Acoustic Values of Double and Triple Glass



What is Rw?

Rw is the ‘weighted sound reduction index.’ It is a number used to rate the effectiveness of the glass as a noise insulator and is measured in decibels (dB). It also takes into consideration a correction factor for the response of the human ear. For example, if a busy street has a noise level of 75dB and the required level of noise in a room is 40dB, the Rw value of the required glass is 35dB. Glass types with a Rw value greater than 35dB can then be offered as solutions.

It is worth remembering that every 10dB reduction is perceived by the ear as being half as loud, so that a 20dB noise reduction would reduce the perceived noise by 75%.

Sound reduction figures 

Sound reduction figures for 28mm standard double glass: 

Glass typeExplainRwWeight
4/20/4Standard double glass 20.00 kg/m2
6/16/6Standard double glass 30.00 kg/m2
6/12/10Double glass with different glass thickness  
6/16/6.4 Laminated double glass  
6/16/6.8 Acoustic Laminated double glass39 dB 

If you are looking to achieve a sound reduction with a standard 28mm glass unit, the maximum sound reduction index (Rw) is 39 dB. : 28mm overall. If they want a high sound reduction, it is not always possible within this 28mm available space and often there may be a compromise in the U-values.