After the fact roof air sealing
I have had several phone calls over the past few weeks about water damage from ceiling leaks. Most of the homes have vaulted ceilings with wood paneled, usually the paneling is attached directly to the roof framing, a poorly sealed polyethylene vapor barrier is present but no drywall. I know poor air sealing is almost always the cause, I confirm the leakage points with a blower door test. Suggesting interior air sealing is my prefered method, but have had a few people request the repairs be completed from the exterior. In the past, I’ve suggested closed cell spray foam. The poly vapor barrier needs to be removed before foaming, this can lead to the foam oozing through the finished paneling on the interior. Does anyone used a different method for air sealing after the fact? I’d be interested to know if anyone has used fluid applied air barriers, if they have a low enough perm rating to meet the 1 perm vapor barrier requirement and are thick enough not to leach through the paneling joints. Any other ceiling air sealing methods? My location is zone 7, northern Minnesota.
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I've never before heard the opinion that "the polyethylene vapor barrier needs to be removed before foaming." In fact I've been involved with jobs in which the roof sheathing was temporarily removed and closed-cell spray foam was installed against the poly vapor barrier.
Your right, I could leave the poly. It would probably make removal of the paneling in the future easier. I guess I was more worried about the air sealing at the roof to top plate connection, making sure that the foam was sealed wood to wood rather than poly to wood. That might not even be an problem, but the insulating contractor I deal within with, has in the past, had a couple issues at that junction with the poly in place. The last house I was involved with didn't have any poly present. The homeowners insulated with the plastic wrapped fiberglass batt insulation without any additional air sealing. The home was seasonal until recently, the contractor had lots of fun tearing their roof off in this past February.