Acoustic Performance

Dissimilar Glass & Sound Transmission Class (STC)

Our windows and doors include insulated glass units that are double glazed (double pane). A standard double-pane window or door consists of two panes of glass that are the same thickness.

Dissimilar glass consists of two panes that are different thicknesses. This is the best option to reduce sound transmission caused by outside noise.

Each glass thickness reduces different frequencies of sound transmission. Therefore, two different glass thicknesses will reduce more sound transmission than two of the same glass thickness.

In addition, it does not matter which direction the sound is traveling. And it makes no difference whether the dissimilar glass is installed with the heavier glass to the outside or inside.

  • Choose dissimilar glass, glass panes that are different thicknesses, to improve acoustical properties and reduce outside noise. Dissimilar glass that is 1/8-3/16 is recommended.

Sound Transmission Class (STC) is an integer rating of how effectively an interior building element attenuates, or reduces, airborne noise from one side to the other. This is used to rate various interior elements such as walls, floors, ceilings, doors, and windows. [Source: Intertek Blog]

The higher the STC rating, the better the acoustic performance. Although this is true, trying to achieve a higher STC rating can be costly. This is why choosing dissimlar glass with 1/8 and 3/16 glass is generally a good choice.