Tiles over vinyl

[scmfell]

Hi, I have a kitchen floor with vinyl squares, (over chipboard I believe), that I wish to cover with stone tiles. I am aware that laying tiles directly onto the vinyl is not recommended, although the floor is sound and the vinyl shows no sign of damage. To be on the safe side I believe it would be prudent to cover with plywood. Assuming the floor is stable and flat, what is the suitable minimum thickness of plywood?

[rosebery]

I would say 12.5mm but I'd be veeeerry nervous about doing it frankly.

Personally I'd rip the whole lot up - chipboard included and replace with 25mm WPB ply direct onto the joists.

Cheers