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Double Glazing - Noise Reduction?

Discussion in 'off topic' started by droodzilla, Jul 26, 2015.

  1. droodzilla

    droodzilla pfm Member

    I'm looking to replace my double glazing and want it to reduce noise from outside as much as possible. A number of companies offer special acoustic glass which they claim has extra noise reducing properties. For example:



    Do any PFM members have experience of this kind of double glazing and how effective it is?

    Note, I'm aware of other options such as adding secondary glazing to a double glazed window but, for now, I'd rather not go down that route (mainly on aesthetic grounds).

  2. stevec67

    stevec67 pfm Member

    You need a bigger gap between the glass sheets. Thermal insulation is best with a small gap, as this limits convection currents within the panels taking heat from indoors, sound insulation needs a bigger gap, the bigger the better. I used to work in a street level office on an urban A road, with a 6" gap between outer and inner leaves it was near silent.
  3. Hummer

    Hummer pfm Member

    Hi Nigel,

    I live on a main road and needed to cut out noise in my bedroom in order to sleep so I used a secondary glazing unit behind my existing windows. This is the most effective way of reducing noise, far better than double glazing.

    I investigated noise reduction and having glass spaced further apart and of different thickness makes a substantial difference. You do not require a 70mm unit behind your glazed window - 50mm or less will do. Think mine is 25mm.

    Hope this of help
  4. blossomchris

    blossomchris I feel better than James Brown

    Secondary glazing with acoustic ceiling tiles cut into the reveals between the window and secondary unit is very effective if retaining the original window frames.

  5. muzzer

    muzzer Numb Nut

    Triple glazing?
  6. martin clark

    martin clark pinko bodger

    Stevec67 is spot-on.

    And yes, with a double-glazed IGU, for better acoustic performance a laminated inner leaf is worth it - small uplift in cost for the glass is the best bang for the buck by far. Any laminated glass will improve matters* but specialist types (Pilkington Optiphon etc) have worked on this to maximise the benefit - basically, a thicker interlayer.

    If you want to get better than this, fit secondary glazing with a laminated inner (I'd suggest 8.8mm) and some absorption in the cavity between frames as blossomchris suggested. Do this with 200mm between primary and secondary and a melamine foam liner and it will challenge what a brick masonry wall provides, at least - get to a solid point of dimished returns (drop me a pm if you want a detail/spec for it). Recently finished a building where a key consideration is noise from helicopter operations and with a little attention to detail it has proved subjectively really effective (despite noise survey graphs that started at 100dB at 30Hz at 50m ..!)

    * two reasons: the inherent damping in the interlayer, which provides a small amount of resistive absorption broadband and more seriously, it kills the 'coincidence effect'; and because the two panes end-up different thicknesses it considerably reduces transfer between the leaves via the gas spring between them.

    ETA: Triple glazing units, curiously, is not so effective because it will be 3 x 4mm glass layers and because they are the same size and thickness, with reduced cavities between to meet standard rebates, there will be a chunk of the midband where acoustic isolation is markedly reduced owing to resonant and coincidence effects. Triples certainly can be made to work but still require a fancier glass spec., and as such - end up expensive (because triple-glazing IGU suppliers in the UK are not common - not least because these days good standard IGUs easily challenge a triples' thermal capability). IME the same spent on a double -glazed IGU + even simple secondary glazing will likely romp ahead in acoustic terms. And can be done piecemeal - add the secondary if you think you still need it after living with the base replacement window.
  7. droodzilla

    droodzilla pfm Member

    Hi All, thanks for the comments and suggestions - lots to think about & discuss with my partner. And very interesting too!

    Martin, thanks for the offer - I may well drop you a PM once I've mulled things over.


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