Does foam work as a soundproofing material for windows? No. Plus you can’t see through it. Even as a temporary measure, it has little or no effect on stopping sound. Let’s look at the details so you can avoid wasting your money on foam.

One of the fundamental requirements of soundproofing materials is Density, or how much a material weighs. The more dense it is, the more it can absorb and reflect sound. And, conversely, the lighter a material is, the less it can stop sound.

There are many different types of foam, even if you don’t need to see out your window. But foam shouldn’t be on your soundproofing list, because it is very lightweight – the opposite of what you need to stop sound. It doesn’t matter how it is labeled, i.e., Open Cell, Closed Cell, Acoustic, etc., foam, by its nature (lightweight), is not suitable for soundproofing. It is basically air with a bit of glue and coloring. Because it is only a little denser than air, it simply can’t absorb sound.

What Is A Good Soundproofing Material for Windows

Laminated glass is well-suited for soundproofing windows. It is very dense, 3.2  pounds per square foot, and clear. Although acrylic plastic is clear, it is only half as dense as laminated glass.

Remember the Density fundamental: The denser/heavier a material is, the more it can absorb and reflect sound. And, conversely, the lighter it is, the less it can stop sound.