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What do you think about Mylar-wrapped Styrofoam board for a housewrap / thermal barrier and radiant barrier?

user-5986592 | Posted in Energy Efficiency and Durability on

I would like to know if there is any reason this material might either cause a problem with the envelope or if it will be effective as and radiant barrier (both directions) or not.

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  1. GBA Editor
    Martin Holladay | | #1

    The radiant barrier will only provide a thermal benefit if it faces an air space (for example, if it faces a 3/4-inch-deep rainscreen gap between the rigid foam and the siding). If there is no air space, there is no thermal benefit.

    If you want to install rigid foam insulation on the exterior side of your wall, you need to make sure that the rigid foam is thick enough to keep the wall sheathing above the dew point during the winter. This article will tell you what you need to know: Calculating the Minimum Thickness of Rigid Foam Sheathing.

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