Things You'll Need
Dimensional lumber (1 by 12 inches)
Stairways come in a variety of designs. Straight-run stairways are the simplest in design. L-shaped stairways go up before turning at a 90-degree angle. Circular staircases allow the builder to minimize the footprint of the staircase on the floor plan, as the stairs curl around each other. U-shaped stairways allow for a compact design, often with a landing built in that adds an additional safety feature should someone fall.
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A run is the measurement of a stair's tread. A rise is the height from one stair tread to the next. There are standards for these heights.
Step 1: Calculate number of stairs
Calculate the number of treads you will have in your stairway. Measure from the finished floor of one level to the next with a measuring tape, then divide this number by 7.5 (the standard rise height for stairs).
Step 2: Round up the number
Round your number up to the nearest whole number; this number represented the number of treads you will need, plus one landing. For example, if your finished floor-to-finished-floor measurement was 120 inches, divide this number by 7.5 for a quotient of 16, which equals 15 treads and one landing.
Step 3: Place the landing
Find a location for your landing — most often at or near the center of the rise of the staircase. In the example of 15 steps and one landing, you would have seven treads going one direction, then the landing and then eight treads going in the opposite direction to complete the U shape.
Step 4: Calculate the run of the stairs
Calculate the run and width of your staircase. Multiply the number of treads before your landing by the depth of your tread. Add this number to your landing depth to determine the run of one leg of your U shape. Repeat the process for the number of treads in the second half of the stairway with the landing depth to determine the run of the second leg of the U.
Step 5: Calculate the width of the treads
Measure the width of the space where you plan to build your stairway. Subtract the thickness of building materials that will separate the two halves of the U, if needed. Divide the figure in half to determine the width of each of your treads.
Step 6: Build the landing
Build the landing, and attach the stringers. Per your staircase design plans, build the landing, including attaching the plywood subflooring. Cut three pieces of 1-by-12-inch dimensional lumber with a saw to the length you determined for the run of the first leg of your U.
Step 7: Attach the stringers
Following the manufacturer's instructions, attach the universal stair brackets to the dimensional lumber to form the staircase stringer. Attach the stringers from the bottom floor to the landing, positioning the outside stringers at the width you determined for your treads, and the inside stringer in the center of the other two.
Step 8: Attach risers and treads
Attach the risers and treads. Use a nail gun to nail the risers and treads to the stringers. Repeat the process for the second leg of the U of your staircase.
Step 9: Attach handrails
Attach handrails per your design and per local building codes.
Treads are commonly 10 inches in depth. You can adjust yours to fit your space; just verify they are within building code regulations.
Always measure twice and cut once to minimize the chance of mistakes.
Always check local building codes regarding stairs in your area.
Always obtain needed permits before undertaking any construction project.