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 recommendations

greenaline | Posted in Energy Efficiency and Durability on

We are renovating an older house (1928) and have stripped it down to the studs and wooden walls, which have plenty of cracks between the boards. We are also replacing the siding. We are in zone 3A. What type of insulation would you recommend? (Sorry, I originally said zone 8A, which is the gardening zone!)

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. Tyler Keniston | | #1

    8a? Are you sure you're not using the USDA gardening zones? You want the Department of Energy Climate zones.

    You might try searching 'deep energy retrofit' here to get started with some ideas.

    You're going to want to make the wall air-tight(er). I assume it's something like 3.5-4" thick currently? You'll likely want to add some thickness in some way—either interior or exterior. This usually involves a rigid or semi rigid panel of insulation. If you're replacing siding, there's a pretty strong argument for putting this on the exterior.

  2. Expert Member
    Rick Evans | | #2

    Zone 8a?

    Wow... Whatever you use, use lots of it!

    I'd look up the Arctic Wall from Thorsten Clupp in Fairbanks, Alaska. That or just go full igloo :-)

  3. Expert Member
    Rick Evans | | #3

    Geenaline, just re-read your edited question. That makes more sense! :-)

    I was trying to imagine who would have been building houses in the Arctic Circle in 1928??

    There are lots of options here but if it were me, I'd cover the board sheathing with a peel and stick membrane (like Henry Blueskin) and then add 1" - 2"of Foil Faced Polyiso. Add furring strips and then your siding. I would dense pack the stud cavities with cellulose.

    This will keep your walls air and weather tight, insulated, and protected from inward vapor drive. (Vapor retarder on the exterior in the south!) The rainscreen gap will make the whole assembly more forgiving.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |