And regardless of tiling on tile (which is a no-no,especially with that size tile)dont put blobs on the back of tiles ,you need as much coverage on the back of tile as possible and should be using a cement based adhesive (not ready mixed tubbed stuff)If your planning on doing this as a diy job have a serious re-think,it would take a pro 2-4 days to do it right and would take a diy-er 2-4 weeks to do it wrong.
