Stone? No way. Rectified tile for sure. But large scale tile isn't good on a shower floor because it has to slope to the drain. 4 by 4 or smaller is suggested. Even if you use a linear drain you must consider that that lack of grout lines often makes larger tiles slippery.

Assume lineal drain. We will pay attention to the COF of the tile and also check ourselves for how slippery the tile is when wet using a sample before choosing.

I do frequently see references to tight grout lines with natural stone tiles. Our contractor was clear that we would need to pick carefully. What's your experience to the contrary?

I should probably say that I'm hoping for 1/16 if possible.

Thanks!

We chose rectified porcelain and are very happy with the super narrow grout lines. Do have the contractor had acrylic to the sandless grout to give it strength and prevent cracking.

Thank you! I was thinking epoxy grout. Is it appropriate for tight grout lines?

I always thought it was next to impossible to cut natural stone in order to get pieces of uniform size and thickness. And that's been my experience as well. And without uniform size and thickness, very thin grout lines lead to lippage. So I'm very surprised that stone is suggested for thin grout line applications. But maybe I'm wrong.

I'm no expert on tile, but maybe this thread will be of help on the issue of stone tile and tight grout lines.

Here's the quote I'm thinking of " however, there IS a kind of ceramic that's baked in sheets and then cut to size afterward, making it just as good a candidate for tight joints as granite and marble, and that's rectified porcelain." That's from bill Vincent.

I think the pretty clear implication is that either natural stone or rectified porcelain can be used for tight grout lines.

And I guess that answers my question as well. I had searched using google before but must not have used the right terms because I didn't come up with that thread.

Here is a link that might be useful: GW thread on tight grout lines.

Natural honed/polished stone tiles like marble and granite are cut very exactly and you can go pretty tight with the grout lines, typically 1/16" I believe. On the other hand I have a "natural cleft" rough quartzite tile that is very uneven and has 1/8" lines. That's really the exception though when talking about natural stone tiles.

Rectified porcelain is also cut very exactly, although I've heard that large-format rectified can have warping issues which preclude very tight grout lines. Rectified also seems like it would be much too slippery for a shower floor. Maybe a large honed granite would work, or possibly a slate - something with a bit of fine texture so it's less slippery when wet.

If you go this route (large format, tight grout lines, flat/parallel layout), be sure to discuss lippage with your tile guy or GC. You'll probably want to specify the amount of acceptable lippage in your contract.

Thank you!

What I put in my bathroom was rectified porcelain 12x24 tiles. Only on the walls though. I have a Kohler shower pan for the floor. I did the job myself. I installed it using all the appropriate materials. I used all Latacrete products including epoxy grout. I love all their materials and it is holding up very nicely. I have a 1/16" grout line. I should have used 1/8, because of lipage that I believe I created in laying the tile. I don't think there was any warpage of my tile, it was me :/ So if I would have used 1/8" it would have made nicer transitions to the next tile and not cast shadows, telling on me and my somewhat sloppy plane of tile. If I would have used a darker gray in the grout it might have camouflaged those shadow lines cast by the lipage. Lesson learned. I thought I wanted those 1/16 grout lines because of fashion, when I would have been perfectly happy with the 1/8"!

So, if you have a very good tile setter go for the 1/16" grout line, the epoxy grout goes in there fine. I did not read your link above, but I know Bill V. has mentioned, in posts, that the sand used in Spectralock epoxy grout was so finely graded that it works in the 1/16" and that it is not known to scratch marble, in his experience. That's from my memory of several years ago when I read a post of his. If there is risk of any lipage the wider grout line is a benefit in that it helps transition between the lipage, helping to prevent abrupt changes in the tile edges which could cut the foot. There is a calculation to determine grout width, if you have a known warp factor in your tile - to ward off shape reveals of tile edges. With wider grout lines you also can take advantage of the grout adding traction. The benefit of natural stone is that it can be finished smooth, if needed, to correct for the lipage, I believe.

If it was me, I would use porcelain in a narrower format and with an 1/8" grout line, because I would be installing it myself and those 12x24 tiles were SO HEAVY lifting onto the walls. I laid 12x24 on my room floor, in a different tile, and they were heavy there too :) I like Elphaba's shower floor, it has a long narrow tile that to me takes advantage of a contemporary look and more grout lines for traction then my 12x24 tiles.

Here is a link to Elphaba's finished bathroom thread:
"fini - ikea cabs,curbless shower,porcelain plank floor,fake marble"

Here is a link that might be useful: Elphaba's bathroom walls

Thank you! This is definitely about function for me. For style, I'd be going for a vintage look. But I have had the vintage look with small white tiles with wide white grout lines and it's just too hard for me to keep clean.

Have you considered using a dark grout? I know it's not the same as actually keeping the grout clean, but at least it won't drive you crazy when it discolours.

Or, if it's really important to you that it be cleanable, I would go with a pre-cast shower pan. That would eliminate all issues with grout size, lippage, clean-ability, and slipperiness.

crl_ - we aren't tiling a floor but we are tiling our walls with subway ceramics antique (avalon) white. The tiles are impeccably straight and flat. DH is DIYing the install and we are going to go with 1/16" grout lines. The showroom recommended Polyblend Urban Putty grout to emulate the look of aged white grout. It looks quite dark on their website, but in person it looked nice.

Thank you all!

Because we want a curbless shower, I have decided against a pre-cast shower pan. I considered trying to do something custom (corian maybe) for the shower area, but in addition to expense, that left the bathroom floor and the need for that transition from one material to the other to be waterproof as well. Which led me back to tile.

And if I'm having tile for the bathroom floor, I've got the cleaning issue anyway and I might as well go with just one material to get the continuous look and save some money.

I'd be willing to re-consider though if someone has information about making a pre-cast shower pan for a curbless shower work well with a non-tile bathroom floor.

I'm definitely planning on somewhat dark grout. I'm figuring a medium grey tile and matching grout are going to hide dirt the best. But I also want it to be as easy to get really clean as possible when I do clean.

Thanks for the information about ceramic tile working well for tight grout lines!

"I'd like to pick a large grey tile for my bathroom and shower floor. I'd like the tightest grout lines possible for easier cleaning. My contractor is suggesting that stone will have the tightest grout lines. What about rectified porcelain? Is it about the same? "

A sawn stone (marble tiles, granite tiles, etc, tiles honed or polished with a sawn 90-degree edge) should all be quite uniform in size. Same with rectified porcelain. Either can be set with the tight joint.

The tighter the joint, the more uniformly flat the substrate beneath the tile should be.

Thank you, mongoct!

What Mongo said. It's all about the flatness of the substrate. And I'd highly recommend Tec Power Grout. It's all we deal with anymore. It's colorfast, stain resistant, and just works better, as in handles easier.

Be sure you understand about how to properly construct curbless. The COF of a large tile is realy important for a large tile used in wet conditions. It does no good to create a barrier free shower that is too slippery to use even by the able bodied!

crl, it can be done! We just took our first showers last weekend in our curbless shower. Had been a little nervous about using the 24 x 24 tiles on the floor, due to it being against the "conventional wisdom," but did pay attention to the COF and I'm telling you that floor is not slippery under bare feet when wet. It is actually less slippery than when dry and wearing socks, for what it's worth. We did use a dark gray tile and charcoal grout and I had to go back and even out the color and hit it with a couple of coats of enhancing sealer, but it looks great now. I will be cleaning it just because I feel it's "time," but I don't think anything will show up on it visibly.

Thank you lwo.

Thank you Lori! Do you happen to remember which tile you used?

crl, I don't remember. Will need to rummage around in the office some and find the receipt, since it was ordered locally. My one and only "sample" is actually an off-cut I just used to help recall the color.

Doing a little research on rectified tiles and grout lines and came upon this board.

Note to self, A good contractor, that takes pride in their work, will most often recommend rectified tiles because of their effect on the final product. They offer a smoother, more even finish and allow for the smallest possible grouting.. If you wish huge format tiles, rectified floor tiles could be very effective since the minimum grout necessary can make your floor, or even wall, appear to be one massive tiled surface. One disadvantage of rectified tiles is that they are extra susceptible to chipping, especially on the exterior corners of your floors where the tiles end.