Curt Janzen breaks down three problems with spray foam in vaulted ceilings: unvented assemblies need 2-lb closed-cell foam to prevent moisture and thermal bridging, installers often have to remove drywall to reach the roof sheathing, and any gaps in application will tank the system's performance.
Hey Curt, I got some questions today about spray foam in vaulted ceilings. I was just wondering if you can tell me some of the common complications with spray foam in a vaulted ceiling.
All right, vaulted ceilings and spray foam. There are a few things to watch out for. First, ventilation is a big one. If you're going unvented, you've got to use 2-pound closed cell foam to create an airtight thermal envelope. Anything else and you're asking for moisture issues or thermal bridging. Second, access can be tricky. If it's an existing home, you're likely tearing down drywall wall to get at the underside of the roof sheathing. And third, you've got to be precise with the application. No gaps, no shortcuts, or you'll compromise the whole system.
