Super Absorbent White Tile PROBLEM [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Scott Ross
01-26-2003, 04:31 PM
Hello - I'm a General Contractor and I've got a problem... a tile problem (don't worry, the psychological problems are being handled by other professionals!). I've searched this site to see if it had already been addressed but I've come up dry. It has to do with white tile soaking up moisture and falling off the wall. Allow me to explain:

The Problem: My Tiler (excellent tiler and good friend) installed white subway tile in a shower in March '00. Two years later (March '02) it was falling off the lower half. We repaired it and last week my customer called to say the grout was beginning to fail - crack and become dislodged. I need to know if I or we are doing something wrong or if this has happened to any of you.

The Facts:

- I've had problems three times with white tiles (only some and only white) soaking up water, turning gray and/or falling off the wall. Once in '96 (8x10 Dal-tile,brazil) and twice in the last two years(manufacturer & origin unknown)

-Each time the homeowner supplied the tile from different reputable retail outlets here in central NJ. (It wasn't from one of the big box stores, I don't touch their stuff).

-I've noticed that with each of the three different tiles, if you placed a corner in water, it absorbed rapidly and in a short time was completely saturated, showing gray behind the glaze.

-My Tiler used wall and floor adhesive from TEC for these installations (like he does for all his installations - he said) and white unsanded grout from TEC.

-These were all factory cut tile with tight grout lines.

-On this current shower, the tile that was loose was completely clean on the back, however, some were partially adhered and the adhered part was a bear to remove.

-I called TEC and they said that if the adhesive stayed wet for a long period of time, it would re-emulsify, which is what I think happened.

-The tile distributors gave me a blank (ie:stupid) stare when I explained my problem and they proceeded to tell me it couldn't be their problem! (maybe if I practice that stare I could reduce my psycho issues:drool2: ).

-I'm already telling my customers that I've had problems with white tiles and I cannot and will not guarantee their purchases. I'm not sure I even want to install white tile at all!

Has anyone had this problem before? Suggestions on what to do differently? Suggestions on what to do with my current situation?

I'd appreciate comments. Thanks! Scott

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01-26-2003, 04:42 PM
Hi Scott, welcome :)
We've had some discussions here about the absorbtion rate on wall tiles. Many have a very soft and porous bisque. The beige wall tiles I used on my shower are like sponges. I don't think the color is the issue here, it's the mastic. The folks around here say NEVER use mastic in a shower or bath, because as you found out it can re-emulsify. Some say that if a shower has a proper pre-slope, it helps to keep the lower tiles dryer, because the cbu's are not constantly soaking in a puddle. Does your guy pre-slope the showers he builds?

01-26-2003, 04:46 PM
Sounds like mastic was used for the tile in the shower ( when it shouldn't have been)

My guess is that the tile substrate has wicked up the water and caused the mastic to re-emulsify. Dal tile is notorious for being soft.

Take out the bottom three or four rows of tile, let dry completely, then retile with thinset. This assumes that there are no other issues with the shower

sealing the soft tile won't hurt either...

No mastic!!!!!!!!!!!! especially in wet areas...


Scott Ross
01-26-2003, 05:15 PM
Thanks. I'm not sure what you mean by pre-slope but the shower pans are sloped with shingle points, overlayed with a 1/4" plywood (luan) and then fiberglassed in place. My tiler always slopes the tile surface over mud. Also, the problems were more in the center of the wall.
Thanks also. I did seal the tile after the repair with a high quality sealer. All my showers are wonderboarded or durocked. I did discuss thinset with my tiler but for some reason he didn't like thinset and said he almost never had a problem! Maybe we will have to revisit that conversation.

01-26-2003, 05:46 PM
Definitely revisit that conversation. Mastic is not recommended for use in wet areas precisely for this reason.


01-26-2003, 06:21 PM
Scott, at the risk of offending you, and I hate to be the one to say this but from the sounds of it the way your tile friend does his showers should maybe consider finding someone else to do your tile work...or have him start using more standardized methods of installing showers.

Mastic is diffenatly a big no-no inside of a shower and I am not sure what you were talking about with luaun and fiberglas for the mud pan but it sounds kinda scary to me...

As far a white tiles bieng a problem I can't say I have ever seen what your talking about with them turning grey but if the problem is them falling off then that is something you should be able to remedy easy enough with using thinset instead of mastic and using enough of it to have good transfer to the tile.

I belive there is a photo diagram of proper mud pan workmanship around here somewhere and I think that John has a tutorial on mud beds also that perhaps you can download and printout for your next shower to use as a guide.

Maybe john will show up with the links...hint..hint..

let us know

01-26-2003, 07:28 PM
Scott, check the Liberry (there's an icon up top) for the recommended anatomy of a shower. Does your guy use a clamping drain and a pvc or cpe liner? If so, upc says that the liner should be sloped to the drain at 1/4" inch per foot minimum. This is usually done with a pre-slope of deck mud, and this is what helps to keep things dry. Then the final deck mud, following the same minimum of 1/4" per foot on the surface, and then the tile. As the others said, only thinset to bond the tile to the floor and the cbu, because thinset is not affected by water.

Scott Ross
01-26-2003, 08:54 PM
Hey - no offense taken. I need to understand this and sugar coating only delays the effect of the medicine.

First, let me talk to the tiler and make sure I have my story straight.

Second, I think my shower pans might not be typical but they work extremely well. There is a sub in the area that works for a number of contractors that has perfected a fiberglas shower pan. We provide him with a sloped wood substrate and 8" of blocking around the perimeter of the shower. The drain is PVC with a twist lock cover - the same used for a single membrane pan. He comes in, mixes his resin, puts down a coat, lays dry glass mat in it and lays another coat of resin over that. Shower seats are a breeze because the pan becomes one with the seat. If there is one thing that has proven itself in my showers, this is it.

I'll be back after my conversation with the tiler.

Thanks! Scott

John Bridge
01-26-2003, 08:57 PM
Hi Scott, Welcome aboard. :)

I have to go along with the others. I don't think anyone around here uses mastic on shower walls. We've got setters who use it on shower ceilings, but ceilings don't get wet.

The color of the glaze is not the issue. It's just that you can more readily see the shadow of moisture behind white glaze than you can some of the others.

It's not unusual for wall tiles to have an absorption rate well over 20 percent, with some of them going to 40 percent, even. So the porosity of the tiles, although it has contributed to your particular situation, should not be a factor in a properly constructed and maintained ceramic tile shower.

I think someone mentioned doing the repair with thin set instead of mastic. At this point that is the best thing you can do. It will be crucial that you remove all the residual mastic from the backer board and the tiles. Allow everything to dry out. Then use a modified thin set that is rated for wet areas. Customs Versa Bond would be one, and there are several others. There are also modified thin sets that are NOT approved for continually wet areas, so watch out for that. :)

01-26-2003, 09:58 PM
Can we see some pics of deese F'bglas shower pans ?
Purty please ??....

01-26-2003, 10:14 PM
he didn't like thinset and said he almost never had a problem!

enough said?

Bill Vincent
01-27-2003, 01:29 AM
Scott-- Most likely the reason your tile setter doesn't like using thinset is the tile won't hang from a midpoint level line the way it will with mastic, which would make it alot easier and faster, but like the rest of these guys have said, mastic and showers (or ANY wet areas) don't mix.

Scott Ross
01-28-2003, 02:00 PM
Alright - If you guys are still listening, I have some new information.

First - My mistake, my tiler does use Latex Modified Thinset T346 from TEC. I called TEC tech support and they said that under saturated conditions, the thinset would re-emulsify but only in extreme situations. The rep suggested that perhaps this tile was not approved for wet locations. Is that possible?

Second - RJ, you asked for pictures of the fiberglas pan. I don't have any. But if you email me at, I'll give you the subs telephone number and he can explain it.

Thanks! Scott

01-28-2003, 02:25 PM
Hi Scott,
I hope you didn't feel like you got slammed with the responses above, but everybody here is pretty much of one mind when it comes to mastic in a shower. Hang tight for the pro's to comment on the thinset and tile question. :)

01-28-2003, 03:46 PM
I'm in central NJ. E-mail me and I can look at it if you want me to.

01-28-2003, 04:50 PM
Hey guys,

Fiberglass shower pans are becoming the norm here in the Austin, TX area.

Problem is they get put in pretty early while some of the studs are still being drilled by electricians. This can lead to cracks in the pan.

The pans have large staples placed upside down in the rsin to give the mud something to hold on to.

I'll try to get some photos for ya'


01-28-2003, 05:42 PM

I have mailed you several pictures of fiberglass pans. I couldn't reduce them down to a size acceptable for the attachments.

Maybe you willhave better luck