On Saturday, October 22, 2016 at 10:28:30 AM UTC-4, dpb wrote:
On 10/22/2016 9:18 AM, Chris Jenkins wrote:
Looking for some advice on an issue with a "wall thickness" issue
I'm dealing with in a shower rebuild.

After teardown to studs of the existing shower, I can see that in
previous work done on the house the original plaster/metal mesh make up
of the walls (house built in 1959) has been replaced by a double
thickness of drywall halfway down the walls. As a result the walls are
not plumb, as the double drywall portion of the wall (bottom half of the
wall) is approximately at least 1/4" thicker than the top half, meaning
that if you're standing at the entrance to the shower the walls slant like:
...

I thought you'd torn back to studs--they're not plumb? Or do you mean
you've just exposed the previous underwall surface now?

If the latter, I'd recommend going back to the studs and then replacing
the drywall with rock designed for shower instead; then you'll have both
the water resistance should have as well as a suitable tile backing. If
there needs some shimming done, do it to plumb/square everything before
installing the sheeting.

Sorry, I think I explained poorly; the walls of the old shower were plumb, its all the rest of the bathroom that's not, so I'm trying to figure out the best way to compensate. Everything in the shower is square/plumb/level, it's where it meets the not-plumb walls of the room where the issue is. It looks to me like in the past the lower half of the walls were torn out to upgrade plumbing and electrical, and the drywall they replaced it with makes those new walls thicker than they used to be.

This is our eighth year in this house and the last room to be remodeled, and I swear something like this has come up during every single project we've tackled...