Explanation:
For a simple building layout, such as a rectangle, the outline of the building is marked by a line tied to corner posts - a nail in the top of the post can be used to attach the line to. A theodolite, site square or builder’s square is used to turn off 90-degree angles for the remaining corners. Ranging rods may be required to establish a straight line between corner posts.
Corner posts are usually 50 x 50mm timber posts driven firmly into the ground, with a nail in the post’s centre. The outline may be marked on the ground with dry lime or similar powder. Timber profile boards can be used at the corners. Profile boards are typically between 0.6-1m in height and comprise two 50 x 50mm posts driven at least 600mm into the ground, with a 150 x 38mm crossboard.
Where the outline of a building is more complex than a simple rectangle, it may be necessary to establish a range of points in the same way as for laying out a simple rectangle. However, great care is required, as small errors are more likely to be introduced as more points are positioned. Often the easiest way of laying out an irregular building shape is to first lay out a large rectangle which will enclose the entire building or the greater part of it. Once this is done, deductions and alterations can be made to obtain the precise layout required.
