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

Assembly for bonus room floor

rblackdeegan | Posted in General Questions on

Hi All,

I’m looking for advice on insulating the floor of a bonus room in Vermont that is currently not insulated. The bottom of the joists are around 6 feet off the ground, so the common advice from top to bottom would normally be: flooring, subfloor, joists and bat insulation, foam board, and then plywood. I’m looking to minimize costs (and foam) and I’m wondering if strips of foam and strapping furring out the bottom of the floor joists would work instead of a continuous layer of foam – in theory this should create nearly the same thermal break?



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. Expert Member


    Yes, that would work fine.

  2. GBA Editor
    Brian Pontolilo | | #2

    Hi Ryan.

    I agree with Malcolm that your proposed assembly will work fine from a thermal perspective. Just keep in mind that air sealing is just as important as insulating for both comfort and for a durable assembly. You may find this article helpful: Insulating a Wood-Framed Floor Assembly

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |