Stair stringers are the long boards underneath the stair treads that provide stability for the staircase. In a normal-width staircase there are typically three stringers, one on each side of the stair tread and one in the middle. Building the stringer correctly is crucial to having a safe staircase as well as one that will pass local building codes. Building a stair stringer can be a bit difficult, as it requires precise measurements and a few specialised tools.
- Skill level:
- Moderately Challenging
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Things you need
- Tape measure
- Framing square
- Stair calculator
- Circular saw
- Hand saw
- Saw horses
- Pressure-treated 2-by-12-inch stringer board
Measure from the top of the stairs to the ground below the deck edge. This will provide the deck height measurement.
Decide the rise or height you would like to have for the steps. The maximum allowable rise by most building codes is 7 3/4 inches and the suggested minimum is 4 inches.
Determine the desired run, or depth, of each stair tread. The minimum run for most building codes is 10 inches.
Input your desired rise and run as well as the total deck height into a stair calculator. The calculator will determine how many steps should be on the stringer as well as the cutting angle.
Mark the 2-by-12-inch stringer board with pencil and framing square, using the measurements and angle from the calculator. Start by marking the bottom stair measurements and work toward the top stairs.
Cut the marked 2-by-12 stringer board with a circular saw at the pencil line. Use a hand saw to make finishing cuts in the corners.
Place the bottom of stringer on the stair landing and move toward the deck edge. Hold a level across the stringer to determine it the cuts are square and the fit is good. If not, adjust as necessary by recutting.
Place the first cut stringer on top of the remaining 2-by-12 stringer boards. Use as a template to trace the stair pattern onto the boards.
Cut the remaining stringer boards as noted in step 7.
Tips and warnings
- Never space stringers more than 16 inches apart.
- Place stringers on saw horses to make cutting easier.
- Always use 2-by-12 pressure-treated material.
- Always wear safety glasses when cutting wood.
- Use power tools with caution.