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Unread 12-10-2007, 10:17 PM   #1
Fiddle1
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How thick on that first slope?

While I will be stuck in this mess this on my own, I can tell from this forum that you will all be there in spirit to guide me (and to have a few good laughs).

Here's the scenario:
After two months in our new house (new to us, not new), I notice an increasingly large brown stain directly under the upstairs shower drain. An inveterate DIYer who just put a 34 foot dormer on the house, I said the necessary 4 letter incantations, then got my tools and opened the living room ceiling. I had been informed that this bathroom had been completely redone just before the owners had to relocate, and we had liked that it was nicely tiled converting the tub area to a fully tiled (not the ceiling) shower enclosure with a full height glass door, nice fixtures, etc. The only room to have been redone in the house and we liked it. So I was surprised that something was going wrong, and pissed to have to deal with it, as I am still doing finish work on the dormer.

I open the ceiling, look from underneath and can see that the plywood is wet all around the drain, and can also make out edges of half inch cement board around the drain. I start to get a bad feeling about this. I speculate that the drain had not been clamped properly to the liner, and pray that I can take up the tiles around the drain and do a repair without taking up the whole floor (doesn't prayer always work for you too?)

Taking up the tiles around the drain, I discover that there must be people who are not content just to get it wrong, but insist on creating their own unique approach to doing it wrong. I'm guessing that the tile guy may tile well but doesn't know anything about putting in a pan so he improvises. Screws down half inch CBU over the 3/4 ply, then carefully puts down the neoprene liner, and carries it up the wall (not sure how far). Next he lays 1/4 hardibacker over the liner, then screws that down right through the liner and CBU into the plywood so the floor is real solid and secure. Real flat too. Then two coats of thin set to yield a pitch of maybe 1/4 inch over the entire four feet from the drain to the far wall. We discovered that we had to squeegee to get the water to the drain.

Despite the fact that we had not used the shower for two months by the time I got around to taking up the tiles, the hardiback was still soaking wet as there was no pitch on the liner. It turned out that the liner was not clamped at the drain, and the weep holes were solidly packed, so I might have been able to redo just that section if the rest of the installation had been okay. After seeing all the screws through the liner I used more incantations for the installer and his ancestors, and resigned myself to taking up the rest of the floor. I remove the rest of the hardibacker, then wince at slicing open the still new liner (though I left flaps coming out from under the walls). I demo a section of the cement board and take it out in hunks, since the edges are pinned under the walls and liner. Finally I am looking a the plywood.The surprise was that only the area near the drain was wet under the CBU. The remaining 2/3 of the area was dry with no stains from any leaking. Given that he had driven 30 or so screws through the liner I was a little surprised, especially with standing water. I can only figure that the compression from screwing the hardibacker down on top sandwiched the liner well enough at the punctures to keep a seal.

Having resigned myself to just do the floor over, I go get new liner and special cement to glue the new liner under the flaps from the old liner (I kept 6 inches sticking out to overlap the seams). I read about mortar beds, preslope for the liner, and so forth. Then I measure the curb and discover it is only 4 1/2 inches at the finished height. The enclosure is open at the top, with a full length glass panel running down to the curb, and a similar panel made into a door on the right with flexible seals along sides and bottom. Because the doors seal down to the curb, I can go a little shallower than usual on the curb, but do I have room to put a proper depth pan? My question (after all this) is how much mortar bed depth do I need at the thinnest point - near the drain?

In this forum and other places it sounds like the standard is 1 1/4 inch for the bed and you can get away with an inch if you have to. But I don't have even that if this means that there should be at least an inch bed at the drain (bottom of the preslope), then the liner, another inch, the thinset, then the tile. Following this sequence then from the top of the tile to the plywood floor will be at least a depth of 2 3/4 inches at the drain. Adding one inch of pitch puts the depth at 3 3/4 inches at the back wall. But now the floor is within 3/4 of an inch of the finish height of the curb, so that would mean ripping out the curb as well, which means ripping out the glass panels and the next thing you know I will be running pedestrians down for no reason.

It appears that the outside edge of the clamping drain flange sits about 1/2 inch above the plywood when the bottom of the flange rests on the plywood, so the bed under the liner need to be at least half an inch at the drain unless I chamfer the hole in the plywood and allow the flange to sit down a little lower. But can I go down to only half an inch with the dry pack over the metal lath? Can I use thinset to go thinner around the drain area instead of dry pack?

Or would the answer to the lack of depth here be to use RedGard applied to the top of a single bed, and then thinset directly on the RedGard? Does that save me an inch without sacrificing the integrity of the mortar bed? Since I am under pressure at work, have young kids, and still have to finish the other work I started on the house, I am really not up for turning this into a personal project where I do my usual go overboard to make sure it is done right. Doesn't mean I want to just throw it back together either. If I can go with one inch of mortar bed at the drain, then I have 1 3/4 inches of curb left at the far wall, increasing to 2 1/2 at the drain end and I could live with that.

If you need pictures, despite my thousand words, I will get some, but the question comes down to the minimum depth for each layer of mortar bed, and about whether I can/should go with thinset right over an applied membrane instead of the traditional sandwiched liner in the double bed approach.

Yours in desperation and perspiration,
Marty
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Unread 12-10-2007, 11:27 PM   #2
cx
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Welcome, Marty.

I'd need to read that a couple more times to have much chance of getting it right, but if you go to our whirl-famous Liberry and scroll down to the Shower Construction section you'll find some useful information on making shower floors.

I'm afraid that no matter how many times I read what you've written I'll still be wanting to tell you it's not gonna be possible to build a proper shower pan without tearing out what you have to about a foot up the walls. That would include everything on the curb.

Problem I see is that a fella who doesn't know how to build a shower pan to the extent that he doesn't use any mud and drives nails through the bottom of the pan liner will not have known how to finish said pan liner at the corners of the curb. And that is one of the first places a traditional shower will fail if not constructed properly.

I also don't understand how you intend to get a slope under the liner all the way to the walls. Perhaps that can be done, but I'm skeptical.

Then there's the issue of trying to patch the entire floor of that pan liner with a glue joint all the way around the perimeter and getting a perfect seal. That, too, could theoretically be done, but with dirty liner material and trying to glue the whole perimeter in place all at once......? I dunno.

I'd hafta suggest at a very minimum you do a complete pan replacement. That involves removall of everything to the studs up a foot or so from the rough floor.

I'd further suggest that you take this opportunity to remove the drain and re-plumb it near the center of the shower floor. That will make it much easier to make a proper sloped floor that is level around the perimeter.

Yes, you'll need to remove the doors and re-install them, but that is likely a blessing, too, since it's probable that this installer also used mechanical fasteners through the top of the curb to secure some sorta door tracks or channels.

Not what you wanted to hear, I'm sure, so hang around and let's see if some others read it differently than I, whilst I go to bed.

My opinion; worth price charged.
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Unread 12-10-2007, 11:39 PM   #3
iminaquagmire
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I can't imagine not having to take up the first course of tile and completely redoing the pan any way you go about it. That said, depending on your drain location but you might possibly be able to use a Schluter Kerdi tray and drain assembly. That would save you the thickness of the deck mud issue. At most it would still be less than 2 inches with the Kerdi, tray, and thinset.
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Unread 12-11-2007, 12:08 AM   #4
Brian in San Diego
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Justin,

Marty can't use the Kerdi tray you recommend unless he starts from scratch (complete tear-out). You can't "mix and match" with the kerdi system.

Marty, I've read you very sad story a couple of times and I agree with what cx has said and I have another fear regarding this installation. If the guy had no clue...no wait a minute, the guy had NO CLUE how to build a shower. That being said how are you going to verify if the rest of the shower is waterproofed properly? You could go through all this attempt to salvage the shower spending time, money and frustration trying to fix some other idiot's mistakes only to find the idiot made more mistakes...then it starts all over again. As much as it pains me to say this I think you'd be a whole lot better off in the long run to rip it out and start over. I also wonder how long you've been in that house and if you have some legal recourse under "full disclosure" laws. This is just wrong. The shower doesn't have anything right about it. Anyway you can find the guy who did it and get some compensation? Notice I didn't say try to get him to fix it? A guy this clueless will have no clue how to do it right. I usually try to give people the benefit of the doubt, but there just isn't any doubt here...the person who constructed this shower had no idea in theory or practice how to do it properly.

Brian
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Unread 12-11-2007, 06:59 PM   #5
Kirk Grodske
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Hi Brian,

I think we already covered the fact that you can do hybrid Kerdi showers, so why do you keep saying you can't?

There is the Kerdi Cooli hat, the tie the pan to the walls any which way you can, like overlapping the vapor barrier on to Kerdi with staples and then using thinset the rest of the way down, using Denshield and Kerdi- Band and Redguard, etc.

I do agree however, that if there are any niches, they probably have to be reworked, but if there are not, as long as he does the pan and curb it should last a good long while.
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Unread 12-11-2007, 08:55 PM   #6
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Quote:
Originally Posted by Kirk
I think we already covered the fact that you can do hybrid Kerdi showers, so why do you keep saying you can't?
Not sure just how you established that, Kirk. While it's certainly possible to use Kerdi and other Schluter products in non-standard applications, I don't think you could call what you're suggesting here a "hybrid Kerdi shower."

My opinion; worth price charged.
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Unread 12-11-2007, 11:46 PM   #7
iminaquagmire
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While I understand it would be best to have a completely Kerdi shower, most of the water will be in the pan and the first foot or so up the wall. A Kerdi tray and membrane that continues up the wall even a little ways would still be better than any hacked up and then glued back together pvc pan.
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Unread 12-12-2007, 12:07 AM   #8
Brian in San Diego
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Justin,

The problem is that you don't know how the walls were waterproofed so without knowing that there's no way to determine if the kerdi tray would work. If there is no waterproofing on the walls then water is going to get behind the substrate run down the inside of the drywall/cbu and end up outside the kerdi and tray...and Marty's right back to where he is now and he's invested time and money for nothing. Therefore I disagree with your entire theory and premise. In all likelihood this shower needs to be torn out. So suggesting a "solution" that will not work isn't helping Marty out. If Marty knows how the rest of the shower was waterproofed then perhaps there is a remedy but ask yourself this...if the guy builds a slope and preslope out of CBU and screws through the liner dozens of times what is the likelihood he waterproofed the rest of the shower properly? I feel really bad for Marty, but not half as bad as I'd feel if I offered up a solution that in all likelihood will not work.

Brian
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Unread 12-12-2007, 06:59 AM   #9
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Hey fellas,

This is not the place to get into an argument over which is the best way to rip out the lower part of the shower and replace it. One way or another that's what needs to be done. And to my thinking, an experienced fella like Marty will want to go ahead and replace the entire shower. Then he'll have an opportunity to do a whiz bang job right from the ground up.

As to "hybrid" Kerdi showers, they are not recommended nor warranted. Using the "hat" accomplishes a connection to a clamping drain only, and it's done primarily in commercial situations where clamping drains cannot be changed over. The rest of the shower, including the floor, is a total Kerdi shower. There is no recommendation whatever to go part way up the walls with Kerdi and then stop or switch to some other membrane. There is only one Kerdi shower, and it goes right up to shower head height all the way around.

I encourage argument, love it in fact, but take it to the Hangout, please.
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Unread 12-12-2007, 10:42 AM   #10
Kirk Grodske
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CX,

Meet you over in the hangout :-)

While I think we all agree that it is best to re-do the whole thing completely with Mud walls and Kerdi waterproofing for the best possible shower, there is not always room in the time or budget category to do this. If it leaks, it will show in his ceiling again before doing any major damage, just like it did this time.

I believe that, in a standard shower, only some water penetrates high up on the wall. The bulk happens and the corners and seams of the pan and curb. Fix those areas, and you have stopped the bulk of the water. Niches are another area of concern.

So tear out and redo the pan and drain and then in a 2-10 years do a total rework.
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Last edited by Kirk Grodske; 12-12-2007 at 12:55 PM.
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Unread 01-10-2008, 09:15 AM   #11
irish setter
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good thread

I think very valid points were made here about the incompatibility of bonded waterproof membranes with a traditional shower drain system, with the possible exception of using a membrane on the wall with a traditional floor. In this case that would mean a redo anyways so make a choice, choose your method and stick to it. Just remember though, no one individual is going to warranty your personal work on a mud shower because they gave you advice. There are a couple companies out there however who will
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