Air barrier – taping exterior top plate
tjones1014
| Posted in General Questions on
Does anyone have a video or any resources they can share that shows how to tape the exterior top plate when creating a continuous air barrier with OSB & tape? My contractor pointed out that there won’t be a good place to tape this part with the roof joists that will be butting up against it. We have a hip roof if that helps any.
We plan to use 3M 8067 for the seams and top plate, Siga Fentrim for foundation seam.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Are you planning on continuing the air barrier under the soffit, up the fascia and over the roof sheathing (non-vented roof)? Matt Risenger has some videos of this done with monopoly framing.
The other option is to turn it over the top of the top plate and run along the ceiling. I believe Jake Bruton does this in his homes.
We have a vented roof think (vented soffits and ridge vent - I'm assuming that's the same thing. If not, please correct me. I'm new at this :) ). It's a gut reno on an existing 2001 home, and we didn't have plans to change the roof. We were just told it's a good idea to tape the exterior top plate as well as the other seams and at the foundation, so we're trying to figure out how exactly to do that. Is leaving the top unsealed an option, or will we be causing more issues if we do that? Or should we just try to air seal that area from the inside?
Climate 3A/4A - N GA area
This does help. If you are keeping the vented roof, can we assume insulation is in the ceiling joist and not in the roof line? If so, your air barrier could continue doing something like in this video: https://youtu.be/_yuG75cvgoI?si=ylFuFgs-_SL8EBzP
I live in the same climate zone as you. I’m a fan of having the attic as part of the building envelope. We put our HVAC system in that space and it is conditioned. If you go this route, your air barrier would go along the roof line.
Correct, the insulation will be in the ceiling joist, not the roof line. We unfortunately don't have it in the budget to make the vented roof non-vented.
I'm a little confused by the video, as it looks like he shows installing that Advantech over the top OSB seams before installing the trusses. We won't be able to move/uninstall the trusses to get that underneath. When I feel back there, it also feels like the OSB end isn't flush with the top of the top plate. Maybe I'm looking at his video incorrectly though?
I had someone mention using ZIP liquid flashing, but with it being cold, idk how well that would work.
I should also mention that we have a bonus room upstairs where the HVAC handler will be. That space will be conditioned, but the rest of the vented attic space around it won't be. I've attached a pic of the dormer window for that room. I'm wondering how we will be able to effectively air seal that OSB and the inside space with the OSB bordering the existing roof and with the room being surrounded by unconditioned vented attic space. The chimney is being removed from the home.
Looking forward to replies.
Pictures help. Hard to figure out your problem.
The exterior isn't demoed yet, so this is all I have. The trusses intersect with the OSB, so there isn't a flat surface to tape all the way across the top plate. We would have to tape around each individual truss. Trying to figure out the best solution. Hope this helps!
In this picture, where are the soffit vents? Shouldn't they be open between the outside and inside to provide ventilation? I wouldn't think you want to tape over that opening of the vents, but maybe I am misunderstanding something?
The soffit vents extend out a bit and down from the angle I was able to get for this picture. The soffits are vented, and we won't be taping over those holes. We are just trying to figure out how to air seal the top of the OSB to the 2x4s horizontal across the top of the wall. The roof trusses that extend out touch the top of that OSB, so there is no good way to get those seams sealed up easily.
tjones,
Duplicate question. https://www.greenbuildingadvisor.com/question/air-barrier-continuity-at-top-plate