vapour barrier over or under floor insulation?

Old 04-22-02, 08:31 PM
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vapour barrier over or under floor insulation?

Hi, Now that we've decided on a wood floor in our new workshop we have the question about where to put the vapour barrier. We have a cement floor which we plan to raise up using a wood joist frame with 3/4" T&G flooring on top. We also plan to insulate under the flooring with fiberglass batts. Do we put the vapour barrier right against the concrete, then the wood frame, insulation and flooring or do we put down the wood frame, insulation, then the vapour barrier and flooring? Help! This one has us stumped. We'd appreciate your help!
Old 04-23-02, 08:19 AM
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Frame and insulate the walls first. Then cover that with the vapor barrier. The flooring will only cover a couple inches of the VB, but that's fine. Installing a VB on the cement will cause a LOT of mildew to grow. As you can imagine, that's bad.
Old 04-23-02, 08:25 PM
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Vapor retarders

Go to and and read the articles about insulation and moisture. If you need additional info, email resercon. 3/4" tongue and groove hardwood flooring is not recommended for below grade installations. Go to for technical information.

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