Stick with a 1/3 brick joint. The reason is that elongated large format tiles tend to warp slightly in the kiln when baking. It's nothing that's noticeable, unless you do a 50% brick joint, and then you see lippage like you read about. It's why almost every manufacturer recommends no more of a break than 1/3, whether it be wall or floor.

Ok. It is natural stone so I don't know if that affects things. But 'd rather be safe than sorry!

Bill knows his "stuff" (we missed you around here Bill, welcome back!).

We had the large format travertine tile throughout most of our ground floor laid in a standard brick joint pattern. No lippage whatsoever. Perhaps large format travertine tile isn't as prone to lippage because it isn't prone to warping like porcelain tile?

Our tile guy (and his assistant) are extremely meticulous, and extremely picky about lippage, so they always go above and beyond to avoid it.

Bill, We are considering a similar issue for the tile we want to use, and are wondering whether to just go with 12x12 instead. We are looking at Daltile Unity Ashgrey "colorbody" porcelain tile, which comes in 12x12, 12x24, or 24x24. The larger sizes are almost the same price but cover more area with fewer grout lines, so that seems economical (and looks nice). But does the extra labor and materials eliminate that advantage? Which might be better for a small 8'x5' bath? (Didn't mean to hijack your thread, brightshinynew, but when I saw Bill was participating I couldn't resist jumping in.)

Cat_mom's right-- with natural stone, it's a whole different story. Obviously, nothing's being baked in a kiln, so there should be no warpage. Therefore, you should be able to do a 50% brick joint with no trouble.

Btnik (Gotta tell you, I love the name! :-) ) -- it's really a matter of personal taste. I don't charge any more money for large format tile in the walls than I do for 12x12 (floors is a different story). but the same parameters stand-- you don't want any more than a 1/3. Money wise, the only thing that costs more is the thinset, because the installer will be using a larger notch trowel, and therefore will use more thinset. but on a standard size shower, that might be another 35-40.00 in cost. No big deal.

Thanks guys. I don't mind btnik :)

Now that I've figured out the bizarre steps that Houzz is taking to transition GardenWeb, I have one more question. Bill, why do you say "floors a different story"? It sounds as if you DO charge more for setting larger tiles on the floor. Why is that? (BTW, I think I misunderstood earlier pricing I saw on small vs large tiles. The small tiles were 12x12 so the price was in $/sf. The 12x24 prices I saw were also $/sf, which meant that the tile itself, being 2 sf, was twice the $/sf price. Therefore, I was wrong to think I'd save a lot by buying large-format tiles. I'm slowly learning...)

Before I answer, I have to tell you first, this is still Bill Vincent. Now that GW has changed over to houzz, it defaults to my houzz profile which is my company name, Creative Ceramic & Marble.

Now, btnik-- to answer your question, I charge more on the floors, because it's a little tougher to keep the tile flush on the floor, thanks to gravity. On the walls, especially with a nonsag thinset, they pretty much stay where I put them. Only issue is making sure I shim them to keep the joints aligned, which is why I charge more for ALL wall installations than I do ALL floor installations. But in comparison to other floor installations, I will charge a little more for large format because of the buttering and scraping involved to keep the floor flat.