Soundproof door bedroom / children's room

Unfortunately, he does not have a controlled residential ventilation system.

scary..

My children are not at that age yet... but I will surely be even more grateful once the topic of "listening to music, talking on the phone for hours," etc. gets going..

BER I will certainly be even more grateful once the topic "listening to music, talking on the phone for hours"

Don't worry, that also works wonderfully in the living room. Greetings from the father of three

What do you mean by solid? The standard would be tubular chipboard.

Maybe just upgrade to solid and as already mentioned, don't take the cheapest option. In everyday life, the normal door is also sufficient.

SK1 and different room feeling??? Such nonsense! I have installed SK2 and an SK4 door!

My statement is nonsense because you have even higher classes at home in connection with a controlled residential ventilation system. That is quite a great causal connection.

Maybe just upgrade massively and, as already mentioned, don't go for the cheapest option. In everyday life, a normal door is sufficient.

Since I have no idea or point of comparison: What exactly is meant by "hardware store door"? And does "massive(ly)" mean solid core board? Or actually solid wood?

SSK4 already sounds intense. How much is the surcharge from SSK 3 to SSK 4? In my apartment, there is actually 24 cm aerated concrete to the hallway and the neighboring apartment. But I have now only had SSK3 installed at the apartment entrance door to have more quiet in the apartment. I initially assumed that should be enough?