Specifying for Noise Reduction - Get a good nights sleep!

Getting it Right!

Getting the specification right is critically important, because this should be a “once only” installation that resolves the problem/s - “once and for all” - taking into account all of the following considerations:

- The type/s, frequencies & volumes of noise
- The required level of noise reduction
- Providing well insulated windows that also prevent heat loss
- Attention to the aesthetics, to create a discreet, attractive finish

The following sections highlight the key factors involved in getting the sound proofing specification correct for each individual situation.

The Gap - for Noise Insulation

The gap between the primary window glass & the secondary window glass (the “reveal” depth) is important to maximize the sound insulation.

Standard primary window glass will usually be 4mm thick - or if very old, pre 20^th century, it may be 3mm thick.

- For best noise reduction using secondary glazing with 4mm glass – the gap should be 150mm

- For best noise reduction using secondary glazing with 6mm glass – the gap should be 100mm

Depending upon the reveal depth of the primary window, it may not always be practicable to achieve such a gap when secondary glazing for noise, but bear in mind that:

- For secondary windows using 4mm glass, each 25mm increase in the gap reduces the noise transmission by approximately 0.75 dB - up to the maximum gap of 150mm

- For secondary windows using 6mm glass, each 25mm increase in the gap reduces the noise transmission by approximately 1.25 dB - up to the maximum gap of 100mm

The Gap - Aesthetics

Where the primary window reveal is relatively shallow, less than 100mm, the best solution is to improve the glass specification from float to laminated or acoustic glass.

The alternative, creating a deeper reveal by “boxing-in” the secondary glazing with a deeper, extended sub-frame, will generally result in a very bulky, unattractive installation.

Different Types of Noise & Their Frequencies

The human ear responds differently to high & low frequencies, filtering out the most extreme effects - correctly specified acoustic glazing will further reduce the volume, eliminating it completely or reducing it to a whisper.

Low frequency noise can result in actual vibration of the glazing.

- Aircraft maintaining height & speed
- The general “rumble” of traffic noise
- Heavy goods vehicles, buses, taxis
- Train & railway noise
- Heavy “bass” type music

This can most effectively be reduced by using a thicker glass

High frequency noise can resonate with the glass producing a high-pitched whine.

- Emergency service sirens
- Jet aircraft noise landing or taking off
- Power tools, lawnmowers
- Pop & opera music
- Overhead power lines
- Some types of fireworks

This is most effectively reduced by using acoustic glass.


General noise:

- Nearby clubs & pubs
- Nearby commercial & industrial premises
- Noise from local parks
- Noise from shopping centers & schools
- Busy street noise

General noise glazing is best achieved by using different thicknesses of glass in the primary window and the secondary glazing in order to avoid resonance.

The Glass - for Noise Insulation

Different types and thicknesses of glass in the secondary windows are specified to achieve the best noise insulation, dependent upon both the volume & the type of the outside noise.

In general order of least to most effective, these are:

- 4mm Float Glass
- 6mm Float Glass
- 8mm Float Glass
- 10mm Float Glass
- 6.4mm Laminated Glass
- 6.8mm Laminated Glass
- 7.5mm Laminated Glass
- 8.8mm Laminated Glass
- 10.8mm Laminated Glass
- 6.4mm Stadip Silence Laminated Acoustic Glass
- 6.8mm Stadip Silence Laminated Acoustic Glass
- 7.0mm Stadip Silence Laminated Acoustic Glass
- 8.8mm Stadip Silence Laminated Acoustic Glass

For extreme situations sealed units, creating triple glazing, can be specified in the secondary glazing.

The Glass - for Thermal Insulation

Any of the above will also provide a dramatic improvement in thermal insulation.

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