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

Insulation and Vapor Barrier for Roof and Rim Joist

dsteltz | Posted in Green Products and Materials on

Hi all,
Here is my situation. I really need to insulate my house. It is a 1929 tudor with half the attic open (other half two finished bedrooms though a lot of it, we think, accessible via the ridge). A couple of walls (kitchen, bathrooms) have spray foams insulation from a renovation 5 years ago, though most walls do not.

I’ve been obtaining dense pack cellulose quotes and various open/closed spray foam quotes. I find myself lately shying away from foam quotes (though not enitrely sure why).

Other details:
1. Unvented attic
2. No vented soffits
3. My roof is shingles (normal…) over plywood. Frankly I don’t know if there is a layer in between the shingles and the plywood. If this is necessary I will find the answer.

Pointed questions:
1. Do I need a vapor barrier or retarder in my climate (Westchester County, NY). I think we are a 4.
2. I have been mentally toying with foam board with closed cell from a can to air seal at sides for those areas that are open and accesible. Then rockwool over it. Please provide your critique and what you think is best from a cost/value perspective. Also what I can do with a small crew from a DIY perspective.
3, For my rim joist, most of which is very accessible, what do you think is better. XPS with closed cell foam to air seal or rockwool with closed cell foam to air seal?

Thank you for all your help in advance! Feel free to send a link or article if most of this is covered.

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.


Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |