Attaching and Sealing Smart Air Barrier Under Pine T&G
Hello all – thanks to everyone who contributes to GBA – this website is amazing.
I can’t seem to find this exact question already asked so I apologize if it has or if its just a no brainer. Its a common situation so I’m sure there is something fundamental I’m missing
TL/DR: What are best practices to seal a Smart Air Barrier like Intello at nail holes at wall studs and rafters? Is it even necessary?
I’m in climate Zone 6. Planning a house with double stud walls insulated with densepack cellulose. Ceiling will be insulated with loose fill cellulose. Finish walls and ceiling be primarily V-notch T&G notty pine so can’t use airtight drywall approach.
Given the T&G pine I will be putting up a smart vapor/air barrier like Intello. Since the Intello will be an air barrier, I’d like to have a good seal at the staples and at the nails attaching the pine paneling. I’m hoping to solicit recommendations on best practices here. I was thinking a thin self sealing foam tape, taped to the studs prior to applying the Intello. I figure once the pine is installed the intello will be tight against the foam tape at each nail hole. Double sided tape like Siga’s Twinet could also work but sounds like a nightmare to work with if you need to adjust the intello. I suppose I could also just apply tape to each stud and rafter after the Intello is up but a good tape that would seal around a nail is expensive.
Its worth noting the insulation installer uses traditional netting so there will be netting over every stud. In my feeble mind that complicates things to use the stud to create air barrier continuity at the nail. This is not an issue at the rafters.
Perhaps the answer is that I am over thinking this and I don’t really need to do anything. I definitely wouldn’t worry about it if this were only a vapor control layer but its an air barrier as well
Thanks in advance!
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Replies
I would strap out walls and ceiling and nail the T&G to that. A hole through an air barrier with a nail in its not a leak source, so you don't need to do any extra sealing.
If you use 2x lumber for the ceiling strapping, it would leave enough space to run wiring there and be able to install slim LED pot lights.
Thanks @Akos!
I had planned on strapping out the ceiling for the exact reason you state, to leave room to run cabling and fit low profile lights.
I am curious of the benefit of strapping out for the walls though? Less nail hole penetrations? I already have double stud walls which provides a cavity to run utilities. I also want to run the T&G horizontally on the walls so I'd have to have two layers of strapping which starts to really eat into the room size.
T&G nails are small and T&G will move. Strapping is nailed on with framing nails, not going anywhere so the holes through the membrane will always be covered. For the small amount of labor, I would strap out the walls or cover with plywood.
P.S. OSB with taped seams on the warm side makes for a decent smart vapor retarder/ air barrier.
Recently had my cellulose installed for my double stud wall home. The tops of walls connected and taped to exterior plywood and extended inside as detailed on this site many times over.
I used 1/2" polyiso sheets as my ceiling air barrier (taped to plywood extending inside) and did checkerboard of 1x3 strapping for lights Akos referred to above.
Insulators thought the ceiling air barrier was great as it would not allow sagging as there netting would. They put 3,650 lbs of cellulose in attic....lot of weight.
Tape does not seal very well to osb
Zone 6 in VT. Here is my ceiling detail for raised heel scissor trusses. I did 16" densepack, intello, horizotal 2x4 strapping to hold back insulation. Then strapped again vertically to nail the t&;g and timber beams to. Definitely not the easiest way to do it, but this put the least amount of holes in the intello barrier.