Floor plan design for a single-family house 230-235 m² on two full floors

We also have a concrete ceiling above the upper floor and still have an attic. Is the roof made of wood. Everything is possible. ;)

It could just be difficult with your wishes regarding the room layout and number of floors, which is already shown in the discussion here.

That's possible, but we would like to avoid a living space under a wooden gable roof. Gable roofs made of stone are rare.

I have no statistics on this, but I suspect that independent architect designs are not the majority on the market. Designs by developers and construction companies are probably more numerous, so traditionally, and I put that in quotation marks intentionally, it refers to quantities or majority proportions.

Architect designs are currently not the majority, but they are not exactly new either. The trend is indeed towards Zeichenknecht individual designs, both with masonry and carpentry general contractors alike. It is probably similar to agriculture, where "conventional" is often contrasted with "organic," although "organic" is actually conventional insofar as it was already practiced when the emperor was still called Barbarossa, and industrial agriculture only began its triumphal march little more than sixty years ago.

We prefer the concrete ceiling above the upper floor and would rather not have additional living space above it (even though I know that there are companies that build solid roofs not from wood).

Do you mean a (e.g. aerated concrete) solid roof and that you want such a roof with open underside views?

My experiences with the temperatures in living spaces under sloping roofs are rather poor, even in almost new and very high-quality built houses, so we are reluctant to plan that way. The main argument, however, is the additional stairs; we would prefer to limit ourselves to two floors. Maybe in the end, that is also better for the proportions than placing a "vertical" house with less ground area on the large plot.

mh again Schwörerhaus. Take a look at the E15-244.1.
A bungalow for you and the children would have their domain under the roof. It’s crazy how much attic space you get with a large bungalow.
(Not saying you should build like this. Just an example of how it could be, especially since a bungalow was once high on the wish list)

Modern attics aren’t actually bad. No roof windows in the rooms, but rather normal windows that can be shaded, like in the example mentioned above. Whether with or without slopes, you need shading. If a modern house heats up, it becomes a greenhouse.

To your question. We built with a small general contractor who is an architect himself. Your room program doesn’t fit in the catalog, for us it’s the plot. Our house itself is very standard visually. A functioning house goes wrong if you insert a meter here or add something there.
It’s probably a sum of small things for you to turn the clumsy Tetris into a coherent whole.

My experiences with the temperatures in living rooms under sloping roofs are rather bad, even in almost new and very high-quality built houses, so we are reluctant to plan like that. The main argument, however, is the additional stairs; we would prefer to limit ourselves to two floors. Perhaps in the end this is also better for the proportions than placing a "vertical" house with less floor area on the large plot.

I can tell you from experience that with 28cm insulation (between the rafters) wlg 032 and Velux exterior blinds, even at 30° in midsummer, a pleasant to cool 22-23 degrees prevail. You can’t compare that to a 30-year-old house.
We also have a bungalow.
Ground floor with a separate parents' area and all living rooms including guest room and shower bathroom for guests on about 160m2.
And with a knee wall as a granny flat with 4 dormers in the attic on 110m2 there is a study and the children's paradise ;)