Shower Installation [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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08-27-2010, 01:15 PM
Hey Guys,
This may sound strange, but though I'm not even close to a stranger in the floor tiling world, my shower tiling experience is near nil. Unfortunately the one I did do was my own shower and only now I'm finding out (too many years too late), that mastic and DITRA/Showers do not mix . In general, mastic sucks and I wish they would stop selling the stuff altogether. Even for the few times it can come in handy for kitchen back-splashes, it's way more a curse than anything else.

So my question is: now that I have cracks in my grout in my shower, what can I do about it, besides ripping it all out and starting over? Hopefully someone else has run into this and knows what might work. As well, does anyone know of a better way to finish the top of the tub/shower tile?


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Levi the Tile Guy
08-27-2010, 01:26 PM
First off there is no real way to fix your shower without starting over from scratch. I guess if it's your own you could keep regrouting until the tile finally falls off of the walls, and hopefully you don't have any other more serious water issues. Ditra isn't for walls, and mastic isn't for wet areas.

As far as your question about finishing the top, what do you mean? You can use bull nose, quarter round, ropes, or any other finish piece, or go all the way to the lid with your field tile.

08-27-2010, 01:40 PM
Welcome to the forum !

Being what it is, I would reccomend a rip out and re do. If the grout is cracking, and you used mastic, there is going to be a bacterial issue if there isn't one already.

Pick apart the loose stuff, and maybe replace with epoxy based grout, could hold you off for a while while saving the dough for a new shower.

08-27-2010, 02:20 PM
Welcome, Matt. :)

Don't think we know enough about your shower construction to do much assessment of the problem, but I agree with the others that it sounds like a re-do is the only real option.

You installed Kerdi in your shower using mastic?

Installed it over what backing?

You then installed your tile using mastic as well?

This was a full Kerdi System shower, including a Kerdi drain? All done with organic adhesive (mastic)?


I moved this to the Advice forum, Matt, as it's mostly a project thread and it's something our DIY visitors need to see. They're cautioned often about not following manufacturer's instructions and about using organic adhesives inappropriately. This may be a good lesson on both.

08-30-2010, 06:44 AM
This is not a job that I'm proud of either. It was a "rush through as it's our only shower in the house" kind of job - no excuse though. Thanks guys for clarifying my issue.

I'll also clarify on what I used exactly. I started with regular drywall for backing, then used thinset (not mastic) and applied Kerdi, so that part I know is okay. My real problem is when I used mastic to apply the tiles, that was stupid of me - not reading the instructions properly... at least I know better now and it's not someone else's shower. Just to clarify as well, it's a bathtub shower, not a stand-up. That's why I was asking about what type of profile could I use to finish the tile to the tub.

Brainstorm - What if I would take the caulking out from the bottom of the bottom row of tile, this way maybe the water would run down the kerdi wall and run out into the tub? Don't know if that's even an option, just a thought. I know this isn't a permanent fix, but I'm wondering if it would help things hold up for a little longer. I have a 2nd baby on the way (any day now) and I don't really have the time to re-do everything at the moment.

I will however at least do the grouting as soon as possible. What is the downside, if any, of using epoxy grout in a shower? Why doesn't everyone just use that? Hopefully I haven't put too many questions in one post.

Thanks again guys.

08-30-2010, 06:59 AM
Matt, some of us have long had a problem with using a flexible sealant (caulk) at the tub/tile junction in tub/shower applications, but that's still the industry standard.

If you are, in fact, having a problem with water building up behind your lower tiles, removing that sealant, at least if a few areas, might help a bit. I'm presuming that your Kerdi membrane laps over the tub's tiling flange, yes?

But without some photos of what you're dealing with, we're still pretty much guessing. The use of the organic adhesive (mastic) to set the tiles over the Kerdi membrane isn't doing you any favors, but I can't say it's your only, or even primary problem at this point.

My opinion; worth price charged.

09-07-2010, 01:20 PM
I just uploaded the pics, these should help.
Hopefully you guys can figure out where I'm at and what I'm up against with the pictures. :crap: