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Community and Q&A

Zero-VOC vapor barrier and foam/caulk?

usaalv | Posted in Green Products and Materials on

I have to replace the vapor barrier in my crawl space and air seal all plumbing and HVAC sub-floor penetrations.

I wonder if there’s a zero voc vapor barrier and zero voc foam/caulk that can be used for these purposes.

I live in the 4A geographical area (Raleigh NC).

Thank you.

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  1. albertrooks | | #1


    The easier of the two questions is on the caulking and foam:

    There are caulks and sealants that are suited to different applications. Some are solvent based and some are not. For a broad look, see this page: There are links in the page that will also take you to source articles provided by the good folks at:

    I would also consider that airsealing tape will typically perform better over the long haul then caulks and sealants will. Tape doesn't just fill gaps, it spans openings and seals beyond the gaps. You could consider SIGA Rissan shown here:

    Sadly, I don't know of a foam that comes out of a can that is VOC free. I've looked at stocking even the "green foams" and found that the propellants invariably contain VOCs.

    The sheet form VB's that you would use in a crawl don't contain any active solvents that will off gas. I'm not an expert in this area, but I think your standard choices are reasonable.

  2. GBA Editor
    Martin Holladay | | #2

    I agree with Albert that polyethylene sheeting is not known for any off-gassing problems. (Polyethylene is used to make milk bottles.) If you are bothered by the thought of having exposed plastic sheeting on your crawl space floor, it's always possible (although not cheap) to cover the polyethylene with a thin concrete slab.

    For more information on low-VOC caulks, see these GBA pages:

    Product Guide: Caulks and Sealants

    Q&A: Low VOC sealant/caulk

    Q&A: Choice of caulks/sealants?

    Q&A: Is using spray foam from a can really "best practice"?

    Does anyone have experience with ChemLink caulk?

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