Prefab house construction plans as a template - does that cause problems?

What would the alternative be? Am I supposed to create the plans myself?

You’re not allowed to - but have someone design it who does that professionally? You can do whatever you want - I really don’t want to interfere. It’s just an unusual approach...

Exactly what I intend to do - an architect who works in road construction and has already made plans for dozens of houses in the town on the side. Small additional services included. Costs low

I think that is more than okay.

Another Pandora's box... (HOAI)

It's not like the green forum, where they describe the ideal world ;)

Are there still really architects and engineers who bill straight after that?

You can ask – but first choose an independent consultant whom you will pay, who checks the planner you intend to commission, whether they have correctly formulated the question you want and asked it in the right place...

And if the answer does not fit the question – then you simply had a bad consultant as well as a bad planner, and should have commissioned an independent construction query consultant beforehand to find the right consultant...