stewart killick
The answer somewhat depends on what substrate the kitchen floor is but if it's a wooden floor underneath the tiles it should have been prepared using an anti fracture matting such as ditra mat to separate the tiles from any movement in the floor, the underfloor heating wires should have been installed below this. If this isnt the case movement in the floor will cause tiles/grouting to crack over time. On a concrete floor it's rarer for this to happen but in cases where it does it's usually because the tiles have been installed on a few blobs of adhesive rather than a full bed leaving large areas of tile with no adhesive underneath. Floors should never be tiled this way and even more so with underfloor heating as the wires need to be fully covered in adhesive.
