I need to soundproof one wall in my room - Experts please help!

[ChatOnLeMat]

Hi,

In my girlfriend’s bedroom, the wall that adjoins with the neighbours is incredibly thin. So much so that I can hear them talking, shagging, etc quite clearly at low volumes. Obviously, this means they can hear us too!

I am wondering how much difference it would make to sound transmission between the walls if I were to build some kind of freestanding wall to place in her room, floor to ceiling. It doesn't have to absorb low frequencies so much, as it's speech transmission that is the problem.

I was thinking of just stacking rigid fibreglass of 2" or 4" in a grid pattern, or would it work better if I sandwiched plywood on either side of the fibreglass, increasing reflection back into the room? I could then attach to the wall with hooks, leaving a 1" gap between the fibreglass and the wall.

I know that building a whole room within my room would give the most isolation (it's a small room + I don't have the money), and filling the cavity walls with insulation would help (it's a listed building, owned by the council), and that my solution does not take into account structure born sound (this is mainly to absorb high frequencies), BUT - do the acoustic experts think this will improve the isolation enough to justify the cost? ...perhaps $200-300.

Would I be better buying somthing with lead in it like this instead:
Sound Stopper Acoustic Panel 2M X 1.2M X 14mm at Studiospares

Or maybe this:
"Studiospares" Acoustistop 1.2Mx3M Sound Blocking Sheet at Studiospares

Or this:
"Studiospares" DX40F Foam 2340X25X25 Grey at Studiospares

Many thanks,
Sean

[DanDan]

Well you could eliminate the problem by synchronised shagging!
Fibrous insulation does not stop sound at all. It takes mass/ thickness or an ingenious lightweight system to stop sound. You need to construct another wall, not touching the existing one in any way, floating. This will involve an airgap which should be lightly filled with light insulation blanket or batts.
There is some great information here Soundproofing Acoustic Sound Insulation Sound Proofing Noise Consultants - Custom Audio Designs Ltd Hampshire
For an expensive but easy to install option look up Calibel.
If you could access the cavity walls from the top it may be possible to fill them with sand.
DD

[Pier]

You need mass. Filling the gap with rock/fiber wool (the more dense the better) will do the job IMO.

One thing is sure, you have to fill the whole wall. Leave no gaps.

Also the solution of building another wall would work... but that would be more expensive.

But I'm no expert anyway.

[DanDan]

Filling the gap with rock/fiber wool (the more dense the better) will do the job IMO.

Sorry, this is absolutely not the case.
The difference between insulation and isolation is widely misunderstood. One Metre of dense fibrous insulation will attenuate sound passing through it by very roughly about 3dB. So let's say we need 30dB to keep the passion in check. A 10Metre thickness of fibre might work.

DD

[Dange]

Get onto your local council and get them to do a sound insulation test to prove that the wall doesn't meet Building Regulations. This can definitely done in England and Wales, Scotland's regs differ slightly but I'm sure they are pretty similar (I assume you are in Scotland).

The sound insulation test will involve completely emptying rooms on both sides of the partition then an acoustic engineer testing the wall, looking at around £500, but the council should pay. I'm pretty sure it will fail if you can hear what you describe. There is a bit of an issue with listed buildings, as in developers can get away with doing the minimum for sound insulation by being restricted by the allowed alterations for listed buildings. It does depend what is is listed, it may just be the outside appearance or could be the entire structure.

I'd advise you not to do anything to the structure at the moment as you may be wasting money because the owner should pay for remedial works.

DanDan is right regarding density of mineral wool, there have been tests to show density makes little difference. This is for mineral wool within a sealed cavity. Any wall/barrier treatment added needs to be completely sealed (re hanging on hooks) otherwise you're wasting your money. Plus flanking noise (structure borne) needs to be taken into account

Was this building built or converted recently?

[ChatOnLeMat]

Many thanks for the replies,

I looked into the Calibel/Isover route - I can't seem to find any prices for it.

The wall in question is approx. 5m x 4m.

Are you all saying that my idea won't work? I was thinking hooks like in this picture (if you rotate the pic 90 deg clockwise):



Imagine one 5mx4m version of what's in the photo, or many in a grid without any gaps at the edges...?

I'm expecting that you guys will tell me that this plan won't work, so if I were to build something myself, what would I need to do?

From looking at the photos of the calibel system here, all I need to do is attatch some very high density mineral wool/fibreglass (is there a fundemental difference acoustically?) to the wall with some spray adheasive, and then attatch some plasterboard to the mineralwool, or cover it in fabric.

These panels seem to be just as effective (10dB isolation) as the calibel system, and when coupled with two layers of plasterboard it should only eat about 50mm into the room. £30/m^2 X 20m = £600 = That is why I'm looking for something more DIY - say £150 MAX.

Cheers,
Sean

[Pier]

Originally Posted by DanDan

Sorry, this is absolutely not the case.
The difference between insulation and isolation is widely misunderstood. One Metre of dense fibrous insulation will attenuate sound passing through it by very roughly about 3dB. So let's say we need 30dB to keep the passion in check. A 10Metre thickness of fibre might work.

DD

Really, I'd like to know where does your 1 meter = 3 db rule comes from.

It makes little sense to me.

[ChatOnLeMat]

I forgot to say,

it's not a new build. It's a tenament flat in Glasgow built in 1892. My girlfriend does actually own the flat, but it is a listed building and I'm unsure what that means as for true ownership - I believe the council may own the facade/stairwell, or something like that. I know that we couldn't change the windows without their permission, and they would have to be chosen by the council.

I will look into this examination, but it seems a bit awkward, having to go round next door and tell them I'm fed up of listening to them, not to mention the inconvenience of removing everything from both rooms - we'd have to deconstruct the massive bed and wardrobe.

Cheers,
Sean

[Pier]

Originally Posted by Dange

DanDan is right regarding density of mineral wool, there have been tests to show density makes little difference. This is for mineral wool within a sealed cavity. Any wall/barrier treatment added needs to be completely sealed (re hanging on hooks) otherwise you're wasting your money. Plus flanking noise (structure borne) needs to be taken into account

Yes, a perfect isolation would mean make a suspended sealed room into the room. That way he could play drums without bothering the neighbors.

But I think he's not looking into that kind of isolation...

[SAC]

Yes, ALL are saying "Your Idea won't work"!

You are confusing sound isolation - the reduction of transmitted sound from one space to another - with room treatment, where various energy is redirected or absorbed with respect to a particular listening position within a bounded space.


THEY ARE NOT THE SAME!

And the tools you cite are appropriate for room treatment, NOT the mitigation of sound transmission!

Sound isolation/transmission solutions require MASS, not insulation!

The solution to your problem is NOT trivial, and will most likely require building an additional false wall as well as dealing with the various flanking paths through the floor and ceiling.

You might want to do searches on "Sound isolation" or "Sound transmission".

[ChatOnLeMat]

Originally Posted by Pier

Really, I'd like to know where does your 1 meter = 3 db rule comes from.

It makes little sense to me.

Well, he did say "very roughly". Remember you're talking about fibrous insulation, not rigid fibreglass.

You're right though. I don't need that kind of isolation. I need the cheapest DIY job possible, with a noticeable decrease in sound through that one wall (5-10db). I know that the floor/ceiling/adjoining walls can allow the noise to flank. What I don't know is - how loud does that translate to? Would it still be worth treating the wall anyway?

Cheers,
Sean

[SAC]

Originally Posted by ChatOnLeMat

I need the cheapest DIY job possible, with a noticeable decrease in sound through that one wall (5-10db). I know that the floor/ceiling/adjoining walls can allow the noise to flank. What I don't know is - how loud does that translate to? Would it still be worth treating the wall anyway?

JUST 10 dB? ??

Oh, is that all?

Let's see, for each 3 dB difference you are either doubling or halving the energy!

A dB is not an 'amount', it is a ratio!

So in your case you are reducing the energy by 1/2, more than 3 times!

I know you want a "simple" solution.

Unfortunately, there is no SIMPLE solution to sound transmission through a boundary! Bottomline is that it requires mass.

And you CAN"T ignore the flanking variables, as a boat sinks just as well from small holes as from plugging the big hole! Sound transmission does not 'care' if you address what you think is the the 'biggest problem'. It doesn't work that way.

It must be airtight, and you will STILL need to mechanically isolate and address the flanking paths!

[Pier]

Originally Posted by ChatOnLeMat

I'm expecting that you guys will tell me that this plan won't work, so if I were to build something myself, what would I need to do?

If you do that, try to keep a small space between the wool and the existing wall. It's important to keep the new wall and the existing wall separated. Also leave no holes, the new wall must cover the whole existing wall.

[ChatOnLeMat]

I know that dB is a ratio, SAC.

I was going by this article - "8dB - 10dB improvement (around a halving of the noise)"

so, I assume they are talking about dB SPL, or that someones got something mixed up.

Is a 10dB difference half? Or is 3dB difference half?

[SAC]

3 dB is either 1/2 or double the power.

I might suggest you query articles addressing the nature of the problem and what is required for a solution rather than marketing brochures pushing a particular product!

[ChatOnLeMat]

Okay - I think that they mean 10dB difference in 'loudness' i.e. Psychoacoustics.

Put it this way - if I could hear my neighbours' grunting half as loud, I'd be happy. Is this possible?

Cheers,
Sean

[SAC]

Originally Posted by ChatOnLeMat

Okay - I think that they mean 10dB difference in 'loudness' i.e. Psychoacoustics.

I learn something 'new' every day...

[ChatOnLeMat]

I wouldn't be posting if I hadn't done some research. I came here to get FEEDBACK on my solution. You know, that's the point of a public forum - sharing. I have yet to find an article that tells me if my solution will work or not. If you don't know then that's fine - don't bother. Maybe someone else can help...

Sean

[ChatOnLeMat]

Originally Posted by SAC

I learn something 'new' every day...

Oh, how infuriating you are.

For the benefit of anyone else, I'm getting contradictory information. I am now completely lost.

[SAC]

Several have said it already.

"I was thinking of just stacking rigid fibreglass of 2" or 4" in a grid pattern, or would it work better if I sandwiched plywood on either side of the fibreglass, increasing reflection back into the room? I could then attach to the wall with hooks, leaving a 1" gap between the fibreglass and the wall."

And attaching foam covered lead sheet square meters at time (and certainly not in a 'grid pattern') will get very expensive very quickly, and you will still need to address flanking paths - and partial coverage will achieve little more than a very aesthetic and expensive wall treatment - so make sure your girlfriend likes the color. And while mass loaded wall covering can reduce the sound transmission, they must be applied correctly over the entire wall surface and you have already ruled that solution out ("These panels seem to be just as effective (10dB isolation) as the calibel system, and when coupled with two layers of plasterboard it should only eat about 50mm into the room. £30/m^2 X 20m = £600 = That is why I'm looking for something more DIY - say £150 MAX.") as being too expensive and demanded a cheap and easy DIY solution apparently hoping that absorptive panels will suffice. They won't.

And the information from those on the thread has NOT been contradictory - except that in that it differs from what you wish was effective! The real problem is that the responses you have received are not what you want to hear! And unfortunately simply asking the same question over and over will not change the nature of the problem nor the solution.

The suggestions have ranged from getting zoning/codes assistance to applied sound transmission issues. And regarding the latter, added mass and a room within a room are indeed approaches to comprehensive sound transmission issues. But the bottom line is that, in order to reduce the sound transmission through your wall, it requires properly applied additional mass and the addressing of flanking issues.

Perhaps John &/or Rod will respond, as I suspect they are more familiar with the particular building codes and methods in your apartment. And they can comment on the optimal and most affordable method to address the mitigation of sound transmission. But in any regards, the application of absorptive panel treatment designed for mitigate reflections within a room will not suffice.

[Pier]

Originally Posted by ChatOnLeMat

Well, he did say "very roughly". Remember you're talking about fibrous insulation, not rigid fibreglass.

Being rigid, or "floofy" does't me a difference in acoustic properties. Check andre's post on that. Check the roxul RHT40 and RW40.

http://www.bobgolds.com/AbsorptionCoefficients.htm

One is rigid, and the other is not. But they absorb the same.

[Dange]

Hi again Sean,

I test sound insulation for a living for Building Regulations Part E (in England and Wales, Part H in Scotland I believe). I also specify wall and floor constructions to meet these regs. These regs apply to newly built and converted properties. A sample of the partition wall and/or floors areas have to be tested and pass to be signed off by the building inspector.

I have also dealt with a number of domestic situations like yourself. These can be more tricky sometimes. Here's what I suggest you do:

-Talk to the neighbour the other side of the partition to find out if they have noticed the problem too.
-Get in touch with local building control office to try and establish who is liable to pay for remedial works. This may be the owner of the building or the leaseholder or even the council themselves.
-Have a sound insulation test done, these aren't always necessary but give an idea as to how bad the wall actually is and what would be appropriate treatment. (the rooms should be as empty as pratically possible)

It might be that some work has been carried out in recent years, such as installation of central heating, plumbing etc. that has compromised the sound insulation of that wall.

The CAD20-WP product you posted a link for requires two layers of plasterboard to be bonded on top of it for it to work and give the 'up to 10dB' reduction. For any treatment to work, the wall must be completely sealed and all possible flanking paths taken care of. The key is additional MASS!

Also make sure you are well aware of the difference between absorption and isolation

Paying out for a half cocked 'simple' solution will only end in disappointment. To fix this requires significant structural work. The CAD20-WP may work with the two layers of plasterboard bonded on (I have no direct experience of using this product). But flanking paths also need to be addressed.

For example, you could cover the wall in the CAD20-WP product and plasterboard, but depending on the joist configuration sound could still 'flank' round it over the ceiling or under the floor

[Dange]

I've just had a look at those products from Studiospares, avoid like the plague, they will be over priced anyway coming from SS. Plus there are other companies around who deal directly with domestic sound insulation.

Back to that Studiospares product:

Sound Stopper Acoustic Panel 2M X 1.2M X 14mm at Studiospares

This one gives a very good example of marketing spin, 'This combination yields an A weighted transmitted noise reduction of 27dB'....

So the average joe reads 27dB, Great! However the important bit is that it doesn't say what sort of wall it is attached to and also the 'A weighted transmitted noise reduction of 27dB' phrase is a bit vague, i.e. who knows what measurement and calculation technique they used to arrive at that. Figures quoted as DnTw or DnTw+Ctr are what you should look for

[ChatOnLeMat]

Okay, I stand corrected on many fronts.

The reason I said I'm getting contradictory information is to do with the two suggested acoustic solutions websites - HERE and HERE. They both mention that their product can improve the acoustic performance by about 10dB - which they BOTH say equates to about HALF the noise. I'm pretty sure that they are both technically incorrect, but does anyone know why they are saying that? My guess was that the measureable difference could be 10dB, but it would sound only half as loud (3dB difference - hence "Psychoacoustics"). I guess my train of thought was completely wrong, but I still don't understand why they have that written on their websites if they claim to know so much about acoustics.

SAC, you're right - I was looking for a quick fix to a problem that I didn't think could be fixed easily in the first place. I guess you just come on here hoping that someone will know a better, cheaper way. I just couldn't afford to pay £600 per wall/ceiling.

Dange, your answer presents the answer I needed to hear. Don't bother doing it, unless you can do the whole room, BUT there is another option, and that is testing to see if it's up to building regulations and complaining to the council.

Cheers,
Sean

[avare]

Originally Posted by ChatOnLeMat

They both mention that their product can improve the acoustic performance by about 10dB - which they BOTH say equates to about HALF the noise. I'm pretty sure that they are both technically incorrect, but does anyone know why they are saying that? My guess was that the measureable difference could be 10dB, but it would sound only half as loud (3dB difference - hence "Psychoacoustics").

10 dB reduction is considered to sound half as loud. The relationship in physics has been mentioned several times already in this thread.

Andre

[DanDan]

The reason I stated the 3dB thing was to provide a sharp illustration that fibrous does not stop sound. Let me be more clear, fibrous insulation does not, and is not intended to stop sound. Or more simply, fibrous insulation does not stop sound. Pier, and others do you really need me to quote textbooks? This is page one stuff!
Try holding a panel of 703 or whatever between two people. Does it stop the conversation? Now imagine a full wall of it, 100mm thick. Now does it stop the conversation? Of course not. Fibrous Insulation does not stop sound.
Sean that hanging thing will absolutely not work. I strongly recommend that posters here get an understanding of the fundamental and total difference between Sound Absorbtion and Transmission Loss, between Insulation and Isolation. Without such understanding this discussion will be just a matter of us repeatedly trying to convince them of a well known and understood reality.

DD

[ChatOnLeMat]

Originally Posted by avare

10 dB reduction is considered to sound half as loud. The relationship in physics has been mentioned several times already in this thread.

Andre

Thanks very much for this clarification. So, SAC was right, and so was I?

So - 3dB reduction is half the POWER, and 10dB reduction is half as loud?

Cheers,
Sean

[avare]

Originally Posted by ChatOnLeMat

Thanks very much for this clarification. So, SAC was right, and so was I?

So - 3dB reduction is half the POWER, and 10dB reduction is half as loud?

Yes. Loudness is a very subjective term. People used to hearing level changes AND KNOW the actual dB ratio, start to think in those terms. That is a sound geek, or gearslutz, will hear a 3 dB reduction in volume and will think it is half as loud. An unexperienced person will tend to think of a 10 dB reduction in volume and will think of it as half as loud.

People think the physics end of acoustics is maddening. Welcome to psycho-acoustics!

Psychotically,
Andre

[parachutestudio]

You would gain some reduction in sound passing the wall by placing additional acoustic treatment on the wall. But you would probably not be satisfied. Unless the problem (as it often is) is caused by the corners not being properly sealed, the best would be to (and sorry my english, these are terms I know best in norwegian).:

1: Open you wall, and inspect what its filled with. If its already filled with insulation of ANY type, keep the wall open, and the insulation inside. (if its not filled, you can probably skip point two, fill it with insulation and jump to point three)

2: Build a new "frame" for a wall 1 cm from the existing "wallframe". The wall should be at least 5cm thick.

3: Put two layers of "plaster plates" on the wall. Make sure they overlap.

4: Seal ALL corners - wall to floor, wall to roof, wall to left wall and wall to right wall. Preferably with silicone since it doesn't crack over time, but since you probably want to paint the walls, acrylic sealant should do.

This should make your wall far better than it is. At least 10 db. The more distance, the heavier insulation, the more layers of "plaster plates" the better.

best

Andre

ps
Next best solution from my POW would be just to place another layer of plates on the wall and seal it properly. But 10 db? Don't think so....

[Pier]

To add more info on the insulation vs absorption subject:

FAQ | Acoustic | Rockwool International A/S

So yeah, putting a concrete wall there would make the noise much more bearable. But if there's an air gap behind your wall filling it with rockwool would help, but obviously not as much.

As I said in my first post the problem is mass...

The solution for creating a new wall made of plasterboards with a sealed gap seems the best so far.

3: Put two layers of "plaster plates" on the wall. Make sure they overlap.

What about using wood?
Isn't wood denser than plasterboard?