Fixing plasterboard to lathe & plaster

[pred]

Hi, I'm in a bit of a quandary, I've some cracks in the ground floor ceilings, two different spreads have both said find the joist and screw strait through the lathe & plaster, I would normally baton it out or take the old stuff down.

Could you please advise me of the best route to proceed, many thanks for your advice.

 

[Peter1919]

Both plasterers are correct, its what we had done on our lath and plaster kitchen ceiling in order to cover up artex

 

[Pigeon85]

Advice you have been given is the best option. Less work and a hell of a lot less mess.

 

[pred]

Also will I be OK using 9.5mm or go for 12mm?

Once again many thanks.

 

[noseall]

I personally don't like it but 9.5mm will likely react better to any existing humps or hollows. Just go steady when fixing where there is a hollow, to avoid popping.