Binder roof - alternative to the conventional roof truss?

Maybe that would be another alternative, that is a wooden beam ceiling plus a purlin roof?

But you do realize that this involves more brainpower than the difference in material costs can make, something like "town villa" usually with a hip roof, so without gable sides and such?

For me, the difference would have been 13,000 EUR. I didn't do it then for 10 sqm.

You do realize that we are talking about more brainpower being used here than a difference in material costs can make, something like "city villa" usually with a hip roof, so without gable sides and such?

Unfortunately, we don’t know much about the specific project or which manufacturer is behind it. Maybe they already have everything ready in the drawer. ;)

Where do we see the concrete house design? What exactly determines the feasibility of a reinforced concrete ceiling?

I am still having difficulty posting the design here at the moment, as it is not yet finalized. However, I will do so in due course. The reinforced concrete ceiling was explicitly our wish, due to better resale value, improved sound insulation, thermal insulation, etc. Our builder proposed a wooden beam ceiling. I would also have to suspend the wooden ceiling from below. Those are also costs that are eliminated with the concrete ceiling. However, I am happy to be convinced otherwise.

No known general contractor. A medium-sized, regional construction company. But my main concern was whether the variant wooden beam ceiling/truss roof is a common and good alternative. Provided that I notice it in my wallet.

I have to suspend the wooden ceiling from below anyway. Those are costs that do not apply with the concrete ceiling.
However, I am also happy to be proven wrong.

Whatever the reason for having to suspend it: we are going in circles. I lack the basics to respond to you more thoroughly than with "42," which would be the best in your case. Also happy to do so informally via email if you don't want to show the draft here yet. At gmx (de) and so on (some loyal readers can already sing along, otherwise it’s in my profile) ...