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 20th 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.
If you would like to inquire about getting services Granada offer please contact us on!
Please telephone us between the hours of 9.00am & 5.00pm Monday to Friday on:
01246 453 209 or Freephone 0800 107 5519
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