The ground tracing or the setting out is the method of laying down the center lines and excavation lines etc. on the ground, before starting excavation. After the foundation design is completed, a setting out: plan, sometime it is also called as foundation layout plan. It is arranged with the help of appropriate scale (usually 1:50). This plan is entirely dimensioned.
For setting out the foundations of such buildings, the center line of the long exterior wall of the building is marked on the ground. It is stretched by the string between mild steel or wooden pegs driven at the end. This line work as the reference line. For exact work, nail are to be fixed at the center of the pegs. It is driven at each end of the line. Each peg is spread to equal distant from the central peg. The distance between the outer pegs correspond to width of the foundation trench to be excavated.
Diameter of the peg
Each peg may project almost 25 to 50 mm above the ground level and may be driven at a distance of around 2 m from the edge of excavation so that they are not to be disturbed.
When string is stretched connecting the corresponding pegs (say 2-2) al the two extremities of the line. The boundary of the trench will be excavated. With the help of dry lime powder it can be marked on the ground. The center lines of other side walls are perpendicular to the long wall, and mark it by setting out right angles. The right angle can be set out by forming the triangle with 3, 4 and 5 units long. These dimensions should be measured with the aid of a steel tape. Although, a prismatic or theodolite compass may be utilized for setting out right angles. Likewise, outer lines of the foundation trench of each cross-wall can be set out.