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

How do I insulate the attic stairs to R-38?

dylhill28 | Posted in Green Building Techniques on

According to 2015 IRC Section N1102.2.4:
“Access doors from conditioned spaces to unconditioned spaces such as attics and crawl spaces shall be weatherstripped and insulated to a level equivalent to the insulation on the surrounding surfaces.”

Our Habitat for Humanity affiliate insulates the attic to R-38 with blow insulation, so we are trying to figure out how to insulate the attic stairs to the same value. Currently, we build a box that we fit the stairs into, place a lid on top, and attach two pieces of 1/2″ XPS to the lid to make an R-5 attic hatch. I have looked into products such as the Battic Door and Energy Guardian’s products, but we would like to use rigid foam if possible, since we receive it as a donated product.

Would it be possible to use four layers of 2″ XPS to achieve R-40? If so, how would you attach that to the lid?

Thanks,
Dylan

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.

Replies

  1. GBA Editor
    Martin Holladay | | #1

    Dylan,
    The best solution is NOT to have pull-down attic stairs. Instead, use a well-insulated hatch.

    In some homes -- those with an attached garage and a common attic over the conditioned house and the unconditioned garage -- you can put the pull-down attic stairs in the garage ceiling, so you don't have to penetrate a conditioned ceiling.

    Well-built code-compliant insulated caps for pull-down attic stairs are rare. The problem is weight. I have seen photos of caps that are connected to a hinge and a rope through a pulley, with the rope attached to a counterweight to make it easier to lift the heavy cap. It's complicated to build.

    For more information, see these two articles:

    Insulating Attic Stairs

    How to Insulate and Air-Seal Pull-Down Attic Stairs

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |