Garage Air Barrier Question – GreenBuildingAdvisor

Hey All,

Working through air sealing my garage which is an attached, drive under garage with living space above and to the side. I’ve read a bit and watched Jake Bruton’s video (https://www.youtube.com/watch?v=JaiJH0HXf-g) on air sealing, but just trying to think through a couple details. Electric service is in the garage, so all electric will travel through the garage and poke through this air barrier. HVAC ducts will come from the basement side, and travel through the ceiling cavity that exists isolated from the garage.

Attached is a rough sketched blueprint of what we have going on with my current plan. Also attached is the current bearing wall that separates the garage that I worked on tonight. And as an FYI all will be covered with the necessary Type X fire rated drywall after air sealing is figured out.

The questions:

– In the above video, it seems like he’s putting interior zip on all four walls. In my mind, wouldn’t you only need interior zip on the walls that share a common wall with living space? So in my situation, the ceiling and bearing wall next to the basement? I guess maybe the idea, and risk, would be that noxious fumes could get up through the top plate transition of the other two walls, perhaps?

– I’ll be implementing the one penetration = one object. In a lot of the videos seen, that penetration seems to be happening when crossing through the connecting wall. But, with the use of floor joists for this project, could you consider the floor joist area above the garage an area that is part of the main house envelope? Ie. instead of worrying about crossing between the garage and basement wall, you seal all holes crossing between the garage and the garage ceiling… if that makes sense. So the ceiling directly above the electric service would be where you would make one penetration for each wire. 

Thanks!