Application for terrace roofing or garden shed

No, in this specific BO the structural analysis must then be carried out by an authorized verifier, you cannot just calculate it yourself. It can be quite different in other BOs, I just wanted to point out again that such a BO might possibly have an appendix where all reservations regarding building permit-exempt projects are listed, and these should also be observed. Otherwise, it may be that everything has to be torn down again, and that certainly does not have to be the case. I would not rely on the fact that no one checks it. Too much cost and effort go into it.

In which law is it stated that the structural analysis must be performed by a specific person? As a mechanical engineering engineer, I have the necessary qualification to provide a simple structural analysis. And again, the sellers of such roofs always provide this proof right away. They know what the authorities might require.

Demolition only happens very, very, very rarely. Before that, there is a lot of litigation, and then suddenly different rules apply again.

As mentioned, the HBO states "by a person authorized to provide proof" without specifying further. Which person is authorized to provide proof is probably decided by the building authority - or a judge. I would even risk it with my own planned balcony, but only because it costs little money to build myself and can be quickly taken down again. But with expensive or elaborate things, I wouldn’t risk it. It only takes one neighbor to complain and the building authority is already at the door. It can also go well, for example, my almost floor-to-ceiling windows on the south side have no fall protection because I find it ugly, no children run around here, and I’m not so stupid as to fall out of the window. The building authority has also shown up before (but regarding a different matter) and they said nothing about it. But that doesn’t mean that nobody will ever complain. You have to decide on your own responsibility in each case. The main thing is that you have read the annex to the BO and know that you are taking a risk and don’t fall completely from the sky afterwards.