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Community and Q&A

ComfortTherm Plastic-Enclosed Batting

Andrew Levitt | Posted in Green Products and Materials on

My contractor came home today with some fiberglass batting wrapped up in plastic that says “vapor retarder” on it. It’s this stuff in the vapor retarding form: http://www.rockweilerinsulation.com/documents/JM_ComfortTherm_Batt_Spec_Sheet.pdf

I told him to take it out and rip all the plastic off then put it back. I’m in Philadelphia, this stuff was recommended to him by a local Lowes salesman as a superior alternative to paper-faced batting. The wall cavities it’s going into are all irregular so it was definitely not encapsulated after installation, but there were still sheets of plastic on both the inside and outside. Is there any way this product is a good idea around here? Seems like it’s a mildew-infused vapor enclosure waiting to happen.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Andrew,
    These batts are encapsulated in plastic to make them less itchy.

    It's hard to know how the vapor barrier might work in your climate, but it's possible that the vapor barrier would interfere with inward drying during the summer. If you are going to install fiberglass batts in your climate, I agree that it's better to skip the vapor barrier.

  2. Andrew Levitt | | #2

    Thanks Martin. Also wanted to emphasize that there is vapor-barrier plastic on the front AND back of the batt (and sides, it's totally enclosed in plastic unless it gets cut up to fit the cavities). Any comment on why this product even exists? Doesn't it seem like instant moisture liability?

  3. GBA Editor
    Martin Holladay | | #3

    Andrew,
    Q. "Any comment on why this product even exists?"

    A. The product was developed to address complaints (chiefly from DIY homeowners) that installing fiberglass batts is an itchy job.

    Q. "Doesn't it seem like instant moisture liability?"

    A. In Minnesota, colder areas of Canada, and Alaska, plastic vapor barriers usually don't cause problems. In mixed climates (especially in climates where air conditioning is common), interior vapor barriers can cause more problems than they solve.

  4. DznDrm | | #4

    I've found some of this in a crawlspace in North Carolina. The crawl space appears fairly dry. It has recently had a vapor barrier (10 mil) put down on the floor and penetrations in walls sealed, but insulation with plastic on both sides just doesn't seem like a good idea in the hot humid south. Am I being too cautious? Seems like little mold incubators to me.

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