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Goop and plastic – yes, no, maybe?

Tony2slow | Posted in General Questions on

Hi Guys,

I’m at the stage of my project where I am installing drywall. Wall is 2×6, Roxul insulation, Certainteed MemBrain smart vapor barrier, and I’d like to do an air tight drywall approach for drywall installation.

But – I’ve got plastic stapled to my studs, top plate, bottom plate, window rough in, etc. ADA guidelines say I should be caulking all of these areas when I install the drywall, but, um, there’s plastic there.

I’ve only got one small corner complete, my “trial corner” with a window to see how things would play
out. Tried to cut the plastic back and make room for caulking at the ends of the framing members.

What a pain, the guys doing this for money are definitely not doing it this way. So, what’s the best plan going forward… A) keep the MemBrain, omit any caulking, and just screw up the drywall. B) omit the MemBrain and use caulking to install the drywall per the ADA guideline – not sure what code guys will say about that, will paint suffice as a vapor barrier? C) keep going the same way, keeping MemBrain to edge of stud and leave room for caulking. or D) something else that is better than the above?

I’m sure this question has been asked before, I have seen some information that stated ADA does still require a vapor barrier and that plastic was one option, just haven’t found the right knowledge page to understand the real best way to proceed.

Location is Maine, zip 04240.

Thanks.
..Tony

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Tony,
    Q. "Will paint suffice as a vapor barrier?"

    A. There is no requirement -- neither a code requirement not any requirement from experts -- for an interior vapor barrier. Instead, there is a code requirement for a vapor retarder (a less stringent layer than a vapor barrier). The MemBrain meets that code requirement. For more information on this issue, see Do I Need a Vapor Retarder?

    Q. "I should be caulking all of these areas when I install the drywall, but, um, there's plastic there."

    A. The point of the caulk is to reduce air leakage between the drywall and the layer behind the drywall. The caulk will effectively do that, even with the MemBrain. Install the caulk on top of the MemBrain and stop worrying.

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