GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Can I use spray foam on a ceiling that also serves as the roof under a deck?

TDHunt | Posted in General Questions on

I am replacing an exterior deck over a sunroom.due to leaks in some old EPDM material under a deck.

The sunroom ceiling joists support the flat roof above it, and the deck is suspended above the flat, EPDM covered roof. Can I spray the sunroom ceiling jousts with foam before installing the sunroom headboard ceiling? Would this produce condensation into the sunroom ceiling? The deck above is outside and exposed to summer heat and winter snow.

Terry

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. GBA Editor
    Martin Holladay | | #1

    Terry,
    Q. "Can I use spray foam on a ceiling that also serves as the roof under a deck?"

    A. Yes. All of the usual rules for spray foam jobs apply, of course: the roof decking must be sound and dry, and the spray foam layer must provide the minimum R-value required by your local building code. (In the U.S., this ranges from R-30 in Florida to R-49 in the northern half of the country.) Once the spray foam has cured, it needs to be protected on the interior with a layer of 1/2-inch drywall.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |