I need to finish the outside corner above the shower alcove. The shower ceiling is hardibacker and the wall outside the shower is drywall. Where these two meet, what is the proper way to finish it so it's a nice corner? I will just end up painting it.
The walls were easier because I had tile wrapping around the corner so I just taped and thinset those and tiled overtop. Not sure what to do for the ceiling since there won't be any tile.
I had a similar situation where the backer board extended a few inches past my planned tiling edge in my shower. After I had finished with the tile, I taped the joint and applied joint compound over the backer board and it seems great. It's been three years and there is no cracking or any problem with it. That's not exactly an answer but I hope it helps you decide.
Normally you would get something like the picture below to cover the side of the tile. But it generally has to be installed under tile. (you could still try it out and mud/caulk on the flat end but I don't see it lasting long looking good in a damp area)
Now you will have to go with some kind of bullnose or trim piece, much like you would trim out a door. A chairrail, bullnose, double bullnose could all look good here. From what I can see one of these would probably be the easiest way out of this now.
