Every word penetrates through the windows. Is it the same with you?

As far as I can see, the windows were only generously foamed and fitted with a plaster strip.

That seems to me not to provide tightness against driving rain (from outside) and air (from inside). In my opinion, this is a defect.

Ask your contractor what they say about it...

I strongly recommend:
- find photos from the construction period,
- hire an expert to create a defect report,
- send the defect report as a registered letter with return receipt.

*Apparently you know even less than I do, so you would be hopelessly overwhelmed with everything further. And a company that installs windows like this will hardly respond voluntarily with rectification to a defect report.

- Commission an expert to create a defect report, - Deliver the defect report as a registered mail with return receipt.

Defects can also be reported by laypersons. First, deadlines must be met; professional qualification can be done afterwards – the reverse would be worse. Legal advice does not hurt.

Thank you. Reporting defects is clear and we will do that. But if I am not allowed to refer to DIN or RAL, what should I specify then? Serious question... the symptom is: it is too loud. Tomorrow I will also check if it even sucks in air, then that would be clear as well.
By the way, we have also noticed 2-3mm large cracks on the window reveals, near the plaster strips. Sometimes over the entire window size. I assume this is because the windows are shifting and that the installation was sloppy?! Fortunately, we have not approved the windows so far.

Question is, is soundproof glass installed? Possibly panes mounted upside down.

Luckily, we haven't removed the windows so far.

Are you not living in it yet? Do you remove the windows separately? Tell me more about your contract situation!

But if I’m not allowed to refer to DIN or RAL, what am I supposed to specify then? Serious question... the symptom is: it’s too loud. Tomorrow I will also check if air is being drawn in somewhere, then it would be clear.

You are the customer and you are a layperson. Better omit possibly "wrong" assumptions about causes; you have the license to say in non-technical words where the problem lies. Your expert will clarify that later, first comes the complaint properly formatted and within the deadline as it should be.

By the way, we have also noticed cracks partly 2-3mm wide at the window reveals, near the plaster strips. Partly over the entire window size.

Cracks where exactly – on the frame, on the masonry?