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

Flat roof, non vented — What about furred space for slope?

Keith Messick| Posted inBuilding Code Questionson

I am building a non-vented flat roof in CEC zone 8/ DOE zone 3-92705. Roof structure will be structural sheathing on 12″ I-joist. For slope, sheathing over 2x furring strips (1/4″/12″). I have read all the posts about various ways to insulate.

If the actual roof is something like a 2-ply SBS membrane and the insulation under the structural sheathing is a closed-cell flash-and-batt system, should I worry about the spaces between the 2x furring strips used over the structural sheathing for slope?

This space will not be vented. Will this space trap moisture?

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

    Keith,
    Q. "If the actual roof is something like a 2-ply SBS membrane and the insulation under the structural sheathing is a closed-cell flash-and-batt system, should I worry about the spaces between the 2x furring strips used over the structural sheathing for slope?"

    A. No.

    Q. "This space will not be vented. Will this space trap moisture?"

    A. No. But make sure that the materials are all dry on the day when your spray foam contractor shows up.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |