building a soundproof partition to stop flanking sound

[mikeyw]

Hi,

I'm developing 2 flats in a 4 story building. The sound consultant has recommended the following sound wall lining to pass the sound flanking tests

25mm air gap
50mm stud filled with soundproof insulation
2 x 12.5 soundbloc board
Plaster skim

This is a big cost item in both materials and labor....does anyone know if this is all needed or could a different (cheaper!) solution be used?

 

[tony1851]

Unfortunately there's no way of knowing until the sound-test is done, and by then of course it's too late.

It depends on many variables which we obviously don't know about, but I would think that spec. would be the minimum you need. Anything less is risky when you consider the cost of the test, and having to upgrade it.

Have you considered putting resilient bars across the studs for supporting the boards?

 

[Deluks]

That's not big cost for what you are trying to achieve, feel lucky he didn't specify bizarre layers of rubber matting, which can get really expensive.

With 50mm studs and the airgap, you should be using 70mm acoustic slab, rockwool or similar. (wool does not compromise the airgap and will not flank if it's touching both sides)

 

[noseall]

"...to stop flanking sound..."

Tell 'em to stop flanking so loud.

 

[indus]

Could somebody kindly explain where the 25mm air gap goes?

Thanks