When I moved into my house, the kitchen has large floor tiles on the floor. Quite a few of these tiles are cracked. I've been told that the reason they are cracked is because under the floor tiles is a plywood underlay layer, and where the plywood pieces meet each other isn't exactly even, and so the tiles are cracking at that join.
If I was to pull up the tiles an lay a new floor, what would I have to do to overcome the uneven plywood flooring? Is there something I should lay on top? Or should the plywood be re-layed?