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

Rim joist insulation

kdodson6 | Posted in GBA Pro Help on

Hot/humid climate 3a (South Carolina)..crawlspace w/moisture barrier, unfinished 2nd floor (plan to finish 1450sqft), & it’s a modular home.

I’m sorry to beat a dead horse.  I would like to know if spray foaming the perimeter of a rim/band joist would be as advantageous from an air sealing perspective as insulating the entire area(s) of each rim joist w/spray/rigid foam.

Why not just do the perimeter(s)?  How does air pass through wood if it has no cracks to pass through?

Thank you for the articles and comments—I am learning a lot here.

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. GBA Editor
    Brian Pontolilo | | #1

    Hi kdodson6.

    I am not sure I understand your question, but have you read this: Insulating Rim Joists?

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |