Triple pane windows are great for energy efficiency, but should you buy them for their sound deafening properties? Home expert Bob Vila and others agree that while the windows are a smart choice for many reasons, they do not deliver on sound reduction.
How is Sound Control Measured in Windows?
Soundproofing is rated by STC, which stands for Sound Transmission Class. The classification starts at 25, which indicates that normal speech is audible through a wall. There is little degree of privacy until 40, while very loud sounds are blocked at 50. Ratings of 60 or more indicate superior soundproofing, where few sounds are heard.
Single pane windows have an STC of 26-28, while double pane ones have 26-32 ratings. Double pane windows with dissimilar glass (where the two panes of glass are different thicknesses) can have even higher ratings; around 34. Triple pane windows have less space between panes of glass, which actually works to their disadvantage when it comes to absorbing sound. The result is an STC around the same as double pane windows with dissimilar glass.
There are two way to make window more sound proof:
- Laminate them, by adding a layer or more viscous material between panes of glass. Laminating the window can raise STC to 35 or more. The downside is that laminating the glass adds 30-50% to the cost of the window. However, an added benefit is that laminated windows blocks 99.5% of the sun’s ultraviolet rays, which prevents drapes and furniture from fading.
- Use dissimilar glass, such as 1/8″ and the other 1/4″. According to research by a top window company, the effect of dissimilar glass is that each pane reduces different frequencies of noises, thus providing better overall sound control and a higher STC rating than regular double pane windows. Dissimilar glass typically has a rating of 34 STC or more, which is only a few points lower than the sound rating of the exterior envelope of the house. This means that even if the windows have a higher rating, sound can still penetrate the siding.
Finding the Best Windows for your Home
If reducing sound is one of your concerns when installing or replacing windows, a contractor who sells and installs all the major window brands can help you find the best product for your situation. Mountain States Windows and Siding can order you the specially treated double pane window treatments you need for increased STC and noise reduction, or install triple pane windows to make your house more energy efficient.