Which size plasterboard for ceilings 11.5mm or 9.5?

[eastender3]

I am removing an old lath and plaster ceiling in both downstairs and upstairs but confused as to which type is best. My builder is suggesting the smaller size, as he says that's common in ceiling and 12.5 is mainly for walls

However, I think he should fit the larger depth, at least in downstairs celing, for extra noise insulation, even I'm going to fit rockwool between the joist for downstairs.

All the ceilings are being replaced. He has ripped the whole house old ceiling and putting plasterboard and skimm over it.

Is he right in choosing 9.5mm over 12.5

 

[Karis]

Is he right in choosing 9.5mm over 12.5

No, he’s being a lazy cheapskate because 9.5mm is (slightly) cheaper & is lighter/easier to put up. He’s right that 9.5mm was mainly used for ceilings in the past not any longer, nobody uses 9.5 for ceilings anymore. The additional cost of using 12.5mm is negligible & it’s a much better bet.

 

[eastender3]

Is he right in choosing 9.5mm over 12.5

No, he’s being a lazy cheapskate because 9.5mm is (slightly) cheaper & is lighter/easier to put up. He’s right that 9.5mm was mainly used for ceilings in the past not any longer, nobody uses 9.5 for ceilings anymore. The additional cost of using 12.5mm is negligible & it’s a much better bet.

Thanks Karis, for your reply.

Does the choice of depth of plasterboard affect the size of joist.

 

[Karis]

Does the choice of depth of plasterboard affect the size of joist.

No, if it did then the joists will have been seriously undersized; is your builder replacing the joists?

Additional weight is something you would consider when over boarding but it would rarely be a problem where there is a floor above. Don’t forget you’ve also removed the old lath/plaster & all the crap that would have been lying above it!

 

[eastender3]

Thanks for the reply.

Will insist on him to fit the larger version at least on the lower floor and maybe 9.5mm on the upper floor. Thinking to put rockwool on the lower floor for added thermal and sound insulation, what do you think?

 

[joe-90]

12.5 all round. 9.5 can bow if it gets a bit damp.

 

[Karis]

Will insist on him to fit the larger version at least on the lower floor and maybe 9.5mm on the upper floor. Thinking to put rockwool on the lower floor for added thermal and sound insulation, what do you think?

I would insist he uses 12.5mm throughout & make sure it’s screw fixed not nailed, nobody uses those anymore either! Loft insulation wont help much; you need a dense medium for effective sound insulation, cavity insulation bats would work a little better but not much.

 

[eastender3]

Thanks fellas,

Just came back from house being renovated, builder was dissapointed when I told him that he should get the larger plasterboard. His face gone red when I told him, maybe due to extra effort required to put them up by him and his mates, and will ensure he used screws to fix them.

Now not sure if he ****ed, he could deliberately use poor workmanship.

 

[stevethespreader]

Now not sure if he p****d, he could deliberately use poor workmanship.

your being a bit paranoid no trademan in his right mind would do bad workmanship deliberatley you have told him the specs you want if he dont like it get some one else in