What roof pitch is appropriate?

Thank you very much for the answers.

Is there a development plan?

There is an inner area statute, but it does not specify the roof pitch.

a classic rafter roof or a nail truss roof

I am working with a construction supervisor (an acquaintance who has already built a dozen houses here) and therefore have all freedoms. Do I understand your post correctly?: "General contractors prefer to build with nail trusses for cost reasons, thus avoiding the (more expensive) open construction method (with rafter roof) for visual/aesthetic reasons."

If we could go a bit higher we would have taken 30

Why? Does it not make more sense to raise the knee wall if allowed (i.e., at the same ridge height) instead of changing the roof pitch?

Depending on how the roof surfaces are oriented...

The roof faces SW, so the ridge is SE-NW.

I’ll first take with me what Zubi123 wrote:

You have advantages and disadvantages everywhere.

Are there greater cost differences depending on the roof pitch?

The pitch makes the least difference. You've already said gable roof, hip / half-hip roof would be more expensive - especially over a non-rectangular floor plan (which as far as I remember, you do not intend). In detail, it would have to be looked at specifically. Why don't you use the ways you know to get in touch with me? Would you consider a mansard roof?

The higher roof pitch results in more usable space in the attic. At 25 degrees, we have 1.88m in the middle. At 30 degrees, it should be 2.3m or similar. This means you have more options to use the attic.

But then you are assuming a constant eaves height. Only then is your sentence correct. Because if you are generally allowed to build higher, is right, you can create even more higher storage space with a lower DN.

In other words and starting from the extreme: I prefer 10sqm at 1.88m rather than 1sqm at 2.3m, 1sqm at 2, 1sqm at 1.7, 1sqm at 1.4, etc...

Do I understand your post correctly?: "GU prefer to build with nail plates for cost reasons, thereby eliminating the (more expensive) open construction method (with rafter roof) for visual/aesthetic reasons."

GU will gladly build you a classic rafter roof as well, but whether it is worth the extra cost ultimately has to be decided by the builder. And I do not believe that an open gable is necessarily ruled out with a truss roof. I only said that based on my own experience, the GU does not like to offer the open gable. They have their standard construction method, and this rarely includes the open gable.