How to Build Staircase Stringers

Measure the distance between the staircase's lower and upper landings; this dimension is your staircase's total rise. Decide the height of each riser. Although building code requirements vary, 7-inch risers are widely acceptable and comfortable to climb.

Divide the total rise by the height of a riser to determine the total number of risers in the staircase. For example, 7-inch risers divided by a total rise of 43-1/2 inches equals six risers with a remainder of 1-1/2 inches. Determine the depth of an individual riser, typically a comfortable 10 inches. Multiply the number of risers by the depth of an individual tread to determine the total run of the staircase. For example, 6 risers multiplied by 10-inch treads equals a run of 60 inches.

Adjust the height of the risers to fit the overall rise of the staircase. For example, 7-inch risers over a rise of 43-1/2 inches equals six risers with a remainder of 1-1/2 inches distributed equally among the 6 risers. In this example, six risers at 7-1/4 inches each fits the staircase rise of 43-1/2 inches.

Lay a carpenter's square on the stringer material with the square's short leg, called a tongue, near one end of the board and the square's long leg, called a blade, closer to the center of the board. Move the square approximately 1 foot toward the board's center; beginning away from the board's end leaves room to layout the staircase's top step.

Find the inches mark on the inside edge of the tongue that corresponds with an individual riser's height. Align the inches mark with the edge of the board. Find the inches mark on the inside of the blade that corresponds with the depth of a tread. Align the blade's inches mark with the edge of the board. While holding the square in position, attach stair gauges to the outside edge of the both the tongue and blade; square gauges allow you to repeatedly and accurately layout these measurements.

Run a pencil along the inside edges of the square to layout a step. Move the square down the board and align the tongue's stair gauge with the corner of riser line from the previous step. Butt the gauges against the edge of the board and run a pencil along the inside edges of the square to layout a second step. Layout adjacent steps until you reach the total amount of steps.

Subtract the thickness of a tread from the height of a riser to determine the height of the bottom tread; you must subtract a tread's thickness from the bottom riser to compensate for the top step's tread. For example, if you are building treads with 1-1/2-inche lumber and each riser is 7-1/4 inches, the bottom riser equals 5-3/4 inches.

Remove the stair gauges from the square. Find the bottom riser of the staircase; this is the last riser that you marked. Mark the modified height of the bottom riser on the bottom riser's layout line. Position one side the square on the rear of the bottom riser's layout line and the other side perpendicular to the line, running toward the rear of the staircase.

Align the perpendicular side of the square with the height mark and use a pencil to layout a cut line across the bottom of the staircase; this line runs from the bottom of the bottom riser to the rear of the staircase.

Align the square perpendicularly with the top riser line, the first line you laid out, and use the perpendicular side of the square to lay out a line for the top tread. Lay the square perpendicular to the top tread line with one side of the square parallel the top riser line. Use the square to layout a line parallel to the top riser; this line forms the flush surface that attaches the staircases rear to the upper landing.

Cut the stringer along the layout lines with a circular saw. Use a hand saw to complete inside corner cuts, such as the intersection between risers and treads.