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  1. #1
    Join Date
    Jul 2010
    Posts
    24

    Default how much air gap does R-30 RIGID insulation need on ceiling?

    Does anyone know what is the general thickness of R-30 Rigid Insulation?

    Does it need air gap and how much?

    Which is the best company name to use?

  2. #2
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,919

    Default Re: how much air gap does R-30 RIGID insulation need on ceiling?

    Where are you fixin to install the stuff?


    Have you checked the manufacturers instructions?

  3. #3
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,700

    Default Re: how much air gap does R-30 RIGID insulation need on ceiling?

    If you are talking about rigid foam insulation, it depends on the type of foam used. Some are rated as low as R4/inch, some as high as R8/inch but R-6 to R-6.5/inch is pretty typical. No gap between the foam and the interior side wall siding, at least 3/4" gap to the exterior side wall siding.

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