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Community and Q&A

Insulating Floor of Bedroom Above a Garage

B3V1156 | Posted in General Questions on

Hello, I am building in zone 6B and have a garage that will be directly below a master bathroom and bedroom. I was looking for any input on how I should insulate the floor system in this area to make it as comfotable as possible. Some things that come to mind are:

Which insulation would work best?
Is a vapor barrier recommended?
Would drywall or ZIP make a difference for the garage ceiling?
Could ZIP R be used as the subfloor in these areas?

Floor system will be 11-7/8″ open web trusses.


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  1. nynick | | #1

    Insulate the garage and heat it. You'll have to insulate the ceiling anyway to separate it from the living space. I keep the garage at 60 with a mini-split. Only "major" change here would be insulating the garage slab.

    1. Expert Member
      DCcontrarian | | #3

      There just aren't garage doors that are insulated and air sealed to the standard of other exterior doors.

      The heat that flows through the ceiling of the garage will flow through it as well. If the garage is insulated it will be warmer than outdoors.

  2. Expert Member
    DCcontrarian | | #2

    With any insulated assembly you want either a vapor barrier on the warm side, or enough impervious insulation on the cold side to prevent condensation.

    With a garage you're required to have 5/8" drywall on any surface that borders a living area to prevent the spread of fire. You also want to pay extra attention to air sealing to keep gases and odors out of your living space.

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