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Is a vapor barrier needed in a floor over a garage?

Tony2slow | Posted in Green Building Techniques on

Not sure if a vapor barrier is absolutely required for the floor of a room over an unheated garage.
Reference: https://www.greenbuildingadvisor.com/question/flooring-install-vapor-barrier-or-glue

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Tony,
    There are no code requirements for vapor barriers in floor assemblies. Nor are there any building scientists who recommend a vapor barrier in a floor assembly.

    If you plan to install OSB or plywood subflooring, these materials will act as a vapor retarder.

    In all cases, attention to airtightness is very important.

    (By the way -- even though it doesn't matter in this case -- it's usually a good idea to tell us your climate zone whenever you ask a building science question.)

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