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Community and Q&A

Sealing holes in attic — in outside walls insulated with cellulose?

whitenack | Posted in Green Building Techniques on

Hi all,

I am planning my attack on attic floor air sealing. What about the penetrations in the attic from wires running through the outside walls? The outside walls will be filled with damp blown cellulose. Do I still need to seal those or will the cellulose do that for me?


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  1. user-2310254 | | #1

    Clay. You should seal those openings with canned foam or caulk. Martin has an article on air sealing attics that you should read if you haven't already. ( Also check out the links in the sidebar.

  2. whitenack | | #2

    Thanks Steve. I read that article but didn't see anything specific about outside walls.

  3. user-2310254 | | #3

    Clay. This Energy Department guide might be helpful. It addresses exterior walls starting on page 25.

  4. whitenack | | #4

    Thanks Steve, but I think you forgot the link. :)

  5. GBA Editor
    Martin Holladay | | #5

    Cellulose insulation reduces the rate of air leakage, but it's not an air barrier. The best way to proceed is to seal the wiring penetrations through the top plate with caulk or canned spray foam.

  6. whitenack | | #7

    Thanks everyone!

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