Setting out in technology

For us to understand and appreciate what setting out operation is all about, let us first discuss the preliminary roles of some professionals in the job.

(A) Preliminary Site Operations

Anybody wishing to construct a building usually first consults an architect to discuss the need for a building and the type of building wanted. The architect will find out from his client, the land area available for the project and nature of the ground, his preference for single-storey buildings to two-or three-storey buildings, and perhaps how much he intends to spend on the building. After obtaining all the necessary information and data, the architects plan and design a building that satisfies the wishes and need of the client.

This architectural damage is then sent to a structural engineer. The structural engineer works within the civil engineering field as a specialist. He determines and specifies the strength and types of building materials to be used in different parts of the building structure. The structural engineer studies the building design sent to him and recommends the sizes of steel bar and positions and methods of placement in the different parts of the building to reinforce the concrete. He also specifies the ratio of mix of the concrete required for the building for maximum strength.

The building design is returned to the architect who now prepares the building plan in greater details, as he adds all the information specifications and advice from the structural engineer.

He finally prepares the contract documents for the building project. The quantity surveyor may be consulted to study the working drawings of the proposed structure to determine the cost of materials, labour and workmanship that can be charged to the proposed building structure.

Finally, a construction company or a contractor wins the contract for the construction of the building and having finished the preliminary operations of site preparation, is now ready to set out the building.

(B) Setting Out – The Need for Accuracy

Setting out is, therefore, a process of driven pegs into the ground here and there, in a manner that agrees with the dimensions of the buildings specified on the architect’s drawings.

Setting out a building is a simple job. Although a simple job, it is very important that it be skillfully executed to have the building true to shape or square and level.

Indeed, the satisfaction and the success of the whole project depends upon the setting out. It is certainly impossible to make any amendments if the rooms of a building are found to be out of shape, and that building shall forever remain a good and living advertisement for an unskilled and inexperienced builder at least as far as setting out is concerned.

Setting out is the process of transferring, with a high degree of skill and accuracy, the details of the foundation plan from the drawing sheet on to the ground, with pegs, line and tape. In setting out, the exact positions of the foundation trenches which will carry the entire walls of the building are properly located on the ground, true to the dimension and squareness as specified in the building plan sheet.

Simple Drawing Practice

An architect plans and designs building structure and prepares all the drawings and specifications required to successfully carry out the building project. The working drawings usually contain the various drawings discussed below:

1. The floor planshowing the layout of the building, the dimension and location of the walls, rooms doors and windows. The floor plan may or may not show the foundation trenches. When it does, the foundation trenches are shown in dotted lines.
2. The elevationshowing the building as viewed from the East, West, North and South.

iii. The sections showing the building as it would look when cut through from the roof to the foundation.

1. The detailed drawingsshowing extra details to aid the builder in carrying out the building operation to be required specification, e.g. the fixing of the flashing of or method of placing and spacing the reinforcement bars.
2. The schedulesshowing the different types of doors and windows, their sizes and their locations in the building plan. The schedules will also show the types and locations of the kitchen cabinets, or any other room divider, such as a shelf.
3. The electrical plangiving a layout of the electrical installations and wiring of the building.
4. The plumbing plan showing the plumbing network of the building including the drainage and sewage system. it will also show the water supply system and distribution in the building including the size and location of the septic tank and soak-away.

Builder’s Square

This is a wooden version of the steel square. The square template is made out of 150mm x 38mm timbre, framed and braced, and the arms should be about 2 metres or longer. It is used in the same way as the steel square, and has the advantage that it is bigger and can give an easier and more accurate setting out.

Tape and Pegs

Tape and pegs can be used in setting out the square end of a building, based on the Pythagoras’ theorem which proves that any triangle whose sides in the ration of 3:4:5 is a right angled triangle.

When the building line is established, and a distance of 3m is measured along the building line, a peg is driven into the ground at this point. A nail is driven into the centre of the top of each peg.