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Does this appear to be “tar paper?”

Austin G | Posted in General Questions on

Found hiding under the EPS.  Assuming it’s at least 60-70 years old.  And if it is, it would be a vapor barrier correct?

Thank you all.

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  1. Expert Member
    Zephyr7 | | #1

    Looks like tar paper to me, which is usually a kraft paper material with a black coating. If it’s thick and tough it might be asphaltic fiberboard.

    I think both materials act as smart vapor RETARDERS, not full vapor BARRIERS. These materials aren’t like a sheet of polyethylene, for example.


    1. Austin G | | #2

      Any possible way to determine perm rating on something this old? I sprayed closed cell on the interior knowing that the exterior was only 1/2” of eps... but only just realized this papaer was hiding under the eps.

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