Your problem is one that so many people face. The question asked almost weekly online.

Read this first:

[WHY MARBLE MIGHT BE WRONG FOR YOUR BATHROOM[(https://www.houzz.com/magazine/why-marble-might-be-wrong-for-your-bathroom-stsetivw-vs~12133357)

I have been reading postposts like yours for years. I have also been looking into ways of improving the drain rate of water when it enters the section of the shower below the tile and grout. Trying to improve on older methods by older plumbers.

My new favourite approach is to use a drain mat by Schluter. Cut into strips and used in replacement of Candle Wick. My shower builds tend to look like this prior to the installation of the mortar bed and ACO linear shower drain. This is not a topical approach to shower building but rather the old school method - but with modern material choices.

This shower is using a 30 mil membrane and a clamping drain. The orange white suff is drain mat. I also used a weep hole protector in addition to the drain mat. Then a nice 2" layer of Laticrete 3701. Then the tile and grout.

So if water was to get behind the shower walls and run down under the floor tile. Look at all the road ways of clear space to the drain.

Maybe one day the TCNA or TTMAC will look into the spike in failing showers. Maybe one day someone will say that our cement is not the same - or that the additives and latex elements are ruining our shower builds. Don't hold your breathe. Changes like that will take years. I doubt they will ever take place.

Thank you for your input, and yes, I've read a lot of posts on this topic (including the 26 page staceyneil post on John Bridge). However, I can't seem to find the answers to my questions above. Can anyone help answer them?

If it doesn't dry out for five days then I should think it would be harmful, especially in terms of producing mold.

I have a porcelain floor in my shower and there is a kerdi membrance under it. There is absolutely no seepage either from top to bottom or from bottom to top. In fact, the water kind of beads and we can squeegee it down the drain.

Carrera and similar natural stone products will tend to hold water and turn darker, which is why I recommend against them in a wet environment.

If using a traditional preslope/liner/final slope, it is not unusual to have residual moisture collect near the drain....possibly because of clogged weep holes. The other area of moisture indicates to me that the final mud bed is, perhaps not sloped adequately and moisture collects there.

With a SAM (Surface Applied Membrane) such as Hydroban or Kerdi, there is only ONE sloped mudbed and the membrane sits atop of that...so that the moisture rushes out to the drain and the mud never becomes saturated. I seldom, if ever see your type of problems with this system.

First I would try to completely dry out those tiles to original white color, to speed up drying I would use torch to slightly time to time heat the spots.

Then I would seal those areas with a sealer, I would not just seal tiles according to a sealer instructions, I would pour and spread some sealer on tiles and let it dry on surface.

I know it may be too easy to be true, but it worth to try.

ABC Stone: the tile was sealed after installation. The time we let it dry out for 5 months, it was then sealed again. The gray areas showed up again within a couple showers.

Avanti Tile & Stone: is it possible to do a SAM now? Would that involve redoing the floor only or the lower walls also?

Dora's anyone know the answer to question 1 above? We have had no mold in the past 2 years...

Thanks!!

The mud bed is wet from the time you start using the shower until the day you bust it out. It is a water in - water out system. Excessive sealer will actually slow the evaporation process. As for question #1 If you can live with the dark spots (probably low spots in the mud bed) all should be fine. John's photo above is a great idea for evacuating water from the bed.

The difficulty in "after-the-fact" replacement of the pan with Kerdi or any SAM is the problem of tying it into the waterproofing system (if any) on the walls. CAN it be done? To a certain extent, yes. SHOULD it be done? In my opinion, a pan replacement should include a complete redo. Sounds scary, but, with the labour involved, it is not terribly much more expensive to simply gut the shower and do it properly.

A complete monolithic shower will last a lifetime, and I hesitate to just do an "interim" fix. As to the liability I incur when attempting this, "The last man that touches it, owns it." I don't want that liability.

"Creative Tile" said it. If you can live with the discoloration and stain, it will probably last quite a while.....

Avanti: what does "complete redo" mean? Do you mean take off all the tile from the walls and ceiling as well as the floor? Can a surface applied membrane just go on the lower walls and floor or does it need to be on the entire walls & ceiling?

Thank you very much

Might be possible to save the ceiling, but I would remove the floor & walls to the studs. A SAM is continuous from the floor up the walls. Trying to "tie it in" from the floor to a couple of feet up the walls creates a questionable area where one waterproofing system meets another. In the overall scheme of things, once you have committed to the floor, adding the walls doesn't add THAT much more cost to the project.

Avanti: our builder's new tile person just proposed to fix the shower by taking out the floor tile only, then putting on 2 coats of "Red Guard", then putting on new Carrera floor tile.

What is the danger of not tying in to the original waterproofing? Is there then cement in between two waterproof layers that is always wet and is that dangerous? Creative Tile said the mud bed is constantly wet.

Also, please pardon my lack of knowledge, but in a traditional non-SAM installation, what is the waterproofing on the walls and how far up does it typically go?

Thanks again for all your help!

"...our builder's new tile person just proposed to fix the shower by taking out the floor tile only, then putting on 2 coats of "Red Guard", then putting on new Carrera floor tile...."

Or maybe you could try a VooDoo fix.

Maybe pour some sealer everywhere and cross your fingers.

Of course with both suggestions I'm being sarcastic.

Your shower is leaking. Have you looked from below yet?

In a Traditional shower, you will have either lapped tarpaper or plastic sheeting attached to the studs before the wallboard goes up. This creates a vapor barrier to protect the studs from moisture that WILL inevitably work it's way through the ceement backer boards. With a SAM, the moisture never has the opportunity to penetrate them, so...less moisture and the shower dries out MUCH faster.

I think you can see the difficulty of tying together these two systems...

Do not pay Money for this redguard patch attempt.

Your shower pan needs to come out to the drain flange and be tied in properly and flood tested up to the curb and its corners..

The next hurdle in a Half repair is tying the walls back in with either a lapped poly behind cbu or topical SAM or thinbed waterproofing.. The key there is Tying it in (new to old)..... while meeting installation specs from both the MFG's and TCNA.

I fear you are about to waste more money and regret it.......sorry!

The leaking shower pan epidemic is in full swing maybe more so than ever with all the DIY kits being sold:

I had to turn down 2 Jobs for Leaking shower pans this week alone Both in the same city of Eden Prairie & were newer homes . Both of these clients were being sold on a cheap fast patch type repair like yourself...one that most if any real pros would NOT recommend or be able to stand by.

Likely the builder had hired a novice or the price driven tile installer to slap the showers up quick, had they been flood tested the new homeowners would not be going thru their scramble to a cheap repair.

Our shower is not leaking, everything is intact. I believe as Avanti said before that the issue is clogged weep holes and lack of pitch or low lying areas in the mud bed in combination with the marble tile revealing these wet areas.

I don't really understand why the waterproofing has to tie in together. If there is outer waterproofing below the mud bed and interior to the studs that is intact (and is this not the way most showers are constructed?) then what is the concern about having an extra layer of SAM in just a portion of the shower, such as the floor only or the floor and part of the walls?

Thanks again.

It looks like hard water build up to me. We also get it. But we have tile. CLR cleans it well. No experience with marble.

@rlew

Its hard for any homeowner to get all this .......

The likely problems needing correction: The preslope underneath pan/liner must be just right as that is where the water drains and is how it is directed to the drain " Underneath the mud bed!"

You likely as others and I have already stated have both or 1 thing going on. Clogged weep holes blocking water from draining "THRU the mud bed".

and a combination of:

If the preslope has any flat spots such as I predict in the upper shower pan corner it must be corrected to the extent of taking out the whole shower pan and re building it.

If its a thinbed shower the membrane comes out and the pan screeded fla to remove low spots in grading.

Its a lot to take in and I dont expect you to understand it ! it takes years to grasp these things for many.

The proper repair approach will be revealed when the shower pan tile is removed. A plan of redgard and 1/2 wall repairs is pre emptive at this point and not smart period. You can share a few pics when you start tearing out the pan tile and get to the drain.....

To simplify seeing it does not leak either live with what you have or rip it out and do it correctly.

Yeah......ain't no "Grey Areas," here.....

Okay, Avanti & Creative Tile! Yes, to simplify, either we do nothing or we do it correctly, which is......take out the floor & entire walls and redo with a SAM? Is that correct? (Right now we're leaning towards doing nothing.)

I am following your thread with great interest. I posted the same issue, https://www.houzz.com/discussions/carrara-hex-tiles-on-shower-floor-wont-dry-out-dsvw-vd~3124883 . Someone alerted me to your thread. I also had a spot not near the drain that dried within a week, and two on the walls that also dried quickly. My drain area circumference that is dark may not be at its peak yet, and it is dark on tiles up to 17" away from the drain opening. There is a clear circle of affected tiles, but many of the tiles are unaffected. It is odd to see a dry tile in the middle of a patch of darkened tile.

Could you please provide an update? Has anything new happened since you last posted?

Thanks.

Hello, this is staceyneil, referred to above with the 26-page John Bridge post ;)
I'm sorry to say that our shower fiasco has gotten even worse. The wet-looking areas in the shower floor are nothing compared to the fact that the shower wall tiles are all falling off now on the lower walls. I'm heartbroken. I'm just here to caution other people against using marble tile in a shower, regardless of how gorgeous it looks. Our beautiful dream bathroom is a total nightmare now.

Stacey, weren't your shower walls glass tile? I thought only the shower floor was marble.

Stacey, that is truly terrible to hear. My contractor has told me to start using the shower, which I have today. There are wet spots on the walls also. I am getting very nervous. Had your contractor thought the problem had been rectified? What is he going to do to fix it? Are you concerned about damage behind the tiles?

teri... id suggest using the shower a bunch if your contractor says too. This can really help confirm whats Likely happening.....

are the wet spots on the walls down at the bottom? adjoining the floor?

Yes and no, Tundra. I just showered again (twice in one day!) and the largest spot spans 4 subway tiles (2 each and 2 each underneath). There is a point where they do reach the floor, and then to the left of it there is a section of 2 subways with a wet area adjoining the floor. Then there is another on the wall with the fixtures where the hose hangs, about 3 tiles away from the floor. I'll try to post pictures.

Stacey: As a person who actually followed the 26 page thread on JB, I am so sad that your shower is not working out. Is anything being done to fix the problem of the tiles falling off the wall?

Stacey and Teri: I am so sorry to both of you, especially Stacey after all you have been through already with the shower. We never asked for marble in the shower. The kitchen/bath designer just spec'd it in and we had no idea of the possible consequences. We had enough going on with the million other decisions in building a home that we did not give enough time to the shower floor. I'm just glad we don't also have marble on the walls.

Our tile really took 5 months to dry out to the original color, so needless to say we don't love the guest bathroom shower enough to do that again. We are not going with the builder's fix. We are just going to keep using it with the gradually enlarging wet/grey areas and hope that it is just a cosmetic issue and does not portend trouble below.

Best of luck to Teri & Stacey. Please let me know what you end up doing.

imo, if the wet area is gradually enlarging you really need to find out what's causing that. Getting smaller, good; getting larger, bad.

"...The kitchen/bath designer just spec'd it in and we had no idea of the possible consequences...."

Most desingers have no clue how to set tile. How to prep for tile. What is required. I stopped listening to designers years ago. Now I work with builders and clients designers but I do not set any tile I do not want. If the designer says. I want a flush transition from the hall to the tile I act cheeky and ask how should I install that? I ask them questions like "So you don't want a crack isolation membrane and you are happy with tiling over the old plywood?" If they say yes then I ask them to bring in their tile guy and ask why am I here?

People think that tile men have the clients best interest at heart when the truth is most times they are looking to only please the builder or the designer since this is the source of their income. You need to be careful here. Some of the worst mistakes I have seen have come from the designer making stupid calls and the trades just following them.

rlew, as of now we started using the shower again and watching it. There are spots on the wall getting larger, but they are all within a foot of the floor where there is a Chloroloy liner, so I guess they are having trouble drying out.

The floor remains unchanged, although since it took several weeks for the water spots to get to such a large area around the drain after just one shower, I expect that it will get worse.

If I ever had to sell my house, nobody in their right mind would buy it. I need the problem fixed, but my contractor thinks it is just an aesthetic problem.

A quick plea to the pros out there: this hasn't happened on this thread or on my thread, but in my research I have come across other threads where the pros seem to fault the homeowner for choosing marble. As a homeowner who contracts out so that the work is done by professionals, it hurts a little bit to see that kind of criticism. We just want something nice that we have seen in magazines and other houses and are willing to pay the experts to do it. It is not our job to know about the ins and outs of bathroom construction ahead of time. When no one tells me no, I can't do that, or warns of any problems, then heck - I just paid for their expertise. It should be on them.

In my case, I picked the marble. I didn't have a designer; I just knew what I wanted. It looked beautiful until it got wet. This was my big splurge item, and it is heartbreaking to see it this way. Not to mention the anxiety of trying to get to the bottom of the problem and the stress on the contractor/client relationship.

The problem arises when you hire a tile installer for the labor only, after picking the materials, instead of finding the tile expert who will consult with you on materials. You're not hiring advice at that point. And you wouldn't take it if it were offered. No tiler is going to have a business long if he tells customers that he won't install their product because it sucks. Yet, that is what you want to happen. You cannot have it both ways. You cannot pick "magazine worthy" inspiration pics, without first picking the person that is capable of creating that photo shoot quality and who will advise you about how to properly go about that. Choose your installer first. Then your products.