Is there a shower in the tub? What is behind the tile in the way of substrate and waterproofing? Looks like water seeping up at the tub/tile joint line. Silicone caulk at that joint line?

yeah, There is a shower in the tub. Behind the tile is concrete board. The contractor had mortar grout? I guess. I am asking him to come back to put silicone caulk at that joint line. Only that piece is showing the water mark.

Is that porcelain or ceramic tile? My understanding is that porcelain is pretty much impervious to water so should not be doing that even with a faulty installation?

It is porcelain. I was surprised too. Talked to the boss of the tile store. He said he has seen something like that before. I have a light color glazed surface so I am able to see throught what's under the surface. Water got absorb at the back of the tile. With a light color glazed tile, I can see it. Basically, he told me to add silicone caulk at the joint line.

But porcelain should only absorb less than 0.5% of water so I’m still not understanding why this is happening. If you know the exact specs of your tile they should show the tech specs with water absorption ratings. That photo definitely looks like a significant amount, not close to zero… And wouldn’t adding silicone without drying it out just trap the existing moisture in?

Actually, I washed that area with some bleach and washed with some water. So I let it seep some more water. Yeah, you right. porcelain only absorb less than 0.5% of water. Maybe that piece is bad quality ?

Well, I have seen newly installed tile with dark spot on them after the contractor use the spot adhesive method to install tile. So a faulty installation can still ruin a tile.

any Porcelain tile expert here?

Cement board is not waterproof so unless he put poly behind or a topical liquid waterproofing over it there is no waterproofing.

Not sure if he put poly or topical liquid. My father was checking over on him. Well, Let's say if he didn't put those. So you are saying, at this point, we have to redo the tile ? Take the tiles out and redo?

even Silicone caulk the joint is not waterproofing ?

Grout is not waterproof. the silicone will seal the gap but water will still get past the tile. Cement board alone is not waterproof and will will pass thru that as well to the studs / insulation, whatever is back there and not really dry out. Up to you whether or not to redo the tile just be on notice that there is nothing you can do to waterproof this after the fact.

I think I’m still bothered by the fact that this is happening to porcelain. Waterproofing issues aside, porcelain tile should not be absorbing water even if submerged. Is there some way to contact the tile manufacturer and have them take a look? I had three similar tile samples - one ceramic with an absorption rating of <20% and two porcelain - that I left partially submerged in water overnight. No stains. I can’t imagine that spot by the tub getting a larger amount of water than that. Something just isn’t right.

What kind of surface are those? Matte finished or glazed?

Those are all polished

Back to millman’s comment, My father confirmed they used waterproof board behind. Not sure if it is poly but I will find out. Actually, I was there before they put the tile up. I saw what was under but didn’t take photos and didn’t pay much attention to it. What if I wait 2-3 years for a tile redo? Doable? Are cement boards cheaper than poly waterproof boards? If the contractor wanted to trick me and got me something else , I wanna know why. Just wondering.

Recordaras, maybe I got the fake porcelain tiles? Lol. I don’t know. Let’s continue to watch what is happening next.

Do you know the manufacturer? I’d try reaching out. Wondering if this could be a bad batch? So sorry you are having all these troubles - we’re starting our bath remodel in a few months and I feel like you never know what you’re getting into till the work is done.

Recordaras, I already throw away the boxes. Let’s see if I can get the info from the store. Maybe you can try splash some water behind the tile. Maybe submerge it doesn’t replicate the same effect.

Recordaras, the manufacturer is ECOCERAMIC. They are from Spain.

I know there are a lot if great tile manufacturers in Spain. I’d send them that photo and ask if this is normal

Through body porcelain vs porcelain glaze. I have seen this with glazed. Never solid porcelain. Not all imported porcelain meets ANSI standards.

Porcelain Tile Certification Agency (ptcaonline.org)

Recordaras , https://www.ecoceramic.es/index.html. That's their website. I think they only speak Spanish.

Creative CT, So only American made tiles meet ANSI standards?

Recordaras, try splash your sample tiles with bleach. see what happens. I did splash it with bleach and it darkens the water marks.

"So only American made tiles meet ANSI standards?"

Not what I said at all.

@Creative Tile Eastern CT do you have an explanation as to how/why this is happening? I always assumed that since porcelain barely absorbs water this would not be an issue (I’ve seen many photos of similar problems with marble though).

@Sam tried bleach and it just ran off the tile samples, no discoloration or any other effect on the tile

Yeah, because marble is stone which is porous

But is it a problem or we can live with it few years? Does it affect the longevity of the tile or tub or the bathroom?

Hey sam, what ended up happening with this? I just finished a bathroom reno a couple weeks ago and I noticed the same kind of thing on some but not all of my vertical subway tiles on the edges in certain areas of the shower. I noticed it after a long shower.

I waterproofed everything behind the tile, used hardibacker with redgard and a quality modified thinset as well as one of the best grouts on the market (can be used in pools)

Did you end up leaving it? Is it still holding up?

I added the silicone caulk on that edge. It seems like problem solved. Tiles are still good.