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Sill plate seal missing

bonai | Posted in General Questions on

Hi there,

Garage is on concrete foundation but framer didn’t use any sill plate seal. I’m worried the moisture from the concrete will damage the frame in the long run. There are gaps along the sill plate and the concrete, is there any product that I can use, maybe spray in to make the sill plates more water resistant?

Edit: Sill plates are pressure treated


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  1. Expert Member
    BILL WICHERS | | #1

    With pressure treated sill plates, you're in pretty good shape. If they were NOT pressure treated I would have recommended Copper Coat (a paint/spray on coating), but that's not needed with pressure treated wood since you already have the preservative in the wood. You could treat any cut ends of the sill plate with copper coat though.

    In your case, sill seal would be acting more as a capillary break than as an air seal. My guess is the framer was thinking a garage doesn't need air sealing the way a house does, so skipped the use of the sill seal gasket material.


  2. bonai | | #2

    Thanks for the explanation!

    Another question. I am planning to air seal the exterior sheathing (OSB/ICF) with Siga Wigluv tape.
    Is it a good idea to also air seal the interior side of the sill plate with either tape or some acoustic sealant? or would that trap the moisture too much?

    1. kenmarcou | | #3

      would also be curious about this and the efficacy/risks of double air (not vapor) barriers in general.

      1. Expert Member
        BILL WICHERS | | #4

        There is no risk with a double AIR barrier, there is a risk with a double VAPOR barrier. Vapor barriers are always air barriers, but air barriers are not always vapor barriers. Drywall, for example, is an excellent air barrier, but is very vapor open. Polyethylene is both an air AND a vapor barrier. What you use where depends on what you're doing.

        It is no problem to have an air barrier on both sides of a wall as long as at least one of those air barriers is at least somewhat vapor open.


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