# Forum Home Renovation Structural Renovation  sound proofing problem

## jags

hi all   
 I am in the process of reinstalling new wardrobes that divide my master bedroom from the second bedroom  .
I have constructed a wall at the back of the wardrobes made out of 35mm (being the thickness of the wall ) by 70mm pine with vertical beams at  450mm centers it is 3400mm  wide and 2600mm high .I am using 13mm gyprock for the wall but this will only be on one side   . I brought some insulation accoustic bats but  because the wall is only 35mm thick ,due to the fact that i am trying to line the new wall up with the old conice on the ceiling  the bats will not compress enough and i think this will put to much outward presure on the gryprock . 
I was thinking of dividing the bats in half to reduce there thickness hense reducing the presure on the gyprock wall.  But this will also reduce the sound proofing  .The other option i have thought of is to use 35mm styrofoam instead ?
What would be the best option ?
Will the one sheet thick 13 mm gyprock and the half thick bats and the  wardrobes full of cloths be addiquate ? 
Only one  room will be used on a daily basis and the other is a spare room . 
thanks for any advice it is greatly appreciated . 
Rob

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## billbeee

Hi Rob
We used to build two wardrobes side by side, one pointing into one room and the other into the other. These on government housing contracts, they formed the wall and the 3/4" board on the back was the only thing with the doors and contents between each room.   
You should be OK with your half batts, unless you have a teenager learning the drums in the spare room.  In which case think about more insulation and insulate the ceiling as well.
Cheers 
Bill

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## Rod Dyson

Hi Jags,  Sound proofing is made up of 3 very specific componants.   
Isolation 
Density 
Absorbtion 
Depending on just how much you want to reduce the sound transmission by will dictate the measures you take to achive this. 
Typically the 3 componants working together give you the best results. For one compnant or the other to work on is own, it needs to be dramatically increased to counter the LACK of effect from the missing componants. 
The only componant you have working here is absorbtion (the insulation) reducing the quantity will almost render is use useless.  Particularly when the other componant Mass is also reduced (the thickness of the wall). 
Isolation is also non existent and made worse by the studs on there flat section rather than the edge.  
If sound proofing is important to you then to sound proof between these rooms. I would build another wall in front of the existing wall there by improving the isolation.  Then fill the cavity between the walls with sound proof insulation.  Then use 13mm plasterboard each side. Even consider using 2 layers of plasterboard.   
Replacing cornice is not a huge task unless it is a decorative type that requires pattens to match. Then you may need to replace the cornice in the entire room. 
By doing this you will have reduced the sound transmisson considerably.  The other areas that you need to address is the ceiling and floor. These are the weak points in the above solution.  If the floor is concrete not so bad,  but if it is timber you will get quite a bit of sound trasmission. To reduce this, provided you have access insulate under the floor as well.  
In the ceiling make sure the insulation is over the wall for about 1m either side of the wall. 
Not what you wanted to hear I guess. But it is up to you as to how important sound reduction is.  There is no point spending money on something that just won't work and be disapointed with the result. 
Cheers Rod

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## nev25

There is a plaster product named (from Memory) "Sound Check" I believe is made by gyprock.
Thats is a form of sound deadening plaster

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## Rod Dyson

Yes Nev25 there is a product called Sound check and is a total waste of money in my opinion. It is certainly better than standard 10mm plasterboard manufactured by CSR as CSR manumacture a "light" weight plasterboard that has a lot less density that Sound Check. Sound Check is only marginally better than 13mm plasterboard and no better than 13mm firecheck but is more expensive than all of them. BGC plasterboard is denser and their standard 10mm board is very very close to the sound check. 
The sound check is made denser and they charge twice the price! The same result can be achieved with a far cheaper option. 
I have a chart here on my website where you can compare sound check against other products and see the cost comparison. I would be extremly surprised if it cost more than 20 cents per m2 more to manufacture sound check yet they charge double the price. I sell the stuff very begrudgingly when a client demands it! 
Also sound check on its own will not achieve a noticable result.  You still need to consider all the above components. 
I see many people wasting money using sound check in the wrong application and not getting the expected result.  If you want to isolate sound in an area of your home I suggest you research the options very carefully and not just assume using sound check will do the job.    http://www.how2plaster.com/sound/compare.html 
I hope this post either saves people some money or helps them get the result they desire. 
Cheers

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## RufflyRustic

Jags,  I hope you don't mind me asking a few more questions in your thread, as my situation seems very similar to yours.  
I've got VJ walls and they let all the noise through.  I want to reduce the sound penetration on 3 walls by simply attaching the soundproofing to the walls, finishing the front and then redoing the cornices etc.  Insulation in the ceiling will be a must but I'll live with not insulating the floor for the time being. 
What could I use for the sound insulation?  I don't want hugely expensive, or complete sound reduction, just something that will stop people being able to hear each other clearly through the walls. 
I like the idea of Soundblock's Barrierboards, but I bet it will cost a bit.  
cheers
Wendy

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## Rod Dyson

Barrierboards work ok. expensive yes! 
A cheaper alternative that works well is this. 
Screw furring channels over the exiting wall on each side through a rubber block. effectivly sandwiching the existing wall. Then fill the cavity each side with insulation. Double sheet each side with plasterboard. Even a single sheet will by ok. 
Go to Clark Rubber and buy a strip of 30mm x 10mm rubber and cut it into 30mm x 30mm blocks. Use a Rondo 237 clip and screw the clip to the studs with the rubber block behind. 
This rubber block acts as and isolation clip that would cost $5 per clip. This is the only real effective way to sound proof between rooms. To really do the job properly the ceiling should also be done in this way.

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## RufflyRustic

> Barrierboards work ok. expensive yes! Ouch! 
> .....

  
So, it will end up as finished wall, insulation mounted between furring channels, clip? then rubber block, original wall? 
What insulating material could be used? Polystyrene? fibreglass, polyester, wool? but whatould work best? 
Thanks
Wendy

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## Rod Dyson

Hi Wendy, I assume the wall aready there has a lining,  it is better that this stays in place as it adds to the mass of the wall. 
With the clip, the rubber block and the furring channel you will have a cavity of approx 40mm.  In fibreglass, wool or polyester products the maximum thickness you could use is 50mm allowing a little for compression.  If you chose any of these productucs choose the one that gives you the most density per m2, (I have not researched this enough to give you a specific product).  If you choose Polystyrene (which I would use) make sure it is a max of 40mm thick as you won't get the compression as with the other products.   
You could pack the clip out a little to give you a wider cavity to fit a larger size insulation.  
It would be like this. Original wall, clip with rubber block behind both screwed to the wall with a single screw, furing channel fixed to the clip, Insulation between the channels, plasterboard fixed the  furing channel. 
This will give you the best possible results at a reasonable price. 
Cheers Rod

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## RufflyRustic

Thanks Rod.  makes sense, very clear and by the sounds of it, shouldn't be impossible for me to do most of it myself  :Biggrin:  
Cheers
Wendy

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## notenoughtoys

Just wondering Rod, if they are going to build a second wall anyway, what about the hebel blocks (The thin blocks for internal walls)?? I had a house built out of this product some time ago and was inpressed with both it's thermal and noise insulating properties. 
Bob K

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## Rod Dyson

I'm no expert on hebel block and their qualities.  I have installed plsterboard to the hebel blocks in the past and I would imagine as you say they would have good thermal and acoustic properties.   
Without looking up the specs I could not say if it would be better or worse. I would imagine laying hebel blocks as opposed to screwing on a few clips and fitting furring channel, would be a more difficult and more expensive.  Logistically it would be more cumbersome way of going about it as well I would think.

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## mange_76

hello can someone hep me im building a new house and im doing a home theatre room just wondering if its worth while using soundchek gyprock or cheaper and just as effective to use 10 or 13mm gyprock and double sheet it? thanks adam

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## mange_76

hey rod my name is adam and i was wondering if you could help me with a few questions about sound proofing my home theatre room would you be able to help matey

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## brickman

Built my home theatre as part of house few years back, from memory went 20 mm fireboard then covered with 13 mm normal plaster , was advised this was the most cost effective method , and if you wanted to save money you could easily install the fireboard yourself as this does not need to be stopped , Have kids bedroom adjacent to theatre and it certainly is effective , although if your subs are on max. , and the sound turned right up there is an audible rumble , and the only way to prevent this would be through isolation.

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## ivan_351

Hi , _Sound Check plaster_ by gyprock sounds like a interesting product for suppressing noise 
What other materials have very good noise suppression qualities ? 
Great ready guys 
cheers

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## PlasterPro

min 2 layers 16mm Frycheck on furring channel on acoustic mounts with soundscreen batts in wall all perimiters sealed with acoustic mastic even internals before stopping up and between layers must be first coated.
will be a good start, yes expensive but what cost do you put on silence? 
Was on a job in Canterbury just recently  where the theatre room had 5 layers of 16mm (Boral the most dence frycheck on the market) 3 layers inside and 2 layers outside, with double doors (air lock) 
Now thats how you sound proof a room!  :Biggrin:

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## ivan_351

> min 2 layers 16mm Frycheck on furring channel on acoustic mounts with soundscreen batts in wall all perimiters sealed with acoustic mastic even internals before stopping up and between layers must be first coated. will be a good start, yes expensive but what cost do you put on silence? 
> Was on a job in Canterbury just recently where the theatre room had 5 layers of 16mm (Boral the most dence frycheck on the market) 3 layers inside and 2 layers outside, with double doors (air lock) 
> Now thats how you sound proof a room!

  
Wooooooooooooooooooo PlasterPro that certainly is a room , " Now thats how you sound proof a room!" 
The line of products Bradford Insulation produce maybe of interest to people are http://www.bradfordinsulation.com.au.../Fibretex.aspx " Fibertex Industrial Rockwool - Bradford Insulation  , Fibretex 350 - Bradford Fibretex 350 a lightweight medium density rockwool insulation product designed for applications up to 350˚C. 
Fibretex HD - Bradford Fibretex HD is a high density industrial insulation for use in applications where high compressive resistance is required. It is a heavy duty thermal and acoustic insulation suitable for continuous operation up to 450oC. 
Found these web sites forum's with some useful information also maybe of interest to some to fossick through.   http://www.gearslutz.com/board/bass-...c/index11.html  http://www.ausband.com.au/modules.ph...topic&t=138902  http://forum.lowyat.net/topic/871474

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