Substrate needs to be flat,id go with 1/3 off set,a crack iso membrane.

Properly applied tile will crack on the fault unless it's a really small tile and the grout is weak. Make sure that the floor is dead flat and it's a good idea to put a straightedge on several of the tiles to see if they're crowned. The longer tiles make lippage harder to manage. The style is getting more popular so you might as well join the crowd.

For floor tile prep I always use a crack isolation membrane rather than cbu now. I bought some rolls of NobleSeal from Daltile(rebranded DalSeal) a couple years ago and I've still got some left. It's good bang for the buck and faster than waiting for the liquid to dry.

I've done lots of floors with 12x24. Earlier comments suggested making sure the floor is flat, and I couldn't agree more! My standard prep is 3/8 plywood over the existing 5/8, (some SLC if required) then install an uncoupling membrane like Laticrete stratamat.
I usually use 254 platinum thinset to set the stratamat and 4XLT to set my tiles. Most large format tile I've seen have a slight bow in them which is why it's recommended to install them on a 1/3 bond vs 1/2 bond.

Flat floor, isolation membrane (Ditra is my standard), a more deeply notched trowel (1/4" wide x 3/8 deep at least) so that you don't have areas without thinset adhesion and so that you can adjust levelness. One of the tile leveling systems is helpful with large tiles (I personally don't like the QEP LASH system (the one carried by the big boxes), but you can find threads on the subject). Go through all the tiles and find the ones that are most-bowed - even the most expensive tiles will have some bow. If you don't have enough tiles to do without them, use the bowed ones for cuts.

It wasn't your question, but adjust your thinking about ordering tiles and managing or planning for breakage or waste. With big tiles in small spaces, you can't just measure the square feet and add 5% for breakage and waste. The layout and the quality of the tile (will it break when you cut it) can have a big effect on how much tile you need.

Thanks for the replies fellas. I'm trying to absorb as much about this type of tile and the unique way it's installed as I can.

Bob, 5-7% is my rough waste add on. Do you recommend 10% or even higher? It doesn't offend me to take a box back if not needed...

With large tiles in a small room I figure out the tile layout completely, and count the tiles. Then I add a few for shipping breakage or quality issues, and a few for cutting mistakes and breakage. Let's say you have a very small bath - 32 square feet of tile - that you're tiling in 12x24 tiles. Maybe the layout results in 4 square feet of waste. If the tile has a long delivery schedule and it's unacceptable to slip the schedule, you order 4 extra tiles to account for quality problems and breakage. That's 6 tiles, 12 square feet, for 32 square feet of tile. Those 6 tiles are 37.5% of the square footage.

That may not be your case, but it's not an unusual scenario. Obviously, it can affect pricing, too.

MattK said:

Thanks for the replies fellas. I'm trying to absorb as much about this type of tile and the unique way it's installed as I can.

Bob, 5-7% is my rough waste add on. Do you recommend 10% or even higher? It doesn't offend me to take a box back if not needed...

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12x24 on a floor with a 1/3 offset.....never heard of it :laughing:



Set on Ditra XL to perfectly match to adjacent hardwood floor.

Who the ef are you? :laughing: Welcome back!

angus242 said:

12x24 on a floor with a 1/3 offset.....never heard of it :laughing:

Set on Ditra XL to perfectly match to adjacent hardwood floor.

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Good to hear from you again Angus