9.5 or 12.5mm plasterboard for ceilings?

[diyreg]

I'm going to board over existing lathe and plaster. Is there any disadvantage to using 12.5mm board apart from 30p per sheet and the extra weight to lift? (it's stronger apart from anything else)

 

[spada01]

I've always used 9 for ceilings and 12 for walls. Maybe the weight would cause problems on the rafters as it's also holding up the old lathe and plaster?

 

[noseall]

I don't use 9.5mm plasterboard full stop as i think is is amateurish tat.

12.5mm everywhere.

 

[fulguros]

I wouldn't say that 9mm is amateurish tat, but I never ever use it over 12.5mm if I have the choice. It is purely an option when space is tight.

Eg. Removed old plaster off an internal brick wall and had to dry line the wall and get the plaster to finish flush with the existing door linings and there wasn't space to dry line 12.5mm boards to get them back enough.

The other problem is strength with 9mm boards. Ceiling joists at a 600mm span may be too much of a gap for some brands of plasterboard and end up with sagging between all the joists. Especially if the boards already seem like they have been stored damp like some of the boards we have been getting delivered recently.

 

[theoldun]

9,5mm board is plenty good enough for joists at 450mm centres, providing you have a perimeter noggin and all long edges have noggins.
12.5mm for 600mm centres plus perimeter noggins and all long edges have noggins.
On new housing work we are now on 15mm boards, both up and down with ceiling and floor joists at 600mm centres. No noggins and we comply with NHBC acoustics.
oldun