Noggins needed to plasterboard this ceiling?

[Albumen]

Room is a bathroom, 7.5 feet by 9 feet. Old lathe and plaster ceiling. Rough, patchy and I'm having a ceiling mounted fan fitted.

So I think I'll take the old one down and replace with plasterboard and get someone to skim it.

The ceiling joists are at 12 inch centres. The joists go across the short way, across the 7.5 feet width. So the 'bound' edge of the boards go across the joists and the 'cut' ends butt together at a joist, yes?

But do I need to fix the bound edges to noggins between the joists?

What board thickness does anybody reccomend?

Thinking about it if I use 8' x 4' board (but cut down a lot lengthways) this is going to be 4 pieces, but with long cut edges down the edge, against the wall. I'm expecting to tuck those in above the existing wall plaster. Is that enough or do I need noggins to support those?

Many thanks.

Presumably foil backed in a bathroom.

 

[Micilin]

Use a 12.5 board or thicker - you could use a firelined or soundblock board if there is a need.

You want a noggin wherever boards butt together ie join at the narrowest edge, and one around the perimeter . The boards should not 'flap' when fixed

 

[Richard C]

I’m assuming you’re skimming & not tape & fill. Use 12.5mm as stated but if your joists are spaced @ 300mm, you don't need to fit intermediate noggins; you can safely go up to 450mm joist spacing with 12.5mm boards no problem. Strictly speaking, you should have noggins to support the two perimeter edges but it should be OK @ 300mm. Board across the joists as you said but stagger the board joints to avoid cracks developing. You don’t really need Duplex (foil back) but it won’t do any harm.