What's happened to imperial sized plasterboard?

[RichD1]

Last time I used p/board (quite some while ago!!) it was available in 2440 x 1220 sheets to match the 16" stud centres. Now I can't find any supplier which has an imperial sheet size and the metric sheets just miss my studs which have imperial sized ply on the outside.

Is there any alternative to cutting and fitting every sheet with the added waste?

Richard

 

[RichD1]

For further information I'm planning on using Soundbloc boards which are 12.5mm thick for both walls and ceilings.

If I laid the boards across the ceiling joists would the long edge sag between the 16" joist centres if not fitted and fixed against a noggin? Or would it be strong enough being 12.5mm thick.

Richard