Symptoms
- Stairs shift, bounce, or wobble when stepped on
- Visible gap or movement at the top or bottom connection
- Cracked, split, or soft treads or stringers
Likely causes
- CommonLoose connection where the stringers meet the deck frameThis top connection carries the most load and can loosen or fail if under-fastened.
- CommonUnanchored or shifted bottom of the stairsStairs resting on soil, pavers, or a footing that has settled or shifted lose their stable base.
- PossibleRotted stringers or treadsStairs see more water exposure at ground level, and wood there rots faster.
What to do
- Identify exactly where the movement is coming from by watching the connections as someone steps on the stairs.
- Check and tighten or replace fasteners at the top stringer connection to the deck frame.
- Check the bottom of the stringers for a solid footing, pad, or anchor, and re-level or re-anchor if it has shifted.
- Probe stringers and treads with a screwdriver for rot, especially near the ground.
- Replace any rotted stringer, since it's a primary structural member and shouldn't just be patched.
- Add proper structural stair connectors at the top and bottom if the original build lacked them.
- Test the rebuilt stairs thoroughly with weight and side-to-side pressure before normal use resumes.
Tools and parts
- Drill/driver
- Level
- Screwdriver (for testing)
Stair stringer connectorsSearch: “deck stair stringer connector”
Concrete deck footing padSearch: “precast deck footing pad”
When to call a pro
Call a deck contractor for stringer replacement or if the stairs were never properly anchored at the base.
Safety
Use caution
Restrict use of wobbly stairs until repaired, since a structural stair failure can cause a serious fall.