Tim S wrote:
Timothy Murphy coughed up some electrons that declared:

b) I'd propped it well - acro-props are dirt cheap to hire and you'd need
two, with a 4 offcuts of ply or plank to acts as pads top and bottom to
protect the floor and ceiling finish.

I'd go along with TS's advice and disclaimers, other than to say that
depending on the size of the ceiling joists, it's quite likely that you
wouldn't need acrows; unless they are stonking great heavy joists I
would expect the plasterboard to hold them up while you're doing the
work. If you *were* concerened, you could poke your head up through the
new hole in the ceiling, screw down a perpendicular batten across the
top of the joist you're cutting and its two neighbours, which will take
the weight temporarily.

David