NeedforSwede2 wrote:
In article ,
says...
Use 6X3 plasterboards or 4X3, don't attempt to use 8X4's, and
whichever you use, make sure someone is with you when you put them
up.

Going with 4x3 9mm, they fit in the car and will be easier to hold up.

Seeing as she stepped through the ceiling, I now have two visible
joists to start with and measure centres from. Will mark walls etc,
but at least I have two go with as starting refences to measure from..

I wouldn't measure the centres of the two you can see and assume that the
others are the same, they rarely are, you need to break into the boards /
laths to see the joists at each end.

Also you'd be wise to put some spacers along the joists which are showing,
otherwise the p/b will have a gap above it in that spot, some strips of p/b
will suffice and also make the job easier.