Roll-on membrane + shower drain [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Dan Paleczny
06-05-2012, 11:37 PM
I am using Flextile's WP900 roll on membrane in a new shower installation, making my own bed. The key problem that I have is how the WP900 intersects with the standard 3-piece drain. Can you please review and correct my steps below, paying close attention and detailing to how/when the wp900 is used around the drain?

1. install drain base on the plywood floor.
2. attach and tighten the clamping ring to the drain base. (no waterproofing here, unlike pvc membrane)
3. build cement shower floor with correct slope, so that the floor cement is 1- 1/4 above the drain base/clamping ring, to allow for sufficient mass.
4. apply multiple coats of wp 900 over the cement, including over the drain base/clamping ring.
5. thread the adjustable drain barrel in place, to the correct height.
6. apply thinset mortar and tile.

Thanks for your help! Dan

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Houston Remodeler
06-05-2012, 11:56 PM

Our buddy Brian of Ceramictec has a thread on here somewhere doing the steps you describe. I'm sure he'll post a link sometime soon.

This method isn't for the faint of heart and many Pro's shy away from it. I'm not saying it can't be done, but it isn't very DIY friendly. Just sayin :stick:

06-06-2012, 12:11 AM
Welcome, Dan. :)

I've not used that product and am not familiar with it. Reading their Data Sheet troubles me a good bit, though, when considering it for a shower pan. Not just the fact that they consider a total dry thickness after two coats of no more than 20 mils, apparently even for a shower pan, with any reinforcing fabric being optional, but the lack of useful instruction for use with a standard clamping drain. Closest thing I could find is this:Remove drain flanges and apply
liberal coat of WP-900 over and around the drain flange. Apply
liberal coat of WP-900 around pipes. Allow to dry then apply a
second liberal coat. Allow to dry. Apply bead of urethane sealant
around drain flange, pipes or other penetrations, to join with the
WP-900 system seam.I'm guessing from your description that you intend to use what we commonly refer to on this forum as the "divot method" of forming your shower floor. If so, I can't imagine not putting your waterproofing membrane between the two faces of the clamping drain as is done with any other waterproofing method using such a drain.

The "urethane sealant," as I read Flextile's instructions, would render the weep holes useless, but at least you'd have some method of sealing your membrane to your drain.

I worry about the liquid-applied shower pans in general. I worry more about those that use no reinforcing fabric at all. I now worry still more about one with limited installation instructions and the thinnest allowable section I believe I've encountered thus far.

But if you like it, and if you can figure out how they really want it applied, go for it, say I. :)

My opinion; worth price charged.