Three years ago I had a flood in my apt. Only a couple of my ceramic kitchen tiles became loose. One year later... The contractor I hired to lift them and replace them ended up lifting over 20 kitchen tiles (Octagon shap) and taking them home to remove all the cement and thereafter replacing all of them. They seemed to be OK, except now I notice a couple of them are actually RAISED slightly on the edges and this makes the floor not completely level in that spot. What would cause the tiles to raise like this very slightly on the edges? As I see it, the solution is to have the entire kitchen floor re-done with 18 X 18 or larger ceramic tiles WITHOUT GROUT and close together. I have matching baseboard under the cabinets as well as wallpaper in kitchen. Any suggestions?

You ask a big question, but give little details. Did the tile always stick up after they were replaced or did they change sometime afterwards? What type of material was the tile placed on? Was the floor beneath the tile soaked? Big tiles mean fewer grout lines, but if something raises in the middle of a big tile it will probably split depending on the amount of movement and the grout type. Did they use modified thinset or non modified thinset? Still a lot more questions could be asked.

Ungrouted ceramic tile are asking for future problems... and it looks bad and unfinished.

Significant ammounts of water would get in and lay in those spaces for a considerably length of time every time the floor was washed. One of the reasons it MUST be grouted.

A properly installed and grouted ceramic tile installation could last a very long time, far longer than your appartment will be standing....(Roman ruins have been discovered with intact mosaic tiles).

Your bigger issue is why did it flood and how to keep it from happening again.