Are you asking About the Cement board... the tile or a flexible floor and how are they all connected?
Durock Cement Board
The workmen in bathroom said it is better to take up the old ceramic mosaic tiles
from 1951 from the bathroom floor. Instead of going over them with the ceramic 12x12 tiles.
I may be wrong but it seems to me the floor as some play in in it. I hope the tiles don't pop up later?
Your Opinion?
what your options are depends on what's between the old tile and the sub-floor... more like HOW MUCH as in how thick is it.
If its on a mortar bed you have a lot more options. In my case I ripped it all out, had room for TWO layers of cement board thinseted and screwed to the sub-flooring on top of which I installed the tile. But how much flex and for what reasons its flexing are key.
Ceramic tile and springy floors are a very poor combination.