How to Fix Squeaky Hardwood Floors From Above or Below

A squeaky hardwood floor is rarely a structural emergency. Most squeaks come from wood rubbing against wood or against a nail: a floorboard that has lifted slightly off the subfloor, a subfloor that has pulled away from a joist, or a nail sliding up and down in its hole as you step. St. Louis’s big swings between humid summers and dry, heated winters make wood swell and shrink, so floors that were quiet in July often start talking in January. The good news is that most squeaks can be quieted in an afternoon once you find where they come from.

Difficulty: Beginner to intermediate · Time: 1–4 hours, depending on access

Tools and materials

A helper to walk the floor while you listen
Painter’s tape or chalk to mark squeaks
Tape measure and a flashlight or headlamp
Drill/driver with bits
Wood shims (cedar or pine)
Construction adhesive and a caulk gun
1-1/4 inch wood screws (shorter than the combined subfloor and flooring thickness)
A squeak-repair kit for working from above (breakaway trim-head screws with a depth-control jig), sold at home centers
Powdered graphite or talcum powder
Wood filler or color-matched putty and a putty knife
Safety glasses and a dust mask

Step 1: Find the squeak

Have a helper walk slowly across the room while you listen. Mark each squeak with a piece of tape. If you have an unfinished basement or crawlspace below, go down there while your helper steps on the marked spots. Watch and listen for subfloor that moves, a gap between the subfloor and the top of a joist, or nail points that shift. Measure from a wall or a heat duct on both levels so you can line up the upstairs mark with the spot below.

It helps to know where the joists run. In most St. Louis-area homes, joists run across the shorter dimension of the house and are spaced 16 inches on center, but older homes can vary. A stud finder or the nail pattern in the floor will usually show you.

Step 2: Fix it from below (the best option when you can)

Working from the basement lets you fix the cause without touching your finished floor.

Gaps over a joist: shim it. If you see a gap between the top of a joist and the subfloor, coat a thin wood shim with construction adhesive and tap it gently into the gap. Stop when it’s snug. Driving it hard will push the floor up and can create a hump or a new squeak.
Long gaps: use a cleat. For a gap running several feet along a joist, glue and screw a length of 2×4 to the side of the joist, pressed tight up against the subfloor, instead of using a row of shims.
Loose flooring: pull it down with screws. From below, drive a short wood screw up through the subfloor into the bottom of the hardwood, with a washer under the head if needed. Measure first. The screw has to be long enough to bite into the hardwood but at least 1/4 inch shorter than the subfloor plus flooring thickness, or it will poke through your floor. For 3/4 inch hardwood over 3/4 inch subfloor, a 1-1/4 inch screw is typical.
Test as you go. Have your helper step on each spot again after every fix.

Step 3: Fix it from above (finished ceilings below)

If the room below has a finished ceiling, or the floor is on a second story, you’ll work from the top. The trick is to get a screw through the hardwood, the subfloor and into a joist without leaving a visible head.

Locate the joist. Find the joist nearest the squeak with a stud finder, or by measuring from a known joist. Drill a tiny test hole in a gap between boards if you need to confirm.
Use a trim-head squeak kit. These kits include a depth-control fixture and special screws scored partway up the shank. Drive the screw through the fixture into the joist; the fixture stops it at the right depth, and then you snap off the top. The broken end sits just below the surface of the wood.
Fill the hole. Dab a little color-matched wood putty into the hole and wipe the excess. On a matte or oiled floor the repair is nearly invisible.
Carpeted floors: Many kits include a tool that lets you drive the screw right through the carpet without damaging it. Same idea: find the joist, drive, snap.

If you can’t hit a joist, a pair of finish nails driven at opposing angles into the subfloor (pre-drill in hardwood so it won’t split) will often pin a loose board.

Step 4: Quiet board-on-board squeaks

Some noises come from the edges of two boards rubbing together, not from a loose floor. Work powdered graphite or talcum powder into the seams over the squeaky area, then lay a towel down and walk on it to push the powder in. Sweep up the rest. It’s a quick fix that often lasts a season or more. Keep graphite off light-colored rugs; it smudges.

Mistakes to avoid

Screws that are too long. Measure twice. A screw tip popping up through a finished floor is a much bigger problem than a squeak.
Driving shims too hard. Snug is enough. Forcing them lifts the floor.
Nailing straight down into hardwood without pre-drilling. Oak and maple split easily.
Ignoring humidity. Keeping indoor humidity around 35–50 percent year-round with a humidifier in winter and air conditioning or a dehumidifier in summer reduces seasonal squeaks and gaps.
Disturbing old finishes carelessly. If your home was built before 1978, sanding painted or finished surfaces can release lead dust. Keep repairs small and clean up with a HEPA vacuum and damp wipes.

When to call a pro

A squeak is usually just noise, but some floors are telling you something bigger. Call a contractor if you see:

A floor that sags, feels bouncy or slopes noticeably
Cracked, notched or sistered joists, or joists that have been cut for plumbing or ductwork
Squeaks spread over an entire room that keep coming back after repairs
Boards that are cupping, crowning or have soft spots, which points to moisture
Water stains on the subfloor from a bathroom or kitchen above

Those can mean the subfloor or framing needs work, and the floor may need to come up. Our flooring team can check the subfloor, fix what’s underneath and install new hardwood or LVP that stays flat and quiet. If the problem is in the framing itself, it often goes along with a larger interior remodel.

Rather have it done for you? RossBuilt Construction serves the St. Louis metro. Request a free estimate or call 636-380-2574.