Floor plan design / draft single-family house flat roof with double garage

...I had completely overlooked... so you only have the front door as an opening on the ground floor on the south/west side? Phew, I would think about that again....

Yes, mirroring is indeed worth considering, although whether I have a window to the utility room facing east or west makes little difference to me. In the dining/living area, we thought that a 7m high glass front would provide enough light. To the east and west, it will anyway be the view of the neighbor’s wall, which will be built 3m away.

I don’t know if I would just mirror it. Why is the garage actually built completely onto the house if there isn’t even a direct access? Shift the house and garage. Garage further forward. Do you have the option to install a window behind the kitchen? The glass front surely gives you light. But the sun shines only for a limited time into your living space... in summer that might be acceptable... I also consider the house too narrow but you don’t need 100 sqm for a straight staircase per floor. But about 10 m I do find necessary

I don't know if I would just mirror it.
Why is the garage actually built completely attached to the house when there isn't even a direct access? Shift the house and garage. Garage further forward. Do you have the possibility to install another window behind the kitchen?
The glass front surely gives you light. But the sun only shines into your living space for a limited time... in summer that may be bearable...

I also think the house is too narrow but you don’t need 100sqm for a straight staircase per floor. But about 10 m I do find necessary

We found the exterior view / flat roof with attached garage more visually appealing... than the freestanding building... but yes, a shift might possibly make sense.

We will widen the upper floor to 9.75m by 0.75m...

I will then soon post the revised stuff...

Thanks first of all for your honest feedback.

There is no development plan.. only a positive preliminary building permit that states the following..

But you do know what a development plan is, right?

The information in the preliminary permit must have some basis, either a development plan or according to §34. But somewhere a concrete building height comes from. Floor area ratio 0.4 and plot ratio 0.3 can still coexist on their own - in the rather atypical case that a plot ratio of 0.3 is aimed for the building, single-story, and for the floor area ratio 0.1 points have been added specifically for access paths etc. But by two full stories at the latest, it clashes: if the plot ratio is 0.3, the plots would have to be huge or the two-story design is not really wanted. That would consequently mean only 0.15 for the house in the floor area ratio. So there is a worm somewhere in that.

The 120sqm lower limit for a straight staircase, is that in your personal opinion?

No, a lot of experience in floor plan design. It is not only the immediate area around the staircase that increases enormously with a staircase with a straight and unfolded axis. It is also the effects on the overall floor layout that create extra areas in many rooms (or from the room user's perspective: wasted square meters). This staircase type impresses a main axis on a floor plan very dominantly. The mentioned sizes are those from which a floor plan can absorb that painlessly.

Why is the garage built completely attached to the house if there is not even a direct access? Just offset the house and garage. Garage further forward. Do you have the option to install a window behind the kitchen?

Now that you mention it: has anyone here on the forum ever installed a window to the garage so that you can see the Porsche from the dining table?

The thing with the Porsche sounds great, then you can also save the exterior blinds on the annoying sunny west side.

A straight staircase causes more hallway and restrictions in the floor plan.

Not everyone here agrees that children’s rooms must be larger than 15 sqm; the living area has to allow for it. Only more hallway area than children’s room area is a disproportion.

Take a look at your drawn upper floor
The left one: children’s room with 11 sqm is okay
Parents’ bedroom not usable. You have to get into the bed over the foot end.
Right: parents have more space to sleep than children to sleep, do homework, play, meet friends.
No storage space on the upper floor at all

2 children’s rooms, 1 bedroom, 1 study, 1 bathroom
That is quite a lot for the floor size. You don’t have to restrict yourself with the staircase.