In article ,
Ian wrote:
And here is my quandary: - is there any straightforward way of telling
how the ceiling is constructed? (I couldn't find anything in Google).

If there's a dry bit left, tap it with your knuckle. Plasterboard will
'ring' - rather like tapping a sheet of wood - a sort of hollow sound.
Lath and plaster will not.

--
*We are born naked, wet, and hungry. Then things get worse.

Dave Plowman London SW
To e-mail, change noise into sound.