Quiet a squeaking floorboard

Locate it precisely

Get somebody to walk slowly over the area while you kneel beside it with a hand flat on the boards. The squeak will feel like a small movement under the palm at one particular spot, and the spot is usually not where the noise appears to come from.

Mark the exact point with chalk or a piece of low-tack tape. Squeaks are remarkably hard to find twice.

Rock the board by hand. If it moves up and down against something fixed, you are looking at a board lifting off a joist. If it does not move but the noise appears when weight shifts sideways, the board is likely rubbing its neighbour along the joint, and screwing it down will not help.

Find the joists

Existing nail or screw heads run in lines across the floor, and those lines are the joists. Follow them from a clear area into the area you are working on rather than guessing.

Joists in most floors run at a consistent spacing, so two known lines give you the rest. Mark them lightly along the board you intend to fix.

If the floor is sheet material rather than boards, the fixing pattern is still visible once you look, and the same rule applies: fix into the joist, not between them.

Check what is underneath

Between the joists is where services live. Central heating pipes, water pipes and cables all run in that space, often stapled to the sides of the joists and sometimes threaded through notches in the top.

Sweep the area with a detector before driving anything. Where the floor is over a room you can get into, a torch from below is better evidence than any detector.

If you cannot establish what is under a given spot, move the fixing along the joist line. There is almost always another sound position within a hand's width.

Fix it down

Drive a countersunk screw through the board into the centre of the joist, close to the squeak but not in the same hole as an old nail, which will simply follow the nail's loosened path.

Choose the length deliberately. The screw needs to pass through the board and well into the joist, and it must stop short of anything on the other side. A screw that suddenly goes soft has found something it should not have, and the correct response is to back it out immediately.

Set the head just below the surface. A proud head becomes a new noise the first time something is dragged across it.

Test, then leave it alone

Walk the area again, slowly, in both directions. One screw often kills the squeak completely; occasionally it moves the noise a short distance, which means there is a second loose point along the same board.

Resist filling the floor with screws. Every additional fixing restrains the board a little more, and a board with no freedom to move at all eventually splits along the grain instead of squeaking.

If the noise is a board rubbing its neighbour rather than lifting, the fix is to relieve the friction at the joint rather than to fix the board harder. That is a different job, and forcing the wrong fix first makes the right one harder.