Knee wall height in a shed roof dormer

For our house construction project, the expects a "very low" knee wall when installing a shed dormer in the attic and has mentioned a cross gable as a potential alternative.

I already see a cross gable here just because of the entrance projection , and I hope for a significantly raised knee wall; otherwise, the conversion would be pretty pointless.

hope for a significantly higher knee wall

I hope so too, and have communicated this accordingly to the architect. Let's see what comes back. As soon as available, I will present the result in the main thread.

I hope so too, and have communicated this accordingly to the architect. Let's see what comes back. As soon as available, I will present the result in the main thread.

The problem is, without a significant knee wall increase, a noticeable increase in living space would only be possible with an extension - at least with a gable-side overhang of the ground floor over the basement. I find it surprising in this context that although you have already presented a concrete discussion draft, there is still no fundamental work (potential study) from the architect. That is usually how it all starts.

The plan is to expand the attic by raising the knee walls und adding dormers, keeping the same floor plan (as defined by the basement).

The floor plan from post #1 of the main thread is now a partially discarded design from a prefabricated house salesman. I posted it for the sake of completeness, to make all data available at that time. This probably causes more confusion now.
In the meantime, we have started fresh again, with pencil and paper, with a "real" architect...

The floor plan from post #1 of the main thread is by now (at least in parts) a discarded design from a prefabricated house vendor. [...] Meanwhile, we have started fresh once again, with pencil and paper, with a "real" architect...

And did he then verify how approvable the knee wall 140 shown there would be?

You mean approvable in the sense of the development plan (ridge height, eaves height, ...)? The working hypothesis is still that a high knee wall (and a steeper roof) will also be approved. There is no development plan available, and around us there is a wild mix of houses (two-story, three-story, flat roof, hipped roof, gable roof). Our current bungalow is already very inconspicuous there. Last week the surveyor was here; he also measured the neighboring buildings. With his results, we will then know more precisely how well we fit into the existing development. If there should then be doubts, a preliminary building inquiry will probably be considered.