Assessment of the floor plan for a semi-detached house, flat roof with full basement

Indeed, the staircase is actually, I think, the decisive structure for the overall floor plan.

It ALWAYS is, but it's good that you have already realized that. :)

For room 1, I would consider reducing the window area so that the child does not feel like they are in a showcase. 8.5 sqm of glass area is very MUCH for the room size.

She ALWAYS is, but good that you have recognized that already. :)

The question is, is there even a "better" or at least alternative solution? If the house were freestanding and somewhat wider, I would also prefer to have the staircase in the middle and straight. Otherwise, you would plan it in the entrance area, and there would be quite a lot of "dark space" (12.50 the entire length) behind it up to the terrace. Therefore, I think the staircase was planned in the middle on the closed north side and for lighting, a skylight in the flat roof.

For room 1, I would consider reducing the window area so that the child doesn't feel like they are in a display window. 8.5 sqm of glass area is very MUCH for the room size.

This is a very good point that I will take on board and probably have implemented. Indeed, there are too many windows here. This happened because I originally intended it as a home office for myself with a panoramic view of the garden, but over time it became the children's room. :)

What is a kitchen island? As drawn, your island seems very small to me. I would have suggested a peninsula that docks at the bottom of the plan. That means the floor-to-ceiling window would have to be reduced. What is enough space for you? What do you need there? For me, it would be far too little, but it’s not my kitchen

I obviously meant a cooking island. Unfortunately, you can only correct posts for a very short time afterwards. We have already had a kitchen planned and everything fit. Sure, you can extend the workspace by turning the patio door into a window and making the kitchen island an L-shape around the wall. Then you have a "dead end" and no longer have the possibility to go directly from the kitchen into the garden. But that is exactly the compromise we are still weighing up as to whether it is actually too "small" or sufficiently large and whether we should now tweak the floor plan to give the kitchen more space. I can’t think of anything without throwing the basic design overboard.

Apparently it is enough, there is also enough storage and workspace area according to calculations, but the layout is suboptimal. The largest contiguous surface is located in the furthest corner and in front of the main window sash. However, machines are usually placed there based on experience, so no work can be done there at all.

If the kitchen is only meant for show, that can work, otherwise I would also enlarge the island into a peninsula here and reduce the window. Then preparation can take place next to the cooktop.

The site plan including height information of the property would be important if you absolutely want to plan with a basement living area.

Okay, then I have to discuss that with the planner. The property is level at 110m above sea level. A basement living area was planned because the land price is very expensive (urban area) and the space is to be used accordingly – it is also needed for a regularly used sleeping and bathroom option in the basement and as storage, since an attic or recessed floor is not allowed in this area.