I'm having the following staircase and railings (with glass inserts) installed. Note that the each railing has a run of metal that runs along and is attached to the floor. I've been told that such railings should NOT be installed over tile, only wood (i.e., the subfloor); that if somebody pushed laterally on the railing, it could break the tile beneath it and fail. Is this correct or is there a way to install the railing directly over porcelain tile?