Real Estate

Different Methods of Setting Out in Building Construction

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Setting out in building construction is a process that ensures that the outline of the excavation and the centre line of the walls are clearly defined. This helps in carrying out the construction according to the plan. It is considered to be a very complex engineering process but with experience, the complexity reduces.

Following are the different methods of setting out in building construction:


1. The 3-4-5 method

This 3-4-5 method is used to set a right angle from a certain point on the base. It is done with the use of measuring tape, two ranging poles, pegs and requires a minimum of three people to carry out.

The first person between his thumb and finger holds together the zero mark and the 12-meter mark of the tape. The second person holds the 3-meter mark of the tape between his thumb and finger. Finally, the third person holds the 8-meter mark between his thumb and finger.

When all sides are stretched, held by the three persons a triangle with lengths of 3 m, 4 m and 5 m is formed and the angle near person 1 is a right angle. The same process can also be followed in a multiple of chosen numbers like  6 m, 8 m and 10 m or 9 m, 12 m and 15 m.

2. The rope method

This method is used to set out a perpendicular line to the base but of course, starting from a point which is not the base. In the rope method, a line has to be set out perpendicular to the base from peg (A). However, peg (A) is not on the base.

This method requires as the name suggests a long rope with a loop at both the end and also measuring tape. The rope needs to be longer than the distance from peg(A) to the base by a few meters.

3. Optical square method

Optical squares are simple sighting instruments used to set out the right angles. These instruments either come with mirrors or one or two prisms. Prismatic squares are of the following types-

  • Single prismatic square:

In a single prismatic square, the prism is fitted to the metal frame with a handle. The handle has a hook to which a plumb bob is connected. The single prismatic square enables the user to see at right angles when looking through the instrument.

  • Double prismatic square:

The double prismatic square has two prisms. The prisms are placed in a way where it is possible to look at the same time at a right angle to the left and to the right. The observer can look straight ahead through openings in the instrument above and below. Compared to a single prismatic square in the case of the double, no assistant is required and a single person can see the base and the perpendicular line at the same time.

Complete Survey Solutions is your one-stop shop for setting out when it comes to building construction. Be sure to get in touch as soon as you possibly can!

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