How to Cut a Simple Stair Stringer

Cutting stair stringers requires precision and accuracy.

Stair stringers are the basic element of a staircase structure that support the treads and define the equal spacing of the steps between two floor elevations. Cutting the stair stringers is accomplished with some basic calculations and the accurate layout of the cuts required.

Things You'll Need

• Tape measure
• Calculator
• 2-by-12 lumber
• Framing square
• Framing square guides
• Pencil
• Circular saw
• Handsaw
• Sawhorses

Instructions

1. Place a 2-by-12 board on sawhorses or a flat surface for the stringer layout.

2. Measure the vertical distance between the first-floor and second-floor surfaces, using a tape measure. Divide the measurement by a number that gives you an equal step height, or riser, between 7 inches and 8 inches each. The standard riser height for residential stairs is approximately 7½ inches.

3. Attach a framing square guide to the shorter arm of the framing square at the riser height you determined. Attach a second framing square guide to the longer arm at the 11-inch mark for the standard stair tread dimension. Be certain both guides are to the outside of the measurement lines.

4. Define an end of the 2-by-12 at the bottom end of the stringer and edge the to be cut for the steps. Place the framing square against the edge of the 2-by-2, with the tread measurement toward the bottom end and approximately 10 inches from the end of the board.

5. Mark a pencil line along the edge of the framing square at both angles on the same edge as the guides are attached. This marks the first tread and second riser location. Note that all of the remaining stringer layout lines will be marked using these same sides of the framing square.

6. Align the framing square with the first tread line marked in Step 5 and mark a 90-degree angle from the board edge of the line toward the bottom end of the stringer to mark the cut line of the first riser. Measure the riser distance on this line from the tread line minus the thickness of the tread material and mark a line parallel to the first tread line marked in Step 5.

7. Position the framing square on the edge of the 2-by-12, with the tread measurement aligned with the second riser line marked in Step 5 and the square guides against the edge of the stringer board. Mark a pencil line at both angles. Repeat this step until the number of risers determined in Step 2 have been marked on the stringer board.

8. Mark the top end cut of the stringer by marking a 90-degree angle to the top tread line, measured from the front edge of the tread line to the depth of the tread minus 1 inch. This line will be parallel and aligned with the top riser line.

9. Cut the stringer on the layout lines to the point where the back of the tread line meets the riser line, using a circular saw, then use a handsaw to complete the saw cuts at these inside corners. With the cuts complete, the stringer is ready to be installed.

Tips & Warnings

• Framing square "guides" assist with accuracy of the repetitive marking of the tread and riser layout, and are available at most hardware and home supply stores.

• It's recommended to cut the top end cut and the bottom base cut of the first stringer and hold in place before cutting tread and riser cuts to allow confirmation that the layout is correct. Once the cuts are completed for the first stringer, it can be used as a template to mark the remaining stringers.

References

• Home Tips: Staircase Construction