Foam OSB seams instead of taping
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My insulation contractor has recommended using closed cell spray foam on the OSB sheathing seams instead of taping the seams. Any thoughts on this approach?
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Replies
Norman,
I can't quite visualize this.
Is he talking about the flash-and-batt approach -- which requires about 2 inches of closed-cell spray foam to cover the interior side of the sheathing?
Or is he only planning to address the OSB seams?
I can understand sealing the horizontal seams from the interior (sort of). But the vertical seams land in the middle of a stud, so you can't address them from the interior. Does the contractor intend to run a vertical stripe of closed-cell spray foam at the intersection between the stud and the interior face of the sheathing?
Taping is simpler, in my opinion, unless this is a flash-and-batt job. Of course, if your siding is already installed, and you forgot to tape the sheathing before the siding went up, it may be too late for tape.
I assume you are asking about the exterior of the sheathing. We've used urethane caulk in the past, but have changed to a good peel & stick building tape which will last far longer. Foam in a thin bead between two surfaces, unlike urethane caulk or tape, can easily crack and leave the seam open to infiltration.