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We have a garage/workshop that is occasionally heated

Mike Tomlinson | Posted in Energy Efficiency and Durability on

We have a garage/workshop that is occasionally heated with an overhead suite that is kept at 5 degrees Celsius. The ceiling of the suite is vapour-barriered and insulated.

The floor of the suite is about to be insulated. Should there be vapour barrier in the suite floor/workshop ceiling, and, if so, where?

We live in Hazelton, BC – near Smithers, BC.

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  1. GBA Editor
    Martin Holladay | | #1

    You don't need any polyethylene in your floor assembly. And you don't have to worry about vapor diffusion harming this assembly -- either vapor diffusion from the garage to the room above, or from the room to the garage.

    For what it's worth, your subfloor (either plywood or OSB) is already a vapor retarder. (Not that you need one.)

    While you don't have to worry about vapor diffusion, it always makes sense to worry about air leakage. Do your best to limit air leaks when insulating your floor assembly.

    For more information on insulating this assembly, see How to Insulate a Cold Floor.

    For more information on vapor barriers, see Do I Need a Vapor Retarder?

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