The Easy Way to Lay Out Stairs

Lay a 2-by-4-inch stud on the top landing for your stairs. Use your level to check that the stud projects straight outward from the landing without rising or dipping. The idea is to extend the height of the landing until it reaches the location over the floor below where the stairs will land.

Extend your tape measure from the stud above to the floor below and record the distance. Divide this measurement by 8 to calculate the amount of steps you'll require to bridge the two floors, as 8 inches is a typical average height for steps. For example, if your height measurement is 120 inches, your step count will be 15. Now that you know how many steps your layout calls for, you must calculate the depth of each step.

Multiply the amount of steps you'll require by 11, because 11 inches is a typical tread depth measurement. For example, if you have 15 steps at 11 inches each, the total length of your staircase will be 165 inches.

Use your circular saw to cut a pair of 2-by-12-inch boards into stringers. Cut the boards to a total length that matches your staircase length. Lay your stringers onto a flat work surface.

Place your carpenter's square onto your 2-by-12s with the corner facing inward on the wood, then trace the outline of your steps. For example, if your riser height is 8 inches, and your tread depth is 11 inches, make sure the short end of the square lines up at the 8-inch mark, and the long end lines up at the 11-inch mark. Use your marker and trace along the outer edge of the square. This guide line will serve as your step outline.

Use your circular saw to cut along your marker lines. Lay your cut stringer over your uncut stringer and trace the rise and tread lines. This is an easy way to ensure even cuts, and will save time.

Measure the width of your upper landing. Use your tape measure and straight edge to mark your 2-by-10-inch boards to this length. Add 1 inch at each end for a bit of overhang, which will hide the joint and create a more finished look once installed. Cut the risers to the exact width of the landing so they don't project past your stringers once installed.