Measure the height of the staircase. Measure the length of the staircase. Divide each measurement by the number of stairs you would like to install. Compare these measurements to an existing set of stairs that are comfortable to you. The height of each stair rise plus the depth of each stair run should equal no less than 17 inches and no more than 18 inches. For example, a stair depth of 10 inches and a height of 7 3/4 inches is a comfortable ratio.
Attach brass stair gauges to a framing square at the desired measurements. Place the framing square on a piece of stringer lumber (a stringer is a board with notches for steps cut out) and trace the steps onto the lumber with a pencil.
Cut the notches out with a circular saw or a jig saw. If you use a circular saw, cut the side with the pencil marks first. Then flip the board over and lengthen the cut on the back side of the board. Break the wedge out of the cutout and chisel the small, remaining piece of wood away from the lumber.
Measure the width of the staircase. This measurement equals the length of the stair treads. Cut the stair treads to length and to the desired width. If you are enclosing the stair rise, cut the lumber to the proper length (probably close to the same measurement and the stair tread), and then to the proper height.
Attach the stair treads and the stair rise lumber to the stair stringers with wood screws long enough to penetrate the stair treads and rise lumber and sink into the stringers at least one inch.
Things You Will Need
- Tape measure
- Circular saw
- Framing square
- Brass stair gauges
- Stringer lumber
- Stringer: A straight board, with or without notches cut out, that supports the stair treads. Stair tread: The stair tread is a piece of wood, or other material, that makes the run of the stair. This is what you step on to climb the staircase. Rise and Run: The rise of a stair is the vertical portion of the stair; the run of the stair is the depth, or the flat portion of the stair that you step on.