How to Fix a Squeaky Subfloor

Squeaky subfloors are usually caused by loose subflooring that rubs against joists or nails when you walk on it. Fix them by securing loose boards with screws, adding construction adhesive, or installing bridging between joists.

1. Find the Noise Source First. Walk slowly across the squeaky area and have someone listen from below to pinpoint exactly where the noise originates. Mark the spot with chalk on the subfloor from underneath, or have your helper tap the ceiling so you can mark the floor above. Most squeaks happen where the subfloor meets the joists or where two subfloor panels join.
2. Confirm the Culprit Below. Examine the marked area from underneath if you have basement or crawlspace access. Look for gaps between the subfloor and joists, loose nails, or subfloor panels that have separated. Push up gently on the subfloor while someone walks above to confirm movement. This is the most effective approach since you can see exactly what's causing the problem.
3. Lock Down with Screws. Use 2½-inch wood screws to secure loose subfloor to the joists from below. Pre-drill pilot holes to prevent splitting, then drive screws every 6-8 inches along the joist where squeaking occurs. Make sure screws don't penetrate the finished floor above by measuring your subfloor thickness first. This method provides the strongest, most permanent fix.
4. Seal Gaps with Adhesive. Squeeze construction adhesive into any gaps between the subfloor and joists using a caulk gun. Work the adhesive into the gap with a putty knife, then immediately secure with screws before the adhesive sets. This eliminates movement and creates a solid bond between materials. Clean excess adhesive immediately with a damp cloth.
5. Brace for Lasting Stability. If squeaking persists across a large area, cut 2x8 or 2x10 blocking to fit snugly between joists at the problem area. Nail or screw the blocking in place to prevent the subfloor from flexing. This adds rigidity to the entire floor system and prevents future squeaks from developing in adjacent areas.
6. Work from the Top Down. Drive 3-inch finish head screws through the finished flooring into the subfloor and joist below. Pre-drill to avoid splitting hardwood floors. For carpet, pull it back to access the subfloor directly. Countersink screw heads slightly below the surface and fill holes with wood filler on hardwood floors. This method works but is more visible than fixing from below.
7. Verify the Fix Works. Walk across the repaired area to test your work. If squeaks remain, repeat the process in nearby areas where the subfloor may have loosened over time. Sometimes fixing one squeak reveals others that were masked by the louder problem. Check that all screws are fully seated and that no new gaps have opened during your repairs.