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Certificate I in General Construction

BCGCM1003B Plan and Organise Work

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This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.


Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures


Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

To the Trainee

This booklet is one in a series of booklets prepared for the course Certificate I in General Construction. Your answers to the questions contained in the booklet will be assessed as an important part of your Course work. If you have experience, knowledge or skills in the content area of this Unit, particularly in relation to the objectives on page 1, it is your responsibility to draw this to the attention of your Trainer. Should you be able to provide evidence of your competence, then you may be given recognition for your current competence. The booklet must be kept in good condition and must not be defaced with graffiti or other material. Your Trainer will collect the booklets for assessment purposes.

Terminology

These booklets are designed for use by school students, trainees, apprentices and other learners in a learning environment, such as a school, training institution or a workplace where the training of Certificate I in General Construction is carried out. The terms ‘Trainer’ and ‘Trainee’ which are used throughout these booklets also relate to the following: > ‘Trainer’ – teacher, supervisor, trainer, lecturer, facilitator, Registered Training Organisation (RTO) > ‘Trainee’ – student, trainee, apprentice/new apprentice, learner, participant

This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.


Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Contents Aim ......................................................................................................................................................... 1 Introduction ........................................................................................................................................... 1 Topic 1: Planning and Preparing for a Levelling Task ..................................................................... 3 Work Instructions ............................................................................................................................................... 3 Selecting Tools and Equipment .......................................................................................................................... 5

Exercise: Topic 1 ................................................................................................................................... 7 Topic 2: Basic Levelling........................................................................................................................ 9 Spirit Levels........................................................................................................................................................ 9 Water Levels..................................................................................................................................................... 11 Boning Rods ..................................................................................................................................................... 12 Plumb Bob ........................................................................................................................................................ 13

Exercise: Topic 2 ................................................................................................................................. 14 Topic 3: Advanced Levelling.............................................................................................................. 15 Exercise: Topic 3 ................................................................................................................................. 19 Appendix A .......................................................................................................................................... 20 Glossary of Terms ............................................................................................................................................ 20

Appendix B .......................................................................................................................................... 22 Suggested Resources ........................................................................................................................................ 22

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Aim The aim of this unit is to provide the trainee with the ability to: > carry out levelling in a single plane > establish correct and accurate set out points of building components > set up, test and use levelling devices > establish and transfer heights using a range of levelling devices.

Introduction The term level could mean any of the following > flat > even > horizontal > flush > plane > uniform > parallel to the horizontal or in line with the horizon. The principal of levelling is to transfer a given height from one point to another point, or to compare the height of one mark to the height of another mark. Throughout the construction industry it is essential that all types of construction are erected level. For obvious reasons, if buildings are not level structural integrity would be compromised. This unit will cover: > planning and preparing a levelling task > the basic principles of levelling > levelling terms > types of levelling equipment > basic and advance levelling > clean up after a levelling task.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

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This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.


Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 1: Planning and Preparing for a Levelling Task

Topic 1: Planning and Preparing for a Levelling Task Planning and organising a specific task involves preparing and implementing a logically sequenced work plan. To effectively prepare a work plan for a particular task you need to consider the following: > work instructions. These need to be obtained, confirmed and applied > tools and equipment required > materials required > quantities of material required > safety, signage and barrier requirements > environmental responsibilities. The above information applies to any task including levelling. Therefore you need to consider all of the above when undertaking a levelling task. This procedure is covered in more detail in BCGCM1003B – Plan and Organise Work, however information specific to a levelling task is detailed below.

Work Instructions Read, interpret and identify key work instructions. These may include verbal or written instructions. Whilst building any project common sense dictates that you should always make sure it is level and plumb. However there may be instances where further instructions are supplied such as having to work to certain heights, reduced levels and benchmarks. The information required to carry out specific levelling procedures will be stated in the plans and/or specifications.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 1: Planning and Preparing for a Levelling Task

LEVELLING TERMS Level

Any flat surface, which is horizontal to the ground such as the finished height of a concrete footing.

Plumb

Any vertical line that would line up with the centre of the Earth

Datum

A reference point to transfer a level usually on a wall or column.

Site Datum or Temporary Bench Mark (TBM)

The position from which the new building levels are compared. It is a clearly identified marker usually at ground level.

Simple Levelling

The difference between the heights of two points, for example, to determine the finished height of a concrete footing.

Compound Levelling

The difference of two or more points in relation to each other, such as pegging and checking the outline for a proposed extension to a building.

Spot Levelling

the levels taken at each intersection of a grid system

Reduced Level

a level on a new building which when compared to the datum may be above or below the datum

TYPICAL SPOT LEVELLING GRID

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 1: Planning and Preparing for a Levelling Task

Selecting Tools and Equipment Selecting the correct tools and equipment for a specific task will increase efficiency and quality of output. Care also needs to be taken to ensure that tools are used, maintained and stored correctly. A list of some common levelling tools is set out below: 1. Spirit Level – A piece of timber or aluminium fitted with a glass tube which contains water and air. The position of the air bubble will determine if an object is level or plumb based on the principle that liquid will find its own level when at rest. 2. String Lines – Also known as bricklayers lines. These are durable pieces of string pulled taut to create a straight line. 3. Straight Edges – Straight pieces of timber with parallel edges used to measure heights or transfer levels down sloping sites. 4. Water Level – A piece of plastic tubing filled with water and air mainly used where there are obstructions between level points. 5. Theodolite – An instrument used in surveying to measure vertical heights and also to set 90º angles. Used in areas such as engineering, steel erection and tower construction. 6. Boning Rods – Rarely used nowadays, they are a set of three tshaped frames 7. Plumb Bobs – Are weights on the end of string line used to determine plumb 8. Laser Level – Uses a rotating laser beam to provide both vertical and horizontal reference points. 9. Automatic (Dumpy Level) – A tripod mounted device used for levelling over distances. 10. Levelling Staff – A measured rod used in conjunction with an automatic or laser level.

Builders Square

String Line Plumb Bob Boning Rods This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 1: Planning and Preparing for a Levelling Task

Other essential equipment necessary to complete the setting-out process would include: > various measuring tapes ( 8m, 20m, 1m, four fold rule) > large double faced sledge hammer > claw hammer > timber or steel pegs > shovel > wheelbarrow.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 1: Planning and Preparing for a Levelling Task

Exercise: Topic 1 Key in your answers in the boxes provided. 1. List 5 words that could explain the meaning of level.

2. Why is it so important for buildings to be erected level and plumb?

3. Explain the meanings of the following terms: Simple Levelling

Spot Levelling

Site Datum

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 1: Planning and Preparing for a Levelling Task

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This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.


Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

Topic 2: Basic Levelling Trades such as bricklaying, plumbing, paving and concreting would use basic levelling techniques. Prior to commencing any levelling procedure it is essential that tools and equipment are accurate.

Spirit Levels The spirit level is essential for basic levelling tasks. It is most important that the spirit level to be used is accurate. Check the accuracy of the spirit level by following the procedure below: 1. Drive 2 nails into a bench top or a securely held timber surface, approximately 30-40mm less than the length of the spirit level to be used. 2. Adjust the nail height until bubble fits exactly between the graduations. 3. Turn the spirit level end to end and check again. If the level is accurate the bubble should fit exactly between the graduations. 4. If the bubble does not align within the graduations, the level is not accurate. 5. Either discard the level and use another one after checking it for accuracy or have the level adjusted by the trainer. 6. A similar procedure is necessary to check the spirit level for plumb or vertical accuracy.

This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

Transferring a Level The procedure for transferring a level (i.e. a horizontal reading), is detailed below. The spirit level is used in conjunction with a straight edge for spans in excess of one metre. 1. Place one end of the straight edge on the existing datum peg or level mark (chalk or nail) and support the other end by the newly positioned peg or your hand. 2. Place the spirit level in approximately the centre of the straight edge and gently hammer the new peg until the bubble of the level is evenly centred between the graduations. If not using pegs, position level until bubble is centred and then mark transferred level with chalk or nail. 3. Check your reading by end for ending (rotating) the spirit level to confirm the reading. 4. Should additional levels be required, repeat the above process.

Tap peg until level

Datum level

Using a straight edge with a spirit level

Using a Spirit Level without a Straight Edge A spirit level can be used alone when the distance to be spanned is less than the length of the level. A straight edge would be used where pegs are spaced at 1200mm up to 2400mm centres. The procedure for transferring a level without a straight edge is detailed below. 1. Place one end of the spirit level on the existing datum peg and support the other end by a newly positioned peg. 2. Gently hammer new peg until the bubble of the level is evenly centred between graduations. 3. Check your reading by end for ending (rotating) the spirit level to confirm the reading. In conjunction with straight edge Testing wall frame corner for plumb

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

Taking Vertical Readings The spirit level can also be used for taking vertical readings (plumb readings). This procedure is listed below. For simplicity we have used an example for testing the corner of timber wall frames. Place the straight edge against the top and bottom plates. Position the spirit level against the outer edge of the straight edge. Adjust the wall frame until the spirit level records correct reading. Reverse spirit level and confirm reading. If reading corresponds, the wall frame is now plumb.

Water Levels A level line can be obtained by using a water level. This type of level consists of a length of clear hose or flexible tubing which is filled with water (for ease of use colour the water). It is necessary to have the last 50mm of the tubing to both ends clear of water. Just as you would check a spirit level for accuracy you must check a water level also. Once the coloured water has been placed in the tubing, care must be taken to remove all air bubbles. This is achieved by allowing the water to flow through. The tubing then has both ends sealed to prevent the water from spilling. Check that there are no air bubbles in the tube by removing the seals and holding the two ends together – the water in both ends of the tube should be at equal heights. If it is uneven there are likely to be air bubbles in the water. To remove the air bubbles seal one end of the tube and hold the unsealed end high up to allow the air to flow out of the unsealed end, reseal the tubing. The water level is now ready for use.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

Transferring a Level The procedure for transferring a height using a water level is detailed below. 1. Bring both ends of the water level together at site datum marker. 2. Make sure the height of the water mark is the same for both ends of the tubing. 3. Keep one end of the water level at the datum marker. 4. Transfer the other end of the water level to the next required level point. 5.Move the tubing up or down until the desired level is reached.

Boning Rods Boning rods can be used to obtain a straight line. They consist of 3 ‘Tee’ shaped rods accurately cut to the same length. They are used by placing 2 rods on given heights and by sighting to a third rod. The 2 set rods may be accurately levelled and the third rod is used to fix level points further away. Another use is to obtain an intermediate point by fixing and levelling the 2 end rods and using the 3rd rod to locate the intermediate point. Therefore boning rods are especially useful in checking levels in drainage trenches. GRADED LEVEL ROD

LINE OF SIGHT

REQUIRED

GRADE LEVEL

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MAKE A MARK ON THE PEG WHEN THE TOPS OF THE THREE RODS ARE IN LINE WITH

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

Plumb Bob Plumb Bobs come in many different shapes and sizes. They are pointed at one end, relatively heavy and have a place to attach a line from which the Plumb Bob hangs. The Plumb Bob is used to test the corner of a building construction for plumb. The Plumb Bob is suspended over the top plate and measurements are taken at the top and bottom. The frames are adjusted until the measurements are the same.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

Exercise: Topic 2 Key in your answers in the boxes provided. 1. List 3 levelling devices.

2. List 3 plumbing devices.

3. What does Plumb mean?

4. Explain how you would check a spirit level for accuracy.

5. What levelling devices are best used over short distances?

6. What levelling devices are best used over long distances?

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 3: Advanced Levelling

Topic 3: Advanced Levelling This section will focus on more advanced levelling techniques and setting up procedures. Trades such as carpentry, ceiling fixing, shop fitting and surveying would use advanced levelling.

Automatic Level (Dumpy) The Automatic or Dumpy Level is a device used by builders and surveyors for levelling over larger distances. They are set up on a tripod and by using the various control screws the correct level is obtained. It is used in conjunction with a Levelling Staff. This levelling procedure requires 2 people, one to hold the staff and the other to look through the eye piece, lining up the cross hairs on a particular measurement on the staff. This measurement can then be used to determine a level from the datum. Automatic levels can be used for determining heights of concrete foundation, transferring datum marks, depths of trenches and gradients of trenches.

Laser Level The Laser Level is a relatively new levelling device. It is either mounted on a tripod or wall bracket and therefore only one person is required to operate this device. It is used with a staff and a receiver to determine heights and differences in heights or levels. Prior to using a Laser Level you must ensure the Laser Level is level itself. Levelling screws and air bubbles are in-built to test the level of the Laser. As with most levelling equipment the Laser Level should be stored and maintained as per manufacturers’ instructions. It should be stored in its appropriate housing, windows should be kept clean and free of lint and knocks or falls need to be avoided. Laser levels have a wide variety of uses, depending on the model used, including levelling ceilings measured from datum marks, measuring finished floor levels, levelling bearers, blocks and retaining wall heights. They can be used to determine both horizontal and vertical levels (plumb). In addition to these uses the laser level can also be used to set a 90º or mounted onto plant to assist in excavation of gradients, roadworks, mining.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 3: Advanced Levelling

Hurdles and Stringlines Hurdles are used at external and internal corners, situated approximately 600mm beyond the footing lines. Hurdles consist of 2 timber pegs which are driven into the ground approximately 400mm apart. On top of the pegs a timber plate is fixed. The plate is clearly marked showing the width of the footings and external walls. Nails are partly driven into the required line and the string line is attached and continued until setting out is complete. Hurdles and stringlines are also used to set 90ยบ angles when setting out a construction site using the 3:4:5 triangle. Refer to Unit BCGCM1005B Carry out Measurements and Calculations for more information. 1. Set up a peg at the required distance from the boundary 2. Measure and set an offset peg 600mm towards the boundary 3. Set up a hurdle at the off set peg 4. Set a string line from the original off set peg to the distance required, taking into account your 600mm off set 5. Set up a hurdle at the second off set peg 6. This process is undertaken to measure out both the length and width of the structure 7. Take Measurements from the original peg and check to ensure the structure will be square using the 3:4:5 method. 8. Measurements taken include the length, width and diagonal of relevant stringlines. For example if you were constructing a building measuring 6m x 8m your diagonal measurement should be 10m. It is important to remember that all stringlines should be level when used for setting out purposes otherwise it can result in inaccurate measurements.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 3: Advanced Levelling

Gradients

A gradient is an incline or slope and is generally expressed as a ratio. For example a gradient shown as 1:20 means that for every 20m of distance the height falls or rises 1m. An example of gradient use would be stormwater drains. To enable an even flow of water through the pipes a smooth gradient must be established.

Relevant Housekeeping Procedures for Levelling > All tools should be thoroughly checked, cleaned and stored correctly > All timber pegs should be checked and those that are damaged should be discarded. All reusable pegs should be neatly stored. > Steel pegs should be checked, straightened and stored similarly as for timber pegs > All water levels should be emptied, rolled up and returned to the site store > All Automatic (Dumpy) or Laser Levels should be stored in their appropriate housing, avoiding knocks, bumps or falls which can affect the accuracy of these levels.

Digging a trench for a PVC stormwater pipe provides a good example of the use of boning rods. To allow for an even flow of water through the pipe a smooth gradient must be established.

Once you know how deep the pipe has to be, then a rough cut trench is dug between the two known levels at either end. By using the boning rods, the base of the trench can be made smooth.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 3: Advanced Levelling

The two boning rods with crossbars are placed at either end of the trench. The black boning rod is placed a short distance from boning rod 1 and the soil around removed or built up until all three crossbars are level along the line of sight. The black boning rod is then moved along the trench and the procedure repeated.

Gradients are generally expressed as a ratio, such as 1 in 20. This means that if the distance between A and B is 20m and the fall is 1 metre, the gradient is 2 in 20.

The boning rods we have discussed here are fixed boning rods. It is possible to buy or make adjustable boning rods as shown.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 3: Advanced Levelling

Exercise: Topic 3 Key in your answers in the boxes provided. 1. Describe in your own words the importance of the accurate set out and levelling.

2. Describe how you would check the heights of set out pegs 2.4m apart using a 1.2m spirit level.

3. List what precautions you would take to ensure a Laser Level is maintained in good working order.

4. What information would you expect to find on the top plate of hurdles?

5. Express the following as gradients. Distance 10m, fall 2m Gradient = 1 in Distance 25m, fall 5m Gradient = 1 in Distance 12m, fall 1.5m Gradient = 1 in Distance 15m, fall 1.5m Gradient = 1 in 6. Determine heights around your learning facility using an automatic level from a datum mark. Heights and datum mark will be specified by your trainer. 7. Using the 3:4:5 triangle check the accuracy of angles on a local tennis court, basketball court or similar open area. 8. Is the door opening to your training area level and plumb? Check using a spirit level. 9. Are the walls in your training area plumb? Check using a spirit level.

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Appendix A

Appendix A Glossary of Terms adhere align apron assumed datum

obey, conform arrange, line up surrounding area a point of assumed height above sea level

back sight

the first reading taken on a levelling site before moving the levelling instrument to a new position

confirm contour line contour

verify, check a line used on plans or maps to join points of equal height outline, shape, form

datum datum discard disperse

a point from which heights and depths are measured the starting point from which all other ground levels on a site are measured put aside, reject, throw away scatter, spread

exterior

outside

fall flexible flush foresight

the amount by which a point is lower than a preceding point able to bend or shape level the last reading taken on a levelling site before moving the levelling instrument to a new position

graduations

marks, measurements

hessian horizontal

coarse bag-like material level, flat

intermediate sight

any reading taken between a back sight and a fore sight

levelling instrument

any piece of equipment that can be used to measure variations in the height of the ground a telescopic staff showing metric units of measurement, used with automatic and dumpy levels

levelling staff maintain

look after

ordinance bench mark ordinance datum

a point of known height above sea level which has been officially established sea level

perimeter plumb plumb line

boundary vertical, square, upright a line that points directly to the earth’s centre

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Appendix A

reduced level rise

the height of any given point above or below a datum the amount by which a point is higher than a preceding point

slab squeegee

area, sheet rubber scraper or blade

transfer tripod

shift, copy three legged support

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Appendix B

Appendix B Suggested Resources Basic Training Manual 14.1 - Carpentry & Joinery, Basic Hand Tools, Department of Employment and Youth Affairs, 1980. Basic Training Manual 14.5 - Carpentry & Joinery, Walls & Floors, Department of Employment and Industrial Relations 1982. Occupational Health & Safety Act, OH&S Act - Approved Codes of Practice. You will also find useful information in Technical Specification Sheets and Manufacturer’s Data Sheets

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Certificate I in General Construction

BCGCM2006B Apply Basic Levelling Procedures

Topic 2: Basic Levelling

This material remains the property of the Construction Industry Training Board. No unauthorised copying is permitted without written permission.

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