I just ripped out everything from an outdated bathroom, tile walls, tile
floor and tile shower.
I discovered severe water damage to the plaster - lathe and sheetrock in the
shower area. I would like to repair the damage and install new tile.

Where does cement board go in a bathroom? If shower, how high? Should I
install cement board on the floor before installing tile? Would plywood and
metal lathe work just fine on the floor?

Thank you.