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Where to Put the Vapor Retarder in this Finished Garage

Genassy | Posted in General Questions on

I’m finishing an attached garage that has bedrooms above and living space on two sides. That leaves only one exterior wall.

Everything is getting new insulation as the previous installation was damaged.

The garage isn’t always going to be heated in the winter time, maybe 3 days a week for exercise.

Before the damage to insulation was removed, vapor barrier was on the warm house side. Because the garage isn’t always heated I will have to insulate these walls, which side should vapor barrier go on?

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  1. Expert Member
    Akos | | #1

    There is no benefit to a vapor barrier on any of the outside garage walls. I would leave it out.

    You only want a VB between the house and garage, which should always be on the warm side if in heating dominated climate (ie behind drywall at the house side and bellow the subfloor for the bonus room).

  2. johnmann1 | | #2

    I have the same situation. 9' high block basement with single car garage bay where the other side is going to be an office and bedrooms above. I would rather not use foam due to off-gassing but I have read that I have no choice on the block wall side. When it comes to the 2x8 joist above and the 2x6 wall separating the single bay garage from the office can I use Rockwool in the ceiling and 2x6 wall and then drywall the whole garage for air tightness or do I need to do a smart vapor barrier over the insulation and then drywall the garage? I'm in climate zone 4 and the garage will not be heated

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