I'm interested in doing something like that wet room. Can you use cement
board on under the tile on the floor or is it not necessary? I've seen
a certain kind of water barriar that they recommend. Is that needed or
can you just tile your brains out.

My parents had that kind of shower in the basement of a home they
purchased from a tradesman from Italy (old school). I loved that shower.
Walk right in , heck bring a chair if you wan to..

I've got one of my baths ripped down to the studs and I'm looking to go
'old school'..