Quieter - Secondary Glazing

Secondary glazing is a fully independent internal window, fitted on the room side of the existing primary window. This provides significant noise reduction, improved thermal performance and enhanced security.

In this ever changing fast paced world, it is hard to sit and enjoy peace and quiet. Many of the buildings we use for living, studying, working and socialising were built many years ago to standards of their time, but are now unsuited to the demands of life today. So how do we relax when we encounter noise from heavy traffic, aircraft, noisy pubs and clubs or even noisy neighbours. By using the right combination of Selectaglaze secondary glazing to block out the disturbances, you can create comfortable environments to concentrate, enable a peaceful night’s sleep, relax and raise your quality of life.


  • Creates a quieter environment
  • Reduces sleep disturbance
  • Meets noise planning constraints
  • Aids increased concentration and productivity
  • Protects hearing
  • Keeps annoyance and stress levels low


Sound is transmitted through the primary window by a direct vibration of the glass. By adding a layer of secondary glazing, a cavity is created which helps to reduce resonance, as well as providing a second barrier for the sound to travel through. 

  • A reduction of 45dB is easily achievable and 56dB has been registered in combination with double glazing
  • Insulation increases as the gap widens between the primary and secondary glazing. 


Sound is measured as a pressure and expressed in dB (decibels), where to the human ear a change of 3dB is just about noticeable. An increase in pressure levels to 10dB approximates to a doubling of loudness.

Reasonable noise levels at a glance:

Bedrooms 30 - 35 dB
Music rooms 30 - 35 dB
Living rooms 30 - 40 dB
Meeting rooms 35 - 40 dB
Librarys 35 - 40 dB
Open office 45 - 50 dB

Effect of glass

Thicker glass has greater mass and will provide better performance. Acoustic laminate glass will show further improvements particularly at higher frequencies as it provides further dampening. Ideally the secondary glazing should have a different thickness of glass to the primary window to avoid symathetic resonance which will increase noise transmission.

Effect of cavity

The cavity is the space between the existing primary window and the secondary window. A larger cavity will make a significant difference to the level of noise insulation.

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