TIL cheap spray foam and high-end spray foam aren't the same when sealing a crawlspace

I picked the cheap big box store stuff over the professional closed-cell kit and now I'm dealing with moisture seeping back through 3 months later, anyone else regret that money-saving call?

2 comments

2 Comments

martinez.karen5d ago

Oh man, that sucks. Just a heads up though, the cheap stuff isn't really meant for sealing up crawlspaces against moisture, it's more for filling gaps and cracks around the house. The closed-cell kits are way denser and actually block water vapor.

drew_chen5d ago

Yeah the cheap stuff from the hardware store is basically just expanding gap filler, not a moisture barrier. I made that same mistake on a shed foundation once and had to scrape it all off and start over. For a crawlspace you really need the closed cell stuff that's at least 2lb density, otherwise you're just trapping moisture behind a layer of foam that breathes. If you're already three months in you might want to look into cutting out the bad spots and patching with the proper kit, it's a pain but cheaper than dealing with rot later.