Rigid foam for sound proofing interior walls/floors
user-2423385
| Posted in Energy Efficiency and Durability on
Hi,
i’m working on my interior mooney walls with the first layer of insulation to the outside being 3″ of Cavitymate from dow. After cutting all the pieces for the stud bays I’m going to have a ton of scraps. I was wondering if there was any sound proofing benefit to putting the leftover pieces in the interior wall cavities and or floor joist bays to lessen sound transmission. Sound proofing isn’t a priority but if it will help I might as well do it. Also, would there be any downside to doing this? I’m thinking it may interfere with heat transmission between rooms? House is a two story, balloon frame with full basement.
thanks much
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Replies
I've tried putting insulation scraps in floor joist bays and haven't noticed much of a difference in sound transmission between floors versus where there isn't any, but that's just my anecdotal experience.
"After cutting all the pieces for the stud bays ..."
You cut up Cavitymate for stuffing between studs!?!
Cavitymate is designed for ease of fit between brick-ties on masonry-clad cavity walls. Trimmed to 14.5" and installed between 16" o.c. studs the high R/inch is kind of wasted, given the severe thermal bridging of the studs. In stud bays you'd get better performance at lower cost using R15 rock wool batts and some caulk for air-sealing the framing to the studs since with the full-cavity fill of 3.5" rather than 3" you have ~R4.2 of thermal bridge on the framing rather than ~R3.6.
But to answer your questions, yes installing any type of cavity-fill on partition walls will reduce sound transmission, and yes it will impede heat flow between rooms (it's insulation, after all), potentially increasing room-to-room temperature differences.
I installed the cavity mate because I got two bunks for the price of 15 sheets. I'll be furring the walls out to 6-7" with a Moony wall filled with cellulose so If it's wasted it should still be better than the rosin paper that was my insulation before :) I think I'll install it between bedrooms (the scraps) and put the rest in the front yard with a free sign...thanks for your input..I really appreciate it.!!