Spray foam walls in vented crawlspace
joenorm
| Posted in General Questions on
I was doing some work in a very high-end, recently constructed home and I noticed they had fully spray foamed the interior crawlspace walls.
At first I thought it was a rare unvented crawlspace for my area(4C PNW) but then I noticed all the vents, they were hard to see with the mounds of foam in the way.
Also, they insulated the underside of the floor with fiberglass batts.
Having read a lot here about crawls, I thought this to be an odd combination.
One thing I noted was the crawl was bone dry and had a conditioned feel to it. I wonder what the contractors were trying to accomplish here? It must have been thousands of $ in spray foam.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Joe,
Was there a rat slab as well? Just guessing but this sounds like the builder doing whatever the owner requested.
As you describe it, this crawlspace doesn't make sense to me Joe. Maybe someone else has an idea why it would be built like this and we'll all learn something today. We'll see...
Soundproofing the mechanicals?
Not a helpful comment here but very similar situation. I was working in an attic recently that had what seemed to be 4-5 inches of closed cell foam in the rafter bays but 3 attic fan penetrations that were unsealed and appeared to be functioning and i was able to see sunlight and the attic seemed to be only slightly different than the outside temperature. He said the contractor told him it wasn't necessary to seal those up. What Am i missing here?
There are all sorts of misconceptions and bad ideas brought to life in the homes all around us. Then there are the choices accumulated over time. I could see it going something like this..
Fiberglass batts installed in the floor "cause that's the way we've always done it."
Floor seems a little cold.
Homeowner complains and builder foams the crawl.
Inspector says you have to keep the vents "cause that's the way we've always done it."
So you wind up very close to a system that could work, but instead wind up with two systems that don't.