How to Lay Out Deck Stairs

Estimate where on the ground you want the last step to bring you. A general rule of thumb is to picture a 40-degree slope from the stair landing to the ground. Lay a 2-by-4-inch board on the deck's stair landing, and extend the board out until it's end reaches the landing ground.

Place a level on the board and adjust it until it's straight. Ask a friend to hold the board in place. Measure from the board's bottom end to the ground landing. Divide this number by 7 to determine how many rises your staircase will have. Adjust this calculation to somewhere between 7 and 8 until you end up with a whole number of stairs. The staircase will have one more rise than tread.

Multiply the number of treads by 11 to determine how far the staircase will extend from the deck. Draw out the deck stairs to scale on a piece of paper, using the calculations you performed.

Lay a 2-by-10-inch board on a flat work surface. This board will be one of the stringers. Clamp two stair gauges to a carpenter's square -- one at 11 inches for the treads and one at the number you determined in Step 2 for the rises.

Hold the carpenter's square against the 2-by-10 board with the gauges pressed against the board's edge. Use a pencil to trace along the carpenter's square. Move the carpenter square up one full stair and trace along it again. Repeat until you have the appropriate amount of treads and rises traced. You will be left with what looks like connected V's going up the length of the board.

Lay the 2-by-10-inch board at an angle from the deck landing to the ground landing with the final tread line resting on the deck's edge, where it will be once the board is cut. Draw a straight vertical line up the board, using a level where it hits the deck landing's edge. Draw a straight horizontal line across the board where it will rest on the ground landing.

Cut the 2-by-10 board, following the lines you drew with a circular saw. When you cut out the stairs, do not cut all the way to the point of the V. Stop about 1 inch away and finish the cut with a handsaw.