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Unread 10-16-2020, 12:08 AM   #213
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Join Date: Jul 2001
Location: Boerne, Texas
Posts: 91,904
5. I'm thinking Dan was not considering that you still had a full moisture barrier behind your wallboard that lapped over your tub's tiling flange, but we'll need to let Dan address that.

The difference I see between the unavoidable penetrations of the moisture barrier when the wallboard is installed and the penetrations you made when using screws through the membrane to secure the flange is location. Yes, the wallboard fasteners also penetrate the membrane, but experience has shown you can get away with that. It's not ideal, but it's known to work. The holes you poked in the membrane at the tub flange are not at all compressed between wallboard and framing, but just open holes directly where gravity fed moisture is likely to try to make an exit. And instead of exiting into the tub, it can exit behind the flange.

Will that cause your installation to fail next week? No, it won't. Will it cause your installation to fail sooner than it should or would had you not done that? Yes, I think it will. Is that sufficiently worrisome for you to take drastic action to fix the situation? That's entirely up to you. Will adding the strip of waterproofing membrane at the bottom of the wallboard and gluing it to the tiling flange help at this point? I don't think it will help at all and I think it will actually exacerbate the problem. Can I prove that? No, I can't.

Again, the different methods, moisture barrier behind the wallboard and lapped over the tiling flange or the direct bonded waterproofing membrane on the face of the wallboard and attached to the tiling flange are an either/or proposition. You've currently got a damaged either, which cannot be corrected by adding an or.

My opinion; worth price charged.

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