Squeaks in the wood or plywood subfloor under carpeting are usually caused by loose nails in the subfloor or joints in the subfloor rubbing together.
How to stop squeaks under a carpeted floor:
Remove Carpet: Carefully pull back the carpeting from the tack strip on a wall near the squeak.
Find Floor Joists: Determine the location of the floor joists under the wood or plywood subfloor near the squeak by the location of the nailheads in the subfloor or by using a stud finder.
Secure Subfloor: Drive 2” to 3” long screws through the subfloor and into the floor joists as needed to stop any squeaks. If the squeak is in the joint between two pieces of subflooring, apply wood glue to the seam and then drive screws in the subfloor on each side of the joint.
Reinstall Carpet: After making sure there are no more squeaks in the floor, have a flooring professional restretch the carpet.
Watch the video for details.
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