I have a new-construction bathroom with a shower stall. I am tiling all the walls and using greenboard drywall for the ceiling.
On the wall, the substrate is HardieBacker with Hydrodefense. The instructions from HardieBacker say to use a liquid waterproofing membrane on all edges and joints. I've used this liquid membrane on all of the wall except the inside corners of the wall and ceiling.
But, I don't know how to handle these ceiling inside corners. So far I have applied alkali-resistant glass fiber tape to the corners, as instructed by HardieBacker. Then I applied mortar on the wall part of the corner, and a thin layer of joint compound on the ceiling part.
So my question is, how do I finish the ceiling part? Do I put two more layers of joint compound there to smooth it out? And then liquid membrane on the wall part? Or do I apply the liquid membrane on both the wall and the ceiling? If I put the liquid membrane on the drywall ceiling, will it look bad? Or do I do something else?
I've tried to pinpoint this on Google but I can't find a clear answer. Please see the image below.