We have large 60cm sq porcelain tiles in our kitchen /conservatory. They were fitted about two years ago. One tile by the sink has cracked almost the whole width, no idea why. We have under floor heating. Any idea how this can be fixed please?

Clean out grout line of broken tile. With a chisel remove tile starting in center. This will keep u from breaking surrounding tile. After cleaning area install new tile and regrout.

Chuck