Setting-out must be carried out in a horizontal plane. The tops of the pegs for setting-out must be level so that ranging lines can be attached horizontally and accurate plan measurements may be achieved.
There are two simple methods of transferring levels from one point to another: using a spirit level and straight-edge, or a Cowley Automatic Level. The two methods are not limited to levelling the tops of setting-out pegs. Both can be equally applied to any setting-out situation involving the principle of transferring levels between two points, such as transferring the site datum level to the corners of the building or levelling the tops of pegs in the bottom of an excavation to set the thickness of foundation concrete.