Drywall manufacturers do not allow their products as a shower substrate regardless.

Unlike tile, properly detailed solid surface shower walls are waterproof. I put regular drywall behind mine, sold the home 8 years ago, and the new owners haven't called me back yet.

I'd probably use cement board next time.

Thank you for your replies.

If using cement board, what would be the proper way to construct the shower:

Option 1 - ply vapor barrier, followed by cement board, followed by thinset and fiberglass tape on all seams and joints, followed by liquid waterproof membrane applied to all seams and joints only.

Option 2 - cement board, followed by thinset and fiberglass tape on all seams and joints, followed by liquid waterproof membrane applied to the entire surface.

Option 3 - some other method

I may start to ramble here. I am leaning toward option 1 although option 2 appears to be the preferred method when constructing a tile shower. When using a solid surface, it appears that the purpose of the substrate is to provide a stable surface on which to caulk the solid surface. I have also read that the liquid waterproof membranes are meant for tile/thinset applications and not necessarily as a surface to caulk panels to. Not sure if that is true or not. On top of that, for a recessed shower caddy, manufacturer's instructions show to place a properly sized cutout in the substrate wall -- in other words whatever waterproofing methods used in option 2 go away at that point. With option 1, the ply barrier is still there.

As an aside, I have also thought about using Densshield/Densguard as the backer although I don't know how well that material would hold up if there was a plumbing leak. I also run into the cutout-in-the-backerboard issue, similar to what I indicated above.

Mabey I am overthinking this, but it is better to do it right the first time.

Thanks!

your question requires a schematic of prefab shower bases integral flange detail and drain assembly. Hire wisely hire one crew to handle the entire process and get inspections and wrrty paperwork best advice.

"@Joseph Corlett What adhesive do you generally use to adhere the solid surface to the substrate?"

I like a French cleat system. The panels hang off the cleat so the wall can move a bit independently of the stud walls and the thickness of the cleat allows for the manufacturer-required seam support. If you make slots in your cleats, they can be adjusted precisely so you can get perfect spacing at the shower pan silicone joint and adjacent walls.

I wrote an article about this twenty years ago, the the magazine is out of print.