I just completely gutted my bathroom down to the wall studs and original plywood sub-floor. Which do I install first -- the new bathtub or the cement backer board on the floor? The original tile floor was over an inch thick. The new tub will be fiberglass, and I plan to put ceramic tile around the tub area as well as the main floor.
If you got the standard enamelled metal tub you will see that the top edge may have screw holes already in it. I don't think fiberglass was much different- maybe no holes and you have to drill them yourself as the tub is in place This is screwed to the studs. Can't see studs behind cement board.(Don't care if you have better than 20:20 vision) CB is just a board for tiling onto. Before that was Greenboard basically gypsum board with a waterproof coating. Before that it was just gypsum board. The Tile& grout is the waterproof layer. Many houses were done on gypsum board. Mine has been done that way because neither Greenboard or Cementboard were not invented yet. Mine has been up for 35 years not a problem at all.
you are into some deep RE-construction if I were you it would be best to visit the hardware giants and take those classes that will help you get a professional finish to your new bathroom ..... surr
