Plasterboard vaulted ceiling

[robbie77]

Hi

I am approaching the end of insulating between my rafters and will soon be overboarding with more insulation.
I chatted to a builder who suggested fitting 2 x 1" batten through the next insulation (running perpindicular to the rafters) and then fixing the plasterboard to this making it eaiser working at height and leaving a void for electric cables with use of a small scaffold tower.
I chatted to a mate who said just fix them straight into the roof rafters with long 100mm screws.
The ceiling is quite high and the job will be quite cumbersome so what would you do??
I have never boarded a ceiling but reasonably fit and healthy.

So option A
Attach 50mm plasterboard to rafters using 2 x 1 battens every 400mm. Then attach plasterboard to the battens

option B

Attach 50mm insulation board to rafters using 80mm screws then attach plasterboard over the top of this (using 100mm screws , will this be enough fixing into rafter?) trying to eye in the rafter that will be covered in insulation.

What would you recommend?

thanks

 

[garyo]

I lay them straight on using 100mm screws. I lay them landscape orientation and then only use a batten when two boards meet because I don't like trying to hit the edge of a 47mm rafter without getting too close to the edge of the plasterboards. You may be a bit late for this if you've already got your 100mm pir fitted.

 

[garyo]

And yes it's a pig of a job single handed at height!

 

[robbie77]

I lay them straight on using 100mm screws. I lay them landscape orientation and then only use a batten when two boards meet because I don't like trying to hit the edge of a 47mm rafter without getting too close to the edge of the plasterboards. You may be a bit late for this if you've already got your 100mm pir fitted.

100mm screws through 12.5mm plaster board then through 50mm insulation into rafters?
Is it not all or nothing with the batten method? You can't just screw to the rafters and then use a batten halfway down can you?
What about lighting cable do you just clip this to the PIR?
So many questions!
Thanks

 

[23vc]

Yeah, B.
But you don’t need to screw the insulation, just put a clout nail here and there to pin it in place until the plasterboard goes up.
The 100mm drywall screws can be hard work and a bit bendy, try and get half decent ones from your BM, most recent ones I used were from toolstation and they struggled, think they were a bit thin

 

[dontbelieveawordofit]

yep , what the 1st builder said,
lay insulation over rafters. then 2x1 over the top every 12” . and foil backed boards over.
100mm screwtites from screwfix.
then 32mm drywall screws.

 

[garyo]

You can't just screw to the rafters and then use a batten halfway down can you?

I mean the odd batten is fixed to the side of a rafter every 2.4 metres so that it's easier to catch the rafter edges. So your 47mm rafter ends up being 73mm thick instead.

 

[garyo]

What about lighting cable do you just clip this to the PIR?

I'd have had the lighting cables first fixed before insulation. On the last vaulted ceiling I did I had non structural collar ties so that I had a 500mm wide flat ceiling at the apex to hang lights from, and used that space to run the cables through.