DIY Stairs

Calculate the number of steps you will require as well as the rise of each step. Measure the height from the landing to the floor below. Divide the height by the desired step rise and you will have the number of steps required to make the climb. Decide on the depth of your treads based on practical factors such as average foot size. Multiply the number of steps you expect to install by the depth of each tread and you will have the length of the staircase when completed. Check to see that your staircase will fit in the space you have.

Lock your stair gauges onto the framing square based on your calculated sizes. For example: if your desired rise height is 8 inches and your desired tread depth is 10 inches, place one gauge along the first side of the framing square 8 inches from the angle. Place the other gauge on the opposite side of the same angle at 10 inches. This will set your square to the dimensions of your stairs and allow you to cut the risers properly.

Lay your 2-by-12 board on the ground. Set your framing square against the wood using your stair gauges as a guide. Mark the outline of each step along the outer edge of the framing square using a pencil. Cut along each line with a circular saw only up to the end of each line. Use a hand saw to cut the very corner of each line, because the circular saw may not reach. The resulting jagged-tooth board will serve as one of your stringers.

Cut one end of the stringer to be flush with the joists at the top landing. Cut an amount equal to the thickness of your tread material (measure it first; it's usually about 1 1/2 inches) from the bottom of the notched stringer, using your circular saw. Use this completed stringer as the stencil with which to measure and cut the remaining stringers.

Attach your stringers to the top staircase landing by screwing them into the existing joists with L-brackets, your screw gun and screws.

Cut your risers and treads to fit the desired dimensions. Use your tape measure, straight edge and pencil to mark the measurement and your circular saw to make the cuts. Attach each riser to the vertical part of the stringer notches using the screw gun and screws. Attach each tread to the horizontal part the same way. Use a level to check that each step is laying properly before fastening it. Use your plane to shave away any bits that make the step uneven.