DIY: How to Attach a Stair Stringer

Stair stringers must be anchored at the top of the staircase.

Stair stringers are the main support system for many staircases. When building a staircase, the top end of the stringer is attached to the upper landing, while the bottom end rests on the floor below. The structure of the lower level floor provides sufficient strength to eliminate the need for an anchor at the bottom end of your staircase stringer. To attach your stair stringer to the floor joists at the upper landing you will require a sturdy anchoring system and a bit of know-how.

Things You'll Need

• 3/4-inch thick subflooring
• Tape measure
• Circular saw
• Pencil
• Wood glue
• Hammer
• Nails
• T-square
• Eye protection
• Work gloves

Instructions

1. Create a hanger board to serve as the point of attachment between your stringers and your upper landing. Use your tape measure to record the width of your staircase. Use your circular saw to cut a 3/4-inch thick piece of subflooring to the same width. Cut the length of your subflooring to 16 inches. For example if your staircase is 32 inches wide, your subflooring should be cut to 16-by-32 inches. These measurements assume that you have 10-inch floor or rim joists at the top landing and 6-inch stringers. Adjust the sizing accordingly for any variation in materials.

2. Place your hanger board against the floor joists at the top landing of your staircase. Apply a bead of wood glue around the edges and in the center of your hanger board. Fasten the hanger board in place using your hammer and nails. Once in position, the hanger board acts as an extension of the floor joists, and allows the stringers to be attached at the proper height to support the first step down from your upper landing.

3. Use your measuring tape to measure and mark your stringer mounting locations on the hanger board based on the width of your staircase. Use your tape measure to mark the center point between your two side stringers. Your center stringer will go in this location. Use your pencil to mark each mounting point.

4. Place the top end of your first outside stringer against the hanger board along your pencil marks. Use your T-square to check that the angles between your stringer and the hanger board are square. Variations of up to 1/8 inch are acceptable. Inspect both ends of the stringer to ensure that there is sufficient room for your top riser on the upper end, and that the three stringers align properly at the lower end.

5. Apply a heavy bead of wood glue to the mounting edge of your stringer and use your hammer and nails to fasten it in place. Drive nails through the hanger board from the rear and into the edge of your stringer. Repeat the process with your other side stringer first, and then your center stringer.

Tips & Warnings

• Fit a piece of 2-by-4 inch stud to the bottom end of the risers in your bottom-most step. This reinforcement will serve as a kick plate and provide more stability in an otherwise vulnerable location.

• Always wear eye protection and work gloves when using saws, hammers and nails.

References

• Decks: Stair Stringer Attachment
• Carpentry-Pro-Framer: Learn How to Build Stairs