Best makeup for double glazing noise reduction windows

lockystrike

I am going to replace existing double glazed units with ones geared towards reducing external traffic noise.

I have spoken to a few IGU suppliers and found one that I want to use and have priced up for three different IGU makeups, 

1. 6.4 softcoat lam, 12mm silver, 10mm toughened glass
2. 6.4 softcoat lam, 16mm silver, 6.4 laminate
3. 6.4 softcoat lam, 16mm silver,  6.8 acoustic laminate

I have been advised that opt 1 may cause a little frame sag over time due to weight, the largest of windows which open (Side hung) being 450mm x 1000mm so I have got that In the back of my mind. 

Has anyone had experience or know what the best makeup to select would be? 

Thanks 

grumbler

Personally, I don't believe that replacing with any double-glassing units can make significant difference. I'd look at triple.

Rosa_Damascena

grumbler said:

Personally, I don't believe that replacing with any double-glassing units can make significant difference. I'd look at triple.

Is the cost difference between the two marginal or significant?

grumbler

In other countries they are a norm and don't cost much more. Even quadruple glazing units, and even with various thickness of glass and various gaps in one unit - for better sound isolation.

In UK, I guess, the difference it's significant - and not because of higher production costs, but because of the lower scale of production.

https://www.google.com/search?client=firefox-b-d&https://www.google.com/search?client=firefox-b-d&q=uk+double+glazing+vs+triple+price

Triple glazing is, however, more expensive than double glazing, costing roughly 33-50% more for exactly the same style of window.

.

A simple guide to understanding triple glazing prices is to use a representative example. Let’s say a double glazed window costs £350, for a triple glazed window of the same size, you can expect to pay around £500 or just under.

Below are price estimates for triple glazing windows for different types and sizes of houses in the UK. The list below should give you an approximate figure for budgeting purposes before you go ahead and invite triple glazing installers to provide quotes to you.

• Two bedrooms flat – costs to replace four windows with triple glazing will set you back around £1,950.
• Two bedroom terrace – most terraced houses of this size have five windows, which will cost nearly £2,500 to triple glaze.

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ComicGeek

More importantly, do you currently have trickle vents, as they would have to be installed in any replacement windows and would circumvent any glazing performance anyway.

It's the different thickness of inner and outer lanes that provide the acoustic performance, so no point having triple glazing with 3x6mm panes. That's why secondary glazing is used a lot in your situation.

Whatever the option, they should be able to provide sound reduction values for you to compare.

grumbler

ComicGeek said:

It's the different thickness of inner and outer lanes that provide the acoustic performance, so no point having triple glazing with 3x6mm panes.

Absolutely untrue. Different thickness is one of the factors, and I don't think that it's more important than an extra air chamber. At least because it affects very limited range of frequencies.

ComicGeek

grumbler said:

ComicGeek said:

It's the different thickness of inner and outer lanes that provide the acoustic performance, so no point having triple glazing with 3x6mm panes.

Absolutely untrue. Different thickness is one of the factors, and I don't think that it's more important than an extra air chamber. At least because it affects very limited range of frequencies.

Nope, absolutely true - a double glazed unit with correctly specified pane thicknesses will perform better than triple glazing with 3 panes of the same thickness. Vibration frequency of the glass is much more important than 16mm air gap - normally 50-200mm for an air gap providing significant noise reduction.

Yes you can get triple glazing systems with different pane thicknesses for acoustic systems, but they don't perform significantly better than a well specified double glazed unit or secondary glazing set back from the original windows. 

grumbler

Is it just your your word you you can show any proofs? Why on earth do they make quadruple glazing units then?

"well specified double glazed unit " - what does this mean if the ONLY change is the thickness on one glass pane?

ComicGeek

grumbler said:

Is it just your your word you you can show any proofs? Why on earth do they make quadruple glazing units then?

"well specified double glazed unit " - what does this mean if the ONLY change is the thickness on one glass pane?

Just happens to be the industry that I've worked in for the last 20 years. Windows are designed for either thermal or sound reduction properties, and the answer is different for each.

This is the website for one of the main secondary glazing providers https://www.selectaglaze.co.uk/benefits/window-noise-insulation - the sound reduction values show that it's the glass specification that's important. Yes it does show that the air cavity width is important, but it needs to be much wider than a standard window cavity to have an effect. The windows need to be sealed well and not have trickle vents or sections providing direct air paths.

Using the same pane thickness regardless of whether double, triple, quadruple increases sympathetic resonance which will increase noise transmission. Acoustic windows solutions have to use different pane thicknesses - if they don't then they don't work.

lockystrike

Thanks all for the comments. I read elsewhere that triple glazing was on par with noise reduction double glazing when you only had 28mm unit thickness to play with and I’d much prefer to reduce the noise without having to resort to secondary glazing…yet ) so I think I’ll try (opt 1) 6.4 softcoat lam, 12mm silver, 10mm toughened glass as it has the greatest difference in pane thickness. Cheers

lockystrike

As a side note if anyone else comes across this thread the DB values for all three are 

1. 6.4 softcoat lam, 12mm silver, 10mm toughened glass = 39db RW 
2. 6.4 softcoat lam, 16mm silver, 6.4 laminate = 39db RW
3. 6.4 softcoat lam, 16mm silver,  6.8 acoustic laminate = 39 db RW

The most cost effective solution is option 1 but due to the weight has only been recommended for fixed (non opening units) any side/top hung units I’ll being using option 2 makeup (slightly dearer). I’ve currently got standard double glazing units (4mm pane, 20mm silver, 4mm pane) which has a db RW rating of 27