Wall backing for Onyx Shower base and panels
I've ordered an Onyx shower base and wall panels to go in an existing 36" x 48" alcove. Before the plumber came to install the pluming, I tore out the drywall on all 3 walls, intending to replace it with Greenboard (recommended by the manufacturer) before the shower base arrives.
But the plumber says no, you have to install the shower base first, as it goes up against the studs, then you install the greenboard so it slightly overlaps the "lip" on the base.
So I'm confused, and Onyx's installation instructions give no clarity on this detail. Can anyone advise me?