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Sealing up gaps in OSB exterior sheathing before insulating stud cavities?

CTSNicholas | Posted in Green Building Techniques on

My OSB sheathing on the exterior side of my exterior walls has many a gaps varrying from 1/8″ to 1/4″ as the proper installation instructions require the sheathing to be gapped with a nail to allow expansion due to humidity changes.

So…I’m looking at these gaps (some rather large) and getting ready to stuff mineral wool in. Should I take any time now to a.) caulk or b.) spray foam these gaps? I have a decent house wrap over the sheathing of course but that doesn’t stop everything.


  1. GBA Editor
    Martin Holladay | | #1

    Most energy-conscious builders tape the seams of OSB or plywood sheathing. The idea is to use the sheathing layer as your exterior air barrier. For more information on this issue, see these three articles:

    Airtight Wall and Roof Sheathing

    Questions and Answers About Air Barriers

    Return to the Backyard Tape Test

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