How to Fix a Squeaking Floor With Shims

Assign a helper to walk on the flooring while you inspect the subfloor for movement from the crawl space or basement below. If you are working alone, measure the squeaking spot on the floor from a wall so you can register it when you step down. For carpeted floors, drive a finishing nail through the floor to mark the spot where it squeaks.

Step into the basement or crawl space and locate the gaps between the floor joist and the subfloor at the point where the floor squeaks.

Hold a wooden shingle or shim -- a piece of scrap wood -- in each hand and drive them lightly into the gap between the joist and subfloor, ensuring they form a tight fit. Avoid pushing the shims too hard, since you could cause the gap to widen.

Draw a pencil line on each shim to mark the depth line, or the amount inserted into the gap. Avoid pushing the shim into the gap when forming the line.

Pull out the shims carefully and set them aside. Score the shims along the pencil using the tip of a utility knife. Snap the shims to remove excess.

Spread construction adhesive over both sides of the shim before pushing these back into the gap, one on each side of the floor joist. Wipe away construction adhesive that seeps out through the joint with a moist rag.

Drive a drywall screw at an angle into the floor joist so it penetrates the wooden shingle or shim and through the subfloor. The screw provides additional support to the shim. Repeat this process to add shims into the remaining gaps between the subfloor and the floor joist. Allow the adhesive to cure for the time specified on the label directions.