Method 1: Spirit Level and Straight-Edge
Transferring levels over a long distance between one point and another, such as one corner of a proposed building to another, cannot be achieved with a spirit level on its own, as the span between the two corner pegs will be too great. Even using a 3-metre straight-edge to extend the effective length of the level is unlikely in the vast majority of cases to prove effective in spanning between one corner peg and the next.
Any length of sturdy timber can be used as a straight-edge, provided its sides are parallel and the timber is, of course, straight. This may seem obvious but timber, even when it has been accurately planed all round, has a tendency to warp, especially when it is exposed to the conditions on a building site. As a result, it is better to use a straight-edge that has been purposely machined and shaped out of good-quality, seasoned timber. Better still, a straight-edge made out of aluminum box-section will always remain straight and true.
1. Drive a temporary intermediate peg into the ground along the path of the straight
line between the first and last peg. It should be placed at a distance from the first peg that is a little less than the length of the straight-edge.
2. Using the spirit level and straight-edge together, check the peg as it is hammered into the ground until it is level with the first peg.
3. Depending on the distance involved, repeat the process with additional temporary intermediate pegs until the position of the final corner peg is reached. At this point, all the temporary intermediate pegs can be removed
When transferring levels in this way, the accuracy of the spirit level should be checked, and adjusted if necessary, before use. In any case, it is regarded as good practice to reverse the spirit level and straight-edge every time they are moved on to a new peg, turning them end-to-end through 180 degrees, in order to compensate for any slight inaccuracy. If there is any inaccuracy, simply moving them along without turning them will exacerbate the error. Reversing them at every peg may create an ‘up and down’ effect but by the time the last peg is reached, the first and last pegs will be level with each other, provided the number of temporary intermediate pegs is an odd number making the number of stages an even number. This compensatory measure will not work as effectively with an even number of pegs and an odd number of stages.