Can we talk about subfloor squeaks that show up after the carpet goes down?

Last month I redid my sister's bedroom in Columbus, replaced the plywood and glued every board down, still got a squeak by the doorframe three days later. I thought I had accounted for all the movement, but the joist had a slight crown that I missed until I was on my knees tracing the noise with a flashlight. Has anyone else had luck fixing post-carpet squeaks with shims from the top, or do you always end up cutting a patch out of the new flooring?

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lucas4981mo ago

Shims from the top can work if the squeak is from the subfloor lifting off the joist, but that crown you found means the shim might just push the board up against the carpet with no real fix. The real issue is the joist itself, you probably need to plane it down or sister a straight piece next to it so the subfloor actually bears on something flat. Cutting a patch is the honest answer though, because chasing a squeak through carpet and padding from above is a fool's errand, you'll never get the shim seated right without seeing the gap. Next time, check every joist for crown before laying a single sheet, run a straightedge across them and mark high spots with chalk.