Full fill or partial fill with insulated plasterboard - sound

[MrSnowy40]

Hi Board,
I'm currently involved in the construction of a new dwelling which is located next to a busy road and I'm currently debating which is the best form of external cavity wall construction for better sound transmission purposes, with the following options:-

Option one - 100 brick/150 cavity(100 celotex cw4000 insulation/50 clear cavity) /100 block/plasterboard on dabs finish
(sap calculations recommendation)

Option two - 100 brick/125 cavity (125 full fill dritherm 32 insulation) /100 block/35mm knauf pir insulated plasterboard

U-value same for both options.

Cost implications as well with potential savings in mind.

Opinions would be welcome.
Many thanks

 

[stevie888]

I'd go first option if it was mine:

1. Clear cavity prevents moisture infiltration
2. Easier to fix things to wall.

 

[Deluks]

Depending on exposure and altitude, I'd go with the wool option and increase the cavity, and wool thickness.
You'd probably still need insulated plasterboard on the inside but with a wider cavity you could use a thinner product on the inside, which would make the fixings easier.

You could also use a thicker inner block, which would help reduce noise, or an extra layer of plasterboard internally.
Also consider resilient channel instead of dabs.

But realistically, your best way to reduce external noise would be to invest in triple or secondary glazing. Secondary glazing internally, on top of double glazing makes a big difference.