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Seal the bottom of the sheathing to to stem wall?

BrunoF | Posted in General Questions on

I have regular 2 x 6 stud construction with OSB that will be taped as my primary air barrier.  Since the brick is too irregular to tape to, is there any reason that I should not put Sealant in between the bottom of the sheathing and the top of the stem wall to create an air barrier?

pic attached.

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  1. Expert Member
    Michael Maines | | #1

    Sealant would work if it remains adhered and flexible. I recommend Pro Clima Contega HF for that kind of application. Depending on the size of the gap, you might want to use a backer rod--the sealant should be no deeper than it is wide.

  2. Chris_in_NC | | #2

    Could also use something like Prosoco Fast Flash, overlapping onto the OSB and brick by an inch or two each.
    The nice benefit to liquid flashing is if there is a big gap, or little gap, or no gap, and if the OSB is in-plane with the brick, or out-of-plane with the brick, it still works no matter what.
    May still need a backer rod depending on the gap size, for all the normal reasons that sealants would need a backer rod. If it's a small gap, backer is likely not needed (see application instructions).

    I have used this method to tie ZIP sheathing to concrete for WRB and air sealing, and it's easy and effective.

  3. BrunoF | | #3

    Thx. I have a bunch of Dymonic 100 and Contega HF on-site and think that the Dymonic might work best since it can be used as liquid flashing and as a sealant for concrete expansion joints so backer may not be needed.

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