I was working at a job toady and a woman had a tile guy there who was preparing a quote to install some travertine. He pointed out that the existing floor was poorly installed because it was a butt joint installation and as the tile expands, it will loosen the tiles. I tried not to laugh and kept my mouth shut.
My experience is that a butt joint install is more of a stone-masons way of doing it, and the average ceramic tile guy likes wider joints so you will not notice the lips as much.
As far as with delimitation, grout dries rock hard and I fail to see how he could say that 1/8” of grout would allow the tiles to expand…? The only way I know of is to provide a proper urethane expansion joint.
Am I missing something here?