The short version
- Every squeak is movement between two parts. The fix is to fasten them, and anything that only lubricates them is temporary.
- Squeaks that come and go with the seasons are usually boards shrinking in dry winter air. Squeaks in one spot all year are usually a loose fastener or subfloor.
- The best repairs are made from below, where the joists and the underside of the floor can be reached. Repairs from above work and leave small filled holes.
- Refinishing does not stop a squeak. Sanding changes the surface and leaves the movement underneath exactly as it was.
- In our data at /data/, 138 of 635 places have 35 percent or more of their housing built before 1940, where strip flooring is often nailed straight to the joists.
What is actually making the noise
A squeak is friction: wood rubbing on wood, or wood sliding up and down the shank of a nail that no longer holds it tight.
There are three common sources. The first is board against board, where two strips that have shrunk slightly rub at the tongue and groove as weight comes onto them. The second is board against nail, where a fastener has loosened in its hole and the board rides up and down on it. The third is subfloor against joist, where the plywood or plank layer under the finished floor has lifted from the framing.
They sound different. Board on board is a dry creak across a wide area. Board on nail is a sharper chirp in one spot. Subfloor on joist is a deeper sound, and you can often feel the floor give slightly underfoot.
Telling them apart is most of the work. The repair for each is small once the cause is known, and a repair aimed at the wrong cause does nothing.
Seasonal squeaks and permanent ones
A floor that squeaks in winter and goes quiet in summer is reacting to dry air, and a floor that squeaks in the same place all year has something loose.
Wood gives up moisture in dry heated air and shrinks across its width. Boards that were tight in August have a little clearance in February, and they move against each other when walked on. When humidity returns, they swell and the noise stops.
That kind of squeak is the floor working normally, and the first response is to raise the indoor humidity in winter. A humidifier often quiets a whole room. It also narrows the seasonal gaps between boards.
A squeak that stays in one spot through every season is mechanical. A nail has let go, a board has split along its tongue, or the subfloor has come away from a joist. Humidity will not fix that, and a fastener will.
| What you notice | Likely cause | What fixes it |
|---|---|---|
| Creaking over a wide area, worse in winter | Boards have shrunk and rub at the edges | Raise indoor humidity. Fasten only where it persists. |
| A sharp chirp in one spot, all year | A nail has loosened and the board rides on it | Refasten the board into the joist or subfloor. |
| A deeper sound, and the floor gives a little | Subfloor has lifted from the joist | Fasten or shim from below, or screw down from above. |
| Noise along a line across the room | Movement over a joist or a subfloor seam | Fasten along that line, ideally from underneath. |
| Squeak with a visible bounce or sag | Framing is undersized, cut or damaged | A structural repair first. The floor is not the problem. |
The repairs that last are made from below
Where the underside of the floor is reachable from a basement or crawlspace, squeaks are fixed without touching the finished surface, by closing the gap between the joist and the floor above it.
With someone walking above, the moving spot is easy to find from below. If the subfloor has lifted from a joist, a thin wood shim with glue is tapped into the gap until it is snug, without forcing the floor upward. Where a longer section is loose, a block is fastened to the side of the joist, tight against the subfloor.
Loose finished boards can also be pulled down from below, with short screws driven up through the subfloor into the board. The screw has to be shorter than the combined thickness of subfloor and flooring, or it comes through the face of the floor. That is measured, not estimated.
This is the best repair available, because nothing shows. It is only possible over an unfinished basement or an accessible crawlspace, which is one more reason we ask what is under the room.
If there is an unfinished ceiling below the squeak, tell the contractor before the estimate. It changes which repair is possible.
When the fix has to come from above
Over a finished ceiling the floor is fastened from the top, with slim fasteners driven into the joist, set below the surface and filled to match.
The first step is finding the joists, since a fastener that only reaches the subfloor may quiet the squeak without holding. Joists usually run perpendicular to the floorboards, at regular spacing, and the nails already in the floor show where they are.
The fasteners used are small headed, driven at an angle through the board and into the joist, and sunk just under the surface. The hole is filled with a filler matched to the wood. On a floor about to be refinished, this is the ideal moment, because the sanding and finish make the filled spots nearly invisible.
On a floor that is staying as it is, the filled holes will be visible if you look for them. A few of them in a doorway are a fair exchange for a floor that no longer squeaks.
Why refinishing does not stop a squeak
Sanding and finishing change the top fraction of the board and nothing about how the board is fastened, so a floor that squeaked before refinishing squeaks after it.
This is one of the most common misunderstandings we hear at estimates. A new finish makes a floor look new, and people expect it to sound new as well. The movement that causes the noise is under the surface, between the board and what it sits on.
There is a practical consequence. Squeaks and loose boards are dealt with before the sander arrives, since a sander riding over a board that moves cuts it unevenly, and the finish later cracks along that seam.
So if you are planning to refinish, point out every squeak and every board that shifts at the estimate. Fastening them is quick work at that stage, and the filled holes disappear in the sanding.
Why old floors squeak, and why it is usually not serious
In the oldest housing the strip flooring is nailed directly to the joists with no subfloor, so there is one joint that can move, and it is easy to reach.
The dataset we publish at /data/ covers 635 towns and Philadelphia neighborhoods. In 138 of them, 35 percent or more of the housing was built before 1940, and in Philadelphia 40.0 percent of the housing predates that year. Floors of that age are commonly narrow strip oak or pine laid straight across the joists.
A century of seasons has worked those nails loose a little at a time. Boards have been sanded thinner, which leaves less wood around each fastener. The result is a floor that talks, and in most cases it is a floor with nothing wrong beyond that.
Because there is no subfloor, the repair is direct: the board is refastened into the joist. From a basement the joint is visible. The caution is thickness. A board that has been sanded several times has little wood above the tongue, and fasteners are placed with that in mind.
The quick fixes, and what they are worth
Powder worked into the seams quiets board on board friction for a while, and it does nothing for a loose fastener or a lifted subfloor.
Talcum powder or powdered graphite brushed into the joint between two boards reduces friction, and the squeak fades. It returns when the powder works its way out or the season changes. As a test it is useful: if powder quiets it, the cause is board on board.
Oils and spray lubricants should stay off a wood floor. They stain the wood, and they contaminate the finish so a later coat will not bond in that area.
Kits that drive a breakaway screw through carpet or wood into the joist can work when the joist is found correctly. On a visible hardwood floor the snapped screw leaves a hole that still needs filling, so the kit is a fastening method and not a way around the repair.
When a squeak means something else
A squeak that comes with a bounce, a slope or a new crack in the plaster below is a sign of a framing problem, and the floor should be looked at from underneath.
Most squeaks are an annoyance. A few are a symptom. Joists that were notched for plumbing or wiring, a beam that has settled, or framing damaged by an old leak all show up first as movement and noise in the floor above.
The signs to take seriously are a floor that visibly deflects when someone walks across it, a section that has dropped relative to the rest, doors on that floor that have started to bind, and cracks appearing in the ceiling underneath.
That is not flooring work. It needs someone who can assess the structure, and we say so when we see it. Fastening boards over a moving frame buys a few quiet months and leaves the real problem in place.
