by SandyMc
What base do I need for a flexing plywood subfloor - to lay tile?
We used a large tile that has cracked. It’s a 2nd floor bath.
Suggested Project Book
If you used plywood, as a subfloor, you probably did not put mortar under the entire tile. The air between the tile and thin set made it crack when you walked on it.
If the subfloor is flexing you may have some damage to the joists. I would cut out an inspection hole and check out what is going on.
The subfloor isn't thick enough. You don't want any bounce. Need at least 2 3/4 " plywood as a base.