Shower ceiling repair?

[Surkis]

Hiya. I am by no means a professional however I ended up becoming a sort of "fix-it guy" for my friend's family because I guess even though I never actually did any of this stuff before until recently, it almost comes second nature to me.

That being said, i'm having a problem. I don't know how they managed this but there is sort of a hole in in her shower ceiling (the shower ceiling is very low, as a matter of fact the shower itself seems to be almost sort of a tiny alcove as opposed to just being part of the room).

My thing is though the ceiling isn't a nice neat square shape that I can just drywall and paint and there we go (even then I would need to know what to do with the drywall to make sure that the moisture doesn't damage it). its actually curved, and because of that I have no idea how to even begin repairing it.

I have a few pictures actually to show you what i'm working with that i attatched to this post.

I have no idea what to do to fix this hole. should I cut it out and replace it with drywall and risk messing up their design? Or is there a special plaster that I use? Mind you the goop that's on there right now is not my doing, that was someone else who attempted to repair it (and failed).

[HayZee518]

ok, I can see the metal lath in that goopy mess. use a hammer and remove as much of the junk as you can to expose the lath. for the cover use plaster of paris with a fiber or horsehair binder. work in small areas as the plaster dries rock hard and is even tougher to smooth out. sheetrock mud where exposed to moisture tends to get soft. what you might try is mixing white latex paint into a batch of mud and use this as a filler. use the plaster of paris as a prime coat and the paint/mud compound as a finish. the paint will give the porous mud some water proof ness.

[pushkins]

If it were me, I'd use drywall compound applied in layers (2), this way you could easily maintain the curved ceiling and you would be able to sand back easily to help in doing this. The important thing is the finished ceiling MUST be sealed, this you can do by applying 2 coats of Zinzzer of Kills oil based paint, both these paints are moisture barriers once applied.
The problem is caused by moisture, so, the moisture issue needs to be addressed no matter what avenue you take to repair, or you will end up exactly where you are now again.
Another thing that should be in this room is an exhaust fan, that actually gets used.