Is closed‑cell foam under subfloors worth it for footfall noise reduction?

Trade Talk
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Is closed‑cell foam under subfloors worth it for footfall noise reduction?

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If you want warmer, firmer floors, closed-cell foam is a good choice. If you want to quiet down footsteps, go with acoustic materials – they’re better at keeping things quiet.

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Closed cell foam under subfloors is not very effective for footfall noise reduction. While it provides excellent insulation and air sealing, it’s too rigid to absorb impact sound well. For reducing footfall noise, softer materials like acoustic underlayment, rubber, or fiberglass batts between floor joists are more effective. Closed cell foam is better used for thermal performance and moisture control, not soundproofing.

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Closed-cell foam under a subfloor is great for insulation, but not for footstep noise.

It’s too rigid, so it passes vibrations instead of absorbing them.

For quieter floors, use acoustic underlayment (rubber, cork), mineral wool between joists, or a floating floor system.

You can always pair thermal insulation with one of these for the best of both worlds.