Soundproofing old terraced house, need help!!!

[noseall]

(therefore Joe-90 is wrong)
John

Never!

 

[joe-90]

Hi wobblybox,

(therefore Joe-90 is wrong) although without seeing drawings and layouts is difficult for me to give an accurate solution.

Cheers,

John

No he's not. If the OP is listening for noise next door he will certainly hear it.

While you are there, why is it that you can hear neighbours in houses that are unconnected but close to each other? Is it that similar structures resonate with each other? I used to hear my neighbours through 9 inch brick, 4 inch air gap and nine inch brick. (I used to hear her most when her hubby was away )

 

[noseall]

[ (I used to hear her most when her hubby was away )

Noughty boy. (perv)

 

[joe-90]

She could hum and sing at the same time. Never worked out how she did that.

 

[Braidenacoustics]

Sound can travel through an air gap between dwellings if the wrong wall ties are used or if mortar has breached the gap. This is another example of structure borne noise. Certain constructions require certain wall ties to minimise structure borne noise but this is not always known or even followed by builders. I once did a sound insulation test between some 'high spec' flats where some party walls failed due to this problem - flicking a light switch in one flat can clearly be heard in the adjacent flat! This is not uncommon and due to sloppy construction.

John

 

[joe-90]

But the thing I am saying is that outside you can hear nothing yet through another nine inch wall I could hear 'things'. Does the next door dwelling resonate in sympathy or not? Yes or no? There was an air gap of 4 inches between the two houses.

 

[jeds]

The problem is that noise is generated across a wide range of frequencies but sound insulation products can only generally deal with a narrow range of frequencies. It is a rule of thumb that you need low density components to attenuate high frequency sound but, paradoxically, you need high density components to attenuate low frequency sound. That's why the sounds tapped out by prisoners on the heating system is always the high pitched tink, tink sound. Pipes are high density, which attenuates the low frequencies and allows the high frequencies through. So mineral wool, or dense concrete blocks, heavy plasterboard etc. will only do part of the job. You need both somewhere in the construction.

Is is also a rule of thumb that 90% of sound will travel through 10% of gaps. If you were awake during the bell jar experiment at school, you might remember that, before sucking the air out the jar, the physics teacher pushed the jar down on the mat and the sound reduced dramatically. That's because most of the sound was coming through the gap between the mat and the jar rather than through the glass.

Finally, sound will travel through components that penetrate or touch the wall. i.e. wall ties, rafters, joists, abutting walls, etc. To avoid this a cavity is usually introduced. The optimum cavity depends on the surrounding materials. For glass it is about 200mm. The key thing here is frequency again. If the width of the cavity is equal to the sound wave then the wave will cross uninterrupted. Because sound is generally comrised of all the frequencies then obviously one or other of those frequencies is going to get through.

So, you need a heavy, light wall with no gaps and no penetrations and all the components seperated by several cavities of different widths.

 

[noseall]

2" thick slabs of lead are good for sound abatement.