How to Build Wood Stairs With No Wall Support

Measure the distance from the upper landing to the lower landing of your stairs. Determine the rise of each step, or how high each step will be, by dividing this distance by 7 and rounding down. For a 48-inch stairway, you will have six steps. To find the real rise of each step divide the height of the stairway by the number of steps. A 48-inch stairway with six steps will have an 8-inch rise.

Calculate the run of the stairs by multiplying the number of steps by 10 inches. For the 48-inch stairway the run is 60 inches. Square the height and the run of the stairway and add them together; take the square root of the answer to determine the length of the board.

Mark the length of the rise on the left arm of the right angle carpenter's square and the run length on the right arm. Place the carpenter's square on the 2-by-12-inch board so that both of the marks are on the edge of the board. Draw the shape of the step along the outer edge of the carpenter's square.

Slide the carpenter's square down the edge of the board until the mark on the left hand arm of the carpenter's square lines up with the mark where the previous step ended. Continue to draw steps until you've finished the stringer.

Subtract 1 inch from the height of the rise and draw a line this distance from the bottom step and parallel to the step, not the rise. Square off the top end of the stringer by drawing a line parallel to the last riser you drew on the stairs from the back of the top step you drew.

Cut the stringer. Use this stringer as a template for the other two stringers.

Cut a face board for the front of the landing out of a 2-by-12-inch board at least 3 inches wider than the stairway. Attach the face board to the edge of the landing with 3-inch screws. Ensure the top edge of the face board is flush with the surface of the landing.

Attach the top of the stringer to the front of the top landing by inserting screws from the back of the landing face board while the bottom of the stringer rests on the bottom landing or the ground. The stringer should be 3/4 inches down from the top of the face board so that when the top tread is attached to the stringer it's flush with the top landing. Ensure the tread support portion of the stringers are level.

Measure and cut risers for each step and attach them, perpendicular to the ground, against the back of each stringer.

Create treads for your stairs by cutting two pieces from 1-by-6-inch boards for every step. Lay two 1-by-6-inch boards side-by-side on the stringer to create each step. Nail the steps into place.