What thickness to cover stone/wooden (floorboarded) for kitchen/bathroom?

what’s going on top of it- vinyl ?

As thick as you want, and as thin as you want – if it’s being fully supported by stone/floorboards.

usually use 6mm or 1/4 in– depending on your view

if the floor is really distorted you may want something thicker.

Depends entirely on what you’re putting on it, how stable and flat the boards and stone are and how you intend to fix it down

If you’re covering it with vinyl, then 6mm will be enough. If you’re going for ceramic tiles, then as thick as you can manage (and even then there’s no guarantee).

Dont forget to take all the doors off first,heard of one chap who did a lovely job of laying ply on his floor and screwed and glued all the joints then couldnt open the doors.

Dont forget on a stone floor to use a sheet of dpc plastic to stop the damp in the stone comeing through.

i guess you are putting down non slip vinyl in those areas , the tiles not come up easy?