Hey there,

What a bummer - sorry to hear and see it! Could it be an insufficient liner slope in a few areas causing the problem? Seems like that might be the case?

Vanessa

www.studiomatsalla.com

I poured a self-leveler on the sub floor of the shower stall, then installed a pre-sloped Schluter shower tray. Don't know if you're familiar with that company, but the pre-formed trays are manufactured with perfect pitch. There is no traditional vinyl liner/mud job here. The trays are coated with Schluter Kerdi, a 100% waterproof membrane. Pitch is not the issue.

Try over at the John Bridge Tile Forum. Lots of knowlegable tile guys there.

http://www.johnbridge.com/vbulletin/

Did you consider plugged weepholes or "birdbaths?" ......might have to remove the floor to figure this out. Ugh!

There are no weep holes to get plugged up. The linear drains are Schluter products as well, and they tie into the sloped tray seamlessly. There is literally nowhere for the water to go except down the drain.

How about a plumbing leak related to shower itself? Behind the wall, percolating through?

Walls and floor are completely waterproofed. If there was a leak behind the wall you'd never see it on the shower side. The stone was sealed by me, not manufacturer. Thx everyone. Trying to eliminate all installation possibilities.

I've seen this before on other white marble. I'm sure it's not your installation and has to do with the porosity of the stone. Talk to those tile guys as recommended.

Adam

I'm out of Danbury CT.

I'm very familiar with all of the products you have used. I use the products weekly. It sounds like you did a great job.

I am also familiar with this type of issue. Basically water has gotten into the underside of the stone through the actual stone or grout lines. The dark spots is water under the stone. It's a lack of sealer/inconsistent sealer/penetration through sealer type issue. It is a porosity issue.

There's a few ways to deal with it.
I will talk to my staff and see what the last best method that worked for this situation. But if memory serves me right it was just remove it, re set with good modified thinset and seal the tiles very well.

I'll be in touch

Our shower floor did this too, we have the Carrara marble in a herringbone pattern. I was worried about a leak somewhere and had all the contractors make sure there wasn't. After a few months it stopped. I would give it time if you are certain there are no leaks.

we're you able to resolve the issue? I'm now facing the same issue.

Would also like to know what happened...

I had forgotten I even posted here, but my problem was resolved after the installer removed the grout and installed silicone where the wall and floor meet. He was supposed to do that during installation but didn't.

Thanks Yolanda

So you mean he didn't put silicone caulking where the wall and floor meet? Is that why the floor was wet under the tile? Was your tile floor marble also? And how long did it take to dry out?

Thanks so much!

Hello,

If your shower pan is waterproof, has the right slope and you made sure you had a very good mortar coverage, then I can tell you with a very high certainty that the cause of your shower floor discoloration is the penetrating sealer. It simply does not allow your stone to fully breathe and moisture is just trapped inside of it.

I am doing "Marble discoloration in wet areas" research and experiment and you can check all the info at the following link: http://startile.us/tiling-by-the-book-blog

Feel free to contact me if you have questions. I believe your shower can be fixed without reaping it out.

While respecting Star Tiles point of view. I recently called the NTCA trainer to find out where the TCNA technical committee stands on this topic.

The complaint about discoloring of natural stone on shower floors has become so common that TCNA (Tile Council of North America) has placed a cover letter in its Reference Manual. To summarize. No one is to blame. There is no way of knowing which stone will show this. It is the risk you take when using natural stone in a wet area.

It can happen with a water-in / water-out system (mud job w/liner) or a bonded system (topical waterproofing).

Sealers are not the solution.

Simply buyer beware.

Star Tile. Please keep me updated on testing. This is surely a issue in the field.

Current TCNA, NTCA and NSI stand on this matter is the very reason why I am doing this experiment. Many contractors who already fell into this problem have absolutely no clear answers on why it is happening and how to fix it. Can you imagine a contractor who reaps out a newly installed marble floor and then re-does it just to have same results?
By the way many great professionals from all over the country already told me they install marble in showers and don't seal it and they never have problems. They just follow the same idea that marble was successfully installed in Europe and Turkey before impregnators were introduced as a good "shield" from moisture in wet areas.

No arguments with that thought process from me. I'll be watching. Feel free to reach out to me with any results.

Thank you for your understanding! We are probably only 30% done with our testing. I am planning to keep posting all the information at Houzz. You can just follow me to get notifications about new posts.

@ mjammjam I am just realizing I left out a key point in my initial response. Not only was my tile (marble mosaic) showing water stains, but the shower was also leaking. So, using silicone in the joints stopped the water leaks, and I assume attributed to no more water stains. In addition, the installer did apply additional sealer.

Anyway to fix this without tearing out the floor?

It is a case by case issue. It would be helpful if you could provide the following information:

• the type and name of waterproofing system (is that Schluter system with a tileable grate?),
• the exact name of thin-set mortar,
• the exact name of grout,
• the exact name of sealer if the floor was sealed.

Hired a contractor to do the job. I know he poured the pan. Used plastic and then formed a pan out of concrete. Not positive on thin-set. Whatever Home Depot sells I’m sure. Grout is from the Tile Shop superior pro grout unsanded. No sealer.

Thin set was superior from the tile shop too. Sorry! I bought it for him. And additive was added to grout rather than water.

Is the waterproofing membrane installed right bellow the stone or it is under the thick-mortar bed that the stone is installed on? That darkening on the floor simply indicates trapped moisture. There is a chance that the installer didn't properly do the preslope if he used the traditional waterproofing system also known as water-in water out.

Waterproofing membrane was installed under the mortar bed. Here are a couple of in process photos.

Hello,

Bellow is the link to my recent article that summarizes the research we have done on the subject of marble moisture discoloration in shower floors:

https://www.houzz.com/discussions/5956434/marble-moisture-discoloration-don-t-blame-the-stone

@Star Tile - Thanks for following up with the test results. Greatly appreciated.

Hi Betsy,

Maybe Star can chime in and confirm, but it looks like your installer didn't properly apply the waterproofing membrane. The ENTIRE installation needs to be red, not just the seams. The red membrane should be about the thickness of a credit card. Usually installers cheap out on this because 1 bucket is much cheaper than 3. Your installer should be completely liable for replacing this. Trapped moisture=mold. This install will fail and cause you more headache if you don't fix soon.