"When we asked our builder about it, he said that that's what happens with marble and that once the rest of the shower and the niches (same material) are wet that they will darken too. "

When did that all get wet? Did he turn on the shower head and that is what he is saying made that round pattern? Has the tile been sealed and was it sealed when he potentially turned on the shower head? You could also test his theory out by pouring water on to another part of it and seeing what color it turns.

When you say mortar, are you referring to grout and grout lines? What color did you specify? I'd like it to match the rest of the shower.

I'd clear this up before closing.

Yes, they just turned on the head and that's what happened, according to him. We haven't wanted to pour any water ourselves as we don't own it yet and are not sure if we're allowed to, but it's looked like this for weeks. We're doing our "homeowner orientation" tomorrow, though, and I'll try it out in front of him - great idea.

The grout is Custom Prism #640 Arctic White - I'm referring to the stuff that sticks the tile to the wall/floor that you can see in the first pic.

This could provide some good education.

I'd play dumb and ask what brand of sealer they used on the marble and how often it should be sealed. Ask how long they had to wait for it to dry. Could be helpful in determining if they sealed it.

I doubt they sealed it. But even if they didn't seal it, it shouldn't stay wet and dark for weeks. I would not close on the house unless you have confidence that there is not a bigger issue with that shower.

What's the thing I circled? Looks unfinished

Honestly I would just throw water around and see if what he is saying is true. If he already wet it I don't see why you couldn't. You could easily see if what he's saying is true

That’s completed now, the circled part. That’s where the temperature or transfer valve is (can’t remember which one off the top of my head).

I’ll test getting it wet tomorrow when the builder is present.

I think the big question is when was it last wet. They’re not wrong that you’ll see a color difference in wet v. dry tile. But if this really hasn’t been wet in weeks, it should not still look like that. If they are still actively working on the shower, though, it’s possible they’ve been using the water in the interim.

Ideally you use white mortar with marble so it doesn’t bleed through and darken the tile, but as long as they used the same mortar throughout I wouldn’t worry too much. We have a marble curb and pony wall top in our shower and I carefully bought white thinset for that with gray that we already had for the rest. Tilesetter got it reversed and used the gray only for the marble. I caught it after the pony wall top was set but in time for him to redo the curb. I honestly can’t tell the difference (though of course those are thicker than tile).

Millworkman, would it be useful for Tova to pick up a $40 moisture reader at a hardware store to test the floor before more water is run on it? Do those read moisture in stone like they do on other surfaces? Would it indicate if the dark circle is still moist vs dry and stained?

What waterprooofing system was used? Do you have pictures of the build out of the pan? Because that is what it looks like when the weep holes are clogged. You have a wet area at the drain that cannot drain. Because marble is little porous sponges, it stays wet. And that skin soup below it starts to breed bacteria.

We have our inspector coming next week - is this something they can test?

" We have our inspector coming next week - is this something they can test? "

Not really, flood test needs to be before the tile are in as the water drains under the tile and you cannot see how well it drains. As Minardi also points out it could pluuged weep holes if the pan if properly sloped. But again no way to test it or investigate now without ripping it out. What was the waterproofing for the floor pan? The walls? What type of build is this (custom, semi-custom, developer/tract home)?

" Millworkman, would it be useful for Tova to pick up a $40 moisture reader at a hardware store to test the floor before more water is run on it? "

Not really it is obviously wet.

Agreed - this is water keeping it wet from below. :-(

If it were from running water above, I feel like it would be a smaller circle as most would fairly quickly go down the drain and leave little standing water on the tile to allow it to seep into the marble.

This would be especially true if the marble had been sealed - as this would help it NOT soak up moisture from the TOP.

If the weep holes are plugged, the water getting "around" the drain can't get "into" the drain and therefore starts to rise under the tile - absorbing evenly out in the circle you have there.

Not really it is obviously wet.

Obvious to us, but sounds like the builder is saying, "Hey this isn't wet, tile just looks like this after water has hit it once."

I have marble tiles in my shower and it was installed almost 6 years ago - how time flies :-)

I don't have any dark spots where the marble has absorbed water.

My shower was really built well and correctly sloped. I can even see the slope right around the drain although the rest of the shower is sloped more gradually but I can "see" the drainage because when I do hair stuff I sit on the bench and then often use the hand spray attachment at the end to rinse my hair and I can see the suds all quickly heading for the drain and then down the hatch.

Pretty obvious that water is "lingering" around the drain. This can be caused by an inadequate slope to the drain, weep holes are clogged, preventing residual water from escaping. Sometimes this can be made to "look" better by applying an enhancing sealer (once it actually dries out) I no longer like to do the "water in/water out" type of installs with a preslope, rubber liner, final mudbed and then tile.. I far prefer ONE mudbed, a topical liner like Kerdi and direct attachment to the drain flange. It eliminates your issues....but short of ripping it out and re-doing it...that ship has sailed.

Do you know what type of shower pan was built by your contractor? You need to know if there is a traditional mud pan or a pan that uses surface waterproofing.

As explained above, it is NOT normal for the tile around the drain to remain dark (= remain saturated with water).

Tile experts over on John Bridge tile forum have told many homeowners that they shouldn’t seal marble tile in a shower (it can actually cause the marble to ”hold” water in the stone - and remain dark - explained further below).

A few years ago, an expert (Pavlo Starykov) in tile installation wrote some articles after he conducted experiments re: the increased number of issues people were having with marble mosaic tiles darkening in shower pans. He constructed several different types of shower pans (using different vatiables) - and concluded that traditional mud pan systems (= water in/water out) were actually the best type to use when marble will be installed on a shower pan. The marble tiles dried out between showers instead of remaining dark (= saturated with water).

Of course, this assumes that the traditional mud pan is built correctly - many times contractors do not add the required pre-slope underneath the pvc liner (they simply lay the pvc liner flat on the subfloor - this causes issues because the pan will “hold water” due to the pvc liner not being sloped towards the weep holes in the clamping drain).

If a surface bonded waterproofing system was used instead of a traditional mud shower pan, water can accumulate around the drain if there is a low spot that circles the drain (different type of drain - so there are no weep holes = no potential clogging). Also, when marble tiles are sealed, water vapor will pass through the sealer, turn back onto liquid form, and then becomes trapped inside the tile due to the sealer.

Mr. Starykov explains that it’s better to use a tradtional mud shower pan in order for the water to not just sit underneath the marble tile (marble is translucent - and becomes dark when wet).

He also explains that if a surface waterproof membrane was used on the shower pan, six sided sealing of the tile + epoxy adhesive + epoxy grout works best to prevent as much water as possible from traveling through the grout/tile and then sitting on top of the waterproof membrane (he explains that even if sloped correctly, some water will remain directly underneath the marble tiles for awhile on the surface of the surface waterproof membrane - and will darken the tiles).

If you Google his name + marble tile, you’ll find the articles he’s posted re: the experiments I’ve explained above.

Custom Building Products has an information sheet (there is a more technical term for it) - that explains how six sided sealing can be done with natural stone - as long as the right setting and grout is used.

In any event, it is not normal. Marble will darken right after a shower, but should lighten once it’s dried out between showers.

Thank you, everyone, for your advice. I do not know anything more than what was shared, unfortunately, regarding materials, slopes, etc. used. I met with the builder yesterday and voiced my concerns. They'll investigate with the tile sub contractor and replace the shower floor if necessary. Really appreciate you all confirming my fears that there's something flawed. Hopefully we'll get to the bottom of it soon!

Glad they listened to your concerns and are investigating. That' great news.

@tova327 You should be aware that the waterproofing in a shower needs to be seamless and so it is often not possible to just replace the tiles on the floor as it will break the seamlessness between floors and walls.

At the very least you should raise this issue with them in terms of remedying it

Thanks, elcieg! It does look like my floor! Once we close on Thursday I'll try cleaning it with that stuff.

Quick update: the inspector took a look today and confirmed what the builder said, that it's cosmetic. We'll keep an eye and come our 11 month inspection see if anything changes. A good cleaning might just be the solution!

" the inspector took a look today and confirmed what the builder said, that it's cosmetic. "

How did he confirm from viewing the shower that it is cosmetic? Is he putting that in writing? Does he guarantee that? What kind of guarantee did the contractor give you? I still have my doubts.

@elcieg Maybe I am missing something but the tiles looked the same after the cleaning as they still have very dark tiles that looked discolored.

Do NOT close on a home with a fundamental build defect. It will then be out of your pocket to resolve when it only gets worse, and the year's labor warranty is over. Push back closing until this is resolved. It won't be the only bath with an issue.

Agreed that closing on this home will lose you money. You will have an improperly built shower and, of course, the builder will keep giving you excuses until the year’s warranty is up. The tile in a shower is just for show. It is not waterproof. The stuff under the tile determines if the shower is correctly built. When it remains wet under a tile, there is a problem. You are lucky that marble shows this to you clearly. Other surfaces would not show it and it might be years before you discover that a bad shower build has rotted your walls or floor joists. The experienced people here have told you two possible issues. Shower drains have little holes around them, called weep holes. They let any water stuck under the tiles drain into the drain. These holes are easily plugged up if a careless or inexperienced person makes your shower. Another issue could be that there is not enough of a slope to your drain and your tiles have water stuck underneath them that cannot drain to the weep holes because of not enough slope. A flat shower floor will hold water under the tile. How does water get there? Tile and grout are NOT waterproof. Minuscule amounts of water get underneath and need to drain away. You can clearly see this is the case because your tiles are wet. They are sitting in water.

Did you find out how the shower pan was constructed?

How can an inspector confirm what the builder said - that it’s cosmetic - without knowing why water is sitting in the pan = causing marble tiles to be dark because they are SATURATED with water??!!?!?

Who is this inspector? Is it someone that the builder claimed came and looked at the shower pan? An inspector from the city will not confirm something like this. So, it begs the question - who is this inspector - and what are his/her credentials? I am 99.99% sure that the inspector is not an independent third party (the only reason I’m not 100% is because I don’t have enough information to actually state that I’m 100%).

Please don’t let your builder talk his way out of this - if your shower pan has been built correctly - marble tiles installed on the shower pan will not hold water. They will darken while the shower is being used - but will dry out beween showers.

That niche is pretty low to the floor. Make absolutely sure it is well grouted and caulked up because it'll be prone to leaking with all the water exposure. Check it once a year for sure.

It was a third party inspector that we paid to look pre-foundation, pre-drywall, blue tape, and final.

I raised my concerns to my builer again and this was his response:

To me it is holding water which is why the tiles are still wet 6 weeks later. And weep holes are at the drain and absolutely they need weep holes.

Amazing the amount of wild guesses and just plain wrong assumptions. This happens with marble tile not because the marble isnt sealed but because modern waterproofing methods waterproof directly under the tile. Water gets through the grout (grout isnt waterproof) and then sits near the drain until it slowly evaporates without use. This is not a waterproofing defect and in fact will happen with every shower that is waterproofed on top of the mud bed. The only way to avoid this with modern waterproofing methods is to use pasha starykov's epoxy method developed specifically for this situation as the problem only became a thing recently as tilers have switched from water in water out mud beds to fully waterproofed mud beds. Essentially the marble must installed into epoxy adhesive instead of thinset, sealed twice with Bulletproof brand sealer, and then grouted with epoxy grout. this allows very little water behind the tile and any minor amount is still allowed to evaporate through the bulletproof. This shower could have happened to anyone and is not a waterproofing failure just an eye sore. The person that said the caulk and grout must be done well to hold water has no lcue what they are talking about. grout and caulk are not waterproofing materials.

" Amazing the amount of wild guesses and just plain wrong assumptions. "

MoBA Construction Amazing thing is you searched for and dug up a 2 year old post for that diatribe on a long since finished project.

A spot that stays dark for weeks while the rest of the stone has dried is a moisture problem, not just the stone's normal variation. A simple check is to tape a square of plastic wrap over the dark area for a day: if moisture gathers under it, water is coming up through the stone or the setting bed. Before the walls are closed, ask for a flood test of the pan and a check of the drain connection, since even a few hours of standing water there will show what the tile hides.