Double Glazing for Noise Reduction

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mattwnz

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#1968064 5-Mar-2018 01:02

Shoes2468:
morrisk:

Another option I think worth looking at is increasing the thickness of the glass without going to the double glazing - is that what "hush glass" is?

I think it would make a big difference we did this in our bedroom windows and it made a big difference. Double glazed with one pane of the glass being “hush” glass we never called it that, but basically it was safety glass, my understanding is one of the panes it was glass then some resin to dampen the noise then a second pane of glass all Moulded together. Then a second pane of ordinary glass

This is one version of Hush glass, called vlam hush, andibasically has a laminated interlayer . I was going to use something like this on a project some time ago, but wasn't needed in the end http://www.viridianglass.co.nz/products/noise/vlam-hush

kryptonjohn

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#1968160 5-Mar-2018 10:10

Dingbatt: As a subdivision beyond our suburb has steadily filled in, the traffic on the road past our house has increased to the point where it intrudes on my well-being. It's not State Highway busy, but the increased traffic combined with A-holes who think everybody likes listening to their petrol powered wet dreams is driving me nuts.
We have ducted air-conditioning and so have been able to have the windows closed most of the summer.

I am now considering double glazing as the next step in our house improvements. As far as I can tell, double glazing is done for thermal insulation primarily, with secondary benefits of UV filtering and acoustic insulation.

In my case, I would like for the acoustic insulation to have a marked effect on the road noise. We have two large ranch sliders and a couple of picture windows that all face the road and are single glazed. The house is 1980s weatherboard with an iron roof (fully insulated with Batts). Am I hoping for too much to expect that double glazing will noticably reduce the transmission of noise into the house? Or will it just find another pathway? My internal walls are wooden sarking so it is not a simple option to add acoustic insulation to the walls.

The next step is to get an acoustic engineer out for a consultation.

Any comments from GZers who have retrofitted double glazing, on the acoustic benefits achieved would be appreciated.

We lived for a while in an apartment across the road from Ports of Auckland Bledisloe container terminal. A very noisy place but when the double glazing was closed... silence.

BTR

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#1968254 5-Mar-2018 13:14

Double glazing is amazing, I have retrofitted most of the windows in my house and it reduced street noise enormously External insulation in the walls will help as well.

We have upgraded our house a room at a time as we have renovated them, we have kept the same design and colour throughout.

bfginger

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#1973687 13-Mar-2018 03:23

Double glazing doesn't automatically make a great difference to sound and UV. Only specific glass options do and you can get nearly the same benefit with single glazing from similar glass options.

Lamination is the big thing for reducing UV and sound. Laminate glass means instead of a pane being just glass it has two layers of glass with a layer of plastic sandwiched in between.

I don't understand what your situation is with the walls but if you have no insulation in there there is only so much a better window can do.

Low frequency sounds require mass to stop them. Dense acoustic insulation, meaning high end acoustic insulation like with a 30kg/m3 rating and not the rebadged standard insulation, is best for stopping low frequency sounds inside walls. Beyond that there are techniques for using triple layers of acoustic plasterboard with special clips, sealants and interlayers.

Standard laminates have two layers of 3mm glass with a 0.38mm interlayer. You can also get other specifications like 4mm glass or a thicker interlayer such as 1 or 1.5mm. On paper it won't make a huge difference over 3-0.38-3mm but the trouble with general acoustic ratings is that they're an average across the sound frequency spectrum and that is not the same as being effective at low frequencies which requires mass. Upspeccing to acoustic laminates ("hush glass") makes a bigger difference in single glazing but helps slightly in double glazing over basic laminates however whether they're worthwhile with traffic noises over standard laminates I can't say. You could end up spending alot of money on the highest end glass and 80% of the cost may be for 15% of the benefit. 4-0.38-4mm laminate should be cost effective.

Wider air gaps in the double glazing help slightly. See if you can secure 18 or 20mm. Secondary glazing such as 120mm+ air gaps is ideal but that's very rare in New Zealand.

Tight window seals are important. It doesn't matter how good the glass is a standard loosely closed window will let sound through. Tighter closing multipoint locking systems are available for PVC, aluminium and even timber windows. If you get aluminium get thermally broken frames. Aside from being warmer it makes sense for them to be quieter as the inner and outer part of the metal is broken up by plastic like with laminate glass.

As timmmay says, PVC doesn't automatically mean great sound performance. PVC frames sold in New Zealand mostly aren't high end units with ultimate performance in mind and some are not assembled to be air tight. In terms of overall mass wood should be best and you can get them with aluminium on the outside to prevent maintenance horrors.

Dingbatt

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#1973696 13-Mar-2018 07:09

Thanks for the input. I have just re-read my OP, and just to clarify, the walls and ceiling are fully insulated with fibreglass Batts, in fact they were redone recently to increase their R value appreciably. Because the house is on piles the next insulation being fitted is underfloor. But that is a whole separate discussion.
My priorities are noise, thermal and UV in that order, so the use of 'hush' type glass will bear investigation. Auckland doesn't get that hot or cold hence my priorities.

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

bfginger

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#1974329 14-Mar-2018 00:14

Acoustic glass is also branded as Sound Stop glass.

Thin underfloor insulation is the norm in New Zealand. Something more substantial like R2.6 may make a difference to sound.

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MikeAqua

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#1975344 14-Mar-2018 08:32

Definitely helps. Doesn't completely block noise, but softens it considerably. You will still know a car is going past but it won't be anywhere near as intrusive.

If you end up going for new windows then have the installers seal between the window reveal and the surrounding framing with expanding foam or similar. This makes a significnat difference to thermal and acoustic insulation as that gap usually provides a clear path between the exterior and interior cladding.

Mike

robcreid

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#1976374 14-Mar-2018 10:17

I just had my wooden framed single glazed windows replaced with uPVC double glazed units and am very happy with the noise reduction.

I went for laminate outer glass in my main bedroom which faces the road which was supposed to offer 13% extra noise reduction over standard double glazed unit. They did offer something called Stadip Silence glass which was supposed to give a 23% noise reduction but was much more expensive.

As others have said they also sealed between the windows frames and the reveals with expanding foam, and the windows have a very tight seal.

Actually took me a couple of weeks to adjust to how much quieter it was when trying to sleep.

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