Windows for noise prevention

Hi,

I am interested in any recommendations for windows that provide good sound insulation. We live on a busy road and are exposed to a lot of traffic noise. We currently have double hung windows and I am looking into options for replacement.

I have done some reading and from what i have seen the best results are achieved with double glazing with heavy glass (6-10mm) with a large (50 - 100mm) air gap. I have also read that casement and awning windows perform better than double hung windows.

I have looked into some of the retrofit options such as magnetite (www.magnetite.com.au) but am concerned about the appearance and that it is not properly integrated with the existing window. Also to open the windows requires removing the panels.

I have called around some of the window companies in Melbourne but so far none of them seem to produce anything in the configuration described above. Some of them have recommended double glazing options with a 12mm air gap, however everything I have read suggests that 12mm is not a sufficient gap for sound reduction.

Does anyone have experience with windows specifically designed for noise prevention? Can you recommend any joiners?

thanks, iain.

In summer, should you have to open the windows for ventilation then all the window specifications for sound insulation 'go out the window'.

Obviously, ventilation is something that has to be considered along with sound insulation.

Zelk

Yes it is a requirement that we can open the windows when required. Obviously when the windows are open they will provide no sound insulation, however this can be timed for quieter times of the day and when we are not trying to sleep.

I've stayed in a few hotels lately that have added a secondary overlay on noisy windows. Think of a frame with a rubber (?) seal and a panel of "glass", where the frame surrounds the existing window. They're usually screwed in place, but I've seen some which slide, and some which are hinged to allow easier access to the window.

The sliding ones are OK for ventilation if you're prepared to accept the noise as soon as you open a window. But open windows aren't usually a priority in most hotels, they're more concerned about noise reduction.

They worked better than I would have expected.

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I am interested in any recommendations for windows that provide good sound insulation. We live on a busy road and are exposed to a lot of traffic noise. We currently have double hung windows and I am looking into options for replacement.

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Standard double glazing in the UK is 2 x 4mm glass with an 18mm gap filled with Argon I think though the gas may have changed.

The 2 panes of glass have an aluminum spacer sealed with a type of silicon to seal the unit.

http://bp0.blogger.com/_hFCZl0ZWv0c/...zing_Glass.jpg

More here » http://srt251psc.blogspot.com/

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Standard double glazing in the UK is 2 x 4mm glass with an 18mm gap filled with Argon I think though the gas may have changed.

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Thanks for the reply. Most double glazing solutions seemed to have been designed with thermal insulation in mind. The link you provided seems to fit into this category too.

Literature on sound insulation indicates that a larger air gap is required than what is normally used for thermal insulation. E.g. See Your Home Technical Manual under glazing:

http://www.yourhome.gov.au/technical/fs53.htm#design

Some residents in the UK even go for triple glazing on extremely busy roads. In some cases if a dual carriage way is installed that will be extremely busy roadside residents will have triple glaze installed by local authorities.

Double glazing is standard and fitted mostly to UPVC awning windows and to a lesser extent double hung UPVC.

Im unsure whether an Australian glazing company has the capacity/infrastructure to produce the sealed Argon units demonstrated?

http://www.pilkington.com/applicatio...ol/default.htm

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http://www.pilkington.com/pilkington...rol-medium.gif
Noise Control


Overview

Pilkington Optilam™ Phon is the ideal choice of glass for sound control in situations where there is excess noise from roads, rail, air traffic and other sources. Using a PVB (polyvinyl butyral) specific interlayer, Pilkington Optilam™ Phon is a high quality acoustic laminated glass that offers excellent noise reduction.
Pilkington Optilam™ is produced by combining two or more sheets of glass with PVB interlayers, and it is this lamination that enables it to offer impact protection and safety. By varying the number of layers and thickness of the glass, it can offer wide-ranging benefits and be used in various applications.

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http://www.pilkington.com/applicatio...ol/default.htm

hello,

i had simialar problem and researched and like you discovered the requirement for a large air gap ie. 50-100mm

so I installed a secondary double glazed window on the inside, so in 2 bedrooms I now have the existing external 4mm window, then around 80-90mm air gap and then a double glazed unit with typical configuration 4mm/10mm/4mm

it is fantastic for both heating, cooling and noise reduction and very happy with results

i also looked into those mentioned by you,

in europe many places have shutter type window systems where you can achieve a 100mm or so cavity and just use 4-6mm glass for each shutter,

i would look to getting a double or single hung double glazed unit as a complete secondary window

in my view the current double glazed systems in aus is really only for show, many single pane would achieve similar results and with sealing around windows and doors probably more important

even if you went with a secondary window frame with single pane the results would be exceptional

thankyou
myla

I think the gas (Argon?) reduces the need for such a large gap between the glass?

Ideally a vacuum would reduce the noise dramatically.

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Originally Posted by myla

hello,

i had simialar problem and researched and like you discovered the requirement for a large air gap ie. 50-100mm

so I installed a secondary double glazed window on the inside, so in 2 bedrooms I now have the existing external 4mm window, then around 80-90mm air gap and then a double glazed unit with typical configuration 4mm/10mm/4mm

it is fantastic for both heating, cooling and noise reduction and very happy with results

i also looked into those mentioned by you,

in europe many places have shutter type window systems where you can achieve a 100mm or so cavity and just use 4-6mm glass for each shutter,

i would look to getting a double or single hung double glazed unit as a complete secondary window

in my view the current double glazed systems in aus is really only for show, many single pane would achieve similar results and with sealing around windows and doors probably more important

even if you went with a secondary window frame with single pane the results would be exceptional

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Hi Myla,

What you are describing sounds a lot more like what I am looking for. How did you go about it getting it done? Did you come up with the design and approach a joinery? Is there anyone you could recommend for construction and installation of the windows?

thanks, Iain.

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Originally Posted by autogenous

Standard double glazing in the UK is 2 x 4mm glass with an 18mm gap filled with Argon I think though the gas may have changed.

The 2 panes of glass have an aluminum spacer sealed with a type of silicon to seal the unit.

http://bp0.blogger.com/_hFCZl0ZWv0c/...zing_Glass.jpg

More here » http://srt251psc.blogspot.com/

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this type of window is very effective agains traffic noise. i worked in a house that faces a highway with trucks and busses as well as heavy traffic and you cant hear the traffic even during peak hour with the windows closed, its whisper quiet (this is also a double brick construction) open them up and its traffic noise galore.

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Originally Posted by iainpople

Yes it is a requirement that we can open the windows when required. Obviously when the windows are open they will provide no sound insulation, however this can be timed for quieter times of the day and when we are not trying to sleep.

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In Sydney, the houses in the flight path had their windows insulated, the various ways already mentioned, in conjunction with fitted ducted air conditioning and timer controlled fan forced air distribution.

Zelk

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Yes it is a requirement that we can open the windows when required. Obviously when the windows are open they will provide no sound insulation, however this can be timed for quieter times of the day and when we are not trying to sleep.

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This is generally a fire escape strategy. If you are installing non-sealed units then you will still need the crystals to stop condensation/misting between the two glass panes.

http://www.eurocell.co.uk/windows.html

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Originally Posted by iainpople

Hi Myla,

What you are describing sounds a lot more like what I am looking for. How did you go about it getting it done? Did you come up with the design and approach a joinery? Is there anyone you could recommend for construction and installation of the windows?

thanks, Iain.

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hello,

i used uPVC from a company who are no longer around (all-ways windows),

my outside was simply timber awning window, and the new one's were double slider i installed my self,

i would consult some custom timber window manufacturer's on the smaller side ie. owner-operator, pick ten out of the yellow pages

my walls are double brick cavity construction with solid plaster on inside with no architraves so I simply put window into opening and sealed around flush,

if you have architraves you may look at taking them off, install new secondary window and then replace architraves, paint patch-up etc

thanks

myla

If you parallel glaze a double glazed window, there is a degree of transmission caused by the outer pane vibration "pumping" the cavity air and in turn exciting the inner panel severely limiting isolation.

To avoid this in isolation windows for recording studios etc, the panes are arranged to be non parallel by offsetting one pane vertically in the frame by about 75-100mm, and the other horizontally by a similar amount. For extreme isolation, a third pane is sometimes added between.

Another piece of the puzzle is the use of differing thicknesses of glass in the double/triple glazing.

As I understand it, a pane of glass will resonate at a particular frequency based on it's dimensions. By altering the thickness of the glass, that resonant frequency is changed, so what resonates the outside pane doesn't transfer through the inside pane.

I have no idea if the thicker pane should be on the inside or outside, or if it matters.

If you are looking for timber frame windows that use european methods of hanging and sealing (ie. methods that have been proven to work) I can suggest and recommend Paarhammer. (Not my company, just a happy customer): http://www.paarhammer.com.au/

woodbe.

We have a similar issue and have been doing lots of research. Its a minefield!

We're looking to replace a house full of windows, as they are 37 yrs old. We want to upgrade some of them for security purposes and others for acoustic purposes. The best option on the acoustic side is secondary glazing, without a doubt. However we aren't keen as our windows are really old and need replacing anyway, and secondary glazing doesn't look particularly attractive.

It does seem to be the case that insulated units (double glazing) are designed for thermal not acoustic insulation. It seems impossible to find prefabricated ones with a larger than usual gap (the standard 16mm gap would apparently do little to reduce the noise of traffic and the party house next door). Also, we might then want to upgrade the glass for security purposes.

We also talked to leading window companies. However the window manufacturers we visited knew little about their more unusual window products and weren't keen to help further. Remarkable, as we want to throw money at this!! They seem to just supply direct to builders for complexes who want the standard cheaper products. They told us to ask builders/ installers about the different glazing options etc.

However, the builders/ installers we talked to were also used to standard glazing and referred us back to the window manufacturers - so its a catch 22!

Even a leading window manufacturer/ installer company couldn't advise us in regard to acoustic options.

At this stage we were thinking of becoming certified in window manufacturing just to figure it out!

Its also the case that acoustic ratings are influenced by the window as a whole, not just the glazing. So we tried a different tack, and asked a leading windows manufacturer if they could provide acoustic ratings for their own windows made using certain Pilkington glass. However, they could only give generic acoustic ratings, as they only had ratings for their more standard windows.

Basically it has been left to us to figure out the best glazing option, then specify this to a builder/ installer or windows manufacturer/ installer, and hope for the best.

We're keen on Pilkington glass, as for increased security their product "Lamguard" seems excellent, and for acoustic insulation (certain frequencies only) "Optilam Phon".

1. Pilkington Lamguard 6.52mm (note has a 1.52 interlayer, which is what gives it the extra strength)
2. Pilkington Optilam Phon 6.5
3. Pilkington Optilam Phon 8.5
4. Pilkington Optilam Phon 10.5
5. Pilkington Optilam 11.5mm (is made up of 2 x 5mm + 1.52mm interlayer)

So we spoke to Pilkington (glass manufacturer) directly, but without great success, as they prefer to deal with companies. In the end they talked to us, but unfortunately their advice seemed off the cuff - it didn't match their website and didn't resolve things.

BTW it looks like Pilkington has recently become "Viridian". See http://www.viridianglass.com/Products/vlam-hush/default.aspx?ProductType=HouseHolder.

We did discover that a decent laminated glass window would cost about the same as double glazing (ie double the price of single glazing). We also discovered that insulated units could be made using different thicknesses and types of Pilkington glass, but would be way too expensive. We have also lightened up on the security factor as we want a chance of getting out if there's a fire.

So this probably leads to single glazed Pilkington Optilam 6.5 or 8.5. Just not clear on how well this would mute voices/ music (which are different frequencies) and traffic.

Thats where we are up to!! Course, we also want multi point ventilation key locks http://www.vantagealuminium.com.au/slidwind/slidwind.htm.

Next we will probably try for quotes from http://www.taylorswindows.com.au/residential.html.

If anyone can recommend a good windows manufacturer/ installer that uses windows with Pilkington glass and multi point ventilation key locks and services Canberra, it would be great to hear from you!

Hope this helps in some way. Sorry for the essay.

P.S. some useful general info is in http://www.adelaidecitycouncil.com/scripts/nc.dll?ADCC:STANDARD::pc=PC_420

We got a bedroom window replaced a while ago by Certainteed (www.certainteed.com.au). Double glazed, 4mm and 6mm, with a high density gas pumped into the gap (not sure which gas).

The window itself is great, but it has highlighted all the other areas where noise gets in (we live near a freeway). It's an old weatherboard place, so I guess that's to be expected...

Hi.

You seem to be looking at aluminium sliding frames? I'm not sure if it has the same effect for sound as it does for thermal insulation, but most of the aluminium frames that achieve good thermal ratings have what is called a 'break' which is a method of separating the inside window frame from the outside frame using timber, pvc, whatever. Those Vantage frames you linked don't seem to do this.

One of ways of getting better frames is to ask for commercial sections instead of domestic. If you look in places like hotels etc, you will notice that the window frames are generally better and beefier than what gets installed by default in houses.

Harping back to my favorite window company, this is what they offer in regards to noise reduction:

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Paarhammer double- or triple-glazed windows with their wider air gap and a thick laminated glass on the outside provide outstanding sound proofing . Together with our unique seals and well installed frames, noise reductions of up to 45dB can be achieved, reducing noise levels by approximately 80%. That is considerably more than conventional windows (particularly aluminium framed windows).

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http://www.paarhammer.com.au/Noise.html

They only seem to do timber frame windows though. I think there is an aluminium facing option, but the frame will always be timber with that company. I've seen aluminium versions of the same type of frames, but don't know where to get them in Australia, sorry. Someone must be doing it.

See if you can get a look at a euro window opening/locking system. You might have to hunt around, but the first time I saw one, I wondered why we were bothering with the same old agricultural framing and locking systems we do in Australia. The first window we put in is also an upstairs emergency exit - we can tilt the top of the window inwards for ventilation, or open the whole window to one side on it's side hinges. The window has terrific seals and a positive multi-point ratcheting locking system. It faces the road, and the reduction in noise in that area is pronounced with just their standard double glazing.

Hope that all helps.

woodbe.

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As I understand it, a pane of glass will resonate at a particular frequency based on it's dimensions. By altering the thickness of the glass, that resonant frequency is changed, so what resonates the outside pane doesn't transfer through the inside pane.

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The outside glass can be a laminated glass and the internal a safety glass.

You have two different panes of glass with different properties so they vibrate at a different resonance.

The gas between the two different panes also provides a reduction in resonance.

For security there is tints called liquid metal used in commercial applications to prevent bricks through windows. I think you can bounce a sledge hammer of it?

There is a commercial aluminium section which provides the profile to produce a double glaze. The section is also much wider which allows easier post installation of windows. The Pilkington double unit gas filled is the most efficient specifically designed. You have to remember nearly every house has double glaze in the UK.
For close freeway/motorway living triple glaze is installed.

Personally I would go to the smaller custom guys than the larger window manufacturers for acoustic/security type of construction. The companies that build commercial window section that can accommodate double glazing units on a smaller more custom scale for shop fronts, etc etc.

Refit windows are made slightly smaller to fit in post fix or refix windows to fit in existing openings that maybe distorted during initial installation. They will be custom sizes not standard opening sizes.

Having read all this thread - its hard not to come to the conclusuion that no-one wants to guaranteee their products, and double glazing is pushed as the be all and end all of sound reduction/. i am suspicious that this is a falsity.

Why? well the theory of air seperation to give isolation reduction applies far more at very low frequencies - think next to a train track that actually vibrates the house - same as for directly under a flight path, or next toi a road that has b doubles trundling passed. the old wine glass on a high cbinet would be the test for this - do they tingle with the noise?

Now i have 2 windows seperated by 3 metres and a door facing a major arterial road thats about 150m away and 30m below us. one is 4mm float, and almost sounds like the window is open at night it blocks so little noise. the other windows are 6mm float (i think - its a louvre and i cant see a laminated film) and large expanse of 6.38 laminated. the difference is chalk and cheese for normal audible noise.

I'd go a replacement from a glazier with 6.38 lam in a test room - if you really want to go overboard try 10.38 - or whatever will fit in the frame. the problem with comparisons to cold countries like the UK, is that all windows are DI units - the addition of a triple for sound reduction implies that the DI of themselves arent very effective and they are adding density with the 3rd layer (i'd bet my left nut its laminated as well)

Went to the home show in Melbourne yesterday and the magnetite guys were there.
I explained our circumstances to him which are similar to others in that we wanted sound insulation and thermal insulation.

He explained that both can be done but requires 2 layers.
A gap of 20mm for the thermal insulation and 100mm for the sound insulation.

The panels they display with were very light, you expect a heavy sheet of glass but we were able to pick up or take of the window easily. So if you wanted to open the windows during the day it is easily removed then when you close them easily put back.

A couple of factors he gave us to consider as we have a 50 year old weatherboard home which has no insulation in the walls is to double clad the walls with plaster and make sure the ceiling has good insulation.

He indicated that doing the windows alone would help marginally but as the house is weatherboard there is a large amount of nooks and crannies that heat and sound can still come in.

We will certainly consider once we get other things tidied up.

From my experience I'd stick with the 'comfort' 6.38 mm or so laminated. DI units will give you better thermal insulation, but unless they are specifically engineered for sound reduction / noise attenuation any claims of reduced sound pressure levels are dubious. The comments about varying thickness and offset panes are correct and the gap size is also vital to achieve noise reduction.

If you really want to be dicked around and treated like an idiot go to Stegbar. The last order we did they changed three times, rang up to say the Pilkington laminated glass we ordered (and payed for up front) was not in stock and they wanted to charge us an additional $500 for a "special run" (they claimed this was Pilkingtons cost), and they didn't call to tell us they weren't going to be delivered on the delivery date, we rang them 3 days later and they realised they hadn't sent them.

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Having read all this thread - its hard not to come to the conclusuion that no-one wants to guaranteee their products, and double glazing is pushed as the be all and end all of sound reduction/. i am suspicious that this is a falsity.

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Its finding the best solution. Considering a lot of housing sits within "close" range of Motorways and large volume traffic the triple glaze units are "best" solution they have found. There is so many variables in sound ingress that manufacturers and suppliers, sure are reluctant to guarantee with the possibility of litigation on a topic that is a complex science.

Like I said the best would be a double glaze with an internal vacuum between the 2 panes.

Vibration is complex and establishing the transportation of sound waves can be like finding a needle in a haystack.

While DI maybe insinuated in the UK the fact is at least 95% is performed by installers.

Installation isn't quite that simple. People purchase their windows/doors/conservatories with all good intentions then realise they need to spend an awful amount of money on tools and without a trade background the job can be a disaster from many angles.

The existing windows tear at plaster, brickwork pulls away, some windows serve a structural purpose especially in bay windows not to mention the large amount of glass coming out. Post fixing windows to existing, modified or newly created openings is not an easy task.

The ideal is don't expect miracles. The most effective solution at reasonable cost to the weakest point in a house "Windows" for sound, light and climate ingress/egress is what people want to achieve. :)

Thicker glass still vibrates through ground, walls and roof space in regards to rail, air traffic. Having a manufacturer specify exact results is a minefield of disappointment. :)

Pharmaboy, the reason no-one guarantees results in your own home, is that there are so many factors involved. The sound can be coming in through the walls, the floor, the doors or the ceiling and the window supplier can only control the sound coming in through the window. Probably, the windows are the weakest link in most houses, so there is better than reasonable chance of achieving a noise reduction though.

My first house was a townhouse built near a busy road. It was brick veneer, but there were so many gaps at window and top of walls etc, that you could feel the internal plaster vibrating to the traffic noise. In retrospect, the windows were crap, and I put raven seals on them all which helped some, but until the walls stopped vibrating we were never going to get any peace in that joint. Thankfully, our first kid arrived, and we dumped the townhouse for something more kid-suitable (and quieter)

woodbe.

hello,

on trips to europe i was amazed to see windows in countries like Hungry and Bulgaria which are basically a "double shutter" timber window,

so one opens inside and the outer opens out and clipped off, this in 100yr old buildings, rubber seals and great hardware,

they provided a 100mm air cavity and had basic single glazing, the performance is outstanding,

if building new, sealing around windows and doors would be more important than DG units,

thankyou

myla

is there any form of tinting that reduces noise?

i am installing some wooden shutters... i was wondering if that would help cut down the noise much or at all

Tinting would probably reduce some vibration, but I wouldn't expect miracles.

We have some internal WRC plantation shutters, and they don't seem to reduce the noise at all. too many air gaps I guess.

woodbe.

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A couple of factors he gave us to consider as we have a 50 year old weatherboard home which has no insulation in the walls is to double clad the walls with plaster and make sure the ceiling has good insulation.

He indicated that doing the windows alone would help marginally but as the house is weatherboard there is a large amount of nooks and crannies that heat and sound can still come in.

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Yes in this case you really need to get some insulation in the walls. Sure, double cross lap gyprock sheets. Id take boards off and get some pump in before I went with the double sheets.

If you do go the sheets cross lap them and make sure the internal sheet is different thickness to the outside sheet.

At least 100mm of insulation in the ceilings right over the wall insulation to get a seal before you even considered windows. Weather board houses are like an acoustic drum without insulation. If you do have weather board consider building some timber shutters for extreme sound reduction.

We lived for at time in Boston, USA where winter temperatures hovered around -10`C.

All windows were double hung wooden sashes about 30-36 inches wide. We had double glazing like that mentioned by Autogenous although the gap was only 6-8 mm. This had great thermal/insulation benefits and also reduced noise.

We also had secondary glazing in addition to the double glazing. This consisted of quite light aluminium, or should I say aluminum, framing with Al sash windows, similar to that commonly used in Australia for fly wire. The framing was screwed onto the outside of the window frames and the Al sashes contained 1/4 inch (6.5mm) glass instead of flywire. We put the sashes in place for winter and stored them in the basement in winter, although the sashes slid up, just like normal sash windows and they could be easily opened and closed. Beside the improvement in the thermal insulation it very noticeably reduced the sound ingress. The gap between the double glazing and the secondary glazing would have been about 100mm.

Good luck

hi all

from what i know about pvc double glazed windows , the preferred system by manufacturers at present is a 6mm glass / 9mm gap / 6mm glass . the spacer bar is now filled with an air drying dessicant not gas . this is sufficient enough for both thermal and noise reduction control . beading in europe is tended to be put on inside of window, preferred to the outside to reduce the risk of burgulary . new retractable fly screens are also now available .

anything above 9mm gap in the double glazing industry is considered unnessary ,added to the fact it distorts the vision .

pilkington glass became a major player in the u.k these last couple of years mainly due to the fact it cut down the u.v rays only not noise reduction.(all windows had to be fitted with this external glass)

more details can be found on my website- innovated solutions via the home improvement web site .


hope this as helped .

This forum may be of help http://supersoundproofing.com/forum/index.php

The consensus on there seams to be that double glazing for heat and cold - laminated for sound.

After telling someone that who is a sound engineer he laughed at me and said laminated glass wouldn't work. That afternoon going home on the bus the driver stopped the bus for a driver change on a busy road and turned off the engine - I noted that it was quiet in the bus while there was a lot of traffic not only passing but accelerating away from traffic lights - this convinced me that the large laminated windows of the bus certainly worked to deaden the sound.

Hi guys, happened about a great littl;e resource written my RMIT for melb city council - has noise recomendations for lots of diffrent problems - enouhg detail, comparisons to keep the nerd happy, and not too much as to make it unintelligble.

click on the fact sheet links.

http://www.melbourne.vic.gov.au/info...a=3005&pg=3008

To sum it up - 100mm gaps are good ofr sound, 6mm gaps make very little difference. Laminated makes a large difference for high frequency noise, no diffrence for low frequency.

So - truck rumbling, heavy traffic - 100mm air gap, light traffic, talking , other outside noise, aircraft - laminated glass - and they recomend a particluar type PDE I think from memory.

edit - David - great site - i think I'll make my own acrylic window inserts now!

hello,

for those in melbourne,

if you want to check out a double glazing system whereby upvc frames and around a 100mm air gap is used then go to the Chevron

on the cnr of commercial and st kilda rd, melbourne

the existing buildings on the corner where converted into apartments and the windows were all upgraded

thankyou

myla

hi everyone

Pharmaboy2 sums it up well on double glazing versus single laminated, as does Autogenous on insulation. Two additional questions...

(1) Has anyone had any experience with using Pilkington Optilam Phon glass in windows for noise reduction?

It now seems to be called Viridian VLam Hush. The "product information" PDF on this page http://www.viridianglass.com/Products/vlam-hush/default.aspx?ProductType=HouseHolder is interesting.

The table in the PDF shows that basic 3mm float glass gives a sound insualtion of 30db, compared to standard 6mm lamintate at 33db, and Vlam Hush glass: 6mm at 36db, 8mm at 38db, 10mm at 39db and 12mm at 40db.And it says that "Every 10dB is perceived as twice as loud, so that a 20dB reduction would reduce the noise by four times" (keeping in mind it means high frquencies not low frequency traffic).

We presently have say basic 3mm float glass, so if I'm reading this correctly, if we installed say the 10.5mm Vlam Hush, it would NEARLY reduce high frequency noise by half. I guess this would be best case, depending on seals, and we also have an old (brick) house which probably wouldn't help. This leads to my next question...

(2) Any thoughts on whether wall insulation is more important than upgrading windows when looking to reduce noise? (hope this is OK in this thread, not meaning to change track)

Our house is 37 years old, with original aluminium windows with aging seals, with an ACT house energy rating of 1.5 stars (average).

The ceiling insulation is apparently good, being fully insulated with fibreglass bats over loose fibreglass throughout (R 5.0).

But the EER report suggested we add additional wall insulation (R 2.5) (it is currently R 0), seal wall vents (not sure about this one as I thought some air vents were needed to allow the house to breathe), seal external doors, seal internal doors, and weather strip the entry door. Apart from thermal benefits this would no doubt help reduce noise.

I know upgrading the windows plus adding wall insulation would be best, but we have a limited bucket of money for renovations.

Thanks again