Ceiling falling plaster

[braindead81]

Any advice on 1m squared plaster fallen from ceiling lathes near back door? Is it best to cut back to solid then either board or use a bonding coat?

 

[bobasd]

odds are that the plaster could be detaching from the laths all over the ceiling. you could put a bit of filler in the patch to bring it out and then board and skim the whole ceiling.
why do you think its detaching?

 

[braindead81]

I'm thinking just age 1930s ,the plaster seems fine elsewhere that's why thinking just cut back square to stable plaster and either screw board to joist or fill.