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Old 05-22-2013, 01:13 AM   #1
costasbrehm
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Default Shower drain flange in concrete slab

All,

I hired a professional to relocate my shower and tub drain pipes that are set in the slab, with the intention of doing the rest of the job myself. Unfortunately, he didn't follow my instructions and set the drain flange directly into the slab when he re-poured the concrete. Now I have a flange that is even with the rest of the slab. My initial intent was to build up a screed bed about 1/2" around the flange to create the sloped floor (which didn't exist in the builder-spec shower I'm replacing) for drainage, but now I'm wondering how to proceed.

Am I correct in thinking that building up a mortar bed that tapers to nothing at the drain flange is a bad idea? I'm worried that it will be too brittle, and regardless of what I use for an anti-fracture under my tile, I'll end up having to re-do it later like I originally planned. I have the plumber visiting tomorrow to explain his thinking (and fix the other things he did wrong), so any advice would be appreciated! Thanks,

Costas



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Old 05-22-2013, 01:32 AM   #2
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What type strainer did he use? Some are adjustable. Are you also aware that you need a shower pan?



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Old 05-22-2013, 01:55 AM   #3
costasbrehm
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John,

He used a standard screw in adjustable strainer.

My original plan was to set the flange into the shower pan that I was going to build myself, seal the entire thing with a waterproof anti-fracture membrane, then thinset and tile over that. Since he's already set the flange into the slab though, how do I go about building the shower pan? I don't feel like building the pan over the flange is a good idea because I will be blocking the weep holes, but I'm open to feedback. Thanks,

Paul

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Old 05-22-2013, 01:59 AM   #4
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I guess there's a reason why they say a picture's worth a thousand words...

IMG_20130521_205657_199[1].jpg  
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Old 05-22-2013, 02:02 AM   #5
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This is the type shower strainer you need.

shower strainer.jpg  
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Old 05-22-2013, 02:22 AM   #6
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The pan goes in between the two sections of the strainer that are bolted together. The pan serves as a gasket between the two sections. The weep holes allow the water to run into the drain over the gasket formed by the pan.

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Old 05-22-2013, 03:38 AM   #7
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John--I'm think tracking what you're saying, but I still don't understand how I can make this work with a mortar shower pan. Given the flange that they've already installed, I'm not comfortable building the pan below the bolt-on threaded strainer receiver, as there's not a lot of surface area there to support the strainer itself. On top of this, building the mortar pan to an unsupported edge that borders the drain seems ill-advised. Am I over-thinking this one and missing your intent?

Thanks for you patience and advice,
Costas

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Old 05-22-2013, 10:51 PM   #8
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To meet current IPC code, you have to do a sloped mortar bed underneath the pan material or liquid membrane. Then you will have to install another sloped mortar bed on top of the membrane or pan material to adhere the tile to. So there will be a considerable thickness of mortar built up by the time you install tile. That should be plenty to support the strainer.

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Old 05-23-2013, 11:36 PM   #9
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I was under the impression that I could tile directly on top of the sealed membrane. Is that not the case? If so, what I plan to do is:

Build up the standard sloped mortar bed (1/4" per 1') up to the outside lip of the flange, then seal it with the liquid antifracture. Then put another layer of mortar on top, which will fill all the way into the adjustable shower screen, taking care not to clog / seal the weep holes. From there, I can tile directly on top and have a functional shower without 1/2" of stagnant water under the preformed shower pan.

Thanks for all of the help,
costas

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Old 05-23-2013, 11:42 PM   #10
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I am not too familiar with the liquid membrane systems, so it is possible that you could tile directly on top of that. If that is the case, though, the drain you currently have would not work at all, even raised slightly above the sub floor, because you would still need to add a mud bed to get the tile up to the strainer height.

My foggy understanding of the liquid membrane systems is that they use a special drain.



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