The Best Way to Cut Stair Stringers

Calculating the Stringer Size

• 1

  Measure the rise. Stairs have to go up a specific distance, known as the rise. Measure the rise from the landing location to edge of the level of the top floor.

• 2

  Determine the number of stairs. Each stair is typically 7 inches high. Divide the rise by this and round down to determine the number of stairs you'll need.

• 3

  Determine the run. The run is the horizontal length the stairs require to claim the rise. Each step should be no shorter than 10 inches wide. If you need nine steps, for example, you need a run of at least 90 inches.

Cutting the Stringer

• 4

  Attach the stair gauges. Take the first stair gauge and attach it to the square's tongue at the length of the rise. Take the second gauge and attach it to the other arm of the square at the length of the run.

• 5

  Mark each tread notch. Lay the adjusted square on the 2-by-12. Mark each notch using a square and a pencil and repeat until you have the correct number of notches. Make sure each notch is aligned with the previous notch.

• 6

  Cut the notches. Use a circular saw to cut the notches out. Do not extend the cut until the notch is removed, but cut only until the edge of the saw blade reaches the edge of the notch. Complete the cut with a hand saw or jigsaw.

• 7

  Trim the stringer. Cut off a portion of the bottom of the stringer equal to the thickness of the treads you plan to use. For example, if each tread is 1 inch thick, use the square to mark a 1-inch line across the bottom of the stringer and cut this portion off with the circular saw.