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Soundproofing...

Discussion in 'Home Cinema Building DIY' started by Jimbo73, Feb 21, 2005.

  1. Jimbo73

    Jimbo73
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    I live in a mid-terraced house, with just 2 breezeblock walls and an airgap between me and my neighbours. I dont even have plasterboard on the party walls.

    The soundproofing is so bad I can even hear one side snoring at night... and on the other side, they like to sleep with their TV quietly playing News 24 (which is bl**dy annoying to say the least). When I have a movie on at a "normal" listening volume, it is audible from pretty much every room in my house - so they must be able to hear it too. You get the picture.

    As this problem affects the whole house, other than moving, what options do I have?

    I cannot install false walls in every room - and even the lounge (where all the HC kit is) would be difficult to say the least (new flooring in place, radiators and power sockets to relocate, cupboard with door flush against existing party wall, etc).

    I was wondering if there was some kind of acoustic foam I could have pumped into the airgap between the houses which would reduce the amount of sound that is transmitted..? Or should I get it on the market asap and get into a detached house where I can watch Hellboy as the Director intended? :devil:
     
  2. pemberto

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  3. Jimbo73

    Jimbo73
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    Thanks Paul -saw that thread but it looks like the poster doesn't have any problems at all with sound from next door!

    Customaudiodesigns suggest some M20 mat but they dont recommend that for HC use. Guess that leaves false walls or moving then :(
     
  4. Brian Ravnaas

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    hey jimbo, from your description it sounds like your walls are VERY poor - the breezeblock / air space / breezeblock...

    usually one finds, when faced with a situation where the performance of a wall is EXTREMELY bad, open air paths from point A to point B.

    breezeblock = concrete block, correct? lightweight concrete? So it should be fairly heavy? if so, then you have mass / air space / mass, and that should certainly be ample to stop the TV and snoring noises you describe.

    check for air paths - even if it's the porosity of the breezeblock itself - and get a few bags of plaster or caulk or whatever you need to use...

    a good rule of thumb for sound isolation is this: if it won't float, it needs more caulk :)
     
  5. Brian Ravnaas

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    basically, jimbo, if i understand correctly, you have

    heavy wall / air space / heavy wall

    now adding insulation or absorbing material to the cavity can/will certainly help, BUT if the performance is VERY bad, then it almost has to be some form of open air path.

    concrete/air/concrete has tremendous sound-isolation potential.
     
  6. Jimbo73

    Jimbo73
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    Well, I agree with what you are saying, the problem is that it is in every room! Open air would suggest a hole between both walls which might explain one room, but not the whole house.

    The party walls have a thin (1/4 inch) layer of plaster on top of concrete which is less than 60mm deep (I know this from when I put my plasma up) - then the air gap, and then I guess the same on the other side.

    I am trying to weigh up the pros and cons of decent soundproofing versus moving. I would have to soundproof all the living / sleeping areas, the stairway and the bathroom - this would be a major undertaking, but would probably cost the same as moving house.

    Question is - would soundproofing come close to (say) a solid Victorian-built wall?
     
  7. Brian Ravnaas

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    hey jimbo, you have to pardon me, as i don't know what a victorian-built wall is (i'm a yank)

    i hadn't imagined that the walls were that thin, that could well explain a bit. When you said breezeBLOCK, i was thinking like 8" blocks (190mm) :p

    concrete of ~that thickness has a resonance problem called "coincidence" right smack in the middle of the speech range, which may be the culprit...

    it's a perplexing situation you describe...

    how deep is the air space?
     
  8. Jimbo73

    Jimbo73
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    not sure, looked to be approx 2". Certainly wasn't much!
     
  9. woody67

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    There are two ways for the sound to reach you, one via vibration through the structure, the other via airborne reverberation.

    The cavity (air gap) in the party wall is actually a good thing as it reduces the transmittance throught he stucture. It is unadvisable to try and fill it, and if you did want to you should notify your neighbour to seek their approval under the Party Wall Act - and remember half of that air gap belongs to your neighbours, so it could be a trespass too

    Your problem seems to be related to airborne sound which ideally should be contained from the neighbours side with some thick floor and wall linings.

    As this is a bit impractical, you could line the walls with some dense board such as Fermacell - see http://www.fermacell.co.uk and have some heavy linings and carpet. But results can be unpredictable.

    You need something dense and isolated to form a good barrier, but trying to achieve it retrospectively is difficult.
     
  10. Jimbo73

    Jimbo73
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    Just an quick update on this. I went ahead and had fermacell installed on both party walls which made a pretty significant and noticable difference. I would have liked to have been able to build the new walls away from the party walls, but the builders were not confident that the studs would be strong/stable enough to hold 5 meters x 240 cm of double boarded 18mm fermacell (this stuff weighs a TONNE!) without being properly connected to something, so they screwed the studs onto the party wall.

    Of course, this has reduced the effectiveness of the soundproofing, but it is still a vast improvement.

    One thing I have noticed since having the fermacell installed is that the outside wall is also transmitting a significant amount of noise. I can hear their TV and conversations at any point along the rear outside wall - even at the furthest diagonal (i.e. their TV is on the ground floor next to the back wall - from the upstairs bedroom, I can still hear it within the room). In fact, the transmission is so clear that if I were to put my ear to the wall in the bedroom, I could even hear what they are saying to each other above the sound of their TV.

    It's not really going to be possible or practical to fermacell this wall, due to windows etc. Is there anything else I can try, short of physically seperating the two houses (or moving!!)..? Has anyone else ever lived in such an acoustically poor house..?!
     
  11. BadAss

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    Mines not too bad but the inlaws have thin walls or no cavity inbetween their house. Your only solution is to move house Im afraid.

    Sound vibrations travel best through solid mass because density does not absorb sound it only passes it on. The cavity isn't the problem its the fact your bricks are fused together with your neighbours.

    The only way to stop sound is to reflect it or absorb it. As you've explained, you cant do either. :(
     

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