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-   -   HELP! Water under marble shower floor (https://www.johnbridge.com/vbulletin/showthread.php?t=128349)

Jepjep13 12-03-2019 04:26 PM

HELP! Water under marble shower floor
6 Attachment(s)

We recently finished our master bath shower after gutting it to the studs and removing the fiberglass shower pan. We chose a porcelain “marble look” 12”x24” tile for the walls, 2” Carrera marble hexagon on the floor and in the back of the niche, and solid marble for the dam cap and niche shelf and trim.

I first filled in the gapping hole around the drain in the foundation with concrete that was hidden under the fiberglass shower pan.

Built a curb out of 2x4’s and scabed in 2x6 pieces in between each stud

Set the drain and packed a dry mud base for a presolpe.

Put in the rubber liner, siliconed to the drain and installed the locking ring and water tested it.

Packed in the dry mud mortar bed and used stucco mix and wire for the dam, putting pebbles around the weep holes of the drain.

Durarock the walls, filling all screw holes and seaming joints with webtape thin set

3 coats of red guard on everything down and out to 1” around the outside of mud bed.

Tiled the walls starting with the second row, then laid the floor and dam cap, then the bottom row of tiles.

Grouted everything with bostik hydroment vivid sanded grout that is supposed to be good down to 1/16 grout joints. Waited 72hrs per bostik to seal

Used 511 sealer on everything, waited 24hrs and repeated, waited another 24hrs

Set the frameless shower doors and everything looked great!

Then we hook half a dozen showers and I could see water being retained under the marble floor. We took a few more showers and it spread.

I searched the around the web and found about the exact same thing here:


Although it was seemingly repaired it unfortunately did not state the cause.

We have obviously stopped using the shower and I have a heater running in there to hopefully dry it out and hopefully the tiles will go back to their lighter, original color. If so, my question is now should I grind all the grout out and regrout with maybe epoxy or start pulling up tiles. I hope that is enough info and I will try to post all of the pics I have. Thank you for any assistance you may provide. James

speed51133 12-03-2019 04:31 PM

it may be the nature of the beast with marble. This issue comes up time and time again. One of the reasons why real marble is frowned upon, despite it being in all the instigramz.

I would not blame your grout. Grout and tile, ESPECIALLY marble, are NOT waterproof. If anything, marble is very absorbent. Your preslope or final slope MAY have a puddling spot in it exacerbating the issue.

Jepjep13 12-03-2019 05:29 PM

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Thank you. And yes I have heard that about marble but others say it’s notbthat bad, idk. Water seems to sit on the marble dam cap just fine but it’s 5/8” thick too;) Where the discoloration is around the drain is where the water puddles some when showering as it’s going down the drain, I don’t know what would be considered excessive, but there is no standing water within seconds of turning the water off. The hydroment was stiffening up when I was doing the floor so maybe it’s faulty and passing too much water, that’s what I feel it is. The floor grout now has some micro cracking, but these are the only cracks I can find. This shower was used for the first time less than 2 weeks ago. I know some of the cheap marble may be more prone to being porous but I think it’s going through the grout too quickly. In some areas on the wall grout it will really not absorb water and change color, in other areas it’s immediate.

Also, when we took the last shower, water was being expressed out of the grout around the drain 12 hours later, it dried up within the following 12 hrs sometime to point where it was not wet to the touch. Seems like it should be going out the weep holes more so than the surface around the drain.

jerrymlr1 12-03-2019 06:23 PM

Was redgard applied to the shower floor? The cracks in the grout would indicate some kind of movement IMO. Does everything sound solid? No hollow spots?

speed51133 12-03-2019 06:44 PM

Was the floor waterproofed??

Jepjep13 12-03-2019 06:49 PM

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Everything is solid as a rock.

There is no surface water proofing other than red guard coming about in inch or so off the wall. See pic. The only other thing, and I don’t have a pic of it, is that I skim coated the floor with thin set and when dried I sanded it smooth with an orbital sander but afterwards I can’t imagine any of it being very thick as I went back to mortar in several places, wanted to eliminate any minute bird bathing

The area with the cracking is circled in yellow. There was a small void under the green tape as well, my fault, and I believe that is why those tiles went dark. When we continued to use the shower I put frog tape over that void and that area seemed to lighten as other areas darkened and spread. This is another reason I believe this is an excessive grout penetration issue.

But if water is expressing at the grout around the drain for over 12 hrs I am concerned about the weep holes too.

speed51133 12-03-2019 08:14 PM

did you test and measure both the preslope and final slope for proper slope and consistency?? Is the drain set too high in the mortar bed?

Your issue is NOT water getting "under" the tile through some crack in grout. Water soaks through the grout AND tile.

Davy 12-03-2019 08:19 PM

How did you make your dry pack, what did you use? The grout is not the problem.

Tool Guy - Kg 12-03-2019 08:36 PM


Originally Posted by speed51133
Soo.....how did you waterproof the pan??????

Was there a liner?

Mike, he’s got a liner and 3-piece clamping drain. Take a look at the 4th & 5th picture near the top of the thread to see the drain and liner.


Originally Posted by Jepjep13
...I have heard that about marble but others say it’s notbthat bad, idk.

Any installer who says it’s not too bad hasn’t had the pleasure of the problem. But the problem is very real. And it’s very unpredictable. The unpredictability is the key problem.


Originally Posted by Jepjep13
I know some of the cheap marble may be more prone to being porous...

No, not really. The same good quality stone from the same quarry sometimes is good and sometimes problematic.

From the way you’re describing the grout getting hard on you as you finished, the little cracks, and the varying display of porosity, the grout may be contributing to the problem, but isn’t the main problem. Can I ask a bit about your grout? As the grout was stiffening, did you add a little bit of water to soften it up a tiny bit? I ask because properly mixed grout will be homogeneous. And if the parts that are absorbing additional moisture are the same parts that had a little water added to the mix, that would help explain.

Also...what did you do, if anything, to protect the weep holes?

But one problem is very clear: your stone is absorbing moisture. So, even if the grout was 100% non porous (which non are), it certainly looks like you’d still have something of a problem.


jadnashua 12-03-2019 08:39 PM

Thinset, tile, and grout are all less than waterproof. Deck mud, OTOH, is pretty porous, so moisture SHOULD pass through it fairly quickly, the others, less so, but still potentially noticeable. How thick was the thinset you used on top of the finished slope prior to adding the thinset and tile at the end?

THat thinset layer could slow the water getting to the weep holes as it's less porous than the deck mud beneath it, potentially holding that moisture longer.

Since marble is a natural substance, the quality and performance issues will vary between not only types, but also from where in the quarry it was mined. Smaller tile like on your pan, could have come from multiple locations, thus, they could respond to being wetted in a different manner.

Sealers don't actually block moisture. They are designed to help slow down the absorption of stuff, giving you a chance to clean it up prior to it sinking in far enough to permanently stain.

Some grouts are more water permeable than others (most epoxy grouts are nearly impermeable). Cement based one, much less so.

Industry standards call for changes of plane and material should have a soft joint. In a shower, that typically is done with caulk. Grout often does not fare well in those locations. The alternative is to use an engineered profile joint, but that adds to the initial costs, and people often don't want that expense (often will end up seeming cheap when the caulk needs to be dug out to refresh, though, maybe many times over the life of the shower!).

Jepjep13 12-03-2019 09:34 PM

6 Attachment(s)
Here are some pics of the slope.

Facing the shower head - about 29” from wall to center drain with a good 3/8”+ fall

Rear wall to center drain 29” with 7/16”+ fall

Left to center of drain 11 1/2 with 1/4”+ fall

Right wall to center drain 15 1/2” with 1/2”fall, yeah I know the drains off center

A little flat on the long sides I guess

I used Portland cement and sand in 1:5 mix I believe , but I did pack the hell out of it.

As far as the thin set skim coat or float coat I would say would range from 0-maybe 1/4”

As far as the grout stiffening. Yes it was getting clayish and may have had more water introduced to it to some degree, the directions stat to wipe water over the tiles as you grout. It was really sloppy in the beginning, oh and I did break the bag into 3 batches

I protected the weep holes with a bunch of gravel

Kman 12-03-2019 09:51 PM

Kurt, he mentioned in post #1 that he had gravel around the weep holes.

James, my opinion, and we know what that's worth, is that the water is very slowly draining out through the weep holes and through the mud, and it's just always going to be that way. That's assuming that the low end of the liner around the drain is above the weep holes, so that it can drain properly.

If I could have steered you in a different direction early on, o would have told you to use a surface-applied membrane rather than a PVC liner.

Would that have solved the problem? Maybe. I don't know. But I think you'd at least see less of what you're seeing now.

My advice at this point, is to not look at it. :D

Seriously, I don't know anything you could do to fix it.

Jepjep13 12-03-2019 10:49 PM

I think it will just become too saturated at some point to the degree it causes damage in some fashion. I just don’t think I can look at it and watch it continue. I really feel that the grout, especially around the drain area, is just letting an excessive amount of water through. I see my options as:

1. Wait to see if the marble around the drain lightens up as some areas have. Hard to do when it’s been raining for 3 days straight. Then cut out the grout and either regrout with what I have or probably go with epoxy.

2. If the tile doesn’t lighten up, break those dark ones out and repair/replace and cut the grout out of the rest and regrout. Again probably with epoxy. Could test the mortar bed for water absorption and recovery while I have it open. If I went this route do you think I could chip down to the locking ring and inspect the weep holes?

Did anyone read the linked thread. Same situation and the installer said they removed some tiles and let it sit open for something like 24 days and the tiles right next the ones they removed, the tiles never lightened and was still positive for moisture after all that time. He pulled up the whole floor, and I believe applied a topical membrane and regrouted and did not seal it.

speed51133 12-03-2019 11:34 PM

Again, your issue is not the grout. I would not fixate on it at all. Grout can be underwater 24/7. Getting it wet doesn't matter. Even missing grout is not your problem.

jadnashua 12-03-2019 11:41 PM

First off, your slope does not meet the standards...it's a minimum of 1/4"/foot. The first one was almost 2.5', so 5/8" drop or so, to what you stated as 3/8" assuming I read it right.

THen, replacing the grout with epoxy might help, or hurt things. For any moisture that might have gotten through, there are probably three paths to get rid of it: back through the grout, out the tile, or to weep out the weep holes. Using a nearly impervious grout might prevent that path for moisture to escape. Water wants to go towards dry areas, and gravity helps, too. So, if more water goes through the tile than can either be wicked away underneath or evaporate out the top, it will build up.

Were there any dips in the preslope, and, did the WHOLE pan drain after you did the water test, or were there pockets of water left standing?

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