Granite tile in a shower [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-15-2017, 03:15 PM
Hi all, I have a job coming up that I could use some advice on. It is a 4x8 shower that she would like to use 12x12 granite (dark almost black in color with some green) on the walls. I use Kerdi board on all my showers and that is what I plan on using on this one, unless there is a problem with that that I don't know of. I use Kerabond T normally and looking at the specs it can be used on this as well. I am assuming that I need to seal all the stone before and after I put it on the walls. Any advice would be greatly appreciated on this since it is my first stone install. Thanks!

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03-15-2017, 07:50 PM
Granite comes in so many varieties, it's kind of hard to say, but in at least some cases, granite will just laugh at a sealer...some are so impervious, it literally won't make a difference whether you use it either before or after or at all. So, can't say for sure. Some can absorb moisture and as a result, will (temporarily) change color which can give some people a heart attack. The granite I used in my shower took almost two weeks before it returned to its 'normal' color because of the moisture in the thinset took that long before it dried out. In the process, I found that it made the colors pop in the tile and I opted for an enhancing sealer which makes it look wet all of the time. So, in my case (Kashmir White), sealing did make a difference, but I found no good reason to seal it first. Now, if you were going to maybe use a light color grout (IMHO, not a great idea on a dark granite tile), sealing might make cleanup easier, but probably not unless the tile has lots of microfissures on the surface. On a really dark tile, you can probably use nearly any color thinset, because it will be dense enough to not show through. If you can get it, I really do like how DitraSet feels and works out, but any premium (not an entry grade unmodified) should work. As with any tile, but especially a dark one, be very careful about cleaning the grout joints really well. Two things happen if you don't: it could leave a bit showing, making a big contrast between the tile/grout/thinset, and, because thinset will absorb more water out of the grout, that can cause variations in the cured grout color...that applies to both the sides of the tiles, but the depth of the grout joint as well.

03-16-2017, 06:48 AM
excellent! I appreciate your comments. I have done many showers over the last 4-5 years with Kerdi/Kerdi Board but have never done any natural stone. I was seriously thinking about turning this job down.

Shady at Best
03-16-2017, 09:55 AM
Does the granite have resin or netting on the back? I would be concerned about non modified thinset holding on top the granite.

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03-16-2017, 12:54 PM
no netting, it is kind of grooved from what I remember. I don't want to assume anything but, I am assuming that you burn the thinset into the back like I do all my other tile...thats my plan anyways

03-16-2017, 03:10 PM
The backs of most granite tile is essentially rough-sawn. While there might be some granites that need mesh backing, that tends to be much more common on marble and travertine stones. Regardless of the tile you use, the quality and strength of the bond will improve if you back butter it. That tends to be even more true when the back of the tile is not flat, or has a pattern, or is rough. A good back buttering job essentially creates a nice flat surface (assuming your trowel is big enough!) with an already good bond with the thinset prior to you setting it on the surface.

03-17-2017, 01:22 PM
Here is a new spin on this. The customer has decided that they want the ceiling tiled also. I am thinking tear out the sheetrock and put some cross blocking and CBU. I don't like the idea of putting Kerdi over the top of the sheetrock, even if I screwed the sheetrock off every 6" or so to make sure that it will stay. Also the ceiling is spray foamed, so I should be able to get it down without too much mess as long as they used plastic above the sheetrock that is.

03-17-2017, 06:23 PM
If the drywall is properly installed, Kerdi then tile is not an issue. Go for it if you'll sleep better, but cbu there isn't required.

Tool Guy - Kg
03-17-2017, 09:38 PM
Cement board is in danger of drooping when used on the ceiling if the joist spacing is exceeded.

What cement board are you considering and what is the ceiling joist spacing?


03-21-2017, 02:52 PM
ok thanks on the sheetrock. I would rather do that but thought it wasn't right to do so. I suppose if nothing else I could screw off the ceiling with Schluter washers also since it will be covered in Kerdi, rather then removing the drywall and installing 5/8" Kerdi board.

03-21-2017, 08:21 PM
Drywall + Kerdi is only a problem with a steam shower...if, it is installed properly. Many installers do not use the industry standard screw spacing, and that can be a problem, as can going too deep and tearing the paper face.

03-31-2017, 03:27 PM
thank you sir