GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter 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

Vented vs. non-vented roof

cWLhdRGx3P | Posted in GBA Pro Help on

I live in zone 2A north of Lake pontchartrain. I am building a gable house with living area upstairs. The roof is galvalume with a metal ridgevent. The ceiling in the upstairs living area is cathedral then it goes flat. Should I go to the trouble of providing air space under the roof sheathing or close off the ridge vent with closed cell foam and foam the underside of the sheathing?

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.


  1. GBA Editor
    Martin Holladay | | #1

    Whether or not to include ventilation under the roof sheathing depends on many factors, including the type of insulation you intend to use to insulate the sloped sections of your ceiling. If you choose to use closed-cell spray foam, no ventilation is necessary -- although some builders prefer to provide ventilation channels to facilitate future roof sheathing repairs.

  2. cWLhdRGx3P | | #2

    Thanks alot Martin, I do intend to use closed-cell foam.Should i insulate the roof to R-38? Do you reccomend removing the ridge vents or just let foam seal them?Zone 2A

  3. wjrobinson | | #3

    Dwight, if your spray foam company has done hundreds of homes like yours with success, then they should guide your install best not someone hear posting from the northeast.

    The key to your needs is hiring the best contractor with the most solid track record and make sure you get his best crew and they work during good weather.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |