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Air sealing rim joists

Nicole_OregonCoast | Posted in Energy Efficiency and Durability on

We are in the process of creating a conditioned crawlspace. Our exterior zip panel wall sheathing is sealed to our foundation stem wall. Do we still need to airseal the rim joists? We are trying to decide whether to spray foam the rim joists, or use batts.

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  1. Expert Member
    ARMANDO COBO | | #1

    If there is continuous insulation outside the sheathing, is best to use open cell spray foam between joists at the rim. As good a sealant job you did between the sheathing and the foundation, it may fail at some point. If you don't have continuous insulation outside the sheathing, you can use closed or open cell foam. I have no reason to ever use batts, other than sound mitigation in some applications.

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