One of the things we all want to keep out of our windows is noise. At the same time, when we get new casement or sliding windows, our focus is mainly on insulation. Right? Now, there’s a misconception when it comes to that. There’s often the mistaken belief that by getting energy efficient windows, the outside noises decrease as well. And truth be told, it does so but to an extent. If we like to talk about soundproof windows, the story is a tad different. Let’s hear it.
Energy efficient windows don’t necessarily reduce noises
The double or triple glass panes – a common characteristic of energy efficient windows, do isolate noises. No doubt. But the thermal insulation of windows mainly comes from the low-E coatings and the argon gas in the spacer.
What makes windows soundproof?
As already said, the number of glass panes makes a difference. With double or even triple glazing, you get one more and then still one more layer of protection from outside noises. But the real difference comes from two other characteristics of soundproof windows.
• Thicker glass
The glass thickness plays a huge role in noise reduction. What’s even more important than that is the combination of glass thicknesses. For example, if you get a double-glazing window, one glass pane may be 6mm thick and the second pane 6.8mm thick.
Why is this glass thickness combination important?
It has to do with the way sound works. How does sound work?
You can view sound as the vibration an item makes as it travels through air or water. We know these vibrations as soundwaves with different pitches, frequencies, and duration. What you likely know is that sound intensity is measured in decibels. High pitched sounds have more oscillations than low pitched sounds, and so are perceived as louder by the eardrum. Also, low frequency sounds travel far.
How does the glass thickness combo fit in all that?
To reduce noise, the soundwave’s journey must be interrupted. The soundwave must be absorbed by an object. And so, when external noises hit your window glass, the frequency of the soundwave is partially absorbed by the glass. Notice that the key word here is ‘partially’. If it were to absorb entirely the noise, the glass would have to be very, very thick. Now, what happens is this: with the first glass pane absorbing some of the soundwave’s frequency, the vibrations are reduced as the noise is transmitted to the next obstacle in its path – in our case, the second glass pane. The two different glass thicknesses reduce oscillation and vibration – hence, disrupting the frequency and consequently reducing the noise arriving inside the house. The gap between the two glass panes is also important. Let’s see that.
• Air space
The wider the gap between the two glass panes, the most effective the noise reduction. Why? Because it gives the chance to the soundwave frequency to reduce its movement – both the vibration and oscillation.
Steps to take to soundproof windows even more
So far, we’ve seen that noise reduction is achieved when the window glass is thick, the panes are at least two, the thickness of the glass is not the same, and the gap between the panes is large.
The question is this: will these things be enough to eliminate outside noises? The short answer is no. The longer answer is that a window cannot completely eliminate noises but it can reduce them to a great extent. When you consider getting new windows, you need to think of all the above based on your personal needs too.
There’s often a need to reduce all kinds of noises – from the street, nearby airport, bars and clubs, neighbors, construction, et cetera. It’s fair to say that all these sounds are different. It’s one thing to opt for peace of mind by eliminating aviation noises and another story to opt for the reduction of natural sounds because they annoy you. The sounds are different but, in all cases, you need to follow the above steps and get the right window glass options for the best possible soundproofing. Since these steps are good enough but soundproofing windows is far more demanding, it’s best if you pay attention to a few more things.
• Choose glass panes with a polyvinyl butyral (PVB) layer between the panes
• Make sure the windows are seamlessly sealed
• Use acoustic caulk and place weather strips
• Make sure the window installation is impeccably done
When it comes to windows, their soundproof quality is measured with the Sound Transmission Class (STC) rating system, which tells you the volume of noise that can be transmitted through the window in decibels. To get sufficient window noise reduction, make sure the STC rating is 40 and above, depending always on the noise pollution in your area.
