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Tar paper as housewrap

stryped1 | Posted in General Questions on

Do you see anything wrong with using tar paper as a housewrap when remodeling?

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  1. GBA Editor
    Martin Holladay | | #1

    Yes, it's perfectly possible to use #15 or #30 asphalt felt as a water-resistive barrier (WRB), as long as it is properly installed and lapped.

    For more information, see All About Water-Resistive Barriers.

  2. Expert Member
    Dana Dorsett | | #2

    #30 felt is on the low-permeance end, and may limit the drying capacity of the sheathing. It's customary (and better) to go with #15 felt on wall assemblies, since it has higher (and variable) permeance that won't impede drying nearly as much, but is still a sufficient WRB. (#30 felt is better for roof shingle underlayment though.)

  3. fitchplate | | #3

    It depends ... and to quote Martin who is quoting JLC:

    "Asphalt felt has a permeance of only 5 perms when dry, but a much higher rating of 60 perms when wet. Fans of felt note one of its advantages over housewrap: If water gets behind felt — either due to a flashing leak or condensation from solar-driven moisture — the felt can soak up the liquid water and gradually dry to the exterior."

  4. mackstann | | #4

    Tar paper is a less effective air barrier because you don't seal its seams with tape.

  5. GBA Editor
    Martin Holladay | | #5

    While that may be true, no one should be depending on housewrap to be an air barrier. The purpose of the asphalt felt (or the housewrap) is to be a barrier to rain that gets past the siding.

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