A squeaky hardwood floor is rarely a sign of serious damage, but the noise can be maddening once you start noticing it. The sound comes from movement: a board rubbing against a nail, a subfloor lifting off a joist, or two planks shifting against each other as the wood expands and contracts with the seasons.

What Causes the Noise

Most squeaks trace back to one of a few sources. The fasteners holding the subfloor to the joists loosen over time, leaving a small gap. When you step on that spot, the wood drops, then springs back, dragging across the nail shaft. Humidity swings make this worse, which is why floors often go quiet in summer and noisy in winter.

• Loose subfloor-to-joist connections
• Nails that have worked free of the framing
• Gaps between the subfloor and the finished planks
• Seasonal shrinkage from dry indoor air

Fixing It From Above or Below

If you have an unfinished basement or crawlspace, the easiest fix is from underneath. Have someone walk on the noisy area while you watch for movement at the joist. A hardwood shim tapped gently into a gap, with a bead of construction adhesive, often silences the spot without any visible repair upstairs.

When you can only work from above, locate the joist with a stud finder and drive a trim-head screw through the flooring into the framing. Predrill to avoid splitting the plank, and fill the small hole with matching wood filler. For carpeted areas, specialty squeak-stop kits let you drive a breakaway screw through the carpet without leaving a mark.

Living With Wood

Some seasonal noise is normal and not worth chasing. Keeping indoor humidity in a stable 35 to 50 percent range does more to prevent squeaks than any single repair, because it limits the constant swelling and shrinking that loosens fasteners in the first place. A simple humidifier in winter can keep an old floor remarkably quiet.