We have a property (not our primary residence) that we're remodeling. The bath needs redone in the tub area. Old tile was not grouted/sealed well, or if it was as the grout fell out it was replaced with caulk. As a result water seeped behind the tile and damaged the drywall. We've ripped it out and are down to 2x4's.

As it's not our primary residence, we are looking into putting in a tub surround rather than re-tile. (Easier and more economical.)

Here's the arguement: I'm a big fan of rockboard for water damage prevention. It's used in any bath we've done that we've tiled. However, the friend doing the work for us insists that greenboard is the way to go for a tub surround (he says better adhesion) and rockboard is strictly for ceramic tile (again, better adhesion but for tile only.)

It's critical I keep water from getting behind the new tub surround. What do you think? Greenboard or rockboard?

Thanks!