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Roxul insulation

Tool1 | Posted in Green Products and Materials on

Does Roxul come with a paper barrier? Do I have to you put a vapor barrier down in the attic before I put down the Roxul?

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  1. Steve Knapp CZ 3A Georgia | | #1

    Advise is climate specific. It would be helpful to know where you are located. Is this new construction or an existing home?

  2. Tool1 | | #2

    This is an older home in Connecticut. Had a air conditioner leak and had to take out some of the old insulation which had the paper on it. Want to replace it with Roxul and it doesn't have any paper on it.Thank you.

  3. GBA Editor
    Martin Holladay | | #3

    Building codes require a vapor retarder in your climate zone, but the requirement can be easily met with vapor-retarder paint.

    The fact is that the presence or absence of a vapor retarder in this location almost never matters. What matters is that you seal any air leaks in the ceiling. Air leakage matters much more than vapor diffusion.

    If I were you, I would do my best to seal any air leaks, and then install the Roxul without worrying about the vapor retarder.

  4. Expert Member
    Dana Dorsett | | #4

    In a vented attic in zone 5 (all of CT is in zone 5A) you don't need a vapor barrier, even if it was a vented cathedralized ceiling(!), which is the worst-case.

    See section R806 for the ventilation & vapor barrier requirements (vented & unvented cathedralized ceilings).

    See also section 1203.2 of Chapter 12 of the CT state building codes:

  5. GBA Editor
    Martin Holladay | | #5

    Thanks for the correction.

  6. Tool1 | | #6

    Thanks to all of you.

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