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

Insulating an unvented roof CZ6

dennis_vab | Posted in General Questions on

I have a few bump outs in my home under construction, where I will not be able to have a vented roof.

I would like to avoid using spray foam. What other options do I have in NY state,  climate zone 6? I have 2×8 rafters 24 o.c. I will most likely start by air sealing this area. 

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.

Related Questions

Replies

  1. Expert Member
    Michael Maines | | #1

    Your only code-compliant, safe option is to insulate the exterior side of the roof, with either rigid foam or a lower-carbon option, with up to 50% (but not more) of the total R-value in the rafters.

    Actually another option would be to over-vent your roof; run 2x furring above the roof sheathing and another layer of sheathing, or cross-strap for a metal roof.

    1. dennis_vab | | #2

      Part of the roof already has shingles on it. Does that leave spray foam as the most viable option?

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |

  • |

  • |

  • |
View More Ask a Question

Featured Blogs

Musings of an Energy Nerd View More

Contemplating residential energy use

Product Guide View More

Double Check

Do you really want to delete the list, ?

Note

This won't delete the articles you've saved, just the list.

This feature has been temporarily disabled during the beta site preview.

You must be a magazine subscriber to access this feature.

Subscribe today and save up to 44%

Subscribe

Or learn more

Already a subscriber?