Batt Insulation for Noise Attenuation
BruceBruce| Posted inGeneral Questionson
We are currently building a metal framed, metal exterior home. We are going with 2″ close cell throughout with a 3″ open cell over the top on the roof. Because this will essentially create a cave for sound to echo in I will be adding some batt insulation to large wall sections and wanted to also add batt insulation in the ceiling areas. A concern for moisture build up in the attic space was raised due the spray foam and the batt insulation, is this a valid concern? The reason for the batt insulation in the ceiling is the air handler is above one of our bedrooms and we don’t want to hear the humming and drumming of it.
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I'm giving your question a bump. For ideas, read through this thread:Real World Soundproofing Experiences.
You're not going to hit code minimums with that level of insulation in the roof. I very much ask that you reconsider your use of spray foam here too. With metal framing, you're going to have a lot more thermal bridging than a wood framed structure would have, which makes spray foam even less desireable here. You would be FAR better off using exterior rigid foam over the exterior of the studs, then batts between the studs. You'll have a FAR better performing wall that probably won't cost any different and might even be a bit cheaper. Since you want to install batts for sound reduction anyway, you can put ALL the money saved on not using spray foam towards exterior rigid foam. I'd use polyiso over the exterior.
Mineral wool is best for sound insulation due to the slightly higher density compared to fiberglass. I think you'll also find it easier to install between metal studs since it doesn't need to be tacked into place -- it will support itself.
Bill