You could do one entire slab of granite if you used a trench drain along a wall. With a central bowl shaped drain, I don't like larger than 2". I've seen 4" done, but I don't like the look of the cuts needed. Or, there's the option of the 4 sloped planes in an X shape rather than a bowl slope.

You could do one entire slab of granite if you used a trench drain along a wall.

But then it would be really slippery when wet.

In addition to being able to slope small tiles, they also require more grout and help make the floor less slippery. If you want to use large tile you should check the COF of the tiles to make sure they will not be too slippery when wet.

COF=Coefficient of Friction

we also did a 12x24 wall tile. it had a matching 2x2 for the floor, but we chose a natural stone pebble floor insteadâ¦love the look. You should generally go with smaller format on the floor so you can slope it properly and it will drain.

Flamed granite like is used for exterior pavers makes a great shower floor if you do want to use a single surface.

I have 12 x 24 tiles on the wall and the rest of the bathroom floor. The contractor cut 4 x 4s from the larger tiles to do the floor of the curbless shower. The tile had a decent wet COF to start with, and combined with the grout from the 4 x 4, I don't have any slipping concerns. The slope doesn't look or feel uneven to me. I can feel some unevenness caused by the larger tiles if I run my hand over it (since I never do, I don't care) It all drains fine.

We also decided to go ahead with the 12x24 on our shower (and use a linear drain.) I have checked the COF of the one I picked out and it scores OK, but I may go back and look at some other options. Daltile has some that resemble the 'flamed' granite described above.

But I did this because it's a small room, curbless shower and I wanted one continuous floor surface. Seem like the conventional wisdom always says 2x2 is best, but you do have to consider the surface of the tile itself if you go bigger.

I thought I posted to this yesterday. Maybe I'm on double-secret probation??

You've gotten good advice. With a bowl-type mud bed, the largest I prefer to go is 4" squares. Larger than that and you can get lippage issues due to the floor not being in plane.

If you have a flat but sloped floor, example, for a linear/trench drain, then you can go with larger tile, but if you I go above a 4" square I'm losing grout lines under the footprint, so you need to look at slip resistance or CoF.

Scroll about halfway through this thread to see 4" squares cut from a faux porcelain slate, DAL Continental Slate Asian Black. Typical sloped bowl base, not an inverted pyramid. Easy install, no lippage issues, and solid traction underfoot.

You mentioned natural stone. Most natural stones can be fine in larger format tile, but it depends on the finish. There's the obvious stuff, like polished stone being more slippery than honed. And it also depends on the specific stone. Example; a marble will typically be more slippery than a slate. So obvious things like that.

When I write "slate" I am not referring to the sedimenty flaky garbage sold at the box stores. "True slate" can indeed be excellent in a shower.

And obviously, if you use large format on the shower floor, let your installer know ahead of time. The larger the tile, the more in-plane the sections of the floor have to be. Small tile can conform to small variations in elevation in a mud bed. Large tile can teeter-totter, causing lippage issues with neighboring tile.

Curbless to a linear drain, you can have a very nice in-plane surface with large format.

Good luck!

Thanks to everyone who took the time to post a response, and especially the link and the great photos, mongo. This has all been really helpful.

I have used as large as a 7" in a shower....but it was BIG! 4' wide by about 12' long. This is, obviously the exception to the rule. Typically, a 2" or at most a 4" tile is the order of the day. Think of it this way....you're tiling a bowel!

WE were the exception to the rule - we used 12" x 12" tiles on the shower floor in our last house, and the shower was about 4'x6'. Worked perfectly.

I would like to see a photo of that.....

I'll see if I can find one. We haven't lived in that house for a year now, but we had that shower done 7 years ago.