I’m finally finishing my cottage basement, and will be closing in the ceiling shortly. (It is a four-season cottage near Parry Sound.) I have heard that insulating the basement ceiling is a good idea not only to reduce sound transfer but also to help maintain a more consistent temperature in the basement. Is that true?—Bob Wiley, Lake Manitouwabing, Ont.
You are correct! At least, you’re half correct: insulating the ceiling will definitely help curb sound transmission.
Almost any insulation—excluding foam—will help “from an acoustic standpoint,” says Tyler Simpson, the principal with TWS Building Science in Hamilton, Ont. (You can also buy specialized acoustic insulation designed for soundproofing.)
The problem with insulating the basement ceiling is that it may “thermally” separate the basement from the rest of the cottage. “My line is always, ‘You need to explicitly define what’s inside the building envelope and what’s not,’ ” says Russell Richman, a professor of building science in the architectural science department at Toronto Metropolitan University. “Is the basement inside or outside?”
We suspect that you wouldn’t be finishing the basement if you didn’t want it to be inside the cottage. And insulating the ceiling would significantly reduce the transfer of heat from the cottage into the basement, says Russell. So, you could end up making that space colder instead of more comfortable.
If you’ve insulated the basement walls and put down subflooring, and you’re finding that the basement is currently too cold for your liking, “the next step would be to reduce any air leakage from the exterior and consider adding another heat source to the space,” says Simpson. “If it’s a ducted system, you might just need more registers.”
But what about the soundproofing? One option to dampen noise while letting heat move freely is to create “resilient channels” when you close in the ceiling. This technique involves using thin pieces of metal to suspend gypsum board to the joists. The drywall and wood framing won’t touch. This creates “a disconnect of a rigid pathway,” says Simpson. “Sound travels via vibrations through rigid pathways. The resilient channel breaks this pathway.” Done correctly, it can be a cost-effective way to soundproof. And it’ll probably work better than just insisting everyone on the main floor take off their shoes and walk very softly. Shh.
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This article was originally published in the Winter 2022 issue of Cottage Life.