�SETTING OUT PROCEDURES

Dr Adewale Abimbola, FHEA, GMICE.

www.edulibrary.co.uk

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Aim & Objectives

Aim: Setting Out Procedures

Objectives: At the end of the lesson, the students should be able to:

• Explain the setting out procedures using traditional tools, equipment and processes to a given level of accuracy.
• Discuss the selection of setting-out tools, equipment and processes for the accurate setting out of a given structure.

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Introduction

• Setting out is the crucial process of translating scaled design drawings for a new construction project into physical markers on the ground.
• This process is essential for accurately laying the foundations, walls, roads, columns, embankments, etc.
• The role is usually carried out by a site engineer or surveyor.
• The process involves establishing temporary marks and profile boards to monitor and control the layout of the construction works, ensuring precision in both horizontal dimensions ('line') and vertical dimensions ('level’).
• The setting out process begins with a site layout drawing that outlines the planned positions of the infrastructure to be built (fig. 1).

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Figure 1. Setting-out of a small building.

The Setting Out Process

• When preparing for setting out in construction, several important steps should be followed to ensure accuracy and avoid errors.
• Verification of Drawings:
• Ensure you have the latest setting-out drawings by checking with the designer or project manager, paying attention to the date and revision number in the title block.
• Avoid Assumptions:
• Always consult with the designer or project manager to seek clarification about unclear or conflicting information in the drawings. Never make assumptions.
• Site Familiarisation:
• Conduct a comprehensive survey of the entire site to familiarise yourself with existing buildings, the outline of new infrastructure, site topography, and visibility considerations.

The Setting Out Process

• Check Drawing Dimensions:
• Verify that the boundary of the infrastructure can be accurately referenced to at least two fixed points or primary setting-out points (SOPs), to which all new construction will be related in terms of dimensions and angles.
• SOPs could be a pre-existing survey station from a control traverse or dimensions from the rear face of the kerb or the centreline of an adjacent road (Monash University, 2002).
• Information on Reduced Levels:
• Ensure the drawing includes information on required reduced levels based on an established temporary benchmark (TBM) on the site.

The Setting Out Process

Essential equipment for a small residential building development typically includes:

• Measuring Tools:
• Two measuring tapes, preferably made of steel.
• Levelling Equipment:
• Utilise appropriate levelling equipment such as optical, laser, or digital levels, theodolite, total station, or an optical site square.

Hand Tools:

• Various hand tools are needed for tasks like setting up corner pegs and profiles. These include a lump hammer, claw hammer, and a hand saw.

• Fastening Tools:
• Have a selection of round-headed nails and/or a cartridge gun for securing materials.
• String:
• Use string to establish wall positions and maintain accurate alignments.
• Marking Tools:
• Spray paint is essential for marking out stations and outlining foundation trench positions.
• Personal Protective Equipment (PPE):
• Ensure personal safety with mandatory PPE, including a hard hat, high-visibility jacket, and safety boots.

The Setting Out Process

Step 1: Establish the front corners of the building (W and X) using the primary setting-out points (SOPs) as references.

• It can be seen from figure 1 that W and X are perpendicular to the rear of the kerb at W’ and X’, which are 4 m and 9.5 m away from the SOP respectively.
• To establish corner W, a 3:4:5 builder’s square, theodolite, total station, or site square can be used. However, in this class, we will employ two measuring tapes and apply the Pythagoras’ rule to establish this corner.

Figure 1. Setting-out of a small building.

The Setting Out Process

Figure 2. Establishing corners with Pythagoras’ rule.

The Setting Out Process

Figure 3. Establishing corners with Pythagoras’ rule.

The Setting Out Process

Figure 4. Establishing corners with Pythagoras’ rule.

The Setting Out Process

Step 3: Erect the profile boards.

• Permanent Reference Profiles:
• Profile boards serve as permanent references for both substructure and superstructure positioning and are to be retained throughout the entire construction process.
• When machine-dug, they should be positioned at least 4 m away from the proposed construction works.
• Marking Foundation & Wall Positions:
• The face of the profile boards are marked using nails or saw cuts to denote the position of the centreline of the foundation, foundation width, and walls.
• String lines are stretched tightly between corner post nails and extended to the profiles to locate these positions accurately.

Figure 5. Profile boards (Road To Learning, 2020)

Figure 6. Solid blockwork foundation with an insulated cavity wall.

The Setting Out Process

Step 4: Excavate the foundations

• Spray Painting as Excavation Guide:
• Utilize a string stretched between marks as a guide and apply spray paint on the ground. This painted line serves as a visual guide for the excavator operator, aiding in accurately excavating strip footings or ground beams.
• Maintaining Position Reference:
• While corner pegs may be lost during excavation, the saw cut marks on the profile board serve as a reference for re-establishing them. This process helps locate the positions of subsequent blockwork walls and other elements with precision.

Figure 7. Profile boards for foundation excavation (Pearson, 2017)

The Setting Out Process

Step 5: Setting Levels

• Vertical Precision in Setting Levels:
• Vertical positioning is as crucial as horizontal placement in construction. Achieving the planned heights for floor levels, window sills, and roof ridges is imperative for accurate construction.
• Establishing Vertical Control:
• On-site, vertical control is initiated by installing a temporary benchmark (TBM), with a known reduced level. It serves as a fixed reference point for all on-site levels.
• In some instances, the TBM may be derived from a local Ordnance Survey Benchmark (OSBM).

Figure 7. Profile boards for foundation excavation (Pearson, 2017)

The Setting Out Process

Step 5: Setting Levels

• The proposed dimensions of the foundation and floor slab of a house on a site are given on the drawing shown (Figure 8).
• Given the onsite TBM value of 10.000 m, determine the reduced levels of the finished flooring screed, & the bottom of the insitu concrete foundation.

(Note: Thickness of dampproof membrane [DPM] is negligible.)

Figure 8. Solid blockwork foundation with an insulated cavity wall.

The Setting Out Process

Step 5: Setting Levels

Determine the reduced level of the finished ground level.

• The height of collimation of the automatic level = Back sight (BS) + TBM

HPC = 10.000 + 0.807 = 10.807 m

• To determine the reduced level (RL) of the finished ground level (FGL), subtract the Intermediate Sight (IS) reading of the ground level from the HPC.

RL of FGL = HPC – IS

RL of FGL = 10.807 – 0.916 = 9.891 m.

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Figure 9. Reduced level of the finished ground floor.

The Setting Out Process

Step 5: Setting Levels

Determine the reduced level of the finished flooring screed (TFS).

• To determine the reduced level (RL) of the TFS, add the reduced level of the ground to the respective depth of the ground floor element.

RL of TFS = RL of FGL + Hard core depth + Oversite concrete bed depth + Flooring screed depth

RL of TFS = 9.891 + 0.100 + 0.020

RL of TFS = 10.011 m

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Figure 8. Solid blockwork foundation with an insulated cavity wall.

Figure 10. Reduced level of the top flooring screed.

The Setting Out Process

Step 5: Setting Levels

Determine the staff readings at the top of the flooring screed.

• Staff reading for TFS = HPC – Reduced level

Staff reading for TFS = 10.807 – 10.011 = 0.796 m

Figure 12. Staff readings for the flooring screed and insitu concrete foundation.

The Setting Out Process

Step 5: Setting Levels

Determine the reduced level of the bottom insitu concrete foundation (BICF).

• To determine the reduced level (RL) of the BICF, subtract the foundation depth from the reduced level of the finished ground floor.

RL of BICF = RL of FGL – Foundation depth

RL of TFS = 9.891- 0.817

RL of TFS = 9.074 m

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Figure 8. Solid blockwork foundation with an insulated cavity wall.

Figure 11. Reduced level of the bottom of the insitu concrete foundation.

The Setting Out Process

Step 5: Setting Levels

Determine the staff readings at the bottom of the insitu concrete foundation.

• Staff reading for BICF = HPC – Reduced level

Staff reading for BICF = 10.807 – 9.074 = 1.733 m

Figure 12. Staff readings for the flooring screed and insitu concrete foundation.

The Setting Out Process

• The staff is moved up and down by the assistant site engineer until 0.796 m is read on the staff. This is marked off on one of the uprights of the profile. This is the top of the flooring screed.
• The profile board is then nailed to the uprights so that the top of the board coincides with the mark on the upright. The profile can now be used to set out all the required levels by using a spirit level or pulling out a string line between two profile boards set at the same height
• Also, the staff is moved up and down by the assistant site engineer until 1.733 m is read on the staff. This is marked off on one of the uprights of the profile. This is the bottom of the insitu concrete foundation.

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Figure 12. Staff readings for the flooring screed and insitu concrete foundation.

You can use this technique with laser levels that have infrared sensors fitted to the staff. These sensors can be adjusted to the correct position on the staff, so that when the staff is raised or lowered a visual and/or audible signal tells you that you have found the required reduced level. Watch for understanding of this: https://www.youtube.com/watch?v=3sLKKhanh9I

Self-assessment Task 1

The proposed dimensions of the foundation and floor slab of a house on a site are given on the drawing shown (Fig. 13). Given the reduced level of the ground floor (10.050 m), determine:

1. The reduced level of the finished floor (FFL).
2. The height of plane of the collimation (HPC).
3. The staff reading needed to set the profile cross-board at the FFL.
4. What is the minimum width between the profile posts, and why have you chosen this?

Figure 13. Setting out levels for a solid blockwork foundation.

Self-assessment Task 2

• Produce a checklist of all the equipment and materials/tools needed to undertake the setting out, including personal protection equipment.

Reference/Bibliography

• Designing Buildings Ltd. (2023). How to layout a building. Available at: https://www.designingbuildings.co.uk/wiki/How_to_layout_a_building (Accessed: 15 December 2023)
• Ministry of Rural Development Government of India (n.d.) Setting out construction works. Available at: https://www.ilo.org/wcmsp5/groups/public/---ed_emp/---emp_ent/documents/instructionalmaterial/wcms_650137.pdf (Accessed: 15 December 2023).
• Monash University (2002) Setting out. Available at: https://azlanppd.tripod.com/topic11.pdf (Accessed: 15 December 2023).
• Road To Learning (2020) Available at: https://road-to-learning.com/2020/11/29/datum-point/ (Accessed: 16 December 2023).
• Rural Works (n.d.) The profile board method. Available at: http://www.ruralworks.com/reports/profileboard/ProfileBoard.html (Accessed: 15 December 2023).
• Pearson (2017) BTEC national construction student book. London: Pearson.

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