I had to cut a (roughly 50cm by 1m) hole in our triple plasterboard bathroom ceiling last year in order to do some work in the loft space above. I then sealed it back up by nailing double plasterboard back in its place, plastering over and sanding. Everything looked beautiful until recently when I noticed a thin crack almost completely surrounding the area where I originally cut the hole. Aaargh!
a) How should I have resealed the hole to avoid this and b) What should I do now?
Raphael