He said he'd replace with cement backer board on the bottom of the closet instead of drywall because it takes a good beating from water if there's an overflow again. I thought that was a great idea. Thinking ahead, now I'm wondering, though, if that will impede easy access to the pipes behind the wall. Also, if there happens to be a leak behind the wall it won't be obvious, as it is with drywall. What do you think? Backerboard ok instead of drywall? Foresee any problems with that? I guess it would mean access from the other side of the walls, room-side, if the pipes needed work for some reason. That closet is tight anyway. Obviously he must have noted where the water lines run, etc.