ᐅ DIN standard for sound insulation between open stairwell and apartment corridor?

Hello,

we currently own a condominium. In my opinion, the sound insulation between the open staircase (completely outdoors) and the apartment hallway is not very good.
So far, I have only found specifications online in the standards for closed staircases -> habitable rooms and closed staircases -> non-habitable rooms, but no information for the case where an open staircase exists (open staircase = completely outdoors).

In our case, if someone talks normally in the open staircase or courtyard, you can clearly hear them through the door.

When I asked the developer, with whom we are currently involved in a legal dispute, they claimed everything is fine and compliant with the standards.
They sent documentation, which I have attached here. I am not sure if anything can be derived from it.

For our windows, the manufacturer and the production number are on the frame and inside the window.
For the door, I cannot find any names or numbers. I am also attaching pictures of the door.

Since I have so far only seen this door on many garages of houses, I am unsure if this door is really suitable. Especially in the morning, when the sun shines directly on the door and it is dark inside, you can slightly see the sunlight shining through as a "horizontal stripe."

Hello, you won’t find a satisfying answer here. This is a very specific issue that requires an expert assessment. Either privately paid and therefore questionable, or court-ordered, which usually means a lawsuit. Sorry, I wish I had a better answer.

Your door has a sound insulation rating of 34 dB, as stated in the document. This means that if a noise of 60 dB is generated, your door will reduce it by 34 dB. Naturally, you can still hear people talking in the hallway, so it corresponds to sound insulation class 2. Unless you specifically ordered something else, you received the standard version—unfortunately.

Whether it was installed correctly is another matter because if it wasn’t, sound will pass through. This, however, can only be verified with a blower door test unless you already notice a draft.

Since I only found information stating that 34dB doors are required from a closed staircase to the apartment, I thought that for doors from the outside area to the apartment, higher values might need to be met.

Generally, I assume that the door installed there is not the one specified, or isn’t it typical for manufacturers to print their company name and possibly some kind of serial number on regular doors?

Otherwise, I have probably just been unlucky... but at least I was able to gain a lot of knowledge from the condominium about how not to do things – and especially that you need everything documented in writing with precise details^^ Lesson learned. Unfortunately, with this apartment, the lessons were costly.

Does the door have a soundproof seal? If not, check if it can be retrofitted for plastic doors.
This bottom flap helps significantly; additionally, increase the sealing pressure around the entire frame.