what screws when fixing plasterboard to old ceiling

[andrewaaa299]

Hello

We are having a plasterer put plasterbaord up on our old lathe and plaster ceilings and then skim over it.

However, the screws he seems to have used dont seem long enough to me - the screw has to go through the plasterboard, through the old lathe and plaster and then into the joists.

But these screws look like they are 5cm long at the most. Surely this is not long enough to go through the board, the old ceiling and then into the joints?

I told him i wanted them into the joints, but i dont think they have done it properly. Is there any way i can check if they have put the screws into the joists?

Most importantly - can anyone tell me what the typical screw length should be for this?

Very worried - thanks

Andrew

 

[PrenticeBoyofDerry]

Unless you can get to the ceiling above difficult to know for defo if screws have gone through joist. Joist are usually about 400mm apart.
When over boarding in to lathe and plaster ceilings I use 65mm Dry wall screws.