How to Square a Slab With a Laser Level

Hammer the legs of the forms together using 2-by-4-inch scabs. To do this, lay 2-by-6-inch boards end to end and scab the joints together to make a leg. The slab has four corners, meaning it has four legs. Put the legs on edge and hammer them together to make a square. To accomplish this, butt the end of one leg up against the side of the end of another and hammer through the other side of the second leg into the butt of the first.

Place the laser level in the center of the forms. Shoot the elevation of the four corners. If the excavator did a good job, the corners will be within 1 inch of one another. If not, remember the low and high corners on the pad. The working elevation will be the highest point on the pad.

Square and stake the forms. To do this, first measure one hypotenuse -- diagonal across the pad from one corner to the opposite. Measure the other hypotenuse. Adjust the position of the corners until the two hypotenuses are equal. Drive rebar stakes into the ground alongside the forms every 6 feet, at each corner and at every scab.

Hammer a staple around the rebar stake into the form at the highest corner. Place the laser level's electric grade rod on the form at every stake, raise the form to grade and hammer a staple around the stake and into the form to hold it in place. Recheck the forms' square after you have stapled them all to grade.