Setting out profile boards

 During building alignment, it is useful to extrapolate the sides of the building to beyond the limits of the ex- cavation and there to erect profile boards on which the extensions are marked exactly by hammering in nails. These can be connec- ted to strings or wires  any time during the con- struction sequence, indi- cating the required positions of the walls. 

ln the following example. profile boards are to be erected parallel to the pro- posed walls of a large building and at distances of a and b respectively from the boundaries (illustration, left). 

1. Establish a baseline AB parallel to the left- hand boundary and at a freely - selectable distance C. 

2. Mark the point A at the defined distance d from the upper boundary; it will be the first location for the total station. 

3. Using a boning rod, mark the point B at the end of the baseline. 

4. Set up the total station on point A, target point B, and set out the points A1- A2 and A3 in this align- ment in accordance wngth of the Side of the building. 

5. with point B sighted, set the horizontal circle to zero, turn the total station by 100 gon (90°) and set out the second line AC with the points A4, A5 and A6.  

6. The points on the profile boards are then set out in a similar manner, starting from the points A1 to A6 respectively. 

lf the foundations have not yet been excavated, you can set out the sides H1 H2 and H1 H3 of the building directly and use them as the starting line for marking the points on the profile boards. 

For smaller buildings it is easier to set out the profile boards using an optical square (right-angle prism and a measuring tape. 

A building- alignment software program incorporated into many Leica total stations enables profile boards to be set out directly, starting with any information station.