Trends, approaches and best practices in drywall estimating

-A practical perspective

Growing industry

The drywall industry has enjoyed tremendous growth since the turn of the 20th century due to refinements in manufacturing processes, coupled with the need for high quality, low cost buildings and houses (National Occupational Classification, 2011 as developed by Human Resources and Skills Development Canada/Statistics Canada and The Gypsum Construction Handbook, 2014). It is estimated that about 90% of interior finished surfaces of buildings constructed in North America use gypsum products in one form or another. The gypsum industry continues to develop new and innovative ways to provide high quality products and services to achieve code requirements of officials, designers and others.

Estimating procedure

For the quantity take-off process, the estimator’s job is to figure out the quantities of materials based on project drawings, specifications and scope of work. One of the commonly used estimating techniques for drywall estimating entails preparing quantities from scaled drawings, using either printed drawings or on-screen take-off procedures. This practice is typically used when a speedier take-off is desired compared to the traditional method of reading dimensions. It is paramount that the estimator be aware when scaling drawings to check that he/she is using the correct scale, and whether the drawings themselves are correctly scaled. If the drawings are out of scale, the estimator needs to make adjustments on measurements.

Estimating quality

Quality control is an essential element of good estimating practices. During the procedure of determining quantities (the take-off process), it is very important to follow consistent steps, forms and documentation for all projects. When preparing take-offs, it is a good practice to organize the estimate so that it follows the construction process of dry-walling as it would occur on the job site. The objective of this practice is to minimize the possibility of missing elements or quantities from the estimate. For drywall estimating it is always recommended that the estimator begin take-off calculations from the lowest level of the building element and move to upper levels. In drywall takeoff, it is recommended to always start with the building shell, following with demising and corridor walls and ending with the interior partitions and ceilings. In multi-floor buildings, it is more efficient to prepare the quantity take-off floor-by-floor.

Where a building has multiple, identical floors a take-off of a typical floor is prepared and applied to all other similar floors. For example, in a 40-storey building with 15 typical floors, the number of floors to be included in take-off process will be reduced from 40 to 25, so by 37%.

Residential drywall estimating

In residential projects, there is a significant difference in the materials used, compared to those in high-rise, residential projects. In housing projects, all framing work is generally installed by carpenters and the estimator has to establish the quantities for various combinations of materials i.e. drywall, insulation and vapour barriers. Therefore, the most efficient technique of estimating, relies on calculating all the materials that form the intended final product. Working with assembly quantities increases the productivity of the estimating process, which is very important in terms of increasing the number of projects priced and increasing the accuracy of measurements.

The waste factor is always related to the company policy, difficulties of the project and qualifications of the working team. Assembly quantities are measured either as length or area, depending on the specific nature of any job. Drywall jobs consisting of a standard height can be measured and priced out on a length basis. However, most drywall assemblies are determined as area by multiplying the wall length or perimeter by the height. In order to determine the lengths of different assemblies, the estimator has to apply different types of measurements, such as on-center

measurements, interior measurements or exterior measurements (The Gypsum Construction Handbook, 2014). For example: • In an unfinished basement, in order to calculate the quantity of the exterior wall insulation the estimator needs to figure out the perimeter of the exterior walls from inside the building, which then has to be multiplied by the height of insulation. • In an exterior wall the measurements must be taken on the exterior side of the studs. When measuring a 2" x 6" woodstud-framed exterior wall, the insulation will be 6” longer and both the vapour barriers and drywall will be one foot longer on each side of measurements which results in a total of one additional foot for insulation and two additional feet for vapour barrier and drywall. • In interior partitions, the measurements have to be taken on the center going through all openings; subsequent deductions for openings will be part of the quantity calculation. • There are two general practices in ceiling calculations: (1) interior dimensions must be taken in uninsulated ceilings; (2) in insulated ceilings, calculations are based on measurements on the exterior side of studs. During installation of drywall on wood frame walls, there is a specific mounting process that dry wallers follow. Drywall is installed horizontally which provides less linear footage of seam, smoother looking wall, shorter length of taping, and easier approach for walls 8’-6” or 9’-0” in height. In high-rise buildings, drywall contractors have to supply and install the metal stud frames as well as drywall, insulation and vapour barrier. The methods of measurement for drywall, insulation and vapour barrier are the same as those for housing projects; however, when it comes to the installation of gypsum boards onto the stud frame, the practice requires mounting drywall panels vertically, rather than horizontally.

Steel-framed walls are measured on exterior sides of studs for exterior walls and on center for steel-stud interior partitions. For metal frames, the first action carried out by the estimator should be to differentiate between load bearing walls and non-load bearing walls. For load bearing walls, a structural engineering

FIGURE 1

Full Height Wall 16" 16" 16"

8'0" Header

Sill

FIGURE 2

12" 12" 12" 12" 12" 12" 12" 12" 12"

8'0"

FIGURE 3

Full Height Wall

8'0" 16" 16" 16"

Header

design is always required in accordance with loads calculated to be supported, wall height and deflection allowed. The design provides the dimensions and strength of metal framing. It is always very important to allow for a deflection system on the tops of these walls. Nonload bearing walls require smaller framing. The estimator must differentiate among walls having drywall on both sides, those with drywall on one side, and those with only one layer or more than one layer of drywall. The calculation of metal frame elements must be provided in length; accessories are numbered in pieces.

When estimating a metal frame, as shown in Figure 1, the practice differs between exterior walls and interior partitions. For exterior walls, measurements at full height sections must be completed separately from sections with openings, in which case measurements are taken for head (top part of openings) and sill (bottom part of openings). The length of metal tracks is equal to the wall length multiplied by two for the full height walls and length multiplied by four for head and sill. The length of metal studs will be determined by multiplying the number of metal studs by wall height. To calculate the number of metal studs the wall length must be divided by spacing and adding one stud. Additional metal studs must be added for corners, intersections and opening, based on the design noted on the plans.

For light gauge metal studs estimators typically calculate the number of metal studs required using the quick method, which consists of using the spacing between studs from 16" on center to 12" on center. Based on this consideration the length of the wall represents the number of studs, as shown in Figure 2. It is calculated that additional studs are enough to cover the extra number of studs required for openings, corners and intersections, as shown in Figure 3.

For suspended drywall ceilings the estimator has to calculate the number and the length of hangers, the length of perimeter track and the suspension system. For acoustic ceilings, besides hangers and perimeter tracks, the estimator needs to calculate the T-Bar system according to the grid sizes.

ICI – drywall estimating

Industrial, commercial and institutional (ICI) buildings, (with single or multiple floors) incorporate extensive drywall application as interior finishes. Drywall application includes metal framing, insulation, vapour barrier and drywall. Different wall assemblies denote different materials. The take-off process for ICI buildings should be based on measurements of the assemblies and is similar to high-rise residential buildings. For industrial and commercial buildings, the estimator needs to pay attention to the height of the heavy gauge metal frames, as they require construction according to the engineering design.

Productivity

Productivity in drywall work depends upon different factors such as: a) type of project; b) seasonal trends; c) type, size and quality of tools; and d) labour skills and experience.

a) Type of project is an important factor in the determination of crew or team productivity. On residential projects, there are many repetitive processes that allow workers to be efficient in their work. For example, in housing subdivisions, there are many repeated models. In high-rise buildings, there are many typical floors where the layout and the heights are the same. Recognizing, the specific nuances of each project, in institutional buildings with repetitive layouts, the practice is generally the same as in high-rise residential buildings. Industrial and commercial projects can be unique, have more individuality and involve less repetition.

b) Seasonal trends are another important factor. Unless drywall work is related to interior finish and requires specific working conditions related to temperature and humidity, high temperatures and humidity during summer and low temperatures and wind chill during winter have negative impacts on workers’ productivity. Thus, for short-term projects, seasonal factors are important in the calculation of productivity. For long-term projects, (a year or more), seasonal factors have less impact.

c) Type, size and quality of tools and equipment have a direct impact on productivity. Updated and well maintained tools are a good resource to guarantee high productivity.

d) Labour skills and experience are other factors having impact upon the productivity of crews or teams. Higher labour skills will guarantee greater efficiency in completion of the job with skilled and experienced workers generally being more effective in determining the work steps in order to complete the job in the shortest time possible.

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A minimum of 2+ years of experience in construction estimating/quantity surveying related to industrial or institutional remediation following accident or disaster, and 12+ months experience managing project costs; Completion of University (Quantity Surveying or related field); English speaking and writing is critical to the position. Annual Salary range: $74,000-$94,000; Excellent Benefits including participation in Company RRSP Please submit your resume: By email: cdeponte@mkainc.com By fax: 403-532-8960

Pricing drywall work

Pricing drywall jobs includes pricing materials, equipment and labour. Each of the above pricing elements is important and the correct determination for each of them is the key for competitive pricing.

1. Materials: Pricing of materials is related to determining the proper materials to satisfy specification requirements and the best value. The best price sometimes is not the lowest price received from suppliers or manufacturers. The estimator has to be careful in analyzing what is included in the price. There are several

suppliers that provide the service of delivering and unloading the materials according to quantities required. Usually their prices are not the lowest but, considering the above productivity factors and quality control requirements, they may represent the best value for the job.

2. Equipment: Pricing equipment usually consists of pricing scaffoldings and scissor lifts. If the drywall company owns scaffoldings and scissor lifts, an equivalent usage fee and depreciation fee will be applied according to the time of usage on the job site. For any rental equipment, the rental price should be evaluated according to the equipment’s condition, the terms of maintenance and shipping policy, etc.

3. Labour: Pricing labour is the trickiest part of the pricing process. In the drywall business, contractors can be union members or non-union members. Due to this reality, the estimator must apply the correct labour rates depending on what type of labour is utilized. For union members, the labour rates are good for one year in a 3 year union agreement. So the estimator can apply the rates for the one year term knowing the escalation for the other 2 years. For non-union contractors, estimators must use the current market labour rates which are variable in seasonal terms and also vary depending on the duration of the project. In union rates there are also two types of labour payments: piece-work, and hourly. Piece-work payments apply to residential projects where the application of labour rates to the quantity of work completed is based upon hourly, daily, weekly or bi- weekly rates. The application of piece-work prices is relatively easy to estimate, as it is a simple process of applying unit labour rates to the quantities determined from the take-off. In ICI projects, the labour cost is estimated according to the number of hours worked.

4. Unit Prices: Knowing the hourly rates alone is not sufficient to price the estimated quantities of work, irrespective of ICI or residential. In converting hourly rates into unit prices, the estimator has to determine the level of expected productivity recognizing the specific nature of the work to be carried out and multiple variables which may increase the estimated cost of labour e.g. location, logistics, availability of labour etc. This structured approach forms the basis for calculating unit rates that accurately reflect the labour component that forms part of the drywall estimate.

Bibliography:

Including, Chapter 11- Planning,

Execution & Inspection (2014) in The Gypsum Construction

Handbook (Seventh edition, page 576 pages). Chicago: Wiley. Division 09: Finishings. (2006) in Method of Measurement of

Construction Works (Eighth edition, page 153). Markham: Canadian

Institute of Quantity Surveyors.

Amir Lopci, B.Eng., PQS has been involved in the construction industry for over 30 years and is currently a professor at George Brown College, teaching Construction Estimating.