In article ,
Deville writes:
Any reason why these can't be laid straight onto the existing
chipboard floor? I'd like to avoid an extra layer of plywood if
possible.

Just a heads-up...
Porcelain tiles can be very slippery when you step out of
a bath or shower onto them. I have them in a bathroom and
I like them, but I keep a rubber-backed bath mat in front
of the bath/shower to avoid slipping. I would think twice
about installing them in a bath/shower room which might be
used by an elderly or infirm person.

--
Andrew Gabriel