Over time what will happen stepping on that corner with no thinset under it? It will crack, there is the answer to your first question. Now as to the quality of the rest of the work, I will let the pros answer that.

Here is an additional image. I really hope I can get some pros to comment before it's too late to stop this install. If there are any pros in Charlotte, NC willing to come out and take a look, I am happy to pay a consult fee.

Thank you both for the comments. My contract says nothing about NTCA guidelines. I trusted my contractor to truly bring his best installer because my contractor has done the majority of renovations in my building with excellent feedback from other owners. It appears I should have done more homework. My contractor is open to professional opinions and inspection. He is offering to put a written warranty on it, but this is a 400 sq ft studio with nowhere to put my things if the floor has to be redone down the road. We are meeting later today and I need to decide before then if I want it all removed.

SJ, I just finished watching the Trowel and Error video from that PDF you linked. So helpful! That made up my mind. The tile has to come out. Thank you so much for your help!

"And where are the spacers? The floor leveling system? "

The lippage tuning system is clearly visible in OP's photos. I use the term lippage tuning as they level nothing. Spacers are not required for a tile installation and will actually make installation more difficult if any tile size variations exist.

"My contract says nothing about NTCA guidelines."

That would be because NTCA (National Tile Contractor Assoc.) does not provide guide lines. They are a wonderful organization of tile contractors which support each other and the industry as a whole. Any tile contractor can join so don't assume being a member guarantees quality workmanship although the odds are greatly increased. There are certified tile installers (CTI) who have taken a written and hands on test through the CTEF ( Ceramic Tile Education Foundation) As for industry guidelines that would be TCNA (Tile Council of North America) handbook. Working in conjunction with ANSI standards.

Trowel & Error Video. Good choice SJ

This link will provide you with questions to ask.

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

Thank you, Creative Tile. All good information and hopefully will help others that find this thread before having tile installed. I wish I had went on more than just my contractor telling me this guy was the best.

The installer is standing firm that this was a good install. He says he only needs 80% coverage on the back of the tile and therefore there can be gaps under the edges. Per ANSI, that 80% should be "sufficiently distributed to give full support" with attention given under all corners. He says I'm wrong. He also says he "backfills" the edges when he works on the next row, but there are areas where he clearly didn't even do that. He says those gaps under the tile will fill in with grout to provide support.

He feels I should keep the tile and allow him to replace a few tiles where you can hear hollow spots when tapping on it. However, there are others that appear to be sitting on trowel ridges. I want it torn out because if there are this many obvious mistakes, there could be others hiding.

Everyone that has seen the photos says it's not properly installed, including the manager from the tile store and a properly credentialed flooring inspector. However, the installer thinks they will say it's fine if they see the whole job in person. I don't see what difference that would make. Perhaps he did a few correctly but that doesn't make the whole thing okay.

This installation was costing $15 sq ft, so this was not a case of choosing the lowest bid. I don't know who is going to cover the cost to remove the tile and thinset, but it shouldn't be me. The installer has already been paid for the work he did.

I may be completely off with this question. Looking at your photo on my computer screen it appears to be a cement subfloor that has a shine as if it was painted. Please confirm.

It is a concrete subfloor. It was not painted, except for any that may have gotten on it during construction (1960s). The installer put a primer on the concrete for the self leveler. However, he didn't pour the leveler over the whole floor. If you are referring to the image of the 4 tiles meeting, that could be the primer. Will self leveling primer affect adhesion? The other images are self leveler and the white is where he got thinset on the floor and rubbed it back up.

Here are some images that I was hesitant to share because the installer said it wasn't fair to count them, even though this area was part of the square footage that I was paying to have leveled and installed. These tiles were going to be half seen and half under cabinets. I freaked when I saw them. I have no doubt the weight of cabinets and granite countertops would have cracked these.

Wow...you are right to have this tile ripped out. That is poor workmanship.

A concrete slab from the 60's will need both grinding and leveling. It could be/should be a couple of days of work...depending on the total square footage/amount to be ground/leveled. Do you remember seeing him using a grinder? Did you see bags and bags and bags of thinset on in your home (could be several dozen bags...depending on how bad the concrete was/is)?

Do you remember the cost for the subfloor prep? It should be in the $2-$5/sf range and is often a separate line on the invoice. The cost of labour to install the tile should start around $10-$12/sf for regular tile...and climb higher for large format tiles like yours. In my neck of the woods, the starting rate for REGULAR tiles is $12/sf. A large format is $15-$18/sf...from a regular stile setter. Anyone who specializes in large format (or high-end installs in $5M houses) will reach $25/sf without blinking.

And the cost of the tile/material is extra. It is possible a large format tile, with BAD concrete slab and a well educated installer could reach $25/sf.

Please find out the price you paid for the subfloor prep work. If your slab is as bad as it looks (from that one photo) then it should be a significant part of the price tag. Which means the $15/sf is very low for large format tile...if it includes the $$$$ for the subfloor prep.

And it is possible that the primer could interfere with adhesion if it was not covered by self leveler...it simply depends on the chemicals used.

SJ, you are a wealth of information. Wish I had met you a couple months ago!

This is an upper floor of a concrete / steel building that was high end construction when built. There were no high spots to grind. It was flat except a slight sag that spanned the center of the 16' x 19' room. They might have put too much self leveler in the center of the room or didn't spread it enough because it looks like the leveler over corrected the sag based on how the tile looks. Only 140 square feet of tile was put down before we stopped. I can't imagine if the whole place were done (there was a hallway, closet, bathroom and shower surround that was also to be done, although most of those were to be smaller tile).

I thought I was paying for a quality install based on my contractor, what I read on Angie's List, and the feedback from employees where the tile was purchased. The tile store said he does work for multiple contractors. The highest option my contractor quoted was $15 sq ft and this was for all labor, no materials. Just before the work started, the installer told me the cost of leveling material could add up and I said I wanted to do whatever was needed. They cleaned, primed, and leveled in one day. He said he had done large format tile before and that my floors were flatter than the last place he installed them. He was given the layout, size and specs of the tile before he quoted. He knew exactly what was involved and should have declined the job if he couldn't perform it well.

I'll post an update here when things are fully worked out. I'm now looking at having the leveling removed as well and doing a professionally finished concrete floor. I can't handle the stress of trying another tile install. I'll take a rustic concrete floor over cracked tile any day.

Thanks to all that have taken the time to comment. You've all been very helpful.

I’m a DIYer and I know that is an unacceptable install. Pull it out and start over. Grout is not meant to fill massive voids under tile. And I've never heard of mortar “puking” out of the gaps.

Not that tv is always right, but I recall seeing big tiles like that installed with mortar that almost looks like wet sand. And they definitely covered the back of all the tiles.