Could it be efflorescence? https://www.tcnatile.com/faqs/31-efflorescence.html

That looks like grout haze washing out. Give it a few more showers.

Thanks for the comments- After reading about efflorescence, I don't think its that as there is no dry residue. After the tile dries (about a day) the white disappears and the tile returns to grey like the perimeter.

Joseph, how long does the washing out take usually? We have one other shower with the penny round in the house, I sent my husband to take a shower in that bath as I am not yet living in the house.

Do you think this is due to the larger amount of grout due to the penny rounds?

Helene

mihelene:

There are folks here with much more tile knowledge than I have. Hopefully some will give their theory.

I agree , that's very strange , unless they colored the grout with pure white cement portland. Let's not assume .

Could you post a photo with a dry version of the shower floor and then another one with water running on it / wet floor ? 2 different ones excluding the one shown above .

I sent my husband on a photography mission but its not exactly what you asked for.

Below is a pic of the same shower floor as above. The view on the left is the floor immediately after a shower- the view on the right is the same shower floor 60 hours after showering. The white area is receding but still there.

I have a picture of that same shower floor just after install but it is too far away to be helpful. The floor color looks the same as the perimeter area in the photos above.

The same thing happened in the upstairs shower, which has the same tile and grout. This is 36 hours after showering. I have no pictures while the shower is running, the one on the left was just after install, the one on the right 36 hours after showering.

Any thoughts?

Hmmmm....... So 2 different showers , I suppose constructed similar , with 2 identical floors , having the same issue . What was the grout used ? Name of the grout and manufacturer .

What sealer was used , if any?

Alright , one more Q , is there any residue present on the grout ? While you have the wet surface -- color of the grout turns white -- pass a soft brush over the grout and see what is happening . It would be interesting to know what your installer is saying about it , did you asked him ?

Is it possibly a urethane grout? It has a milky appearance before it's cured and it's got a kind of long time before it's ready to be wet. I'm wondering if it could be urethane glue leaching out, then drying again that you are seeing. I do hope this isn't the case... getting urethane grout wet before it's fully cured can compromise it.

Well the mystery continues. My DH had the tile installer at the house this morning and he's been tiling for 30 years and never seen this before. They were not sealed so we are going to let them dry out completely and then seal and see if that solves the problem.

I am not at the house so i am unable to answer all your questions regarding grout brand, type, etc. I'm pretty sure it was just plain old grout!

Just got a text from the GC and its was not urethane based. The tile floors were completed back in September so they have had plenty of time to dry/cure.

Wrong type of crete used for pan. Latex containing.....

A. Re-emulsified adhesive (mastic or similar bucket grade )

B. Latex leaching from non submesible grade thinset.

C. Some new age grout not allowed to cure or overmixed, OR...old grout that was out of date code/exposed, contaminants in grout water or while grout in process...drywall dust etc

D.One of the body products you are using........

E. High calcium water content causing efflorecense..

F. Dunno but youve peaked my interest

I'm leaning toward latex migration. Do we know the type of waterproofing system used? If a sheet membrane was applied and latex were to be added to thinset that would be a problem. Without knowing the actual method and products used it is impossible to pin this one down.This thread has captured my interest also. Your installer is the only one that can provide the needed information. Folks above have provided many good scenarios but we are all speculating. The residue question has been asked a couple of times without any answer. None, chalky, rubbery or other? I think we have all hit a wall without all the facts.

I won't be at the house until Thursday 12/8- I will get more complete information on the waterproofing system, the actual grout, etc to answer your questions. There is no residue once the grout returns to its normal color , but he has not tried to wipe off the white discoloration while wet, I will ask him to do that again.

Ok, husband just checked areas that are still white and rubbed- there is a "chalky" residue. When he rubs he can not get down to the grey colored grout- in the corner areas not affected by the discoloration there is a slight chalky feeling but not as much as the white areas. The downstairs shower was completely back to grey this morning. He took another shower this morning and there is no discoloration now. He will check this afternoon to see how it looks.

Thanks for your continued interest in our saga!

So , what are you saying Helene , '' the problem '' observed on the pictures is '' correcting '' -- disappear-- itself ?