Air Sealing Question
When we built our garage/apartment, we sealed the perimeter of every stud bay to the Zip System sheathing panels with Tremco acoustical sealant. We also caulked or foamed every joint and space between the framing members, around windows, doors, header and top plates, etc. It was a lot of work, but along with the other air sealing details, it seems to have resulted in a VERY airtight structure.
One thing we did NOT do was to caulk the drywall to the wall studs, as we were not in town when the drywall was installed.
As we plan to build our house, does it make sense to do BOTH the stud bay to Zip R sheathing acoustical sealing, AND the drywall to stud caulking, or would that be overkill?
Our walls will be filled with mineral wool batts, and we will be using air tight electrical boxes. We are building in Asheville, NC Thanks in advance for your feedback!
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Air sealing is mentioned a lot on GBA. A search will yield all kinds of helpful information. (And other members may post specific recommendations.) He is a good place to start if you want to determine the best ROI for this activity: https://www.greenbuildingadvisor.com/blogs/dept/musings/getting-biggest-bang-your-air-sealing-buck
You also might want to search the site for information on the "pretty good house" approach.
With high density fiber insulation in the cavities the structural sheathing well detailed as the primary air barrier should be good enough from a thermal performance point of view.
Asheville is in US climate zone 4A, and even without insulating sheathing there isn't going to be a wintertime moisture accumulation issue, even if interior side isn't 100% air tight (otherwise most existing homes wouldn't still be standing!). With ZIP-R (any version) you have bought yourself margin for higher than typical wintertime indoor humidity conditions, though you'd still want to hold the line at 40% RH indoors during the coldest weeks.
Taping the exterior side of the Zip sheathing should be your best return on effort/air-tightness. Additional air barriers improve performance but may not be worth the effort.