NOTE: I accidentally posted this twice, so please visit this link instead: https://forum.mrmoneymustache.com/do-it-yourself-forum!/spray-foam-insulation-under-outdoor-storage-closet/My townhouse has a very large outdoor storage closet that currently serves as a bicycle garage and tool shed. It's connected to our back deck. See pictures...
Here:
https://imgur.com/a/Ws3pYHlAnd here:
https://imgur.com/a/LQqvPwzThe door that opens to the deck is the entrance. You can see that it's basically on a post foundation. It's a fully enclosed area at the same level as my deck. There's no crawlspace, just an open elevated area beneath.
I'm considering turning it into a mini music studio, which would involve insulating the walls and ceiling and running a chase from my supply plenum through the house foundation, under the deck area and into the floor of the storage closet-cum-studio.
Given the setup here, it seems like I could spray some closed cell foam to the underside part of the deck that the would-be-studio sits upon. The thing is, the spray foam underneath would be sorta-kinda exposed to the elements. It wouldn't be exposed to rain or anything since it's on the underside of the decking, but it would still be outside, so to speak.
Is there some reason insulating the floor this way would be a bad idea – or is this the way to go? It feels kind of unconventional, but maybe it's fine.
