I think you mean "minimal" grout lines? You would never butt marble tiles up against each other. There needs to be some movement allowance. What format marble are you talking about?

4x12 for walls and 12x24 for floors. He actually said butt up against each other. He said marble is perfect, not warped or something like that b/c it is natural stone. I like a little grout line anyway, so I think I will have some...

Everything needs grout. Marble as well. A really good installer, with the proper prep, conditions and material (marble) may accomplish a fine, minimal grout line. Pay attention to manufacturer recommendations as well. "Marble is perfect".. stone can't handle any movement and I think you may have misunderstood? Minimal, yes, if it is a really good quality marble with exceptional surface conditions and proper prep. No grout? I don't think so.

Sounds like you need a different tile installer. What other mistruths is he feeding you? Did he at least waterproof behind the tile?

You need to read this. And fast. Do NOT move forward with this guy! Marble is nothing more than hard little sponges being applied to your floors and walls. You need to understand how and why it needs to be waterproofed. And it needs grout. Period. Full stop. #getridofthehack

https://www.ceramictilefoundation.org/homeowners-guide-to-hiring-qualified-tile-installer

"4x12 for walls and 12x24 for floors."

For the size of the tiles you are using, the minimum grout line width for the 12" wall tile is generally 1/16" and for the 24" floor tile 1/8". That's assuming the tiles are indeed "perfect" in size; literally zero variation in size and all perfectly rectangular.

You never want tiles in direct contact with one another. Over time, with floor movement, loading, etc, differential movement can result in chipping at the tile edges.

Grout is a must especially in a shower! Don't want to get any water under the tiles!

Marble is a sponge. Grout will never prevent water from getting “under” the tiles any more than it would with any other tile installation. There will always be water under the tiles. They’re sponges. Tile and grout are not waterproof.

This is why waterproofing is Required.

Get this request all the time. I have to explain that whatever the material....tile, marble, granite....EVERYTHING moves incrementally. Material without a grout "buffer" will rub together with temperature and humidity, creating what is referred to as "spalling" or chipping of the edges as it crashes together. Similarly, you tile a large room with variations of temperature, you need to hold the tile away from the walls as well as, many times, a "soft joint" filled with a matching caulk. Why? Ever hear of "tenting?" It can happen and sometimes sounds like a shotgun going off as the tile heaves up. Always use a grout joint.

STOP....tile needs grout clarify what he means, if he means none then head for the hills. Marble rectified would need MINIMAL not NONE. Time to move on if he is not adding grout to the tile....

"Ever hear of "tenting?" It can happen and sometimes sounds like a shotgun going off as the tile heaves up."

This video is pretty cool as the floor is tenting while he films. Good stuff throughout, but especially at the 35 second mark.

Everything I've ever read here or in books or on install specifications for tile (natural stone or ceramic or porcelain) requires some minimum width grout line so I am not suggesting anyone should do otherwise. However, I occasionally have the privilege of traveling to Mexico (usually Playa del Carmen or Cabo San Lucas) and the resort bathrooms seem to be filled with tile that looks like there is no visible grout line. How do they do this?? Do they just risk the chipping, tenting, etc? It does seem like there is often some sort of glossy coating over the tile. Just curious!

“No grout” set tile is Mud set natural stone tile and screeding a mix of stone dust from the actual cut stone mixed with Portland over the whole thing when done. It’s technically grout, but it so closely matched the stone that you can’t see any difference. The mud set tile behaves as a monolithic whole. A giant mass.

Do not use this tile setter ! Walk away from him or you will have to redo your washroom . If there is no grout in joints water will flow under the tiles and within few months your tiles will separate from floor mix .

For the 979th time, water gets under tiles any which way you set them. Tile and grout is not waterproof. That is why the separate step of waterproofing is required.

I think I know what the guy was trying to say about the perfect not-warped material. Manmade tiles warp slightly when fired in the kiln, and it's more obvious the larger the tile. Natural stone is sliced from stable chunks so it can be super completely totally flat (if it's cut properly).

No idea what he means about the rest of it, though.

I have a client looking to have a fancy 3D marble put in a shower with no grout lines. https://tilebar.com/michael-habachy-barcode-medio-white-carrara-8x8-marble-tile.html

The rep said it can be done with out grout, but in the same note said to follow the install instructions on the site and it says to have at least a 1/16 grout line. I understand the science in tenting etc and waterproofing. My question is can it be done, and how can I do it?? I too said it should be grouted. I will be waterproofing the substrate the tile will be put on, but is there some sort of waterproofing to be done on the exterior of the tile as well??

That would not be a tile that I would ever use in a wet area. There are too many places for soap and skin cell residue to cling. That is difficult enough to clean off of a flat porcelain tile. Put the additional recesses in the mix, and combine it with marble, which has specialty pH balanced cleaning care requirements, and someone is going to be very unhappy in a short period of time. Either the soap scum will win, or someone will break down and try something unsuited to be used on marble to get rid of the scum.

At $24.50 per foot, I hope they like the result. Were it me, I would discourage it for the reasons listed above and would have them sign off on the only warranty would be from the people selling the tile....not any problems related to the install, aside any obvious crappy work.

A question for Sophie; What type of waterproofing would you suggest on marble back splash?

MongoCT, The tenting video was crazy. I have never seen or heard of this happening.

D D-

You're not going to get an answer from Sophie....she is not on these forums anymore.

Waterproofing? No waterproofing on a backsplash. Perhaps you are referring to sealing (which is for stain resistance)?

Thank you for this question! My tile installer just asked me the same question- now I’m questioning everything...

Im not quite sure but my apartment in Mexico and many other homes and hotels in México they do not use grout and i think it looks way better, not sure if it’s because houses are not made of wood like the US they are made of brick and concrete so homes are more stable if that maybe makes a difference but here’s a pic of my place

The tenting video show a floor tile product with grout lines. What gives? Grout? No grout?

Grout is always required. It is an industry requirement, documented in the TCNA Handbook. Even the picture that purportedly shows no grout, does have grout in between the tiles.

@d_luoto The above video demonstrates what happens when allowances for expansion are not built into a tile assembly. EJ171 Such as hard grouting around the perimeter.