Help- tiles popping off shower walls

[JgWash]

We built our shower 5ish years ago. It is 3'x4' corner shower with sloped mud bed with curb on 2 sides, pvc liner running up walls, sloped mortar, small hexagon floor tiles and sanded grout. The walls are tar paper that overlaps the pvc liner, durock wall board, thin set (modified) and ceramic tile 4"x12" and unsanded grout.

There was a spot where the glass wall met the curb and the outside bathroom wall where the tiles were coming loose. We took off the glass wall and popped off the loose tiles. The duroc is very wet and the thinset is only set-up around the edges of the tiles. The center is a creamy substance, like the thinset never set up. As we move up the wall the tiles are more firmly adhered but still not set in the middle and the wall behind is dry.

So it seems like we probably have 2 problems- (my best guess)
1. We used the wrong thinset and it was never able to cure due to no air in center of the tile.
2. There is excessive water getting to through the grout- bad seal at corner?, I am not sure we ever sealed the grout either.

So which is the primary problem? How do we ensure this doesn't happen again?

Thank you for your time

[cx]

Welcome, John.

For some clarity here, "thinset" is a method of setting tiles, not a material.

Can you be more specific about the product you used to bond the tiles? Brand name, make and model.

Was it dry in a bag and mixed with water? Out of a bucket, ready to use?

Photos of what you're looking at might help, too.

1. In five years, any polymer modified thinset mortar would have cured and dried all the way to the center of the tile whether you wanted it to or not.

2. Water intrusion behind the tiles should have no effect upon the bonding mortar unless it was actually an organic adhesive, but if that were the case I would expect it to fail on the entire back of the tile, not just the center.

Sealing, or not sealing, the grout would have nothing to do with the problem.

Let's start with my first question and work from there.

My opinion; worth price charged.

[JgWash]

Thank you for your response- it is not making sense why this failed to set. Here are some pictures.

The tile mortar was mapei- ceramic tile mortar- polymer enriched, dry powder we mixed up.

[cx]

Help me some more here, John. The back of the tile in your hand. The white material is the thinset mortar that was not properly cured and still wet? The tan/brown material surrounding the white material is the face of the CBU that pulled off? Or am I misinterpreting the photo entirely?

[JgWash]

Yes! The tiles at the bottom had more of a creamy appearance in the center, it was actually still wet, those at the top were more dry and powdery in the middle of the tile- the tile in hand was more towards the top of the removed section.

[cx]

Well, let me be the first to admit I got absolutely no eye-dee what you have going on there.

I shall try to summon a MAPEI rep to look in on us, and I'll be very interested in what he might say. Likely hafta wait 'till next week, though.

[JgWash]

Thank you, I look forward to hearing what they have to say.

[Kman]

John, did you scrape the excess mortar off the tile and wall? I'm asking because there doesn't appear to be much left on either, and not a hint of any notching.

I wouldn't expect to see notch marks all over, but here and there.

[Kman]

Additionally, I don't know that it matters for the purpose of your question, but did you butt the tiles up to the wood post I see just outside the shower?

And how was the curb constructed?

[JgWash]

Yes, we did scrape the excess mortar off the wall, not off the tile.

The tile extended past the glass wall we removed, behind the structural wood post you see (there is space behind the post, it was not actually touching the tile)

[Autoplay]

You stated you used thin set modified etc. You positive about that? Could you be mistaking mastic,which comes in a bucket, pop the lid and start spreading?

Never seen wet thin set like you described,along with pics. ESP 5 years later. It woulda been wet like that from day one.

[cx]

Originally Posted by John, Post 3

The tile mortar was mapei- ceramic tile mortar- polymer enriched, dry powder we mixed up.

Appears he knows what he used, Rich. Makes it even more perplexing to me.

[Davy]

Yeah, this is odd. Just want to confirm, the webbing I see around the edges of the tile in hand is from the cement board, correct? Is it the actual webbing or just an imprint of the webbing?

[pitterpat]

Was there any waterproofing used?....I just see cement board.

[cx]

Originally Posted by John

The walls are tar paper that overlaps the pvc liner, durock wall board...

Moisture barrier behind, Pat. Quite acceptable.