Porcelain tile separating from gypcrete slab
We recently had our kitchen renovated/enlarged and had radiant heating installed in a gypcrete slab. The floor is one story up over a new basement space and sits on 3/4 inch plywood on properly supported floor joists. Shortly after the kitchen was completed, we began to hear loud cracking noises coming from the kitchen floor and eventually realized that the 18×18 porcelain tiles were separating from the gypcrete. The result was that we had most of the tiles pulled up and reset and that seems to have solved the problem. Standard thinset was used and it looked like most of the thinset was still attached to the tile when it was removed. Why did this happen? The footings of the kitchen addition sit on the granite schist and are secured with rebar so there is no movement there.