soundproofing a ceiling

[stolen stilton]

Hello all. Have quoted to soundproof a big ceiling in a house. I quoted to rip down existing, insulate between joists with 100mm acoustic rock slab, board over in Soundbloc board and skim. Customer has accepted but asked if it is worth spending more and upgrading by putting an extra 50mm of slab in and fitting resilient bars to the joists first so a couple of questions.

I have not used the resilient bars before so is it just a case of screwing them up along the lengths of all joists and then screwing the boards to these.? Do the bars come predrilled with holes for the screws to through? How much do they cost and where to buy them from?

I quoted to put the 100mm slab into what is a 200mm cavity as I believe that an air gap between the floorboards above and the slab is the best way of achieving the sound insulation. Is there more soundproofing to gain by adding the extra 50mm and leaving just a 50mm air gap?

Sorry for the questions but not had much to do with soundproofing before.

They are just trying to negate the noise in their own house between floors, it is not a separtae dwelling above

Many thanks

 

[flynnyman]

The resi bar goes across the joists and normal dryall screws will do.

 

[spunky]

The kids have reached that age aye fair play, you know when you go home to you're girlfriends house and the parents used to say leave the door open I was always tempted to say you can come and watch aswell if you want you don't just have to listen :RpS_lol:

I think there right in what there saying mate from what I know with resi bar you fix the edge then fix the board to the middle so it floats of the joist there's no direct contact, cross batten the timbers at 600mm and use 15mm board, after you've fixed the first row of resi bar get a piece of timber and fix two pieces of resi bar each end set set at 600mm centres then when you offer up you're next length of resi bar sit the template you've made up over the top and keep moving it along as youre fixing and you should get even centres all the way along

 

[flynnyman]

If there are no issues with coving why not drop a ceiling below the existing coz the existing will also give you extra sound proofing.

 

[murplastering]

as flynny says but use mf system and accoustic hangers. I thought resiliant bar was for walls never seen it on a ceiling