I’ll start by explaining how squeaking floorboards starts.
Quite often, over a period of time, the flexing of the floor or expansion and contraction of the timber may loosen floorboard nails.
It is the resulting movement of the wood against the nails or against the neighbouring boards that produces the typical irritating squeak.
The simplest cure is to drive the floorboard nails in deeper with a nail punch, which allows the tapered edges of the nails to grip the wood more securely.
We have found that sometimes, however, this may not be a lasting solution.
If the problem persists, use either a larger or ring-shank nails. The latter are designed to give a better grip however they need to have clearance holes drilled through the boards. Use a normal electric or hand-drill to do this. The clearance holes must be slightly larger than the diameter of the nail to ensure that they grip the bottom of the board securely.
After you have put the nails in make sure that you fill any redundant holes with a matching wood filler – the closer the colour match the better. You can almost completely disguise the nail heads this way.
If the boards can’t be renailed satisfactorily (for example, because of twisting or bowing), use countersunk stainless-steel woodscrews.
Remember that you need to bury the heads of the screws deep enough to cover them with filler or with matching wooden plugs. I also recommend that you dampen the wood thoroughly before fixing – this makes the wood ‘give’ and allows the screw heads to essentially be countersunk as the boards are screwed down.