Build the house yourself 100%

...What still worries me is my flat roof,
because of Paragraph 34 can I even get a building permit for my house in Germany?

Hello,

Why not, that can be clarified with a simple building preliminary inquiry!!

By the way, don’t let yourself be misled! I have personally completed two solid buildings with almost 99% self-performance (self-building contractor) and currently supervise various self-build projects in my region.
However, there are some traps for the inexperienced builder, e.g.:

1. Time: For self-building, a factor of 2.5....4 is usually to be expected depending on craftsmanship skills.
2. Specialist contractor declaration!
3. Safety-relevant issues can only be realized by "authorized" persons.
4. The greatest savings effect can be achieved with the "closed shell".

Conclusion: Self-building only after thorough consultation and construction supervision! Otherwise, it will become a money pit, and hardly anything remains of the originally expected savings except frustration!

Best regards.

Thank you, I also have the feeling that most people I talk to want to talk me out of it.

...Can you please explain to me what the 2nd specialist contractor declaration is? Is it some kind of permit for self-construction? If yes, how and where do you get it?

...Which safety-relevant topics are those? Statics?

We are also doing almost the entire interior construction of our house ourselves.

... You can save a lot - I agree with that. But you can also do a lot wrong. And apart from that: you better not calculate the time!

... On the other hand, I have seen a lot of crap from craftsmen on other construction sites. If you do it yourself, provided you comply with the common standards, you can often achieve a better result.