Recently, I worked on a repair to a large tiled floor where 12 tiles were coming loose and buckling upward in a bedroom and 7 tiles were coming loose in the formal dinning room. The homeowner asked me, “why is this happening?” This house had over 1200 sq. ft. of floor tiled installed over a concrete slab. Most of this tile was in a continuous run from the front door entry to the formal dining room, kitchen, hall, hall bath and finally to the bedroom. When tiles are set on a continuous run exceeding 24 feet indoors, the tile floor needs someplace to expand to when normal movement or expansion/contraction occurs.
If an expansion joint is not installed by the tilesetter at the time of the original installation, the tiles sometimes pop up as they have no place to move sideways. So why wouldn’t you typically see indoor expansion joints in large floors? The reason: the customers don’t want to see open gapping gaps in their floors and the tile setter’s don’t want to bother leaving them open and then having to explain why they are there. I’ve come up with a better solution. In the case of the recent repair to this 1200 sq. ft. floor, I re-set the tiles with an elastic type thin set and I also did not grout one long continuous joint at each repair site. I then filled this joint with a colored sanded caulk custom made to match the grout.