Tried a different underlayment on a concrete basement job and got a weird result

Honestly, I was doing a glue down LVP install in an old basement in Cincinnati last month. The slab felt dry, but you know how that goes. Instead of my usual 6 mil poly, the homeowner had already bought this fancy 3-in-1 underlayment with a built in vapor barrier and sound rating. I figured, why not, it's their material. Ngl, after about three days, I got a call. The planks were making this loud popping sound when you walked on them, like a hundred tiny snaps. It wasn't buckling, just noise. I think the combo of the slab's minor moisture and that specific underlayment's foam layer created some kind of suction or movement. I learned that even if a product says it's for concrete, the exact conditions matter a ton. Has anyone else had a basement floor go noisy from the underlayment choice?

3 comments

3 Comments

the_lucas13m ago

Wait, the homeowner bought the underlayment? Honestly, that's the first red flag right there. Tbh, letting a client supply material for a glue down job is asking for trouble, especially in a basement. You can't control what they pick, and then you're stuck with the call when it fails. That popping noise is the exact reason I'd never use a foam layer directly on a slab, it just traps everything.

victor6512h ago

You said the slab felt dry, but that's the tricky part. Concrete always has some moisture moving through it, it's never truly dry. That fancy underlayment probably trapped it against the planks. The noise was likely the adhesive letting go in tiny spots from the moisture. Next time, stick with the poly and a separate pad if they want sound control.

michael_williams1h ago

Actually, that underlayment might have a vapor barrier built in that failed. Seen specs where they claim 100% coverage but the seams are just taped, not sealed. Moisture finds the weakest spot every time.