buildings, and in a regular grid in concrete buildings). The sooner the water supply is cut off and the corrosion repaired, the less damage will be encountered later. EIFS problems have recently been a major concern for many builders and contractors, particularly regarding the housing market, due mainly to water penetration and mold formation. The most common EIFS related problems include: • • • • • • • • • •

Failure to install or properly install sealant joints around windows, doors, pipes, conduits, and other penetrations of the field of the EIFS. Failure to flash window and door openings in the field of the EIFS to divert leakage through the window or door to the exterior. Failure to install diverters (kick-out flashing) at ends of roof flashing terminating in the EIFS wall. Failure to install expansion joints at floor lines in EIFS applied over wood frame construction. Failure to notch insulation boards at corners of openings for windows and doors to avoid insulation board joint at the corner of the opening. Failure to install diagonal mesh in lamina at corners of openings for windows and doors. Failure to terminate EIFS above grade, especially in termite prone regions. Inadequate base and finish coat application in reveals and at corners. Installation of reveals at board joints. Lack of adequate slope on skyward facing surfaces.

15.5 SYSTEM DIAGNOSTICS The performance and diagnosis of an exterior closure system varies greatly depending on the original design, installation, size, construction materials, and aging of the facility. Some exteriors are simply constructed using only a few different materials. Other exteriors consist of several different materials which interface in complex connections and details. The evaluation of a one-story concrete tilt-up warehouse building will differ greatly in time, effort, and level of expertise required compared to a high-rise curtain wall building. Likewise, shortcomings or deficiencies in the original design and installation can greatly impact an envelope’s performance as can the aging process.


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Prior to conducting an evaluation or field investigation of the exterior closure system, it is particularly important to review the drawings, specifications, and change orders for the system. This review may uncover inadequate or insufficient flashing details or other waterproofing deficiencies which may not be apparent during the physical review. Areas of concern should then be noted and inspected in the field. The forensic architect/engineer should identify and observe the condition of the building envelope including facades and/or curtain wall systems, glazing systems, exterior sealants, exterior balconies, windows, doors, stairways, parapets, canopies, etc. and record physical deficiencies, including masonry pointing and sealant repair requirements. The apparent or reported ages of building exterior elements should also be determined and combined with visual observations, identify the remaining useful life (RUL). Any survey or inspection should be systematic in its approach. One method in conducting the exterior review is to begin at the main entrance. Verify the conditions and operation of the entrance door. The facade should be reviewed for existing conditions. The evaluation should progress from the main entrance around the building and end upon return to the main entrance. High level access, either by ladders, lifting machines or exterior suspended platforms or slings, is excluded. Observations of the building’s exterior generally are to be limited to vantage points that are on-grade or from readily accessible balconies or rooftops. In the case of high-rise buildings, visibility can be improved by several methods. One way is to try and gain access to an adjacent building from which to view the building to be evaluated. Alternatively, the use of magnifying devices such as binoculars or a telescopic viewer can be useful to inspect the exteriors. Powered lifts or platforms in some cases can also be used. Most high-rise and several mid-rise buildings are equipped with powered scaffolding or swing stages which are used by window cleaning crews. For those trained to use the equipment, these devices are excellent in providing access to the system during evaluation. The exterior closure system’s interior side should also be accessed and inspected. This is perhaps most conveniently done during the physical inspections of the interior system. Evidence of any breach of the closure system should be investigated. This is most often damage related to water infiltration at material intersections and penetrations, such as soffits, windows, and doors. In addition to the traditional uses of infrared thermography as outlined in earlier chapters, this diagnostic process can also be used to identify the avenues of air leakage, and excessive heat and energy loss through the building envelope. Since thermography can locate and determine changes in heat patterns, areas of heat leakage can be determined. Areas of missing insulation within the building enveFigure 15.15 Envelope infrared thermographic lope can be observed and located and areas of heat analysis. Large amounts of heat energy are lost to conduction and air leakage, problems that can be loss due to insufficient sealant or caulking can be pinpointed with infrared thermography. identified around doors and windows (Figure 15.15).


CHAPTER

16 Interior Air Quality— Environmental Issues 16.1 GENERAL It is only in the past few decades that the general public has become aware of the health hazards of contaminated air. A variety of factors contribute to poor indoor air quality in buildings, including indoor pollutants, outdoor pollutants adjacent to the building, pollution carried by ventilation systems, and emissions from building materials, furnishings, and equipment. Poor indoor air quality can harm the health and reduce productivity of workers, students, and even families in their own homes. Recent studies show that humans spend up to 90 percent of their time indoors. It is not surprising therefore that we expect our indoor environment to be free of effects that will damage or compromise our health. Yet according to the American College of Allergies, 50 percent of all illness is aggravated or caused by polluted indoor air. Moreover, year after year, cases are documented of building related illness (BRI) and sick building syndrome (SBS). This is because the indoor environment we live in is often contaminated by numerous toxic or hazardous substances, as well as pollutants of biological origin (Figure 16.1). In fact, studies indicate that more than 900 possible contaminants, from thousands of different sources, are present in a given indoor environment. Thus within recent years, the quality of indoor air pollution has become an area of increasing concern, and is now recognized by many as having a greater impact on public health than most types of outdoor air pollution, causing numerous health problems from respiratory distress to cancer. Indeed, a building interior’s air quality is one of the most important factors in maintaining employee productivity and health. This heightened public awareness has resulted in an increasing number of building occupants demanding compensation for their illnesses. Tenants are suing building owners, architects, engineers, and others involved in the building’s construction. Building owners in turn have made claims against the consultant and those involved in the construction of the facility. As indoor air pollution receives more publicity, and as the government continues to emphasize the seriousness of indoor air pollution, more and more

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building occupants can be expected to assert claims against those they perceive to be responsible for their illnesses. While the architectural profession has not yet been a major target of publicity or litigation arising out of IAQ issues, the potential scope and cost of some of the incidents have led to everyone associated with a project being blamed when the air inside a building appears to be making residents, tenants, patients, or customers sick. This has resulted in a loss of reputation, money, and time, and is causing great concern among some design professionals. Fueled by intense competition to maintain high occupancy rates, forward thinking owners and managers of office and public buildings are under increasing pressure to meet or exceed the demands of the marketplace in attracting and retaining tenants. Regrettably today, in this increasingly litigious society, they add another priority: protecting their investment from liability resulting from air quality issues. Fortunately, technological breakthroughs are making facility monitoring systems more affordable for a wider range of building types. The list of benefits continues to expand as access to indoor environmental data and the knowledge it imparts is applied to building performance. Recent technological advances have thus removed many financial and maintenance obstacles, making permanent monitoring systems an appropriate consideration for a broader range of facilities managers. Schools, healthcare facilities, and general office buildings can benefit from measuring a host of environmental conditions and use that information to respond to occupant complaints, optimize facility perform-

Figure 16.1 Percentage of buildings with inappropriate concentration of contaminants (source, HBI Database).


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ance, and keep energy costs in check. In addition, feedback from the indoor environment can be used to establish baselines for building performance and document improvements to indoor air quality. Buildings are dynamic environments—and while the original design calculations may have been sound, after they are operational, the reality is that building use may change, and occupancy rates fluctuate. These changes can have a significant impact on the ability of the HVAC system (as designed) to maintain a balance between occupant comfort, health, productivity, and operating costs. Also, contemporary trends to achieve tighter building envelopes and high-efficiency windows to make buildings more energy efficient increase the need for adequate ventilation to compensate for the air that infiltrates into buildings through cracks and small holes. A facility monitoring system can be a valuable instrument for improving indoor air quality, identifying energy savings opportunities, and validating facility performance. Automating the process of recording and analyzing key parameters and providing facilities managers access to this information can better equip them to meet the challenge of maintaining healthy, productive environments. Indoor pollution exists under numerous diverse conditions from dust and bacterial build-up in ductwork to second-hand smoke and the off-gassing of paint solvents, all of which can become significant health hazards. Causes of indoor pollution: Inadequate ventilation is considered the single most common cause of pollutant build-up (Figure 16.2A), with inefficient filtration being the second most important factor (Figure 16.2B). But despite dramatic improvements in air filter technology, far too many buildings continue to rely on grossly inefficient filters, or are negligent in the maintenance of acceptable filters. General IAQ testing: An investigation for indoor air quality contamination can be triggered by adverse health concerns of occupants, or observations of growing mold, unusual odors, or events of water intrusion. A variety of symptoms or observations, such as respiratory problems, headaches, nausea, irritation of eyes, nose, or throat, tiredness, fatigue, etc. may also trigger an investigation. Useful parameters for evaluating indoor environmental quality and energy efficiency may be classified into three basic categories: 1. Comfort and ventilation. 2. Air cleanliness. 3. Building pollutants. Within these categories, facility-wide monitoring systems can provide independent measurement of a range of parameters, including temperature, humidity, carbon dioxide (CO2), carbon monoxide (CO), total volatile organic compounds (TVOCs), and airborne particulates. The information gleaned from continuous monitoring not

A

B

Figure 16.2A,B A. Inadequate ventilation is the single most common cause of pollutant build-up (source, HBI Database). B. Inefficient filtration is the second most important factor in the cause of indoor pollution (source, HBI Database).


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only facilitates the reduction of investigative time and expense in responding to occupant complaints, but can also be used proactively to optimize building performance. Although there has been minimal federal legislation controlling indoor air quality, several engineering societies such as the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) have established guidelines which are now widely accepted by designers as minimum air design requirements for commercial buildings. ASHRAE has established two procedures for determining an acceptable ventilation rate. These are: 1. The Ventilation Rate Procedure. This stipulates a minimum ventilation rate based on space functions within a given building type and is derived from respiration rates resulting from occupants’ activities. 2. The second procedure is called the Indoor Air Quality Procedure. This procedure necessitates monitoring certain indoor air contaminants below specified values. Air sampling requires the use of a devise to impinge organisms from a specific volume of air onto a sterile agar growth medium. The sample is then incubated for a specified period of time (say, seven days). The colonies are then counted and the results recorded. When testing the air of a potentially contaminated area, it is best to have comparative samples of air from both the contaminated area and the air outside of the potentially contaminated building. Environmentally regulated materials: The field of general building diagnosis and evaluation has in more recent times been expanded to include environmental evaluations. During the past decade an environmentally regulated material (ERM) evaluation has become an important part of both the condition assessment and due diligence efforts. There are several types of basic environmental assessments. The industry generally refers to Level I (Phase I) and Level II (Phase II) assessments. Level I is basically an overall view of the facility, and tends to be relatively general in nature. During the Level I assessment, the information gathered is preliminary and qualitative. A plan is then generated which includes an identification of specific issues which need further investigation. The Level II assessment to further assess the facility when necessary is quantitative and typically includes site sampling and characterization activities when contaminants are suspected. Measurements are taken and the extent of environmental hazard, contamination and liability at the property are determined. The assessor should submit recommendations to mitigate any problem issues.

16.2 SICK BUILDING SYNDROME Sick building syndrome (SBS) is a term used to describe situations in which building occupants experience acute health and comfort effects that appear to be attributed to time spent in a building, but no specific illness or cause can be identified. Complaints may be localized in a particular room or zone, or may be widespread throughout the building. Indicators of SBS include: •

• •

Building occupants complain of symptoms associated with acute discomfort, e.g., eye, nose, or throat irritation; headaches; dry cough; dry or itchy skin; dizziness and nausea; difficulty in concentrating; fatigue; and sensitivity to odors. The cause of symptoms is undetermined. The majority of the complainants notice relief soon after leaving the building.

In contrast, “Building Related Illness” or BRI is the general term for a medically diagnosable illness which is caused by or related to occupancy of a building and can be attributed directly to airborne building


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contaminants. The causes of BRIs can be determined and are generally related to allergic reactions and infections. Indicators of BRI include: • • •

Building occupants complain of symptoms such as cough; chest tightness; fever, chills; and muscle aches. Symptoms can be clinically defined and have clearly identifiable causes. Complainants may require extended recovery times after leaving the building.

It should be noted that complaints may result from other causes. The symptoms of SBS are extremely broad and nonspecific, and it seems they could all arise from any number of ailments completely unrelated to indoor air quality. In light of these types of complaints, technical commentators have searched for a satisfactory definition of Sick Building. This is the most common indoor air quality problem in a commercial building. In fact, it is estimated that 30% of all commercial buildings in the U.S. suffer from SBS, and that the expenses in terms of medical costs and lost production are estimated to be in the tens of billions of dollars per year in the U.S. alone. According to industry IAQ standards, SBS is diagnosed if significantly more than 20% of a building’s occupants complain of adverse health effects such as headaches, eye irritation, fatigue and dizziness for more than two weeks, but with no clinically diagnosable disease identified, and the symptoms are relieved when the complainant leaves the building. The World Health Organization (WHO) defines Sick Building Syndrome as an excess of work-related irritations of the skin and mucous membranes and other symptoms including headache, fatigue, and difficulty concentrating, reported by workers in office buildings. The WHO further describes the symptoms to include the following: (1) irritation of the eyes, nose, and throat; (2) dry mucous membranes and skin; (3) erythema (dermatitis erythematosa, redness of the skin, inflammation); (4) mental fatigue and headache; (5) respiratory infections and cough; (6) hoarseness of voice and wheezing; (7) hypersensitivity reactions; (8) nausea and dizziness. Microorganisms encompass us both indoors and outdoors. Some microorganisms do us good and others can harm us, but the majority of microorganisms are benign. To prevent a building from becoming a breeding ground for the wrong kinds of microbes, one needs to cut off what they need to live. Water is typically the main culprit. From leaky roofs and burst water pipes to the presence of warm moist air, water that gets absorbed by ceiling tiles, drywall, and carpet padding is the commencement of the microbe garden.

16.3 INORGANIC CONTAMINANTS—ASBESTOS, RADON, LEAD Inorganic substances such as asbestos, radon and lead are among the most common indoor contaminants whose exposure can pose significant health risks.


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Asbestos

Asbestos is a generic term given to a number of naturally occurring, hydrated fibrous silicate minerals that have unique physical and chemical properties that distinguish them from other silicate minerals. These properties, which include thermal, electric, and acoustic insulation, chemical and thermal stability, and high tensile strength, have contributed to their wide use in commercial and industrial applications. Generic uses of asbestos include acoustic insulation, thermal insulation, fire proofing, and other building materials (Figure 16.3). Its high tensile strength also makes it useful in many building materials. Many products are in use today that contain asbestos. Asbestos-containing material became a high profile public concern after federal legislation known as AHERA (Asbestos Hazard Emergency Response Act) was enacted in 1987. Moreover, asbestos is the most widely recognized environmentally regulated material (ERM) considered during building evaluations. Asbestos is a natural fire-retardant mineral fiber which has been used in a variety of construction materials in the past. Many asbestos-containing materials are located in concealed areas such as wall cavities, below

Figure 16.3 List of some materials that may contain asbestos.


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ground level, and other hidden spaces. In many older establishments, asbestos-based insulation was used on heating pipes and on the boiler. In order to provide an adequate asbestos survey, the inspector must perform destructive testing (i.e. opening walls, etc.) to inspect areas likely to contain suspect materials. Health hazards: The health danger of asbestos fibers depends mainly upon the number of fibers in the atmosphere and the length of exposure. Asbestos is made up of microscopic bundles of fibers that may become airborne when asbestos-containing materials are damaged or disturbed. Impaction and abrasion are typically the chief causes of increased airborne fiber levels. The type, quantity and physical condition of the asbestos-based material has a significant bearing on the degree of risk. Generally, the risk of airborne asbestos fibers is low when the material is in good condition. However, when the material becomes damaged or if it is located in a high activity area (family room, work shop, laundry, etc.) the risk increases. It has definitively been confirmed that increased levels of exposure to airborne asbestos fibers will cause disease. When these fibers get into the air they may be inhaled and become implanted in the lung tissue, where they can cause substantial health problems including cancer. While the process is slow, and years may pass before health problems are evidenced, the result and, thus, the risk are well established.

16.3.2

Radon (Rn)

Radon is a natural odorless, tasteless gas which is emitted from soil as a carcinogenic by-product of the radioactive decay of radium-226, which is found in uranium ores (although radon itself does not react with other substances). The by-product can however cling to dust particles which when inhaled, settle in bronchial airways. Generally, radon is drawn into a building environment by the presence of air pressure differentials. The ground beneath a building is typically under higher pressure than the basement or foundation. Air and gas move from high-pressure areas to low-pressure areas. The gas can enter the building through cracks in the foundation, floor slab, wall cracks, as well as penetrations associated with plumbing, electrical openings, sump wells, etc. in building spaces coming in close contact with uraniumrich soil. Vent fans and exhaust fans also facilitate to put a room under negative pressure and increase the draw of soil gas, which can increase the level of radon within a building. If there is insufficient ventilation, radon can accumulate in the building space and pose a health hazard. A radon survey will measure the concentrations of radon in the air and determine whether actions will be required to reduce the contamination. Radon levels also vary from region to region, season to season, and one building to another, and are typically at their maximum during the coolest part of the day when pressure differentials are greatest. The reason that it is harmful in a building is that it can become trapped and grow to hazardous levels. Facts about radon: • • •

• •

Radon is a naturally occurring gas that is a decay product of uranium. It is located everywhere and at various levels. The reason that it is harmful in a building is that it can become trapped and grow to hazardous levels. Radon is measured in picocuries per liter of air or Pci/L. This is basically the decay rate for radon in one liter of air. The Environmental Protection Agency (EPA) has set the action level as 4.0 Pci/L as the level at which corrective action be taken. Nationwide the EPA has stated the average indoor concentration of radon is 1.3 Pci/L. Radon levels can vary from building to building and season to season. There are a number of variables that affect the level in your building.


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The United States Environmental Protection Agency states that radon causes an estimated 14,000 lung cancer deaths each year. The main factors affecting radon concentrations in air are ventilation and the radon source. The most common source is the presence of radium-226 in the soil and rock surrounding basement walls and cellar floor slabs. Although you cannot see or smell radon, it can become a health hazard when it accumulates indoors. When radon decays and is inhaled into the lungs, it releases energy that can damage the DNA in sensitive lung tissue and cause cancer. However, elevated radon levels should not necessarily keep an investor from buying a building because the problem can normally be easily fixed even in existing buildings. Since high concentrations of radon in air often go hand in hand with radon contamination in the water supply (if a private water supply is present), a water test for radon is the recommended first step. If high concentrations are noted in the water, evaluation of ventilation rates in the structure as well as air quality tests for radon are recommended. The United States Environmental Protection Agency (EPA) recommends testing a building every few years to assess the radon levels. In general, high radon concentrations are likely wherever large rock masses occur, such as in mountainous regions. Radon mitigation—existing construction: Everything being equal, elevated radon levels should not necessarily keep an investor from purchasing a property, as the problem can usually be easily resolved. For example, a mitigation system for a home can cost between $900 and $2,500, depending on the complexity of the design. Radon mitigation—new construction: Some builders are starting to incorporate radon prevention techniques in their designs. Some municipalities also have local building codes requiring prevention systems. The EPA has published numerous brochures and instructional aids regarding radon-resistant construction. This is the most cost-effective way to handle a radon problem, as it is easier to build the system into the building rather than retrofit it later. If your building has a radon system built in, periodic testing is recommended by the EPA to ensure that the system is working properly and that the level in your building has not changed. The development of foundation cracks is an example of how the radon level could change in your building. EPA studies suggest that the more energy efficient the building, the more likely that there is an elevated level of radon. The reason that radon can become hazardous indoors is that the exposure to outside air needed to dilute the concentration is limited indoors. Although tight construction may save energy bills, it may also increase occupants’ exposure to radon and other indoor air pollutants. Testing for radon is also recommended when any major renovations are made to the building. Health risks: Radon emits alpha, beta and gamma radiation as it decays. The real danger does not necessarily come from the gas itself but from the products that it produces when it decays, e.g., lead, bismuth and polonium. These are microscopic particles that attach themselves to dust, pollen, smoke and other airborne particles in a building and are inhaled. Once in the lungs they become trapped and expose the sensitive lung tissue to the harmful radiation they emit as they decay. The effect is cumulative. Exposure to radon causes lung cancer in non-smokers and smokers alike. Those at most risk would be people with diminished lung capacity, asthma sufferers, smokers, etc. Radon testing methods: For short-term testing, consultants may use electret ionization chambers. These tests generally last about a week. The chambers work by incorporating a small charged Teflon plate screwed into the bottom of a small plastic chamber. As the radon gas enters the chamber and begins to decay, it creates charged ions that deplete the charge on the Teflon plate. By knowing the voltage prior to deployment and then reading the voltage after recovery, a mathematical formula is used to determine the concentration within the building. For long-term testing, consultants use either long-term electret chambers, similar to those used in short-term measurements, or alpha tracks. When the alpha track is deployed in the building it records the


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number of alpha particles that scratch the plastic surface inside the detector. The laboratory counts these microscopic indentations and mathematically determines the level of radon within the building.

16.3.3

Lead

Lead is a natural element which is found in soil, water, and to a lesser degree, as mineral particles in ambient air. It is a heavy metal and does not break down in the environment and continues to be used in many materials and products today. Most of the lead used today is inorganic lead, and it enters the body through breathing (inhalation) and swallowing (ingestion), which are called “routes of exposure.” Lead dust or particles cannot go through the skin if the skin is unbroken. The type of lead used in gasoline is organic lead and it can get through the skin. Lead in the indoor environment: Because of its widespread use and the nature of individual uses, lead has been identified as a common contaminant of interior environments. Lead compounds such as white lead and lead chromate have been used as white pigments in paints for centuries. In addition to their pigment properties, lead compounds were valued because of their durability and resistance to weathering and were therefore more commonly used in exterior white paints. Lead was also added to paint to improve its durability and drying characteristics. However, lead content was gradually reduced until it was eliminated altogether in 1978 (in the U.S.). Many homes constructed before 1978 still contain high levels of lead-based paint. In commercial buildings, lead was used mainly as a paint preservative. Ingestion of lead has been proven to cause several neurological disorders. As the paint peels and chips with age, children have eaten the paint, causing irreparable neurological problems and learning disorders. Lead piping has also been used in some older buildings. While not required to be replaced, in many cases the piping is deteriorating and leaching into the building’s drinking water. In some buildings lead solder has also been used in the installation of copper pipes. This has been banned in most jurisdictions due to water contamination caused by the deterioration of the solder. In an evaluation for lead contamination, the content of the water is analyzed by a laboratory for lead concentrations. Actions mitigating the hazards should be taken to reduce contamination if lead content is in excess of regulated limits. The potential for water contamination can usually be eliminated by chemical treatment of the water. If this cannot be accomplished, the piping may require replacement. Surprisingly, lead is still allowed in paint for bridge construction and machinery. It is used for its ability to expand and contract with the metal surface of a structure without cracking and because it is able to resist corrosion. Unfortunately, this paint is a significant source of lead exposure. Even if its use were banned today, there would still be exposure to workers and surrounding communities for years to come due to the number of metal structures, such as bridges, that are coated with it. Health risks: Lead is a highly toxic substance that affects a variety of target organs and systems including the brain and the nervous, renal, reproductive and cardiovascular systems. However, the nervous system appears to be the main target organ system for lead exposure. Measuring blood lead levels is often considered the best means to assess human exposure because it is a sensitive indicator of exposures that has been correlated with various health endpoints. It gives an immediate estimate of the level of your recent exposure to lead. However, although it will tell you how much lead is in your bloodstream, it will not tell you what is stored in your soft tissues or bones. Moreover, the test will not tell you your body burden of lead or the damage, if any, that has occurred. Effects of lead poisoning are mainly dose dependent. Contact with lead-contaminated dust is the primary method in which most children are exposed to harmful levels of lead. It enters a child’s body mainly through ingestion. Lead-contaminated dust is often hard to see but they can get into the body and create substantial health risks. The dust and chips from lead-based paint are dangerous when swallowed or in-


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haled, especially to small children and pregnant women. Lead can affect children’s developing nervous systems, causing reduced IQ and learning disabilities. In adults, high lead levels can cause high blood pressure, headaches, digestive problems, memory and concentration problems, kidney damage, mood changes, nerve disorders, sleep disturbances, and muscle or joint pain. A single, very high exposure to lead can cause lead poisoning. In adults, bones and teeth contain about 95 percent of the body burden (total amount of lead that is stored in the body). Lead can also affect the ability of both women and men to have healthy children. Testing for lead paint: Several methods are available to inspectors to help identify the presence of lead paint. In the field, the most commonly accepted method is through use of an x-ray fluorescent lead-inpaint analyzer (XRF). The XRF analyzer is held up to the surface being tested for several seconds. The analyzer emits radiation which is absorbed and then fluoresces (is emitted) back to the analyzer. The unit breaks down the signals to determine if lead is present and if so, in what concentration. An XRF analyzer is generally able to read through as many as 20 layers of paint. XRF analyzers are expensive and must be used by trained professionals.

16.4 COMBUSTION-GENERATED CONTAMINATES Combustion (burning) by-products are gases and tiny particles that are caused by the incomplete burning of fuels. When burned, fuels such as natural gas, propane, kerosene, fuel oil, coal, coke, charcoal, wood, and gasoline, and materials such as tobacco, candles, and incense, produce a wide variety of air contaminants. Sources of combustion-generated pollutants in indoor environments are many and include wood heaters and wood stoves, furnaces, gas ranges, fireplaces and car exhaust (in an attached garage). If fuels and materials used in combustion process were free of contaminates and combustion were complete, emissions would be limited to carbon dioxide (CO2), water vapor (H2O), and high-temperature reaction products formed from atmospheric nitrogen (NOx) and oxygen (O2). Combustion-generated contaminates include CO2, H2O, carbon monoxide (CO), nitrogen oxides (NOx) such as nitric oxide (NO) and nitrogen dioxide (NO2), respirable particles (RSP), aldehydes including formaldehyde (HCHO) and acetaldehyde, as well as a number of volatile organic compounds (VOCs). Fuels and materials containing sulfur will produce sulfur dioxide (SO2). Particulate-phase emissions may include tar and nicotine from tobacco, creosote from wood, inorganic carbon, and polycyclic aromatic hydrocarbons (PAHs). Carbon dioxide (CO2): This is a heavy, colorless, odorless, incombustible gas that is present in the atmosphere and formed during respiration, usually obtained from the burning of wood, gasoline, oil, kerosene, natural gas, coal, coke, from carbohydrates by fermentation, by reaction of acid with limestone or other carbonates, and naturally from springs. CO2 is absorbed from the air by plants in photosynthesis. Although carbon dioxide is rarely a safety problem, a high CO2 level can indicate poor ventilation which can lead to a buildup of particles and more harmful gases (such as carbon monoxide) that can impact people’s health and safety. CO2 is used extensively in industry as dry ice, or carbon dioxide snow, in carbonated beverages, fire extinguishers, etc. Carbon monoxide: Carbon monoxide (CO) is a non-irritating, odorless, colorless gas that is somewhat lighter than air. CO occurs when there is incomplete combustion of carbon-containing material such as coal, wood, charcoal, natural gas, fuel oil, kerosene, gasoline, fabrics and plastics, and is the leading cause of poisoning deaths in the United States. Exposure to carbon monoxide can cause headaches, fatigue, unclear thinking, dizziness, nausea, permanent damage to the brain, central nervous system, or heart, or death by reducing the amount of oxygen red blood cells carry. Infants, children, pregnant women,


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the elderly, and people with heart or respiratory problems are most susceptible to carbon monoxide poisoning. CO is especially dangerous because you are not aware when you are being poisoned as it cannot be seen, smelled, or tasted. For healthy people, exposure to low levels of carbon monoxide may be confused with a cold or the flu due to symptoms of headaches, dizziness, or nausea. You may also simply feel tired and stop thinking clearly. Occasionally you may experience headache or fatigue. CO poisoning is often misdiagnosed by both victims and doctors. Dangerous amounts of carbon monoxide can be released when there is insufficient fresh air or a flame is not hot enough to completely burn a fuel. There are four main sources of CO in the environment: •

Automobile exhaust combined with inadequate ventilation is responsible for two-thirds of all accidental CO deaths. Lethal levels of the gas can occur in as little as 10 minutes in a closed garage. People in certain occupations—including highway workers, traffic officers, tunnel workers, professional drivers, toll booth attendants and warehouse workers—are exposed regularly to high levels of CO. Indoor events, such as tractor pulls, car and truck exhibitions, or ice hockey or skating, can expose spectators and participants to elevated CO levels if these areas are not adequately ventilated.

Faulty heating equipment accounts for nearly one-third of accidental CO fatalities. Culprits can include your home heating system, but also improperly vented or unvented gas appliances, kerosene or propane space heaters, charcoal grills or hibachis, and Sterno-type fuels.

Fires can raise CO levels in the blood of unprotected persons to 150 times normal in one minute; CO poisoning is the most frequent cause of immediate death associated with fire. Smoke given off by cigarettes also can cause elevated CO levels in both the smoker and nonsmokers who are exposed to the smoke.

Methylene chloride, a solvent in some paints and varnish strippers, is absorbed by the body and changed to CO. Using products that contain methylene chloride for more than a few hours can raise CO levels in the blood seven to 25 times normal. People with pre-existing cardiac conditions who use these products in unventilated spaces risk heart attack and death.

Symptoms of CO poisoning: At low levels, CO exposure causes no obvious symptoms, although people exposed to low CO levels may experience decreased exercise tolerance and shortness of breath during exertion. Tightness across the forehead, flushed skin and slightly impaired motor skills also may occur. The first and most obvious symptom is usually a headache with throbbing temples. Symptoms of mild to moderate CO poisoning may resemble winter flu or gastroenteritis, particularly in children, and include nausea, lethargy and malaise. As the CO level or exposure time increases, symptoms become more severe and additional ones appear: irritability, chest pain, fatigue, diminished judgment, dizziness and dimness of vision. Higher levels cause fainting upon exertion, marked confusion and collapse. If exposure continues, coma, convulsion and death from respiratory arrest can result. Testing for CO: The only reliable method to test for carbon monoxide is with an electronic device called a carbon monoxide alarm. Fire departments, gas companies and some specialized contractors have sophisticated equipment that can measure and record carbon monoxide levels. Detectors should be placed in areas where the family spends most of its time—family room, bedroom or kitchen—but far enough away from obvious and predictable sources of CO, such as a gas stove, to avoid false alarms. Avoidance of CO poisoning: CO poisoning is entirely preventable, if a number of simple steps are followed: •

Have your gas appliances checked periodically for proper operation and venting.


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• • • •

• •

Make sure flues, chimneys and vents are clear of debris and in good working order. Install CO monitors in the home and workplace. Check them regularly and make sure they are maintained properly. Do not use unvented space heaters, gas stoves, charcoal grills or Sterno-type fuels as sources of heat. Do not cook on charcoal grills indoors. In the workplace, make sure there is sufficient ventilation when working around CO sources, such as propane-powered forklifts and space heaters. Where exposure is unavoidable, workers should wear CO monitoring badges. Employers should regularly monitor the workplace. Check the exhaust system of your car regularly and keep it in good condition. Do not run the car or other gasoline-powered engines in a garage, even with the doors open. Use paint strippers that do not contain methylene chloride. If you do use solvents containing this substance, make sure the area is properly ventilated.

Nitrogen oxides: There are a number of nitrogen oxides but only nitrogen dioxide (NO2) is of concern as an air pollutant. Nitrogen dioxide is an important air pollutant because it contributes to the formation of photochemical smog, which can have significant impacts on human health. Nitrogen dioxide is relatively nonsoluble in tissue fluids. As a consequence, it enters the lungs where it may expose lower airways and alveolar tissue. Breathing in raised levels of nitrogen dioxide increases the likelihood of respiratory problems. Nitrogen dioxide inflames the lining of the lungs, and it can reduce immunity to lung infections. This can cause problems such as wheezing, coughing, colds, flu and bronchitis. Increased levels of nitrogen dioxide can also have significant impacts on people with asthma because it can cause more frequent and more intense attacks. Children with asthma and older people with heart disease are most at risk. Irritants: Combustion-generated contaminants include several mucous membrane and upper respiratory system irritants. Most common of these are aldehydes like HCHO, and in some cases acrolein, RSP, and SO2. Aldehydes cause irritation to the eyes, nose, throat, and sinuses (aldehydes are discussed in the following section). Respirable particles vary in composition, and their primary effect would be to irritate the upper respiratory passages and bronchi. Due to its solubility in tissue fluids, SO2 (associated with some combustion appliances) can cause bronchial irritation.

16.5 ORGANIC CONTAMINANTS—ALDEHYDES, VOCs/SVOCs, PESTICIDES Indoor environments consist of a large number of different types of natural and synthetic organic compounds. Modern industrialized societies have developed such a massive range of organic pollutants that it is difficult to generalize in any meaningful way as to sources, uses, or impacts. These contaminants enter the natural environment through accidental leakage and spills, such as leaking underground storage tanks, or through planned spraying or other treatments, such as application of pesticides to agricultural land. Synthetic organic chemicals can be found virtually everywhere in our environment, including soil, groundwater, surface water, plants, and our bodies. Organic compounds include the very volatile organic compounds (VVOCs), volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs) and solid organic compounds (POMs). In the latter, POMs may be components of airborne or surface dusts. Organic compounds are seen as relatively distinct indoor contamination problems and include the aldehydes, VOCs and SVOCs which include a large


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number of volatile as well as less volatile compounds, and pesticides and biocides which are, for the most part, SVOCs. Organic compounds considered to contaminate indoor environments include a large variety of aliphatic hydrocarbons, which may be straight, branch-chained, or cyclic (contain single bonds or one or more double bonds); aromatic hydrocarbons (contain one or more benzene rings); oxygenated hydrocarbons, such as aldehydes, ketones, alcohols, ethers, esters, and acids; and halogenated hydrocarbons (primarily chlorine and fluorine containing). Concentrations of most volatile organic compounds are greater in indoor environments than outdoor air. Studies suggest that there is a large and variable number of VOCs present in indoor air. In fact, indoor air may contain several hundred different VOCs. Moreover, VOCs can be released from products while being used and to a lesser degree while they are in storage. Fortunately, the amounts given off tend to decrease as the product ages and dries out. The number of identified VOCs has risen steadily in recent years. They have a wide range of physical and chemical characteristics—two of which are of particular importance: water solubility and if the VOC is neutral, basic, or acidic. VOCs are released into the indoor environment by various sources including building materials and furnishings, paints, solvents, air fresheners, aerosol sprays, adhesives, fabrics, consumer products, building cleaning and maintenance materials, pest control and disinfection products, humans, office equipment, tobacco smoking, plastics, lubricants, refrigerants, fuels, solvents, pesticides, and many others. Many VOCs are potent narcotics that cause a depression in the central nervous system and others can cause eye, nose and throat irritation; headaches; loss of coordination; nausea; and damage to the liver, kidneys, and central nervous system (Figure 16.4). Some of these chemicals can cause cancer in animals; some are suspected or known to cause cancer in humans. One of the more common VOCs found indoors is formaldehyde which is an important chemical used widely by industry to manufacture building materials and numerous household products. Formaldehyde: Formaldehyde (HCHO) is the most common of the aldehydes and is now recognized as possibly the single most important indoor pollutant due to its common occurrence and its strong toxicity. Formaldehyde is a colorless, gaseous substance with an unpleasant smell and is omnipresent in both ambient and indoor environments. On condensing, it forms a liquid with a high vapor pressure. Because of its high reactivity, it rapidly polymerizes with itself to form paraformaldehyde. As a consequence, liquid HCHO must be held at low temperature or mixed with a stabilizer (such as methanol) to prevent or minimize polymerization. Formaldehyde is commercially available as paraformaldehyde and is used in a variety of deodorizing commercial products, such as lavatory and carpet preparations. HCHO is also commercially available as formalin, an aqueous solution that typically contains 37 to 38 percent HCHO by weight and 6 to 15 percent methanol, as well as in many different chemical processes such as the production of Figure 16.4 Diagram showing inhalation of volatile urea and phenol-formaldehyde resin. organic compounds (source: Air Advice Inc.).


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Urea-formaldehyde (UF) copolymeric resins are common in many building materials such as wood adhesives which are used in the manufacture of pressed wood products including particle board, mediumdensity fiber board (MDF), plywood, finish coatings (acid-cured), textile treatments, and in the production of urea-formaldehyde foam insulation (UFFI). What is not commonly known is that formaldehyde is given off by other materials besides UFFI. Certain types of bonded wood products (composition board, paneling, etc.), carpeting and other material can be a source of formaldehyde. Many of these products use a urea formaldehyde based resin as an adhesive. Some of these materials will continue to give off formaldehyde much longer than UFFI. Like many other VOCs, formaldehyde levels will decrease substantially with time as well as with increased ventilation rates. Health risks: Formaldehyde can be a respiratory irritant and for some folks, living in its presence can be dangerous. More specifically, chronic, low-level, continuous or intermittent exposure to formaldehyde can cause chemical hypersensitivity and is an accelerating factor in the development of chronic bronchitis and pulmonary emphysema. HCHO also has the ability to cause irritation and inflammatory-type symptoms and symptoms of the central nervous system such as headache, sleeplessness and fatigue. Elevated HCHO exposures may also cause asthma, nausea, diarrhea, unnatural thirst, and menstrual irregularities. Acetaldehyde: This is a two-carbon aliphatic aldehyde with a pungent, fruity odor. It is used in a variety of industrial processes, and is a major constituent of automobile exhaust gases. It is also a predominant aldehyde found in tobacco smoke. As compared to HCHO, it is a relatively mild irritant of the eye and upper respiratory system. Acrolein: It is a three-carbon aldehyde with one double bond. It is highly volatile and has an unpleasant choking odor. It is used in the production of various compounds and products. It is released into the environment as a combustion oxidation product from oils and fats containing glycerol, wood, tobacco, and automobile/diesel fuels. Acrolein is a potent eye irritant causing lacrimation (tearing) at relatively low exposure concentrations. Glutaraldehyde: This is a five-carbon dialdehyde. It is a liquid with a sharp, fruity odor and is the active ingredient in disinfectant formulations widely used in medical and dental practice. Health effects associated with glutaraldehyde exposures include irritant symptoms of the nose and throat, nausea and headache, as well as pulmonary symptoms such as chest tightening and asthma. Polychlorinated Biphenyls (PCBs): PCB oils have been used mainly as a coolant in electrical transformers. Despite the fact that production and sale of PCB was banned by the Environmental Protection Agency (EPA) in 1979, a large number of PCB-filled transformers remain in use nationwide. It is also estimated that about 2 million mineral oil transformers contain some percentage of PCB. PCBs can also be found in light ballasts and elevator hydraulic fluids. Although they are a suspected carcinogen, properly sealed or contained PCBs do not pose a hazard. PCBs become a hazard when they catch fire, creating carcinogenic by-products. These by-products can contaminate the air, water, finishes, and contents of a building. Leaking PCB can also contaminate building materials and soil. PCB evaluations typically focus on identifying the existence of, or potential for, PCB leakage, measuring the level of PCB concentrations, and determining the presence of combustible materials adjacent to PCB-containing equipment. Hydrocarbons: Hydrocarbons are a chemical compound consisting only of hydrogen and carbon. Hydrocarbons derived from petroleum, natural gas, or coal, are cardinal to our modern way of life and its quality. The bulk of the world’s hydrocarbons are used for fuels, electrical power generation, and heating. The chemical, petrochemical, plastics and rubber industries are also dependent upon hydrocarbons as raw materials for their products. Benzene is found in most hydrocarbons and is considered to be one of the more serious contaminants and is known to cause leukaemia. It is a colourless, flammable, toxic liquid. Itchy eyes, watery eyes, nausea, and noticeable odors similar to gasoline and oil all suggest that some hydrocarbon contamination may be present. Likewise, leaking subsurface tanks at fuel stations and other


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facilities have created significant health and safety problems by contaminating the soil around the buildings. Air quality tests may be necessary as well as tests for contaminants in the soil around the foundation. Pesticides: Pesticides cover a range of products intended for controlling, destroying, or repelling pests, weeds and mold. Pesticides are generally toxic and as such are unique contaminants of indoor environments. There are currently thousands of different pesticide products on the market, including some of the most widely used over the past 60 years that have become globally distributed. These include aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, toxaphene and lindane (hexachlorocyclohexane, HCH). Many pesticides (most notably chlordane, used for termite treatment) are serious hazards. Health concerns associated with indoor pesticide exposure include: acute symptoms due to high-level exposures occurring immediately after application; long term risk of cancer from chronic exposures to substances such as chlordane, heptachlor, and PCP.

16.6 BIOLOGICAL CONTAMINANTS—MOLD AND MILDEW, VIRUSES, BACTERIA, AND EXPOSURES TO MITE, INSECT, AND ANIMAL ALLERGENS Biological pollutants arise from sources such as microbiological contamination, e.g., fungi, bacteria, and the remains and dropping of pests such as cockroaches and pests. Such pollutants of biological origin can significantly impact indoor air quality and cause infectious disease through airborne transmission. Of particular concern are those biological contaminants that cause immunological sensitization manifested as chronic allergic rhinitis, asthma, and hypersensitivity pneumonitis. Moisture in buildings is one of the major contributors to poor indoor air quality, unhealthy buildings, and mold growth. Wetting of building walls and rainwater leaks are major causes of water infiltration, but so is excessive indoor moisture generation. Preventive and remedial measures include rainwater tight detail design; prevention of uncontrolled air movement; reduction of indoor air moisture content; reduction of water vapor diffusion into walls and roofs; selection of building materials with appropriate water transmission characteristics; and proper field workmanship quality control. A successful method for deterring rainwater intrusion into walls is the rain screen approach, which incorporates cladding, air cavity, drainage plane, and airtight support wall to offer multiple moisture-shedding pathways. The concept of the rain screen principle is to separate the plane in a wall where the rainwater is shed and where the air infiltration is stopped. In terms of construction, this means that there is an outer plane which sheds rainwater but lets air freely circulate, and an inner plane which is relatively airtight. In terms of pressures, there is no pressure differential across the outer pane and there is a significant pressure differential across the inner plane. Because there is no pressure difference across the outer plane, there is no driving force to move water indoors; because there is no water present at the inner plane, no water will penetrate the inner plane despite the presence of the driving force of the pressure difference.

16.6.1

Mold

The terms mold and mildew are usually used to describe the visible manifestations of the growth of a concentration of organisms that are scientifically classified as fungi. Fungi are primitive plants that lack chlorophyll and therefore must live as parasites or feed on organic matter that they digest externally and absorb. The true fungi include yeast, mold, mildew, rust, smut, and mushrooms. They usually grow best in dark moist


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habitats, and are found wherever organic matter is available. In Figure 16.6, if the peeling of paint at the wall’s base is lifted, it would probably reveal fungal amplification under the paint/paper. There is also a high probability that extensive fungal amplification will be evidenced inside the wall cavity and under the carpet. Molds are part of the natural environment and are present everywhere. The medical community appears to be divided regarding the threat of mold, but seems to agree that some people with allergies are sensitive to mold and that in sensitive individuals mold can lead to respiratory diseases. The issue with mold then is not to prevent any mold growth, or to eliminate any existing mold growth, but to control it within acceptable limits.

Figure 16.5 Table showing typical types of molds found in damp buildings.


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Figure 16.6A,B,C A. View at base of wall indicates presence of moisture at base of wall and carpet area. B. Thermal image shows extent of moisture saturation (darker areas) in both wall and carpet. Moisture levels were verified using a Delmhorst electronic moisture meter. Both carpet and wall are saturated (courtesy, Closer Look Inspections). C. Evidence of mold growth in basement unit in Maryland, USA, which indicates lack of maintenance and presence of the four elements necessary for mold to grow (courtesy, Michel Paruti, IVI).

For fungi to grow or establish itself, it needs at least four elements: viable spores, a nutrient source (organic matter like wood products, carpet, and drywall), moisture, and warmth. Note that the mere presence of humid air does not necessarily promote mold growth, except where air with a relative humidity (RH) level at or above 80 percent is in contact with a surface. Carried by air currents, mold spores can reach all surfaces and cavities of buildings. If these surfaces and/or cavities are warm, and contain the right nutrients and amounts of moisture, the mold spores will grow and gradually destroy the things they grow on. To control mold growth, designers should focus on controlling moisture indoors and on the temperatures of all surfaces, including interstitial surfaces within walls. Also, by removing one of the four elements the growth process will be inhibited or eliminated. The first step in every mold remediation project includes determination of the root cause of the mold growth. The next step is to delineate the order of magnitude of the mold growth via thorough visual examination. Since old growth may not always be visible, investigators may use instruments such as moisture meters, thermal imaging equipment, or borescope cameras to identify moisture in building materials or “hidden” mold growth within wall cavities, HVAC ducts, etc. Mold assessments and inspections should always include HVAC systems and their air-handler units, drain pans, coils, and ductwork. In addition, depending on the age of the building, the inspection should include sampling of building materials, such as ceiling tiles, drywall joint compound, and sheet floor for the presence of asbestos. These organisms may contribute to poor indoor air quality and can cause health problems. Fungi in indoor environments comprise microscopic yeasts and molds, known as micro fungi, while plaster and woodrotting fungi are referred to as macro fungi because they produce sporing bodies that are visible to the naked eye. Apart from single-celled yeasts, fungi colonize surfaces as a network of filaments, and some produce numerous aerially dispersed spores and other chemical substances such as volatile organic compounds (VOCs). Toxic molds and fungi are a significant source of airborne volatile organic compounds (VOCs) that create IAQ problems. Toxic mold growth produces dangerous mycotoxins and infectious airborne mold spores which often cause serious health problems to residents and workers. Toxicity can arise from inhalation or skin contact with toxigenic molds. Humidity control prevents the indoor growth of mold, mildew, viruses, and dust mites. Maintenance of an annual relative humidity range between 30–50 percent will control the source of many of these known


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biological contaminants. Winter humidification and summer dehumidification controls/modules can supplement central HVAC systems when climate excesses require additional conditioning measures.

16.6.2

Bacteria and Viruses

Viruses, bacteria, and other bioaerosols are common in the home and the workplace, and may increasingly contribute to Sick Building Syndrome if humidity levels are either too low or too high, due to how their growth and our respiratory system are affected. Bacteria and viruses are minute in size and readily become airborne, remaining suspended in air for hours. Airborne bacteria and viruses in interior spaces are a cause of considerable concern due to their ability to transmit infectious diseases such as tuberculosis (TB), Legionnaires’ disease, meningitis, influenza, and colds. Figure 16.7 shows two computed tomographic (CT) scans of abdomens of two patients with inflammation of the gallbladder (Source: Center for Disease Control and Prevention). Q fever is an emerging infectious disease among U.S. soldiers serving in Iraq. Fever, pneumonia, and/or hepatitis are the most common signs of acute infection with Q fever. Bacterial aerosols have also been a means to transmit a number of major diseases as shown in Figure 16.8. Ducts, coils, and recesses of building ventilation systems are often fertile breeding grounds for viruses and bacteria that have been proven to cause a wide range of ailments from influenza to tuberculosis. As for viruses, a number of viral diseases may be transmitted in aerosols derived from infected individuals. Selected viral diseases and associated causal viruses transmitted through air are shown in Figure 16.9.

16.6.3

Mites

Dust mites are microscope bugs that thrive on the constant supply of shed human skin cells (commonly called dander) that accumulate on carpeting, stuffed animals, drapes, furniture coverings, and bedding (Figure 16.10). The proteins in that combination of feces and skin sheddings are what cause allergic reactions in humans. Depending on the person and exposure, estimates are that dust mites may be a factor in 50 to 80 percent of asthmatics, as well as in countless cases of eczema, hay fever and other allergic ailments.

Figure 16.7 Computed tomographic (CT) scans of abdomens of two patients with inflammation of the gallbladder (source, Center for Disease Control and Prevention).


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Figure 16.8 Major infectious diseases associated with bacterial aerosols.

Figure 16.9 Major infectious diseases associated with viral aerosols.

House dust mites, due to their very small size (250 to 300 microns in length) and translucent bodies, are not visible to the unaided eye. For accurate identification, one needs at least 10X magnification. Dust mites are perhaps the most common cause of perennial allergic rhinitis. They have eight hairy legs, no eyes, no antennae, a mouthpart group in front of the body (resembles head) and a tough, translucent shell. Dust mites, like their insect cousins, have multiple developmental stages. These include egg, larva, several nymph stages, and finally the adult. Mites prefer warm, moist surroundings such as the inside of a mattress when someone is on it. A favorite food is dander (both human and animal skin flakes). Humans shed about 1/5 ounce of dander (dead skin) each week. Dust mite populations are highest in humid regions and lowest in areas of high altitude and/or dry climates. Control measures necessitate reducing concentrations of dust borne allergens in the living/working environment by controlling both allergen production and the dust which serves to transport it.

Figure 16.10 Drawing of a dust mite (source: EHSO).


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Insect, Rodent and Animal Allergens

Cockroaches, rats, termites and other pests have plagued commercial facilities for far longer than computer viruses. Increasingly, research has confirmed and pinpointed pest infestation as the trigger or cause of a host of diseases. In fact, according to the National Pest Management Association, pests can cause serious threats to human health, including diseases such as rabies, salmonellosis, dysentery, and staph. But in addition to pests presenting a serious health concern to a building’s occupants, they also distract from a facility’s appearance and value. Insects: More than 900,000 species of insects exist and addiFigure 16.11 Illustration of an tional species are identified every day. A variety of insects have been American cockroach. identified as sources of inhalant allergens that may cause chronic allergic rhinitis and/or asthma. These include cockroaches, crickets, beetles, moths, locusts, midges, termites and flies. Insect body parts are especially potent allergens for some people. Cockroach allergens are also potent allergens and are commonly implicated as contributors to Sick Building Syndrome in urban housing with poor sanitation. The following are some of the insects commonly encountered in today’s living and commercial environments: Cockroaches: Cockroaches spread at least 33 kinds of bacteria, six kinds of parasitic worms, and at least seven other kinds of human pathogens. They can pick up germs on their bodies as they crawl through decaying matter and then carry these onto food surfaces (Figure 16.11). Ants: There are more than 20 varieties of ants invading homes throughout the United States during the warm months of the year (Figure 16.12A). Worldwide, there are more than 12,000 species, but of these, only a limited number actually cause problems. All ants share one trait: They are unsightly and contaminate food. Ants range in color from red to black. Destructive ants include fire and carpenter ants. Other ant types include the honey, pharaoh, house, Argentine, carpenter, and the thief ant. Fire ants are vicious, unrelenting predators with a powerful, painful sting. At least 32 deaths in the U.S. can be attributed to severe allergic reactions to fire ant stings. Termites: Termites can pose a major threat to structures, so the sooner a termite infestation is addressed with a qualified termite control company, the better. The forensic expert should look for the tell-tale signs of termites: small holes in wood, crumbling drywall, termite insect wings, straw shaped mud tubes, and sagging doors or floors (Figure 16.12B).

Figure 16.12 Illustration of A. a winged ant, and B. a termite.


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Many mammalian and avian species produce allergens that can be inhaled by humans and cause immunological sensitization and symptoms of chronic allergic rhinitis and asthma. These allergens are associated with dander, hair, saliva, and urine of dogs, cats, rodents and birds. Likewise, pollens, ragweed, and a variety of other allergens find their way into the home from outdoors. Ragweed is the cause of what is commonly referred to as “hay fever,” or what allergist/immunologists refer to as allergic rhinitis. Seasonal allergic rhinitis (hay fever) affects more than 35 million people in the United States and is caused by breathing in allergens such as pollen. When exposed to ragweed, allergy sufferers often experience sneezing, runny noses and swollen, itchy, watery eyes. These symptoms of allergic rhinitis can have a major impact on a person’s quality of life, including his or her ability to function well at school or work. Rodents carry disease and fleas and leave waste. Wild and domestic rodents have been reported to harbor and spread as many as 200 human pathogens. Diseases include the deadly hantavirus and arena virus. Hantavirus is contracted primarily by inhaling airborne particles from rodent droppings, urine or saliva left by infected rodents or through direct contact with infected rodents.

16.7 SYSTEM DIAGNOSTICS In order to properly diagnose air quality problems in a building, one must first consider all of the possible contaminants, causes and concentrations to better be able to address the problems and find suitable solutions. The location where one is exposed may also play an important role. Thus, while the average worker in the workplace is exposed approximately 40 hours per week, many individuals are in their home 24/7. Therefore, exposure times as well as concentrations become part of the equation. Solutions to Sick Building Syndrome usually include combinations of the following: Pollutant source removal or modification is an appropriate approach to resolving an IAQ problem when sources are identified and control is feasible. Examples include routine maintenance of HVAC systems; applying smoking restrictions; venting contaminant source emissions to the outdoors; proper storage and use of paints, pesticides, and other pollutant sources in well ventilated areas, and their use during periods of non-occupancy; and allowing time for building materials in new or remodeled areas to off-gas pollutants before occupancy. Increasing ventilation rates and air distribution often can be a cost effective means of reducing indoor pollutant levels. HVAC systems should be designed, at a minimum, to meet ventilation standards in local building codes. However, many systems are not operated or maintained to ensure that these design ventilation rates are provided. In many buildings, IAQ can be improved by operating the HVAC system to at least its design standard, and to ASHRAE Standard 62-2001 if possible. When there are strong pollutant sources, local exhaust ventilation may be appropriate to exhaust contaminated air directly from the building. Local exhaust ventilation is particularly recommended to remove pollutants that accumulate in specific areas such as rest rooms, copy rooms, and printing facilities. Air cleaners can be a useful adjunct to source control and ventilation but are generally limited in their application. The EPA ranks indoor air pollution among the top four environmental risks in America today. Since the average person spends approximately 90 percent of his/her life indoors, the quality of the indoor air is of great importance. This may be why for many forward-thinking real estate property managers it has nearly become a standard of doing business to have their buildings routinely inspected as part of a proactive IAQ monitoring program.


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Evidence of pests is typically found in different forms such as droppings (especially from cockroaches and rodents) and frass (from wood borers), gnawing, tracks, and grease marks (from rodents), damage (such as powderpost beetle exit holes), and shed insect skins. The presence of feeding debris or frass is an indication of infestation. Window sills should regularly be examined as many pests fly or crawl towards light. Pests may also be found behind baseboards, under furniture, behind moldings, in floor cracks, behind radiators, and in air ducts. The inspector shall check around door jambs for cockroaches and spider webs. Conditions that would invite pest problems should be checked out, like presence of moisture, both indoors and out, which may lead to moisture-related pests such as carpenter ants, termites, or mold. Evidence of damaged screens, doors, and walls which could allow pest entry should be fixed. Any sanitation problems should be noted. Heavy landscaping near the foundation and plants such as ivy growing on walls increases the risk of outdoor pests moving inside and need to be controlled or avoided. Moisture problems around the foundation, gutters, or air conditioning units should be monitored and rectified as they can favor moisture-related pests entering a facility. Bright exterior lights attract insects to the outside of the building, and these insects may then find their way indoors. IAQ investigation procedure: Investigation procedure is best characterized as a cycle of information gathering, hypothesis formation, and hypothesis testing. It typically starts with a walkthrough inspection of the problem area to gather information about the four basic factors that influence indoor air quality: •

the building’s occupants

• • •

the HVAC system possible pollutant pathways potential contaminant sources

An IAQ investigation should include documenting easily obtainable information about the building’s history and of the complaints; identifying known HVAC zones and complaint areas; notifying occupants of the upcoming investigation; and, identifying key individuals needed for information and access. The walkthrough itself entails visual inspection of critical building areas and consultation with occupants and staff. The initial walkthrough should allow the investigator to develop some possible explanations for the complaint. At this point, the investigator may have sufficient information to formulate a hypothesis, test the hypothesis, and see if the problem is solved. If it is, steps should be taken to ensure that it does not recur. However, if insufficient information is obtained from the walk through to construct a hypothesis, or if initial tests fail to reveal the problem, the investigator should move on to collect additional information to allow formulation of additional hypotheses. The process of formulating hypotheses, testing them, and evaluating them continues until the problem is solved. Although air sampling for contaminants might seem to be the logical response to occupant complaints, it seldom provides information about possible causes. While certain basic measurements, e.g., temperature, relative humidity, CO2, and air movement, can provide a useful “snapshot” of current building conditions, sampling for specific pollutant concentrations is often not required to solve the problem and can even be misleading. Contaminant concentration levels rarely exceed existing standards and guidelines even when occupants continue to report health complaints. Air sampling should not be undertaken until considerable information on the factors listed above has been collected, and any sampling strategy should be based on a comprehensive understanding of how the building operates and the nature of the complaints. In conclusion, it is likely that in the coming years we will witness national and state regulations stipulating designers, facility managers, and property owners to meet mandated indoor air quality standards. The EPA, OSHA, ASHRAE, ASTM, and other organizations are currently in discussions concerning national indoor air quality standards.


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17 Natural Hazards GENERAL OVERVIEW Prior to the discussion of specific failure causes, it is important to study and analyze the many forces and agents that are destructive to the built environment. Each year tens of billions of dollars and many lives are lost due to natural hazards. Recovery efforts include repairing damaged buildings and infrastructure from the impacts of earthquakes, hurricanes, floods, tornados, blizzards, and other natural disasters. Loss of life and property would be significantly less if buildings properly anticipated the risk associated with major natural hazards.

17.1 EARTHQUAKES—SEISMIC CONSIDERATIONS Earthquakes are terrifying natural hazards and approximately half of the states and territories in the United States are exposed to seismic risks (Figure 17.1). In the U.S. alone, it is estimated that the average direct cost of earthquake damage is $1 billion a year, while indirect business losses are estimated in excess of $2 billion a year. This is because damage to structures by earthquake forces is the highest risk to most buildings, although newer buildings, particularly mid-rise and high-rise buildings are now generally constructed to a higher level of earthquake resistance than older buildings. In areas of high potential seismic activity, it is appropriate for building evaluations to include a seismic analysis of the building. The issues range from analyzing the degree to which objects and furnishings are fastened down, to evaluating the evidence of deterioration in structural members. What is so unfortunate is that many of the regions that experience strong earthquakes are least prepared for them economically, socially or technically. There are many examples around the world of such events including the 8.0-magnitude earthquake that struck Peru on August 15, 2007 and which left parts of coastal Peru in ruins, without electricity, water or communications. At least 437 people died and over 1,000 people were injured. Many of the more rudimentary homes and offices in the area simply collapsed under the sustained force of the quake (Figure 17.2A,B). Figures 17.3A,B,C,D illustrate other examples of

299 Copyright Š 2008 by The McGraw-Hill Companies, Inc. Click here for terms of use.


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strong and moderate earthquakes that hit Anchorage, Alaska (1964), Northridge, California (1994), San Francisco (1906) and northern Turkey (1997). To mitigate the catastrophic effects of such seismic activity, a successful design necessitates that the architect and engineer develop a multi-hazard design approach that takes into consideration the potential impacts of seismic forces as well as other major hazards to which an area is vulnerable. As a general rule, buildings designed to resist earthquakes should also resist blast (terrorism) or wind, suffering less damage. The design should also ensure that performance-based requirements, which may exceed the minimum life safety requirements of existing seismic codes, are established to respond appropriately to the threats and risks posed by natural hazards on the building’s integrity and occupants. Furthermore, as earthquake forces are dynamic and buildings respond according to their specific design attributes, it is important that the design team work in liaison and have a mutual understanding of the methodology used in the seismic design process. For mortgage loan reports a single loss estimate is typically required, whereas for acquisition reports two loss estimates are normally required. The loss estimate is normally stated as a percentage of the property’s current replacement cost. This number should reflect the consultant’s best judgment of potential repair costs for this particular structure(s) based on analysis, observations and past experiences. A brief description of the methodology used to generate the loss estimate should be provided in the forensic expert’s report. Where loss estimates are generated via mathematical algorithms the values for all variables used as input should also be indicated. General design considerations: Much has been learned from earthquakes around the globe, and engineered buildings today are much better able to cope with the effects of earthquakes than they were just a few decades ago. A variety of issues are included in a typical seismic study. As with building evaluation in general, seismic studies may be performed in a variety of depths to meet different performance requirements. The study may be as simple as a general field survey and a cursory review of the structural drawings, although in a standard seismic study, the drawings are reviewed and calculations are performed

Figure 17.1 Seismicity map of the United States.


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Figure 17.2A Peru: The 8.0-magnitude earthquake

Figure 17.2B Peru: Many of the more rudimentary

struck on August 15, 2007, leaving parts of coastal Peru in ruins, without electricity, water or communications (source, BBC).

homes and offices in the area simply collapsed under the sustained force of the quake (source, BBC).

Figure 17.3B Northridge, CA, 1994: Collapse of freeway

Figure 17.3A Alaska, 1964: Development of surface rupture on a road. No matter how sophisticated the seismic design is, it cannot provide complete safety in a fault zone where ground rupture is likely to occur (source, Earthquake, CSU).

overpasses due to inability to withstand shear forces generated during the earthquake. There were 61 deaths, 9,000 injuries and approximately 112,000 structures damaged (source, Earthquake, CSU).


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Figure 17.3C San Francisco, 1906: Powerful

Figure 17.3D Turkey, 1997: Strong earthquake on

historic earthquake and subsequent fire decimates the city (source, Earthquake, CSU).

the Anatolian Fault causes substantial damage to unreinforced masonry buildings in northern Turkey (source, Earthquake, CSU).

on a representative number of structural members in the building. In typical standard studies, the building is also reviewed for potential seismic hazards, both structural as well as non-structural. In new construction, a design team’s performance objectives can be achieved through various measures such as the use of structural components like shear walls, braced frames, moment resisting frames, and diaphragms, base isolation, energy dissipating devices such as visco-elastic dampers, elastomeric dampers, and hystereticloop dampers, as well as bracing of nonstructural components. Existing buildings can be seismically retrofitted to reduce earthquake risk, based upon vulnerabilities identified in an evaluation report. Besides structural considerations, the evaluation report can include architectural, mechanical, and electrical components. Recommendations should include retrofit items, their costs, and a schedule prepared to improve a building’s expected earthquake performance. Although tall buildings will undergo several modes of vibration during seismic activity, for seismic purposes (except for very tall buildings) the fundamental period or first mode is usually the most significant. In Figure 17.4A we see that height is the main determinant of the fundamental period during seismic activity. Figure 17.4B depicts various modes of vibration of tall buildings during an earthquake. Seismic studies should be performed by licensed structural engineers or qualified geotechnical engineers. The evaluation should take into account the probability of seismic activity in the region, as well as the type and configurations of materials and structural members in the facility. Present building codes, as well as those in effect at the time of construction, are referenced and any retroactive code changes are evaluated. For detailed seismic studies, full structural analysis is appropriate. These may consist of a new set of calculations or a review of the existing calculations. Any seismic analysis should consider both vertical and lateral loads, and the identification, location and recording of overstressed members. A seismic analysis will often consider the following structural related issues: • • •

Primary and secondary structural resistance system Shear walls and lateral load-resisting frame systems Foundations and retaining walls


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Figure 17.4A Height is the main determinant of the fundamental period during seismic activity. The period of vibration is proportionate to the height of the building.

Figure 17.4B Diagram showing various modes of vibration of tall buildings during an earthquake (source, Gabor Lorant, FAIA).

• • • • • •

Columns and support details All walls and their connections with the exception of non-structural interior partitions Diaphragm chord and collector system Shear transfer connections Horizontal framing members and their connections Horizontal diaphragms and sub-diaphragms.

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Items, which do not constitute part of the structural system, are considered as “nonstructural.” Such nonstructural building elements include: •

Exterior cladding and curtain walls

Parapet walls

Elevators

Partitions, doors, windows

Suspended ceilings

Furniture and equipment

Mechanical, plumbing, electrical and communications equipment

Stacks and chimneys

Canopies and marquees.

These items must be stabilized with bracing to prevent their damage or total destruction. Building machinery and equipment can be outfitted with seismic isolating devices, which are modified versions of the standard vibration isolators. Building configuration, whether regular or irregular, generally determines the form that the distribution of seismic forces takes within the structure, as well as its relative magnitude and problematic design concerns. Regular configuration buildings typically have shear walls, moment-resistant frames or braced frames, whereas irregular configuration buildings differ in that they generally have problematic stress concentrations and torsion (Figure 17.5). Performance of cladding, glazing and roofing in earthquakes is discussed and outlined in other sections of this book. It suffices here to mention that the design and installation of cladding systems need great care, and successful performance during a seismic event relies largely on solving the problem of interaction between the cladding and the building structure. Seismic analysis (probable maximum loss): There are numerous firms that specialize in conducting probabilistic studies of the expected loss to buildings from damage associated with earthquakes. The reports assess the probable and scenario loss potential. They are intended to allow the user to satisfy a critical part of the transactional due diligence requirements with respect to assessing properties’ capacity for building losses associated with earthquake potential. In addition, there are now a number of specialized software packages on the market to assist investors in PML evaluation. The building’s history: A seismic inspector should find out how old the building is, its type of construction, and what, if any, changes or alterations have occurred to the facility. The building’s age may be an indicator of potential vulnerabilities. The location of large earthquake faults within a 100-mile radius of the building should be investigated. Estimating seismic risk: Estimates of seismic risk should always be calculated from the building’s structural reproduction cost. In areas with a high probability of damage from earthquakes, an understanding of the seismic vulnerability of a new investment property should always be included as part of the real estate investment underwriting process. Buildings designed in accordance with codes will still sustain direct physical damage to the building structure and to major non-structural elements. In contrast to many other potential casualty loss requirements, there is currently no universal requirement to insure against seismic risk as a condition of a mortgage loan, mainly because many lenders have little understanding of seismic risk.


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Figure 17.5 Diagram illustrating irregular and regular building configurations (source, Gabor Lorant, FAIA).

In processing loans there is a need to put in place a simplified analytical methodology that can provide a rapid assessment of the order of magnitude of the risk that can be expected. There are many sophisticated computer-based rapid risk analysis methodologies available on the market. The best of these are based on a methodology originated by the Applied Technology Council that is based upon the opinion and experience of seismic experts regarding the expected response of building types to a range of seismic events. The methodology provides estimates for expected losses for various building structural types at various earthquake intensities. These expected losses are expressed as probable maximum loss (PML). The probable maximum loss (PML) can be defined as the estimate cost to rectify the damage from a seismic action of a defined intensity, expressed in dollars or as a percentage of a building’s insured value or total structural reproduction cost. It thus reflects the monetary loss potential of a building, taking into account the location of the property and the maximum probable earthquake magnitude of the area. Unless a lender has estimated the structural reproduction cost, he or she will not know the PML represented in terms of dollars (PML$ = PML% x structural reproduction cost in dollars). The PML of a building is often determined during an evaluation of the structural system, even though it is not an exact science. Specific con-


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ditions impacting the PML of a structure are shown in Figure 17.6. For older properties whose market values are lower than their original construction costs, a PML of 20 percent when converted to dollars can represent 50 percent (and greater) of the market value. Seismic Code Compliance: Many building codes and governmental standards exist pertaining to design and construction for seismic hazard mitigation and the diligent implementation and enforcement of these codes is as critical as the codes themselves. Building code requirements are primarily prescriptive and define seismic zones and minimum safety factors for design purposes. Codes pertaining to seismic requirements may be local, state, or regional building codes or amendments and should be researched thoroughly by the design professional. Many govFigure 17.6 Some of the conditions that directly impact the ernmental agencies at the federal level probable maximum loss (PML) of a building. also have seismic standards, criteria, and program specialists who are involved in major building programs and can give further guidance on special requirements. Building codes typically do not mandate seismic retrofit, but state and local jurisdictions may adopt/ issue mandatory ordinances to retrofit existing higher-risk buildings. For example, some building departments have enacted ordinances that require strengthening of Un-reinforced Masonry Buildings (URMs) that are located in high-seismic areas. Structural resistance to the potentially destructive forces of an earthquake has long been a design criterion for buildings. The new International Building Code (IBC) adds a key dimension: maintaining the use of designated life safety systems in certain building types immediately after a seismic event.

17.2 HURRICANES, TORNADOES, FLOODS, ETC. It is important to realize that a well-designed, constructed, and maintained office building may be damaged by a wind event that is much stronger than what the building was designed for; however, except for tornado damage, this scenario is a very rare occurrence. Rather, most damage occurs because various building elements have limited wind resistance due to inadequate design, application, material deterioration, or roof system abuse. Wind with sufficient speed to cause damage to weak office buildings can occur anywhere in the United States and its possessions. Although the magnitude and frequency of strong windstorms varies by locale, all office buildings should and can be designed, constructed, and maintained to avoid wind damage (other than that associated with tornadoes). In tornado-prone regions, consideration should be given to designing and constructing portions of office buildings to provide occupant protection.


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The key strategy to protecting a building from high winds caused by tornados, hurricanes, and gust fronts is to maintain the integrity of the building envelope, including roofs and windows, and to design the structure to withstand the expected lateral and uplift forces. Roof trusses and gables should be braced; hurricane straps should be used to strengthen the connection between the roof and walls; and doors and windows should be protected by covering and/or bracing. When planning renovation projects, designers should consider opportunities to upgrade the roof structure and covering and enhance the protection of fenestration. A variety of windstorm types occur in different regions of the United States and the world. The main characteristics of the type of storms that can impact a site should be carefully considered by the design team. Below is a preliminary overview of the primary storm types that can affect design decisions: Straight-line wind: This type of wind event is typically the most common. This type of wind is considered generally to blow in a straight line. Straight-line wind speeds range from very low to very high. Highspeed winds associated with intense low pressure can last for upward of a day at a given location. Straightline winds occur throughout the U.S. and its possessions. Thunderstorm: This type of storm can rapidly form and produce high wind speeds. Approximately 10,000 severe thunderstorms occur annually in the U.S., typically in the spring and summer. They are most common in the Southeast and Midwest areas of the United States. In addition to producing high winds, they often create heavy rain. Hail and tornadoes are also sometimes produced. Thunderstorms commonly move through an area quite rapidly, often causing high winds for only a few minutes at a given location. However, thunderstorms are capable of stalling and becoming virtually stationary. Downburst: The downburst, also known as microburst, is a powerful downdraft associated with a thunderstorm. When the downdraft reaches the ground, it spreads out horizontally and may form one or more horizontal vortex rings around the downdraft. The outflow is typically 6,000 to 12,000 feet across and the vortex ring may rise 2,000 feet above the ground. The life-cycle of a downburst is often between 15 to 20 minutes. Preliminary observations indicate that approximately 5 percent of all thunderstorms produce a downburst, which can result in significant damage in a localized area. Hurricane: This is a system of spiraling winds converging with increasing speed toward the storm’s center (the eye of the hurricane). Hurricanes are usually created when strong clusters of thunderstorms drift over warm ocean waters. As the storm moves over the ocean it picks up more warm, moist air and wind speeds start increasing. The diameter of the storm varies between 50 and 600 miles. A hurricane’s forward speed can vary between approximately 5 to 25 miles per hour (mph). Besides being capable of delivering extremely strong winds for several hours, many hurricanes also bring with them very heavy rainfall. An excellent example of this is the devastating Hurricane Katrina which blew in from the Gulf of Mexico (Figures 17.7A,B,C). Hurricane Katrina was formed on August 23 during the 2005 Atlantic hurricane season and caused havoc and devastation along much of the north-central Gulf Coast. The most severe loss of life and property damage however, occurred in New Orleans, Louisiana, which flooded when the levee system catastrophically failed. The hurricane caused severe destruction across the entire Mississippi coast and into Alabama, as far as 100 miles (160 km) from the storm’s center. At least 1,836 people are known to have lost their lives in Hurricane Katrina and in the subsequent floods, making it the deadliest U.S. hurricane since the 1928 Okeechobee Hurricane. The storm is estimated to have been responsible for $81.2 billion (2005 U.S. dollars) in damage, making it the costliest natural disaster in U.S. history. Hurricanes also occasionally spawn tornadoes. The Saffir-Simpson Hurricane Scale is used to rate the intensity of hurricanes. The five-step scale ranges from Category I (the weakest) to Category V (the strongest). Of all the storm types, hurricanes have the greatest potential for devastation and when they hit land they can destroy large geographical areas and, hence, can affect great numbers of people.


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Tornado: This is a small scale extremely violent rotating column of air extending from the base of a thunderstorm to the ground. Tornadoes are the least predictable of all natural phenomena and are another source of costly damage. The Fujita scale categorizes tornado severity based on observed damage. The six-step scale ranges from F0 (0–73 mph—light damage) to F5 (261–318 mph—incredible damage). Weak tornadoes (F0 and F1) are most common, but strong tornadoes (F2 and F3) frequently occur. Violent tornadoes (F4 and F5) which have the greatest velocity are rare. Although no two tornadoes are the same, they need certain conditions to form—particularly intense or unseasonable heat. As the ground temperature increases, moist air heats and starts to rise. When the warm, moist air meets cold dry air, it explodes upwards, puncturing the layer above. A thunder cloud may begin to build. A storm quickly develops—there may be rain, thunder and lightning. Upward movement of air can become very rapid. Winds from different directions cause it to rotate. Although more than 1,200 tornadoes typically occur each year in the U.S., the probability of a tornado occurring at any given location is quite small. Tornado path widths are typically less than 1,000 feet; however, widths of approximately one mile have been reported. A tornado can last from several seconds to more than an hour and may travel dozens of miles, but wind speed rapidly decreases with increased dis-

C Figure 17.7A,B,C Aerial views of 17th St. Canal breach, looking south (source, Interagency Performance Evaluation Task Force—IPET).


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tance from the center of a tornado. An office building on the periphery of a strong or violent tornado could be subjected to moderate to high wind speeds, depending upon the distance from the core of the tornado. However, even though the wind speed might not be great, an office building on the periphery could still be impacted by many large pieces of wind-borne debris. Tornadoes are responsible for the greatest number of wind-related deaths each year in the U.S. Except for window breakage, well designed, constructed, and maintained office buildings should experience little if any damage from weak tornadoes. However, because many office buildings have windresistance deficiencies, weak tornadoes often cause building envelope damage. Most office buildings experience significant building envelope damage and damage to interior partitions and ceilings if they are in the path of a strong or violent tornado. Structural damage (e.g., roof deck blow-off or collapse of the roof structure, collapse of exterior bearing walls, or collapse of the entire building or major portions thereof). Structural damage, along with damage to the building envelope, is the number one type of damage during strong and violent tornadoes. Although tornadoes are a common occurrence in several regions of the United States, neither the IBC or ASCE 7 requires buildings to be designed for them, nor are occupant shelters required in buildings located in tornado-prone regions. Because of the extremely high pressures and missile loads that tornadoes can induce, constructing tornado-resistant office buildings is extremely expensive and not very cost effective. Therefore, when consideration is voluntarily given to tornado design, the emphasis typically is on occupant protection, which is achieved by “hardening� portions of an office building for use as a safe haven. Water infiltration: When heavy rain accompanies high winds (e.g., thunderstorms, tropical storms, and hurricanes), it can cause wind-driven water infiltration problems (the magnitude of the problem increases with the wind speed). Penetration can occur between the door and frame, and frame and wall, and water can be driven between the threshold and door. When the basic wind speed exceeds 120 mph, some water infiltration should be anticipated due mainly to the very high wind pressures and various opportunities for a leakage path to develop. Flooding: About 6 percent of the land area in the contiguous United States is subject to potential flooding. Three characteristics that have major effects on flooding potential are elevation, drainage, and topography. Flood mitigation is best achieved by hazard avoidance—that is, appropriate site selection away from floodplains. Should buildings be sited in flood-prone locations, they should be elevated above expected flood levels to reduce the chances of flooding and to limit the potential damage to the building and its contents when a flood occurs. Flood mitigation techniques include elevating the building so that the lowest floor is above the flood level; dry flood-proofing, or making the building watertight to prevent water entry; wet flood-proofing, or making uninhabited or non-critical parts of the building resistant to water damage; relocation of the building; and the incorporation of levees and floodwalls into the site design to keep water away from the building. When Hurricane Katrina hit the north-central Gulf Coast of the U.S. in August 2005, it brought with it winds of 175 mph and catastrophic flooding (Figure 17.7A,B,C). Its enormous consequences dwarfed the losses from previous disasters. The flooding was a result of overtopping and breaching of the London Avenue Canal, the 17th Street Canal, and the IHNC breaches that occurred earlier. The I-wall failure mechanisms at the IHNC, 17th Street Canal, and London Avenue were investigated by field explorations, laboratory tests to measure soil properties, limit equilibrium analyses of stability, finite element analyses of seepage and soil-structure interaction, and centrifuge model tests. These numerical analyses and physical tests all showed that the formation of gaps behind the walls was a key element in the catastrophic failure. Flooding of a property however, can take many forms; it can be caused by human error, negligence, burst water pipes, sprinkler system malfunction, sewage backup, etc. Flooding by uncontaminated sink


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overflows or flows from ruptured pipes is usually easier to “fix� than flooding by water with a degree of biopollutant contamination, such as water from contaminated toilet and dishwater overflows. The most difficult to rectify is flooding by back water that has come into contact with the ground or that contains raw sewage, including, but not limited to, natural flooding. Unfortunately, porous materials like carpet that are flooded by back water must be discarded because of the high-level intrusion of bacteria and other pollutants. In all cases, the first step to take when localized flooding occurs is to pump out all standing water and thoroughly clean and dry the structure. It is important that professional dehumidification equipment be used when the outside temperature is below the indoor dew point or when an open system is impractical. In areas where drywall is used, at least several inches above the level of flood water saturated drywall must be cut and removed. All flood water saturated drywall, fibrous insulation, ceiling tiles and other porous materials must be removed and disposed of. In Figure 17.8 we see an example of a flooded apartment renovation in progress. Forest fires, home structure fires, and other types: Although earthquakes may represent the greatest potential for sudden loss in a single catastrophe, fire in terms of human life and property damage is typically by far the costliest natural hazard each year. In 2006 for example, a total of 96,385 fires and 9,873,429 acres burned were reported. In 2005, home structure fires (one- and two-family dwellings, apartments, and

Figure 17.8 Shows a residential apartment in Capitol Heights, Maryland during renovation after a local flooding incident. Notice that about two feet of drywall has been cut and removed (courtesy, M. Paruti, IVI International).


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manufactured homes) caused 82 percent of the civilian fire deaths, and 74 percent of the civilian fire injuries. The magnitude of these statistics is frightening (Figure 17.9). With the expansion of residential developments into wild land areas, people and property are increasingly at risk from wildfire. A cleared safety zone of at least 30 feet (100 feet in pine forests) should be maintained between structures and combustible vegetation, and fire-resistant ground cover, shrubs, and trees should be used for landscaping (for example, hardwood trees are less flammable than pines, evergreens, eucalyptus or firs). Only fire-resistant or non-combustible materials should be used on roofs and exterior surfaces. Roofs and gutters should be regularly cleaned and chimneys should be equipped with spark arrestors. Vents, louvers, and other openings should be covered with wire mesh to prevent embers and flaming debris from entering. Overhangs, eaves, porches, and balconies can trap heat and burning embers and should also be avoided or minimized and protected with wire mesh. Windows allow radiated heat to pass through and ignite combustible materials inside, but dual- or triple-pane thermal glass, fire-resistant shutters or drapes, and noncombustible awnings can help reduce this risk. Sometimes there is a conflict between local and federal guidelines in fighting fires. This became apparent in tackling the Sofa Super Store fire in Charleston, South Carolina where nine firefighters lost their lives (Figure 17.10A,B). The Charleston City Fire Department stated that it had its own firefighting rules that conflicted in some ways with safety rules adopted by federal and South Carolina fire safety agencies. These conflicts may directly affect the forensic expert investigation and final report. Fires in large buildings can create chaotic circumstances, and it is difficult to ascertain whether following the federal rules in the Sofa Super Store fire incident would have saved the lives of the nine firefighters killed in the blaze. Tsunami: A tsunami is a series of ocean waves generated by sudden displacements in the sea floor, landslides, or volcanic activity. In the deep ocean, the tsunami wave may only be a few inches high. In deep water, the tsunami moves at great speeds, but when it reaches shallow water near coastal areas, it slows but increases in height. Depending on circumstances, the tsunami wave may come gently ashore or may increase in height to become a fast moving wall of turbulent water several yards high. Although a tsunami cannot be prevented, the impact of a tsunami can be mitigated through urban/land planning, community preparedness, timely warnings, and effective response.


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Figure 17.9 Photo of recent wild fires in the United States (courtesy, National Interagency Fire Center).

Figure 17.10A,B Photos of the Sofa Super Store fire in Charleston, South Carolina in which nine firefighters lost their lives (courtesy, Wikipedia).


CHAPTER

18 Additional Issues 18.1 LIFE SAFETY SYSTEMS 18.1.1

Introduction

It is often argued that the life safety system is the most important system to be evaluated in a facility. The objectives of these systems are to safeguard the building and its occupants (Figure 18.1). The various components of modern fire-protection systems should work together to effectively detect, contain, control, and/or extinguish a fire in its early stages—and to survive during the fire. But who is ultimately responsible for the safety of employees, etc. The Occupational Safety and Health Administration (OSHA) states, “Employers are responsible for providing a safe and healthful workplace for their employees.” The workplace should be free from recognized hazards likely to cause death or serious physical harm. The complexity of life safety systems varies with the type, size and use of a facility. In some smaller structures, smoke detectors and fire extinguishers comprise the system. In others, a complete fire suppression system, including the fire sprinklers, is installed throughout the facility. An important aspect of the evaluation of any life safety system includes verification of periodic maintenance, inspection and testing of the main components of the system. Figure 18.2 illustrates some of the many types of life safety systems that are employed to address fire safety requirements. Each of these gives rise to its own set of issues which need to be taken into account in facility surveys. Planning for fire safety involves an integrated approach in which system designers need to analyze building components as a total package. Code compliance is the first objective in any design. Codes are legal minimum requirements; you have to meet the minimum with any design. Of note, fire codes can vary substantially from one jurisdiction to another. According to Frank Monikowski and Terry Victor of SimplexGrinnell, some of the advances and emerging technologies that can be found in today’s Life/Safety systems include: • •

Control mode sprinklers—standard manufactured sprinklers that limit fire spread and stunt high heat release rather than extinguish a fire; they also “pre-wet” adjacent combustibles. Suppression sprinklers—operate quickly for high-challenge fires, and are expected to extinguish a fire by releasing a high density of water directly to the base of the fire. 313

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• •

• • • • •

Fast-response sprinklers—provide quicker response and are now required for all light-hazard installations. Residential sprinklers—designed specifically to increase the survivability of an individual who is in the room where a fire originates. Extended coverage sprinklers—designed to reduce the number of sprinklers needed to protect a given area. These come in quick-response, residential, and standard-response types, and are also available for both light- and ordinary-hazard occupancies. Special sprinklers, such as early suppression fast response Figure 18.1 Main goals of fire-protection systems. (ESFR)—designed for high-challenge rack storage and high-pile storage fires. In most cases, these sprinklers can eliminate the expense and resources needed to install in-rack sprinkler heads. Low-pressure sprinklers—provide needed water coverage in multi-story buildings where pressure may be reduced. These low-pressure sprinklers bring a number of benefits: reduced pipe size, reduction or elimination of a fire pump, and overall cost savings. Low-profile, decorator, and concealed sprinklers—designed to be more aesthetically pleasing. Sprinkler system valves that are smaller, lighter, and easier to install and maintain and, therefore, less costly. A fluid delivery time computer program that simulates water flowing through a dry system in order to accurately predict critical “water-to-fire” delivery time for dry-pipe systems. The use of cost-efficient CPVC piping for light-hazard and residential sprinkler systems. Advanced coatings on steel pipes, designed to resist or reduce microbiologically influenced corrosion (MIC) and enhance sprinkler system life. Corrosion monitoring devices to alert users of potential problems. More efficient coordination in evaluating building sprinkler system need—including site surveys, accurate measurements, and the use of CAD and hydraulics software to ensure that fire sprinkler system designs respond to the specific risks and the physical layout of the premises.

A new Emergency Evacuation Planning Guide for People with Disabilities was developed and recently is-

Figure 18.2 Various types of life safety systems.


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sued by the National Fire Protection Association (NFPA). The document provides general information to assist in identifying the needs of people with disabilities related to emergency evacuation planning.

18.1.2

Fire Life/Safety Systems and Components

Sprinkler Systems Types Automatic sprinklers are the most common, widely specified, and most effective fire suppression system in commercial facilities—particularly in occupied spaces. In fact, automatic sprinkler systems are now not only required in new high-rise office buildings, but in many U.S. cities it is mandated by code that existing high-rises be retrofitted with automatic sprinkler systems. There are several types of automatic sprinkler systems including wet- and dry-pipe, pre-action, deluge, and fire cycle. Of these, wet-pipe and dry-pipe are the most common. In a wet-pipe system, the sprinklers are attached to a water supply, enabling immediate discharge of water at sprinkler heads opened by the heat of the fire. In a dry-pipe system, the sprinklers are under air pressure which fills the system with water when the pressure is eased by the opening of the sprinkler heads. When certain circumstances prevent the use of sprinklers because of special considerations (e.g., water from sprinklers would damage sensitive equipment or inventory), alternative fire-suppression systems might be decided upon, such as gaseous/chemical suppression. In the final analysis, the type of sprinkler system used depends on a building’s function. Of note, most of today’s fire sprinklers incorporate the latest in design and engineering technologies to provide an extremely high level of life-safety and property protection. The features and benefits now available are making fire sprinkler systems more efficient, reliable, and cost effective. Residential use of sprinkler systems has increased significantly in recent years, mainly due to an increased awareness of their many benefits, but also because they have become more affordable. These sprinkler systems usually fall under a residential classification and not a commercial one. A commercial sprinkler system is designed to protect the structure and the occupants from a fire. Most residential systems are primarily designed to suppress a fire in such a way to allow for the safe escape of the building occupants. While these systems will often also protect the structure from major fire damage, this remains a secondary consideration. When a system is operating as designed, fire sprinkler systems are highly reliable, but like any other mechanical system, sprinkler systems need periodic maintenance and inspection in order to sustain proper operation. Figure 18.3 is an example of a fire sprinkler control valve assembly including pressure switches and valve monitors. Figure 18.3 Typical fire sprinkler control valve 1. Wet-pipe systems: Wet-pipe sprinkler assembly (courtesy, Wikipedia). systems are by far the most common and have the


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highest reliability. The systems are simple, with the only operating component being the automatic sprinkler. A water supply provides pressure to the piping, and all of the piping is filled with water adjacent to the sprinklers. The water is held back by the automatic sprinklers (Figure 18.4) until activated. When an automatic sprinkler is exposed to a predetermined heat level, the fusible link in the sprinkler head fuses and the sprinkler head opens, allowing water to flow from that sprinkler. Each sprinkler operates individually. A prerequisite of this system is that the area of the installed must be kept at temperatures above freezing point. Figure 18.5 shows a drawing of a typical wet-pipe sprinkler system. 2. Dry-pipe systems: These are the second most common sprinkler system type in use. Regulations typically stipulate that these systems can only be used in spaces in which the ambient temperature may be cold enough to freeze the water in a wet-pipe system, thus rendering it inoperable. We often find dry-pipe systems used in unheated buildings and in refrigerated coolers. Each sprinkler operates individually and water does not enter the piping until the system operates. When a fire occurs and the temperature exceeds a predetermined point, the fusible link in the sprinkler fuses and the sprinkler head opens. The pressurized air (or nitrogen for a small dry system) contained in the pipe is allowed to vent, causing the dry-pipe valve to open. Water then enters the sprinkler piping system and flows out of the open sprinkler. Water flow from the sprinkler needed to control the fire is delayed until the air is vented from the sprinkler, which is the main reason that this type of system is not as effective as a wet-pipe system in fire control during the initial stages of a fire. 3. Deluge systems: In a “deluge� system the sprinklers are open, i.e. the heat sensing operating element is removed during installation, so that all sprinklers connected to the water piping system remain open. These systems provide a simultaneous flow of water over the entire hazard and are typically used for special hazards where rapid fire spread is a major concern. Water is not present in the piping until the system operates. Because the sprinkler orifices are open, the piping is at ambient air pressure. To prevent the water supply pressure from forcing water into the piping, a deluge valve is used in the water supply connection, which is a mechanically latched non-resetting valve that stays open once tripped. 4. Pre-action systems: The pre-action system works on the principal that in the event of a fire an automatic fire

Architectural Forensics

Figure 18.4 Drawing of a typical ceiling mounted sprinkler head (courtesy, Scott Easton).

Figure 18.5 Drawing of a typical wet-pipe sprinkler system.


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detection device (such as a smoke or heat detector) located near the sprinkler will be activated. This in turn will allow water to enter the piping before the sprinkler is activated, so that when the sprinkler opens at a predetermined high temperature, water can immediately flow out of it. Pre-action sprinkler systems are specialized for use in locations where accidental activation is undesired, such as in museums with rare art works, manuscripts, or books and computer rooms and data centers. Once the fire is detected by the fire alarm system, it basically converts from a dry system into a wet system. 5. Foam water sprinkler systems: A foam water fire sprinkler system is a special application system discharging a mixture of water and low expansion foam concentrate, resulting in a foam spray from the sprinkler. These systems are typically applied to special hazards occupancies associated with high challenge fires, such as flammable liquids, and airport hangars.

Standpipe & Fire-Hose Systems A standpipe system in a high-rise building is a pipe system that is designed to vertically transfer water to the upper floors of the building so that the water can be used to fight fires manually with fire hoses that are connected by manual valves in locations throughout the building. Fire-hose systems are found in many facilities (Figure 18.6A). The main pipe of the system, the standpipe, can be wet or dry, and additional water can be supplied to the system by the fire department using a Siamese inlet connection located at the bottom end of the pipe on the exterior of the building at street level. Most standpipe system points of discharge are located adjacent to or on stairway landings. Types of hose systems on the market include the semi-automatic swing rack, the hump back swing rack, and the swing reel. Figure 18.6B shows a drawing of a recessed cabinet option housing a fire extinguisher and fire hose. The cabinet is designed specifically to maintain the integrity of one and two hour fire walls to meet the requirements of UBC Standard 7-5 (ASTM E 814-83). Fire-rated cabinets are increasingly being used in response to the concerns expressed by fire marshals, code officials, and architects. There are three common classifications of standpipe systems based on the service for which they are designed: Class I standpipe systems provide a 2.5 inch (63.5 mm) hose connection from a standpipe or combined riser for use by fire departments and those trained in handling heavy fire streams of water. Class II systems are directly connected to a water supply and equipped with one 1.5 inch (38.1 mm) outlet and hose that provides a means for the control or extinguishment of incipient stage fires. Typically, each hose connection has a hose, hose nozzle, and hose rack installed on it.

Figure 18.6A,B A. Cabinet with full clear acrylic door housing fire extinguisher and fire hose (courtesy, Larsen's Manufacturing Co.). B. Drawing of a recessed two-hour fire cabinet to house a fire extinguisher and fire hose (courtesy, Larsen's Manufacturing Co.).


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Class III systems are a combined standpipe system directly connected to a water supply and are for the use of in-house personnel capable of furnishing effective water discharge during the more advanced stages of fire in the interior of workplaces. Standpipe systems having the control valve located within a stairwell should ensure that the maximum length of hose does not exceed 100 feet (30.5 meters). If the control valve is located in areas other than the stairwell, the length of hose should not exceed 75 feet. Code requires that the fire hose on Class II and Class III standpipe systems be equipped with a shut-off type nozzle.

Hand-Held Fire Extinguishers There are basically four different classifications of fire extinguishers, each of which extinguishes specific types of fire. Newer fire extinguishers use a picture/labeling system to designate which types of fires they are to be used for. Older fire extinguishers are labeled with colored geometrical shapes with letter designations (Figure 18.7, 18.8). Classification of hand-held fire extinguisher ratings: Class A extinguishers will put out fires in ordinary combustibles, such as wood, textiles, and paper. The numerical rating for this class of fire extinguisher refers to the amount of water the fire extinguisher holds and the amount of fire it will extinguish. Class B extinguishers should be used on fires where the smothering effect of extinguishing is important which include fires of gasoline, oil, grease, and fat. The numerical rating for this class of fire extinguisher states the approximate number of square feet of a flammable liquid fire that a non-expert person can expect to extinguish. Class C extinguishers are suitable for use in electrical equipment where a non-conducting material is required. This class of fire extinguishers does not have a numerical rating. The presence of the letter “C� indicates that the extinguishing agent is non-conductive. Class D extinguishers are special types approved for specific combustible materials. There is no picture designator for Class D extinguishers. These extinguishers generally have no rating nor are they given a multi-purpose rating for use on other types of fires. Many extinguishers available today can be used on different types of fires and will be labeled with more than one designator, e.g., A-B, B-C, or A-B-C. If a multi-purpose extinguisher is being used it should be properly labeled. Types of fire extinguishers: There are several different types of fire extinguishers including: Dry chemical extinguishers are usually rated for multiple purpose use. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant. Halon extinguishers contain a gas that interrupts the chemical reaction that takes place when fuels burn. These types of extinguishers have a limited range, usually four to six feet and are often used to protect valuable electrical equipment since they leave no residue to clean up. Water extinguishers contain water and compressed gas and should only be used on Class A (ordinary combustibles) fires. Figure 18.7 New and old style of Carbon dioxide (CO2) extinguishers are most effective on labeling indicating suitability for use on Class A, B, and C fire extinguishers. Class B and C (liquids and electrical) fires. Since the gas disperses


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quickly, these extinguishers are only effective from three to eight feet. NFPA Code 10 addresses all the issues pertaining to portable fire extinguishers. Recognized as a first line of defense against fires, portable extinguishers, when maintained and operated properly on a small containable fire, can prevent fire from spreading beyond its point of origin. NFPA Code 10 also requires owners of extinguishers to have monthly inspections performed and to maintain records of the inspections. These records should be inspected during a forensic survey. The inspection must determine that the extinguisher is at its designated location and that it is mounted properly, that signage showing its location is visible and readable, and that access to the extinguisher is not blocked.

Smoke & Heat Detection Systems A smoke detector or smoke alarm is a device that detects smoke and issues an alarm to alert nearby people that there is a potential fire. A household smoke detector will typically be mounted in a disk shaped plastic enclosure about 150 mm in diameter and 25 mm thick, but the shape can vary by manuFigure 18.8 Newer hand-held fire facturer (Figure 18.9A). Laws governing the installation of extinguishers use a picture/labeling smoke detectors vary depending on the jurisdiction (Figure system to designate the types of fires extinguishers are to be used on. Types of 18.9B). extinguishers include: 1. MP series multiBecause smoke rises, most detectors are mounted on the purpose dry chemical 2. DC series ceiling or on a wall near the ceiling. To avoid the nuisance of regular dry chemical 3. WC series wet false alarms, most smoke detectors are mounted away from chemical 4. WM series water mist 5. CD kitchens. To increase the chances of waking sleeping occuseries carbon dioxide 6. HT series pants, most homes have at least one smoke detector near any Halotron I (courtesy, Larsen's bedrooms; ideally in a hallway as well as in the bedroom itself. Manufacturing Co.). Smoke detectors are usually powered by one or more batteries but some can be connected directly to household wiring. Often the smoke detectors that are directly connected to the main wiring system also have a battery as a power supply backup in case the facility’s wiring goes out. Most smoke detectors work either by optical detection or by ionization, and some use both detection methods to increase sensitivity to smoke. They may also operate alone, be interconnected to cause all detectors in an area to sound an alarm if one is triggered, or be integrated into a fire alarm or security system. Smoke detectors with flashing lights are available for the deaf or hearing impaired. The main benefit of good detection (beyond triggering the alarm system) is that, in many cases, there is a chance to extinguish a small, early blaze with a fire extinguisher. Modern smoke-detection systems go beyond the small device that senses smoke and triggers the alarm system. Intelligent smoke detectors can differentiate between different alarm thresholds. These systems typically have remote detectors located throughout the facility which are connected to a central alarm station. Heat detectors are another option. They can trigger alarms and notification systems before smoke even becomes a factor.


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A heat detector is a device that detects heat and can be either electrical or mechanical in operation. The most common types are the thermocouple and the electro-pneumatic—both respond to changes in ambient temperature. Typically, if the ambient temperature rises above a predetermined threshold, an alarm signal is triggered.

Fire Doors A fire door is a door made of fire-resistant material that can be closed to prevent the spread of fire and is designed to provide extra firespread protection for certain areas of a building. The National Fire Protection Association (NFPA) rates doors according to the number of hours they can be expected to withstand fire before burning through. There are 20, 30, 45, 60, 90-minute rated fire doors as well as 2HR and 4HR rated fire doors that are certified by an approved laboratory such as Underwriters Laboratories. The certification only applies if all parts of the installation are correctly specified and installed. For example, fitting the wrong kind of glazing may severely reduce the door’s fire resistance rating (Figure 18.10). Because fire doors are rated physical fire barriers that protect wall openings from the spread of fire, they should provide automatic closing in the event of fire detection with governed speed control. Fire doors are also designed for daily use to provide security and access control, but are for use in openings that are not part of a required means of egress. Fire doors should usually be kept closed at all times, although some are designed to stay open under normal circumstances, and are designed to close automatically or manually in the event of a fire. Proper bounding of fire doors should be routinely checked and ensured. They are used in commercial and industrial applications where a fire barrier is required. Fire door closing devices must be UL listed and labeled, and are required to be tested every six months. Release devices are electro-mechanical devices that enable automatic closing fire doors to respond to alarm signals from detection devices such as smoke detectors, heat detectors and central alarm systems. This permits closing the door before high temperatures melt the fusible link. Fusible links should always be used as back up to the releasing device. The closing system can be weight close, spring reel close, or motorized. All fire products should be provided with a multiple fuselink setup to close the door automatically when any link melts. Standard fuselinks are designed to melt at 165° F and are to be located at the ceiling level above the fire door. For units with an automatic closing system or that are tied into an alarm system or local detectors, a fuselink set-up should still be provided as a back up mechanical closing system.

Figure 18.9A Multi-criteria intelligent sensor smoke detector that incorporates both thermal and photoelectric technologies that interact to maximize detection.

Figure 18.9B Drawing showing CPSC smoke alarm recommendations in residential buildings. These include: 1. the installation of a working smoke alarm on every level of the home, outside sleeping areas, and inside bedrooms; 2. smoke alarms are tested at least once a month, and 3. smoke alarm batteries are replaced at least annually (source, U.S. Consumer Product Safety Commission).


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Exit Routes

Figure 18.10 Fire-rated door and glass lites classification.

Figure 18.11 Principles of exit safety. Egress design should be based upon an evaluation of a building’s total fire protection system (courtesy, Yngve Anderberge).

An exit route is a permanent, continuous and unobstructed path of exit travel from any point within a workplace to a place of safety and must be separated by fire resistant materials. Every building has fire exits which enable users to exit safely in the event of an emergency. Construction materials used to separate an exit from other parts of the workplace must have a onehour fire resistance-rating if the exit connects three or fewer stories and a two-hour fire resistance-rating if the exit connects four or more stories (Figure 18.11). Welldesigned emergency exit signs are necessary for emergency exits to be effective. In the United States, fire escape signs often display the word “EXIT” in large, well-lit, green or red letters. Openings into an exit must be limited. An exit is permitted to have only those openings necessary to allow access to the exit from occupied areas of the workplace, or to the exit discharge. An opening into an exit must be protected by a self-closing fire door that remains closed or automatically closes in an emergency upon the sounding of a fire alarm or employee alarm system. Each fire door, including its frame and hardware, must be listed or approved by a nationally recognized testing laboratory. At least two exit routes must be available in a workplace to permit prompt evacuation of employees and other building occupants during an emergency, unless otherwise stipulated by code. The exit routes must be located as far away as practical from each other so that if one exit route is blocked by fire or smoke, employees can evacuate using the second exit route. More than two exit routes must be available in a workplace if the number of employees, the size of the building, its occupancy, or the arrangement of the workplace is such that all employees would not be able to evacu-


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ate safely during an emergency. A single exit route is permitted where the number of employees, the size of the building, its occupancy, or the arrangement of the workplace is such that all employees would be able to evacuate safely during an emergency. The NFPA 101-2000, Life Safety Code can be consulted to help determine the number of exit routes necessary for a particular facility or building. Exit discharge: Each exit discharge must lead directly outside or to a street, walkway, refuge area, public way, or open space with access to the outside. The street, walkway, refuge area, public way, or open space to which an exit discharge leads must be large enough to accommodate the building occupants likely to use the exit route. Exit stairs that continue beyond the level on which the exit discharge is located must be interrupted at that level by doors, partitions, or other effective means that clearly indicate the direction of travel leading to the exit discharge. Exit door access: An exit door must be unlocked from the inside. Furthermore, employees must be able to open an exit route door from the inside at all times without keys, tools, or special knowledge. A device such as a panic bar that locks only from the outside is permitted on exit discharge doors. Exit route doors may be locked from the inside only in mental, penal, or correctional facilities and then only if supervisory personnel are continuously on duty and the employer has a plan to remove occupants from the facility during an emergency. Outdoor exit routes: An outdoor exit route is permitted if the outdoor exit route has guardrails to protect unenclosed sides if a fall hazard exists. The outdoor exit route must be covered if snow or ice is likely to accumulate along the route, unless it can be demonstrated that any snow or ice accumulation will be removed before it presents a slipping hazard. The outdoor exit route must be reasonably straight and have smooth, solid, substantially level walkways, and the outdoor exit route must not have a dead-end that is longer than 20 feet (6.2 m).

Fire Stopping—Compartmentation A fire compartment is a space within a building extending over one or several floors which is enclosed by separating members such that the fire spread beyond the compartment is prevented during the relevant fire exposure. Fire compartments are sometimes referred to as fire zones. Compartmentation is important in preventing fire to spread into large spaces or into the whole building. The division of the building into discrete fire zones offers perhaps the most effective means of limiting fire damage (Figure 18.12). Designed to contain the fire to within the zone of origin, this approach provides at least some protection for the rest of the building and its occupants even if first aid fire fighting measures are used and fail. It also delays the spread of fire prior to the arrival of the fire brigade. Halls and landings should typically be separated from staircases to prevent a fire from traveling vertically up or down the stairwell to the other floors. However, creation of new lobbies can have an unacceptable negative impact on the character of a fine historic interior. To be effective, compartmentation needs to be planned and implemented properly. There is no point in upgrading the fire resistance of a door and then not adequately protecting the plywood duct next to it which runs through to the floor above, or to the adjacent space. The fire resistance required by a compartment depends upon its intended purpose and on the expected fire. Fire stopping should be designed to stop the spread of fire between floors of a building. The flame retardant material is installed around floor openings designed to contain conduit and piping. Firestop is a product that, when installed properly, impedes the passage of fire, smoke, and toxic gases from one side of a fire-rated wall or floor assembly to another. Typical firestop products include sealants, sprays, mechanical devices (firestop collar), foam blocks, or pillows. These products are installed primarily in two applications: 1. Around penetrations that are made in fire-resistive construction for the passage of pipes, ca-


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Figure 18.12 The primary cause of fire and smoke spread is unprotected horizontal and vertical openings.

bles, or HVAC systems, and 2. Where two assemblies meet, forming an expansion joint such as the top of a wall, curtainwall (edge of slab), or floor-to-floor joints. A building owner’s responsibility is to comply with all applicable laws and regulations relating to the property. One of these is the adopted and enforced fire code within a specific jurisdiction. Fire codes govern the construction, protection, and occupancy details that affect the fire safety of buildings throughout their lifespan. Numerous different fire codes have been adopted throughout the United States—the vast majority of which are similar and based on one of the model codes available today or in the past. One requirement in all of these model codes is that fire-safety features incorporated into a building at the time of its construction must be maintained throughout a building’s life. Therefore, this would require any fire resistance-rated construction to be maintained (Figure 18.13).

Alarm Systems & Notification Systems Early warning is vital for saving lives, particularly in large buildings where there may be visitors or personnel who are unfamiliar with their surroundings. Alarm systems are therefore essential to any facility— alarms that alert building occupants of a fire and alarms that alert emergency public responders (police and fire) through a central station link to initiate an appropriate response. Fire detection and notification system requirements, at a minimum, will address the following elements: 1. Detection, 2. Notification, and 3. Survivability systems.


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Figure 18.13 A drawing showing various firestopping methods.

Today’s systems have the ability to provide more information to the fire department and first responders. New systems can tell that there has been an alarm in the building and identify the type of alarm and where the alarm is. Alert systems can also close fire doors, recall elevators, and interface and monitor the installed suppression systems, such as sprinklers. Such systems can also connect with a building’s ventilation, smoke-management, and stairwell-pressurization systems—all of which are critical to life safety. Moreover, many modern systems now include speakers that provide alerts in place of (or in addition to) traditional bell-type alarms. These speakers can also be used in emergencies other than fires to instruct and inform occupants of the situation (Figure 18.14).


Chapter 18 - Additional Issues

Figure 18.14 The newest of a series of audible/visible notification appliances, SpectrAlert Advance (courtesy, System Sensor).

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Figure 18.15 An example of a modern alarm annunciator (source, A.S.P. Electro-Technology Ltd).

Annunciator panels are sometimes installed in large buildings to monitor the fire alarm devices in a designated fire zone. There may be several fire zones in a building. Each fire zone is clearly marked on the panel. Should a fire occur, an indicator light flashes on the panel. The indicator light identifies the fire’s location. For example the light on the panel might indicate that a fire has occurred in Fire Zone 4. This information allows the Fire Department to quickly locate the fire. An example of a typical annunciator panel is shown in Figure 18.15.

18.1.3

System Diagnostics

The evaluation/survey of the life safety system consists of several aspects. The evaluation should include both a review of existing conditions as well as an inspection of previous certifications for the system. In most facilities, the life safety system is one of the best maintained systems. This is mainly due to the importance of the system and the diligence and frequency of inspections for life safety equipment by the fire department. In fact, it is uncommon upon review of a facility to find fire sprinkler inspection paperwork outdated and hand-held fire extinguishers in disrepair. The periodic inspection of a life safety system can significantly increase the useful life of the system. Indeed, beyond the components that actually make up an integrated fire-protection system, maintenance is a vital factor that affects the system. An improperly maintained system lacks reliability and, therefore, true protection. If a system is not maintained properly, its reliability degrades rapidly. A system should not be installed that can not be routinely maintained and easily and effectively tested. Periodic inspection of field-installed sprinklers is an important element of a comprehensive maintenance program for sprinkler systems and is required by code. As specified in NFPA 25, sprinklers showing signs of leakage, field painting, corrosion, damage, or loading are to be replaced. All of these conditions can lead to the degradation of sprinkler performance during a fire condition. The most serious sprinkler system failures revolve around the water supply. Without the appropriate water supply, a sprinkler system is of little use. The importance of a consistent water supply cannot be overstressed. Where a water failure occurs, it is more often due to the water control devices than the water sup-


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ply itself. For example, sprinkler system control valves can be closed inadvertently by authorized personnel, intentionally closed by an arsonist, or closed due to a physical deficiency in the valve. Public water system valves that are closed for maintenance purposes can also significantly impact the sprinkler system water supply. Mechanical failure or sediment accumulation in backflow preventers can cause excessive pressure loss, and dry-pipe sprinkler systems are susceptible to internal corrosion and scale which can clog sprinkler orifices during a fire. The water supply in some locations can cause microbiological influenced corrosion (MIC), leading to pinhole leaks or deposits that can obstruct piping. Obstructions of physical objects in the water supply main can also be a cause for failure. Construction documents should be reviewed to determine the life safety system components designed to be installed in the building. In some cases, last minute changes in construction result in omission of certain components. It is especially important to verify in the field the building areas shown to be protected by fire sprinklers on the documents. It should not be taken for granted that simply because the system is designed one way, the construction completely represents that design. Identify and observe the condition and capabilities of structural fire protection, means of egress, fire suppression systems, and fire detection and alarm systems. Risks to general health and safety should also be observed and recorded. Identify and observe the condition of life safety and fire protection systems, including sprinklers and standpipes (wet or dry, or both), fire hydrants, fire alarm systems, water storage, smoke detectors, fire extinguishers, emergency lighting, stairwell pressurization, smoke evacuation, etc. Identify the apparent or reported ages of life safety/fire protection systems, and combined with visual observations identify the RUL. Inspections should exclude determining NFPA hazard classifications, classifying, or testing the fire rating of assemblies. The certifications are usually filed with the maintenance staff and should be reviewed for completeness, original compliance, and current compliance. Special life safety system forms should be utilized which provide a checklist and information on the various components of the system.

18.2 PROPERTY SECURITY SYSTEMS Physical security is a legitimate concern for property owners, consultants, and project managers. Physical security includes the security of personnel, property, and content. Each of these has different parameters, applications, and operational imperatives. Terrorism in particular is now a recognized international phenomenon against which governments need to institute protective measures. Following the events of September 11, 2001, manufacturers have refined and upgraded many types of technology to address these terrorism threats. These include detection sensor technology, computer programs that manage and monitor systems, video processing, and the ability to send alerts to security personnel. It is vitally important to have a full understanding of the various types of technology systems as well as their capabilities, limitations, and applications. In the World Trade Center attacks of 9/11, nearly 3,000 people were killed (Figure 18.16A,B). These disasters highlight the lack of adequate security in public facilities as well as in the workplace. But today’s disasters come in different shapes and forms, from both inside and outside the building. Even disgruntled employees can become potential time bombs. Planners must therefore study all aspects of security, including the new challenges they face today, whether it concerns employees, the building’s structure, or the business. Security design of facilities often requires a complex series of trade-offs. Legitimate security concerns have to be balanced with other design constraints including, but not limited to, accessibility, implementa-


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tion costs, fire protection, natural hazard mitigation, environmental ramifications, energy efficiency, and aesthetics. As the probability of attack is small, there is a desire for security not to interfere with the building’s daily operations. On the other hand, as the effects of attack can be catastrophic, there is a desire to incorporate measures that will save lives and minimize business interruption in the unlikely event of an attack. But just as the nature and source of threats are constantly changing, building professionals also need to adapt to provide the best defense for their facilities. In today’s adverse environment, designing buildings for security and safety requires a proactive approach that anticipates—and then protects—the building occupants, resources, structure, and continuity of operations from potential hazards. The first step in this process is to understand and assess the various threats and the risks they pose. Based on an assessment and analysis of these risks and threats, building owners and other invested parties select the appropriate safety measures to implement. Such selection will depend on the security requirements, acceptable levels of risk, the cost-effectiveness of the measures proposed, and the impact these measures have on the design, construction, and use of the building. It is necessary to develop a physical security plan. This should preferably be done in consultation with legal counsel and the local police department. Most security system guidelines prefer to create multiple layers of security, also known as zones or “rings.” Zones or rings begin at the perimeter of the site, where methods to control pedestrian and vehicular traffic form the first line of defense. It also provides the greatest potential for detecting, evaluating, and responding to a threat and its level of security is increased with each subsequent ring. Providing facility-hardening techniques (the ability to withstand ballistic and forced entry attack) at the perimeter forms the next defense. Layering then continues from the facility envelope to the interior of the building. Inside the facility, the interior walls can create appropriate zones of protection until reaching the most secured area within the center of the facility. This multi-zone approach provides deterrence, detection, and delay, while the area between the rings provides for an incident response zone.

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A

B Figure 18.16A,B A. The September 11, 2001 terrorist attacks on the World Trade Center in New York created a new imperative on the issues of building security. B. Effect of building shape on air-blast loading.


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Building security—The multi-zone approach: The first line of facility defense is at the site perimeter. There are technologies now in place (although still expensive) which can detect intrusion before arrival at the perimeter. Nevertheless, the ring of security for a typical facility would start at the perimeter and, depending on the level of security, could include: • •

• • • • • • • •

A clear zone Perimeter control: combination of passive (e.g., chain link, concrete, wood fence) and active (e.g., electric, pulsed, fiber-optic) fence technology, bollards, and anti-ram barriers, to stake out property boundaries. Fences and deterrence systems can delay entry by an intruder Traffic control, remote controlled gates, anti-ram hydraulic drop arms, and hydraulic barriers, parking Perimeter landscaping, including plants, trees, shrubs and ditches—chosen and located to stop, deter or delay an intruder Detection devices: microwave and/or infrared sensors to detect movement Electronic barriers that restrict vehicle access Intercom systems that provide communication when requesting entry Card readers that authenticate and allow entry Video and CCTV cameras that record activities occurring along the perimeter Alarms.

The second security zone could include: • • • • •

Perimeter doors and locks Magnetic strip access card reader and keypad combination CCTV cameras Revolving doors Optical turnstiles.

The third and final layer could include: • • • •

CCTV video technology capabilities Electronic locking devices Dual authentication readers (e.g., card and fingerprint or hand geometry) for entry to the facility’s core assets, such as data centers and vaults Other Biometric technology such as facial recognition, iris and retinal scan.

The threat of terrorism against property by a determined terrorist will not be completely resolved in the foreseeable future, and no building can be made 100 percent terrorist-proof without enormous expense.

18.2.1

Types of Security Threats

A threat analysis is used to assess the various types of threats that can occur against a facility or organization as well as identify the possible individuals or groups who pose a threat. These threats can cause harm


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or death to employees, destruction to property, disclosure of sensitive material, interruption of operations, or denial of services. There are many types of threats to an organization that can impact the safety and welfare of its employees, its profitability, and its very existence. The most important of these threats include: Loss from natural disasters (fire, floods and earthquakes): Tens of billions of dollars and thousands of lives are lost annually to natural hazards. Recovery efforts include repairing damaged buildings and infrastructure from the impacts of hurricanes, floods, earthquakes, tornados, blizzards, and other natural disasters. These issues are discussed in the previous chapter. Figure 18.17 Vehicle Weapon Threat— Terrorism—explosive and vehicle weapon appropriate building setback required. The threats: Building security should address the mitigation of concept of setback is to allow as much space explosion effects on the exterior envelope of a new conbetween a vehicle and the building as possible (courtesy, Hinman Consulting Engineers). struction that was designed to meet federal anti-terrorist design requirements. Explosive threats appear to have become the criminal and terrorist weapon of choice. Devices may include stationary and moving vehicle-delivered, mail bombs, package bombs or large amounts of explosives that require delivery by a vehicle. Normally the best defense is to provide defended distance between the threat location and the asset to be protected. This is typically called standoff distance (Figure 18.17). If standoff is not available or is insufficient to reduce the blast forces reaching the protected asset, structural hardening may be required. Effective secure building design involves implementing countermeasures to deter, delay, detect, and deny attacks from human aggressors. It also provides for mitigating measures to limit hazards and prevent catastrophic damage should an attack occur. The design of blast-resistant structures and their subsystems is a long-established discipline practiced mostly by the military; however, these structures are usually located below grade. It is impractical to design conventional above grade structures to be blast-resistant because the potential risk cannot often be defined, nor can the potential threat be quantified, because we are unaware of the type of weapon to be used, its capacity, or the proposed mode of delivery. In addition, as the general impact of blast pressures is far greater than that of gravity or wind loads, this may induce the localized failure of exterior envelope components depending on several factors. And this resultant impact on cost, function and appearance can be enormous and therefore, unacceptable. Nevertheless, major improvements in susceptibility to a car bomb attack can be achieved by the simple use of common sense, good structural systems, effective countermeasures, and a well developed contingency or security plan. Ballistic threats: These threats may range from random drive-by shootings to high-powered rifle attacks directed at specific targets within the facility. It is important to quantify the potential risk and to establish the appropriate level of protection. Weapons of mass destruction (WMD)—chemical, biological, and radiological (CBR): The bombings of New York City’s World Trade Center, Oklahoma City’s Alfred P. Murrah Federal Office Building, and Atlanta’s Centennial Park, and the recent anthrax scare, shook the nation and forced many building owners and occupants to pay more attention to facility security and safety issues. This also led to a heightened realization of the daunting potential for a bioterrorism attack on a building’s air-handling system. Increased attention is now being paid to mechanical systems in terms of security and access, as well as filtering and detection (Figure 18.18A,B). This includes the consideration of impacts to the facility HVAC systems in general, and those systems interacting with the building envelope specifically. Of particular concern are airflow


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patterns and dynamics both inside and outside of buildings, especially pertaining to the internal release or external release of chemical, biological or radiological contaminant, and the measures necessary to limit airborne contamination. Exposure of building occupants to potentially hazardous chemical, biological, and radiological (CBR) agents negatively impacts the indoor environment and can pose serious health threats. To help maintain good indoor air quality and protect occupants’ health, dedicated ventilation and exhaust systems should be installed as well as dedicated HVAC systems to serve perimeter zones and to maintain positive pressurization with respect to the building envelope. Rob Bolin, P.E. of the Syska Hennessy Group says that, “The main objective of chemical/biological/radiological (CBR) safety and protection is to provide building systems and controls that provide a safe and secure indoor environment in the event of a CBR release inside or outside of the building.” A number of basic steps should be implemented to minimize such potential threats. They include:

Figure 18.18A Protecting outdoor air intakes (courtesy, Guidance for Protecting Building Environments From Airborne Chemical, Biological and Radiological Attacks, NIOSH).

Protect pathways into the building

Provide a tight building envelope

Control access to air inlets and water systems

Incorporate dedicated ventilation and/or exhaust systems

Provide detection and filtration systems for HVAC systems and ensure that they have the ability to monitor outdoor air intakes for the presence of chemical agents

Use dedicated HVAC systems for different spaces and sections of the building (e.g., provide separate HVAC for the lobby, perimeter zones, and the building’s core)

• • • •

Provide for emergency HVAC shutoff and control Consider the physical security of HVAC components Consider providing positive pressurization to keep contaminates outside of the facility Provide an emergency notification system to facilitate orderly response and evacuation.

Figure 18.18B Vulnerable outdoor air intakes (courtesy, Guidance for Protecting Building Environments From Airborne Chemical, Biological and Radiological Attacks, NIOSH).


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18.2.2

331

Defining Security Needs

Today, security in the built environment is for the protection of people, information, and property. Security determinations are therefore essential in defining security needs prior to designing new facilities or retrofitting existing facilities. And attempting to overlay security strategies and measures after a design concept is in place can be very counter productive and costly. And while the scope and level of assessments within each facility will vary, the ultimate goal will remain the same—to decide upon an acceptable minimum level of security protection. Ross D. Bulla, an expert on physical security and terrorism avoidance, and president of Charlotte, NCbased The Treadstone Group Inc., recommends the following 10 procedures to be implemented at privatesector and government facilities to deter or mitigate terror attacks: 1. Enforce a standoff zone: A standoff zone is a secure area in which only pre-screened vehicles, bicycles, etc. are allowed to enter. Fixed bollards may be used to provide an effective visible and physical barrier to vehicles, providing security against ram raids, vehicle theft and restriction to unauthorized access (Figure 18.19A,B,C). 2. Implement surveillance detection: Nearly every major terrorist attack has been preceded by months and years of surveillance. Security personnel should be trained to observe and report unusual interest in a facility or activities that are out of context for the environment (e.g., taxi driver photographing a service entrance). 3. Screen deliveries: All delivery, service, and courier vehicles and their contents should be screened. 4. Stagger security: The number of security personnel on duty, as well as the times during which shifts change, should vary each day to eliminate a discernable pattern. 5. Facilitate evacuation: During non-business hours, facility management personnel, including the property manager, chief engineer, and security director, should conduct an evacuation drill using only emergency lighting in the emergency exit stairways. 6. Screen visitors: Where possible, screen visitors at a remote location, distant from any facilities. Visitors should present government-issued photo identifications, which should be held until their visitor passes are returned.

Figure 18.19A Anti-ram bollards detail.

Figure 18.19B Anti-ram knee wall detail.

Figure 18.19C Photo of a government building being protected by a line of fixed bollards along its perimeter which act as vehicle barriers. Notice how they fit in comfortably within the overall setting.


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7. Screen employees: All employees should be required to wear facility-issued photo identification at eye level on their outermost garments. The use of access cards are recommended and are best when used in conjunction with biometric or keypad systems. 8. Review your emergency procedures: Know what to do and when to do it. Review and, if necessary, update your security, evacuation, and life safety procedures and policies. 9. Make security the reFigure 18.20 A sample threat assessment list evaluating potential sponsibility of all users: Everyrisks, threat levels, and consequence levels (source, Walter “Skip” one that works at your facility Adams, CPP and Deborah A. Somers). should be reminded continuously to observe and report unusual behavior. 10. Assess your security: Retain a security consultant to assess your physical, technical, and operational security. Designers and facility managers must recognize and evaluate the nature of security threats to the corporation and the built environment and the relative risks associated with those threats (Figure 18.20). To improve safety and security, steps need to be taken which should include: •

Asset analysis: The space planner/designer must identify and prioritize the assets that require protection. These include people, operations, vital data and property. People are essentially the chief asset of any organization as they have the operational and technical know-how. Prioritizing assets can be achieved by examining the importance of various organizational functions to the survival of the organization. Threat analysis—identify and fortify security weaknesses: This includes understanding the real role of security in your organization and increasing security’s importance in the day-to-day running of the business, and the understanding that security is a continuous process and not an end state. An action plan and contingency plan should be in place with countermeasures for security breach prevention where possible incendiary situations exist, and after the fact when not. Vulnerability assessments and appropriate response: Vulnerability means any weakness that allows the implementation of a threat. Once vulnerable points are identified, corrective countermeasures can be put in place. Your vulnerability assessment and a cost-benefits analysis determine what kind of response is appropriate, passive or active. Risk analysis and threat assessment: Risk potential can be determined from the findings of asset, threat, and vulnerability analyses. These results can help determine the security measures that need to be put in place to effectively counteract a potential threat. Threats must be gauged in the context of the existing facilities. Ira Winkler, author of Corporate Espionage, uses the risk equation shown below to define an organization’s specific level of risk.


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18.2.3

333

Types of Access Control Systems

The most common methods and approaches that are practiced today to improve safety and security of building environments are through the use of access control systems. Access control deters an intruder from entering a facility, particularly when supplemented by other deterrents. These systems basically rely on one or a combination of four basic operating concepts: 1. Personal recognition: This depends on the ability of an individual to recognize employees and authorize access. A facility with a small employee base along with a low turnover rate can make personal recognition very secure. The main disadvantages are that security staff turnover wipes out the access control database, and turnover of employees can make it difficult for the security staff to keep track of who is and isn’t allowed in. 2. Unique knowledge: Unique knowledge requires a person to have special information or knowledge to gain access, for example, a push-button combination lock. The advantage is that there is nothing to lose, such as a key or badge. The disadvantage is that it is possible for an authorized user to give a code or combination to an unauthorized user. Keypad access systems also require a person to have knowledge of the correct numerical access code to gain access. The combination or code is entered into a four-, sixor 10-digit keypad. Keypad systems can be electronic and tied into a system, or mechanical and standalone like a single-door, push-button door access system. 3. Unique possession: Systems based on unique possession require a person to possess something that allows access. The most common unique possession system is a key and lock. A weakness in a unique possession system is that it will allow access to anyone who is in possession of the item, whether or not they are allowed access. One increasingly common way to control access is through card readers. Each person who will require access receives a card. Each access card leaves an audit trail—a record of who enters and when. Most systems allow access time windows to be created, so that the time when each person has access can be limited. Remember, the system records what card opened the door, not who opened the door. Employees must be discouraged from loaning their cards to others, and it is very important for the user to protect his or her card. To overcome this problem, smart cards have been developed with embedded microchips that contain an encoded biometric description of the cardholder, so that when the card passed through a reader, the machine would verify that the card belonged to the person who presented it. 4. Biometric devices: Continuing advances in biometrics are helping to address many of the problems that plague traditional human recognition methods and offer significant promise for greater applications in security as well as general convenience. In particular, newly evolving systems can measure multiple physiological or behavioral traits and thereby increase overall reliability that much more. Biometric security techniques are already widely used in multiple applications. In the U.S., fingerprint scans are used to crack down on persons claiming welfare benefits under different names and several jails have introduced iris scans to ensure the correct people are relocated or released. A number of universities have integrated fingerprint scanners into the ATMs to eliminate the need for bankcards. These examples are only a brief illustration of the various biometric techniques deployed today, and the uses of biometrics continue to increase and develop. The biometrics industry is showing continuous and sustained growth, partly because biometric systems are developing rapidly and are generally considered the most secure method available. These sys-


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tems grant or deny access to buildings, information, and benefits by automatically verifying the identity of people through their unique individual physical features, such as thumbprints, palm scans, voiceprints or iris checks. The information received is translated algorithmically into a complex string of numbers and is compared with a stored template of that person in a central database. Such systems are based on digital analysis using cameras or scanners of biological characteristics such as facial or palm structures, fingerprints (Figure 18.21A,B) and retinal and iris patterns that are matched with profiles in available databases of people such as Figure 18.21A,B Two fingerprint scanners: suspected terrorists (Figure 18.22). Facial recognition A. Plug and play Futronic fingerprint scanner, techniques show promise and are already being used and B. SecuGen Hamster IV fingerprint reader. at several airports (Figure 18.23). Fingerprint readers can confirm if people are who A combination of more than one of these methods they claim to be by matching fingerprint typically offers the soundest security solution. One templates stored in a central database. method is the use of a card access system with a PIN number: Access is achieved by both having the card as well as knowing the PIN number. Modern photo ID cards can contain a combination of unique possession (the card), unique knowledge (PIN) and personal identification (a person’s photo on the card). Figure 18.24 indicates the approximate percentage of biometric applications for each system in which biometrics are defined as automated methods of recognizing a person based on the acquired physiological or behavioral characteristics. Choosing the right system: Before deciding on what system is right for a particular facility, many issues need to be considered, including access time, imposter resistance, reliability and error rate, ease of use, user acceptance, input time and effort, storage, and cost. Access time and imposter resistance are critical factors when selecting access control systems. Access time is the time taken by someone to use the system and for the system to respond positively. Access can take from a few seconds to a few minutes. Access time (sometimes called throughput) becomes critical in situations where large numbers of people require simultaneous passage, for example, during a shift change. The initial amount of time and effort to input everyone into the system is called the input or enrollment time. Biometric systems compare the biological characteristics of a person to those on file in a central database. These biometric features need at some point to be entered into the system. So, if it takes five minutes to input data for an employee into the system, and the organization has a thousand employees, then it would take more than 10 days to input (i.e., create employee files) 1,000 people into the system, and that’s on the premise that one is working a continuous eight-hour day. One must also not forget the importance of reliability and cost of any system considered. Security technology is evolving at a rapid pace and recent developments include intelligent software that generates real-time alert alarming, thus allowing for the appropriate proactive action to be taken immediately.

18.2.4

Miscellaneous Issues

Relevant codes and standards: Highly complex security system design remains not codified and unregulated, and no universal codes or standards apply to all public and private sector buildings. However, we of-


Chapter 18 - Additional Issues

ten find that government agencies, including the military services and private sector organizations, have developed specific security design criteria. Building codes are discussed in Section 18.3. Egress planning and emergency management: The education of owners and tenants about emergency systems of buildings should go hand in hand with engineering and design, and corporate clients are now showing a heightened awareness concerning the security of their buildings and sites. Enlightened clients are more frequently asking architects and space planners to explore increasing the width of exit stairs over code minimums to allow firefighters to travel up while still permitting the building occupants to exit. During an emergency, good communication is vital. An evacuation response to a bomb threat will differ significantly from a fire. One calls for a controlled exit while the other necessitates a speedy exit. The parking problem: Recent parking garage bombings have highlighted the fact that public parking located within a building is a likely target to place a car bomb. To eliminate this potential threat, one of two strategies may be implemented: restrict the garage to building occupants and inspect every car that enters, or eliminate parking in the building altogether. These issues raise serious practical problems, particularly in urban areas, and such an inconvenience may not be acceptable. Possible solutions include requiring employee badges for garage entry, limiting selfparking to badge holders, and restricting large vehicles to controlled areas. New GSA (General Services Administration) standards: Planners can find federal government standards for security requirements for their buildings online, providing a good resource on the subject. The consulting firm Arup Ltd., of London, proved that properly protected elevators can assist rapid evacuation. Its study on a 50-story building in London showed that the use of elevators nearly halved the escape time compared to using stairs only. Reconfiguring the core can provide cost-effective refuge areas with a dedicated eleva-

335

Figure 18.22 Iris scanning is one of the promising biometric devices being developed. At the heart of the iris scanning system is a simple CCD digital camera. It uses both visible and near-infrared light to take a clear, high-contrast picture of a person’s iris. With nearinfrared light, a person’s pupil is very black, making it easy for the computer to isolate the pupil and iris.

Figure 18.23 Face recognition continues to advance and shows considerable promise (source, Cognitec Systems GmbH).

Figure 18.24 Percentage of biometric applications in real life (courtesy, International Biometric Group).


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tor and stairwell for emergency egress without increasing core square footage. The system bundles a service elevator for use by firefighters, a lobby, and a stairwell, in a pressurized shaft. The National Fire Protection Association has commenced with the development of a security code that will mandate minimum levels of protection. Legal and liability issues: This is discussed in greater detail in Chapter 20. And while building owners and managers are not expected to guarantee the safety of their tenants, visitors, and guests, they are required to exercise reasonable care to protect them from foreseeable events. The number of liability lawsuits filed against American companies has increased dramatically over the last decade. Specific laws governing security considerations vary from state to state, but the following common issues, when present, generally form the basis of proving liability in law suits regarding security: 1. Essentially owners owe a legal duty of care to anyone invited onto the property, 2. The crime should have been foreseeable, 3. The owner failed to use a reasonable standard of care in warning or protecting the victim, and 4. The owner’s breach of duty in taking reasonable precautions was the cause of the injury. Finally, since increased security seems like it is going to be with us for the foreseeable future, the psychological and functional requirements for increased security and defensible space should be achieved through the use of integrated security solutions that are balanced, pleasing and do not disrupt a building’s efficiency. Where an inspection of the security systems is required, reputable security professionals should be called in.

18.3 BUILDING CODE COMPLIANCE “When we build, let us think that we build for ever.” John Ruskin, The Seven Lamps of Architecture (1849). Since King Hammurabi’s time, four thousand years ago, building codes have been an essential part of the design and construction process and the law of the land. Building codes govern the construction of public buildings, commercial buildings and places of residence. In the United States codes are enforced by local governments, whereas in Canada enforcement responsibility lies with the provincial and territorial governments. The purpose of building codes is to regulate construction and thereby to protect the people’s health, safety and welfare and provide occupants with a safe and healthy environment. Building codes do this by defining minimum standards for safety and comfort that must be met in new construction and major renovations. Building codes are generally applied by the architectural and engineering professions, as well as by many other professions including safety inspectors, contractors and subcontractors, real estate developers, manufacturers, insurance companies, and others. Moreover, prior to obtaining a building permit to construct a commercial property, a developer is required to produce design plans that, among other things, must conform to the building codes in effect within the jurisdiction of the proposed development. Newer code compliance to existing properties is not normally warranted unless major renovations are performed. When older properties are to be updated, local regulations dictate the conditions when compliance with newer codes is required. Usually, when interior renovation includes reconstruction of 25 to 50 percent of a floor, local regulations require compliance with existing life-safety code requirements. It is therefore important to determine all major life-safety items of functional obsolescence. This is particularly relevant to office buildings and hotels where interior renovations and reconfigurations are periodically performed. Building codes in the United States are essentially local laws and each municipality (county or district in sparsely populated areas) enforces a set of regulations (Figure 18.25). A strong and sustained move-


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Figure 18.25 An illustration showing overlapping code structure and the complexity of current regulations (source, Specifications for Commercial Interiors by S.C. Reznikoff).

ment has been underway for some time to unify the various local codes around the nation, responding to the building industry’s repeated requests for the formation of a single unified building regulatory system. With this in mind, the three main model code organizations came together and forme