Squeaky stairs cry out for repair

Q: I have two steps on my first-floor stairs that squeak loudly when anyone walks on them. How do I stop this? — Jay L., Burlington, Vt.

A: Squeaks in stairs (or any wooden surface) are caused by two or more boards rubbing together. In new construction one rarely hears squeaks, as boards placed closely together don’t “give.”

But as the wood ages, swells and shrinks repeatedly due to temperature changes, and reacts to the stresses of constant use, the spacing between boards can change slightly; a little “give” works in, and you have a squeak. The solution is to tighten up the space between the offending boards as much as possible.

•In a stair, squeaks can occur between the tread and the risers, or between the tread and the stringers (the angle-cut boards on which treads and risers rest). If you can get underneath the staircase to work, you have the best chance of eliminating the squeaks.

•Have someone walk up and down the stairs while you’re underneath, so you can pinpoint the exact stairs that are squeaking and, hopefully, the exact spots where the squeaks are occurring.

•Next, shim the squeaky treads. A shim is a thin wedge of wood that can be placed between boards to eliminate squeaks. Coat several shims with wood glue (as you apply them) and, using a thick piece of wood as a buffer, tap the shims between the tread and the lower riser, the tread and the upper riser, and between the tread and the stringers.

Have your helper test the tread again.

•Another method, if the shims just splinter and won’t go in, is to place a wood block (ideally a 1-by-2-inch piece about two-thirds as long as the tread) between the tread and the forward (lower) riser. Glue the block into place, with the 2-inch side against the riser and the 1-inch side against the tread. Then nail it firmly down.

If you can’t get under the stairs to work, try driving finishing nails at an angle through the squeaky tread and into the supporting riser; and drive finishing nails through the tread into the stringers on either side.

This can tighten the gaps between the boards and lessen or eliminate the squeaks. To hide the nail heads, countersink them (drive them below the board surface using a nail set or another nail) and cover with wood filler.