How can you identify soundproof windows (Class 4)?

Hello everyone,

according to the development plan, windows with sound insulation class 4 must be installed on one side of the house, while the other windows have no sound insulation requirements.

By now, all windows have been installed (we are building with a general contractor), but to us all the windows look exactly the same. Even those that are supposed to have sound insulation class 4 do not look different/thicker/more solid than the others.

Therefore the question: Can a layperson somehow recognize this from the outside? Or what distinguishes the windows?

Of course, we have paid a hefty surcharge for class 4, but at the moment somehow the fear that they are just the standard windows. The general contractor says, of course, that they are class 4.

You can't see it directly because the windows just have a different construction. The total thickness is the same, only the individual panes are of different thickness. It usually also has an invisible film and possibly different filling.

There are 2 ways to find out anyway:

1. The window or the glass must legally have information about the construction. Check it and compare sound insulation with no sound insulation.
2. Tap the windows with your finger. A sound-insulating window sounds much duller than a normal window, which sounds more "tinny."

Personally, I would generally install only sound insulation class 4 in every house, no matter where it is. Great comfort for a small price.

2. Tap on the windows with your finger. A soundproof window sounds much, much duller than a normal window, which sounds more "tinny".

Great, thanks a lot for the brilliant tip! Indeed, the soundproof windows sound extremely dull, almost as if you were knocking on a solid wall. The standard windows, on the other hand, sound really thin and tinny. A huge difference, considering they look practically identical.

Thanks