I'm in Ohio, if that makes a difference for code.
In follow-up to Bathtub impersonating waterbed? , I ended up gutting the whole bathroom - the liner was not in great shape, there were layers and layers and layers of walls and tiles and who knows what. I'm now down to studs.
Currently looking at this surround: https://www.homedepot.com/p/Delta-Sturdifit-60-in-W-x-58-in-H-Five-Piece-Glue-Up-Tub-Surrounds-in-White-40194/204338527
In in installation instructions, it says to go over greenboard. I don't want to go against the instructions, but is greenboard acceptable? I've read a lot of things suggesting everything will leak, etc. If it's not greenboard, I'd worry it won't adhere correctly. If it is greenboard, I'm worried it'll rot in a few years.
Given that I'm currently at studs, what should I put between the studs and this surround? 2/3 walls in the tub alcove are internal, one is external. Should I do a moisture barrier everywhere in the bathroom, or just within the alcove? Should I do insulation in between studs? Greenboard on top, or cementboard?
As a final question, there's a soffit above the tub that I want to take down or at least replace (because it has evidence of moisture damage) - greenboard up there, or something else?
Thanks. Reading a lot of conflicting information, just frustrated.