I've been helping some friends by doing a few drywall patches for them after they had some plumbing work done, only to discover the hole cut in their kitchen ceiling seems to be in cement board, not drywall.
It's about 10" x 5", and it's not on a stud. The ceiling also has the swirl-pattern, popcorn-texture plaster.
Now, I don't know if cement board is common in kitchen ceilings. I've never come across it before, but I can understand why it makes sense to have fire resistance there. I don't think it's required in Massachusetts, though I've never done a new kitchen ceiling.
What's the best way to go about patching this? Should I cut back to a stud and put in a new piece? Is there a practical way to put a piece in without cutting a lot more out? (I'm a little worried about cutting straight edges in it.) Can it be patched with some wet- patching substance?
I haven't had a chance to go shopping to see what's available yet, but I figured I'd ask ahead of time so I'd have a little more background tomorrow when I do.
The ridiculous thing is that the hole accomplished nothing more than telling the plumber he needed to cut a hole through the behind-the-tub (much more easily repairable) drywall instead.