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wasabijim

Effectiveness of Fencing to Reduce Noise

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We are looking at fencing options and some had literature concerning noise reduction. To  my wife some investment committee members, this seemed worth further consideration despite the additional costs.  I wasn't as readily convinced.

 

I've added the applicable marketing material in pics below. I concluded the benefits were probably measured at ground level right up against the biggest 3m fence they do.... 

 

question - in your typical suburban setting, assuming the fence material is a good absorber/blocker/dissipater,  etc., and we're dealing with a 1800mm fence are the claimed benefits (or any for that matter) practically going to be felt?

 

I'm thinking that in the open air a good degree of the sound is still going to find is way to you / from you. and lets say you have line of sight to a busy road from an upper story room, would you maybe get clearer noise because its blocking that which would otherwise dribble along the ground and reflect up. 

 

We're mainly looking at a side boundary to neighbours, but also to the front for blocking traffic although here I was initially only looking at a fence heights of 1200-1500mm. 

 

 

WallNoiseReduction.png.9b7970fc55347d11aa29d10450fb6bf2.png

 

image.png.ccfba2ce457a627d9925368698e2b99f.png

 

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I’m not convinced fencing is much of a noise insulator I wouldn’t be spending extra on that, I would have thought double glazing and good wall/ ceiling insulation is where it’s at.

 

I recently had 1.8m colourbond fencing done and while its excellent for privacy I can still hear my neighbors. 

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2 hours ago, BATMAQN said:

I would have thought double glazing and good wall/ ceiling insulation is where it’s at.

When I built my listening room Seb I thought double glazing for my door was the wtg so I went to G.James glass and they were very helpful and when I said I want to keep noise both in and out they pointed out that they had double glazing that keeps temperature control foremost and sound as a second benefit so If I wanted to 'soundproof the door then 'Acoustic' double glazing was what I needed.

 

They showed me a sample(looked like thick glass to me) and then they explained that acoustic double glazing was two sometimes up to four panes of glass joined together that have a different molecular structure in each pane and by the time noise works it's way through these different structures ot is extremely dissipated.

 

They were right. TV or music can be going in the rest of the house and it barely registers in my room and vice versa when I'm playing music/TV at normal levels.

 

 

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Oh! Just remembered this little tid bit.

My Sister in law lives on the main road passing through our country town it's also a designated highway looked after by the RMA(ex RTA) even though to us it's just a two lane road.. If you live on a highway or a designated highway(there's a difference apparently) you can apply to them to have your house soundproofed. I'd never heard of this.

 

She applied, it took 6 months to get through the approval process and then a further waiting period and then...a letter in the mail saying that the project will be started and this will be the timeframe.

17k worth of double glazing on the windows, an acoustic rated front door and some deflection panels covering as sun shades on windows. 25k all up.

 

Gratis. For free.

 

Amazing.

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44 minutes ago, Luc said:

When I built my listening room Seb I thought double glazing for my door was the wtg so I went to G.James glass and they were very helpful and when I said I want to keep noise both in and out they pointed out that they had double glazing that keeps temperature control foremost and sound as a second benefit so If I wanted to 'soundproof the door then 'Acoustic' double glazing was what I needed.

 

They showed me a sample(looked like thick glass to me) and then they explained that acoustic double glazing was two sometimes up to four panes of glass joined together that have a different molecular structure in each pane and by the time noise works it's way through these different structures ot is extremely dissipated.

 

They were right. TV or music can be going in the rest of the house and it barely registers in my room and vice versa when I'm playing music/TV at normal levels.

 

 

my research suggested that if going double glazing there's a few variables to be across, otherwise you may not get sufficient benefit  - the thickness of each pane and the gap. ideally at least 12mm gap and different thickness for each pane. while there's real benefit with 100-200mm air gaps, the framing etc gets complicated and costly. plus the style of window helps - awnings get a better seal as there's no need to accommodate a sliding interface.

 

We are looking to go with 10.38mm laminate to most of the front windows (awnings)  and the sliding door entry to the listening room. it had a good cost-performance balance. and if needed there's the option to retro fit double glazing, which is meant to be easy enough if the marketing is to be believed.  

 

 

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On 05/11/2019 at 10:18 AM, wasabijim said:

looking at fencing options

I am involved in some aspects of government compliance assessment of quiet house designs to see if they meet basic planning policy and other criteria, seen here https://www.dplh.wa.gov.au/spp5-4

 

Your OP picture illustrations are misleading in claiming 4 fold reduction in noise from a simple road noise barrier wall. It might be true in terms of sound power and noise physics and final distances (not stated in pics) whereas in reality a large no air gap wall with about 3m height achieves about 8dB(A) reduction for certain noise frequencies in line of sight, perceived by the human ear as approaching half less the loudness for mostly upper low, medium to high frequencies.. Lower frequencies bend over the top of the wall and are much less reduced. A 1.8m wall with no gaps will achieve about 5dB reduction in line of sight, which is still worthwhile and perceived as about maybe a quarter less loud. A 1.2 or 1.5m fence will achieve almost nothing perhaps 3dB(A) if you are a hairy footed Hobbit.

 

You should also increase thickness of window glass from standard 4mm to 6.38mm or 10mm laminated with frame acoustic seals, keep the ratio of glass in the room to less than 40%, use solid core external doors and/or orienting your noise sensitive rooms away. Don’t worry about the ceiling unless aircraft noise is present as current building code for five star energy house rating (gyprock and R4 insulation) will be sufficient.

 

First basic question is do you live in a quiet or noisy suburb. You said a typical suburb, so this is what will likely happen within 100m (+6dB) of a major road, rail, industry or commercial zoning (+6 to 10dB) or within 450m (+2dB)of the same (Note: +dB figures added to your existing location ambient noise, generally between 35-45dB night / day, to gauge what total noise you are aiming to reduce and then what height of wall, window glass thickness, ceiling and roof design, and orientation of house living spaces).

 

If it’s just neighbour to neighbour noise issues a wall can help but those noises may be controlled by complaint, noise management and legal controls.

 

There will also be height restrictions of walls according to local shire fence laws and town planning. About 2.1m height is about the max and you won’t get the max 8-10dB benefit, instead about 6-7 dB(A). There is little or no absorption benefit effect involved in different fencing material as such.

 

A typical suburb (outside ambient of 40-50 dBA day and 30-40dBA night) shouldn’t have too much noise to deal with but a no gap type of fence of 1.8m or better 2.1m will help to screen about 6-7dB(A) for relevant sound frequencies. Most houses in such suburbs without any acoustic treatment will regularly achieve very quiet internal noise levels with windows closed of 30dB(A) day and 20dB(A) night and no need to do anything. 

 

Materials like cement sheet, metal, masonry etc recommended instead of pine lap or other gappy fence material.

 

The following pictures generally show how a noise barrier wall behaves to reduce noise, which frequencies are involved and position of source to receiver.

 

 

 

 

 

9917375E-8128-41EF-8217-E3F125FEA8EB.png

C3B6EDCA-9EB5-45EB-BBEA-CAB7CC27809E.gif

A6A4126B-BEFA-460C-9CE1-9B1995B96DA9.png

Edited by Al.M

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13 hours ago, Luc said:

Oh! Just remembered this little tid bit.

My Sister in law lives on the main road passing through our country town it's also a designated highway looked after by the RMA(ex RTA) even though to us it's just a two lane road.. If you live on a highway or a designated highway(there's a difference apparently) you can apply to them to have your house soundproofed. I'd never heard of this.

 

She applied, it took 6 months to get through the approval process and then a further waiting period and then...a letter in the mail saying that the project will be started and this will be the timeframe.

17k worth of double glazing on the windows, an acoustic rated front door and some deflection panels covering as sun shades on windows. 25k all up.

 

Gratis. For free.

 

Amazing.

That is a handy little tid bit Lee I bet there's a few on here that wouldn't have known about this, excellent info.

 

13 hours ago, Luc said:

When I built my listening room Seb I thought double glazing for my door was the wtg so I went to G.James glass and they were very helpful and when I said I want to keep noise both in and out they pointed out that they had double glazing that keeps temperature control foremost and sound as a second benefit so If I wanted to 'soundproof the door then 'Acoustic' double glazing was what I needed.

 

They showed me a sample(looked like thick glass to me) and then they explained that acoustic double glazing was two sometimes up to four panes of glass joined together that have a different molecular structure in each pane and by the time noise works it's way through these different structures ot is extremely dissipated.

 

They were right. TV or music can be going in the rest of the house and it barely registers in my room and vice versa when I'm playing music/TV at normal levels.

 

 

 Mate what you're saying is probably the best outcome most on here could hope to achieve a nearly quiet room for you and the rest of the house not to mention a separate area where other members of the family get less influence for that area, you know what I mean.

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17 hours ago, wasabijim said:

100-200mm air gaps

🤣 Your dreaming. Or do you mean your house frame and not a window with 20cm-30cm gaps?

18 hours ago, wasabijim said:

^^ and the result? 

It's very very quiet. Two storey house with the bedrooms upstairs and two of them facing directly to the road. I was really surprised at how muted the noise was, barely has an impact on you inside the house.

 

The house has a 1.8m high hardwood paling fence I built a few years ago for them..it gave them privacy but did nothing for the road noise. I also planted it out behind the boundary fence, quite densely with Lilli pilli and a smaller thick understory. didn't do much really. but yeah, the D/glazing certainly did.

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For road noise you need mass and height.

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regarding the 100mm+ air gap in between double glazing panes: 

 

https://www.alwindows.com.au/wp-content/uploads/2018/02/AWA-AS1288-Glass-Guide.pdf

A common misunderstanding is that double glazing is effective at attenuating noise. However, studies have shown that ordinary double glazing with a standard gap of about 12 mm does not substantially improve the acoustic performance. This gap is too small to provide any real benefit. The most effective solution is to increase the gap between the two panes to at least 100 mm. This is most commonly referred to as secondary glazing, as it often involves two separate window frames.

 

 

https://build.com.au/window-acoustics-and-noise-control

Double glazing

The most effective barrier against noise is to install a secondary window, otherwise known as ‘add on double glazing’. With an ideal space of 100-200mm between the two windows, your noise problem will be significantly reduced. Note that such large gaps increase air movement and will reduce your window’s thermal performance. Another important consideration is the space required for secondary glazing may not be practical in a normal home.

Standard double glazing with at least a 12mm gap is effective at reducing the transmission of medium to high frequencies (human voice). For low frequencies (traffic) using a different thickness of glass in each pane, or incorporating laminated glass, can help to cut noise transmission.


 

https://www.stegbar.com.au/~/media/Files/Stegbar/Stegbar Data Sheet Downloads/Glass Glazing/Stegbar Data Sheet - Noise.pdf

* Insulated glass units – the key to achieving significant sound wave disruption in an IGU is to have as large an air gap as possible (less than 12mm air gap will provide an STC no better than thick glass); and to have the two panels of glass vary in thickness by at least 50% (so a 10mm panel on one side and a 5mm on the other).

* Secondary window – for heavy traffic and aircraft noise a second window with an air space of at least 100mm is the only viable solution to significantly reduce the noise

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It’s good to ponder all the options, but without quantifying assessment of the external noise to keep out in the particular area its all very academic and most typical suburbs that are quiet do not need any of this. At minimal cost and while in the build most standard aluminium window frames will easily take 6.38mm laminated that is several dB quieter and give a perceptible difference.

 

Here is another good site explanation with sound reductions across more options https://www.viridianglass.com/~/media/viridian-glass/files/downloads/tech-direct/sound-and-noise.pdf

 

Edited by Al.M

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On ‎5‎/‎11‎/‎2019 at 11:05 PM, wasabijim said:

 plus the style of window helps - awnings get a better seal as there's no need to accommodate a sliding interface.

 

 

I'm fairly certain that many sliding windows can't carry the weight of double glazing too...I installed double glazing throughout the house and had to install awning windows.

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12 hours ago, Al.M said:

It’s good to ponder all the options, but without quantifying assessment of the external noise to keep out in the particular area its all very academic and most typical suburbs that are quiet do not need any of this. At minimal cost and while in the build most standard aluminium window frames will easily take 6.38mm laminated that is several dB quieter and give a perceptible difference.

 

Here is another good site explanation with sound reductions across more options https://www.viridianglass.com/~/media/viridian-glass/files/downloads/tech-direct/sound-and-noise.pdf

 

that was one of the more comprehensive reads I came across and that i could keep up with. I agree that the practical application of the theory and even proven test outcomes has many variables and this goes even beyond the flavour of noise to target. So i came away thinking a broad approach would be best.

 

we are close to the crest of a  suburban through road so while not a main road it gets steady traffic. the road is divided  by direction outside the block with traffic going up the hill - and likely to still be gunning the engine for a little bit more - on the far side but 2m higher so at the level of the upstairs rooms. 

 

within the scope of our build project its often the labour not so much the material costs that add up. this extends to making the windows prior to delivery on site. with regard to the thicker glass the effort to make and install the windows vs 3 or 4mm panes was minimal vs making and installing double glazing.

 

 

but back to the fencing - its seems my average Joe conclusion (assuming the fence  material/construction can block sound in the first place) would be that unless it blocks line of site its not going to do much at all but even then the benefit is subjective. and to the point that there not be much at all.  

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