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Community and Q&A

To housewrap or not to housewrap?

Dave De C | Posted in General Questions on

Is housewrap plain and simple overkill?

Wall construction is 2×6 with dense-pack cellulose, OSB sheathing with joints taped (3M all purpose weatherstripping tape), covered by 2-1/2″ of insulfoam Neopor EPS which is faced and joints taped (3M 8087).

The original plan was to housewrap at this point, add furring strips, then siding.

I’m wondering if there is any necessity for the housewrap over what is already a water resistive barrier.

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Replies

  1. Walter Ahlgrim | | #1

    Do you want to bet your home that foam and tape is a waterproof barrier over the next 50 years?

    If the foam shrinks ½ inch across each 4 foot panel can the tape stretch and maintain its water proof seal?

    Will the tapes glue stay attached to the foam for 50 years? Or will tapes glue fall off like duck tape on a heating duct?

    Of course the products manufactures say their products say they will stand the test of time.

    I can think of several building products that failed the test of time badly.

    Walta

  2. GBA Editor
    Martin Holladay | | #2

    Dave,
    First of all, every wall needs a water-resistive barrier (WRB). A WRB is required by code.

    It's true that some (but not all) brands of rigid foam have been approved for use as a WRB. Neopor may or may not meet the legal requirements of a WRB. For more information on this issue, see Using Rigid Foam As a Water-Resistive Barrier. It's probably a good idea to check with your local building official before going forward with this plan.

    If you decide to use rigid foam as your WRB, you need to realize that you will no longer be depending on lapped joints (and gravity) for watertightness. Instead you will be depending on tapes (and the durability of chemical bonds) to keep your wall dry.

    Think through all of the ways that your window flashing needs to be integrated with your WRB, and whether you can accomplish your goals with tapes, before you decide on this method.

    -- Martin Holladay

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