How to Build House Stairs

Building house stairs depends primarily on basic geometry and a repetitive pattern of cuts.

Although building a stair is one of the more complex elements of home construction, success depends primarily on basic geometry and a repetitive pattern of cuts. The formula for the layout and construction of a single run of house stairs between two floor levels can also be adapted to building stairs between any two planes, such as from an exterior wood deck to a landing.



Since there are local and national code requirements relating to stairs, you should consult your local building department before beginning a stair project.

Things You'll Need

• Tape measure
• Calculator
• Pencil
• 2-inch by 12-inch lumber
• 2-inch by 12-inch tread material
• 1-inch by 8-inch riser material
• Framing square
• Circular saw
• Handsaw
• Wood glue
• 2 ½-inch decking screws
• 8d nails

Instructions

1. Use the tape measure to determine the vertical distance between the surface of the first floor and the surface of the second floor. This measurement will be used to determine the number of steps needed in the stairway.

2. Divide the above measurement by a number that gives you a step height, or "riser," between 7 and 8 inches. The comfortable standard step is approximately 7 ½ inches for residential stairs.

3. Multiply this number by the step tread width to determine the "run" of the stairway. Stair treads are typically 11 to 12 inches wide, including a 1-inch overhang or "nosing."

4. Place a 2-inch by 12-inch board on sawhorses for layout. This board will be the first "stringer" and, once cut, becomes the template for marking the remaining boards.

5. Place the carpenter's framing square on the edge where the tread and riser notches will be cut, beginning at the base end of the 2-inch by 12-inch board.

6. Adjust the framing square so the smaller arm aligns the riser measurement determined in Step 2 with the edge of the board. Align the wider arm of the framing square with the tread width determined in Step 3. Be sure to begin the first tread line at a distance from the end of the board that allows for the first riser height to be cut.

7. Mark a pencil line along the edge of the framing square at both angles. All marking must be done from the same edge (inside or outside) of the framing square.

8. Mark a 90-degree angle from the board edge of the first tread line to mark the cut line of the first riser.

9. Measure and mark the first riser line at the riser height minus the thickness of your tread material. (This cut will set on the floor at the beginning of the stair.)

10. Repeat Step 6, placing the tread measurement at the edge end of the previous riser mark. Repeat this step until the correct number of treads and risers established in Step 2 have been marked on the 2-inch by 12-inch board.

11. Determine the top end cut by marking a 90-degree angle to the tread line, measured from the front edge of the step line to the depth of the tread minus the nose overhang and thickness of the riser material. Example: For a 1-inch tread nose overhang and ¾-inch riser boards, the cut would be the tread width minus 1 ¾ inches.

12. Cut the 2-inch by 12-inch board on the pencil-marked lines with the circular saw. Use a handsaw to finish the saw cut at the inside corners.

13. Cut the remaining 2-inch by 12-inch boards to set the finished "stringer" as a template after verifying the fit. One stringer is installed on each side of the stairwell opening and one at the center.

14. Cut one piece of 1-inch by 8-inch riser material to the width of the stairs. Cut down the width of the riser board if it's wider than the riser height.

15. Position the riser piece vertically against the first step riser and nail it into place. Use at least three nails at each stringer.

16. Cut one piece of tread material to the width of the stairs.

17. Place a bead of wood glue on the horizontal surface of the 2-inch by 12-inch stair stringers and secure the tread in place with 2½-inch decking screws. Place the tread tight against the riser board and use a minimum of three decking screws through the tread at each stringer.

18. Repeat steps 14 through 17 for each of the remaining stairs.

Tips & Warnings

• Once the 2-inch by 12-inch stringer has been marked with all of the steps and risers, it's a good idea to make the top end cut and the bottom base cut of the stringer and hold it in place before making tread and riser cuts. This allows you to confirm that your angles and cut layout are correct before completing the cuts and perhaps wasting material due to an error in the layout.

References

• HomeTips.com: Building Codes Regarding Stairs