Floor plan detached house, 2 full floors and a recessed floor

Nice that the story continues. The drawing style of the draft looks familiar to me. ;)

Even if that doesn't make it feather-light right away, I would consider building the top floor in timber frame construction.

That's how we solved it too and are very happy with the decision in retrospect.

However, the arrangement could look a bit "wild," what is your impression, any tips?

From the appearances, I would just tidy up the north and east a bit, but that's about it.

What possibilities do you see to enliven the facade (street side) with (plaster) colors/materials or to give it a structure?

The usual: brick slips, wood (cladding), aluminum (cladding) or just colored surfaces

Do you see a way to generate more ceiling height through a slimmer floor structure?

I think 19 cm is already very little. We're currently at 25, so I don't see much potential to reduce that further.

Do you have experience with this, possibly also how such a thing can be technically solidly solved?

Does it have to be a flush threshold? Otherwise, there are these mini-thresholds (1.5 cm or so). Apparently, they can be installed just like a regular window. It's probably obvious anyway that careful and thorough work must be done at such a critical point (especially regarding sealing), whether it's a regular patio door or with a reduced threshold.

Only the general contractor doesn't like that so much (among other things because of load transfer, sound insulation)

I can understand that... aerated concrete is just not so super stable if it also has to insulate really well at the same time.

What other possibility do you see for the wall construction to achieve at least KfW55 without producing significantly more wall thickness?

Timber frame construction. ;) As mentioned above, this would probably be suitable for several reasons for the top floor, which is the smallest floor anyway, but I guess with that you won't solve the problem yet. Would a slightly thicker wall (in basement/ground floor/upper floor) not be acceptable?

Wall structure: We are planning for KfW55 with 17.5 cm sand-lime brick + 14 cm ETICS = 31.5 cm. There's not much missing to a monolithic structure with 36 cm stones, which I would also like. Only the general contractor doesn’t like that so much (among other reasons because of load transfer, sound insulation)... I understand that this question can't be answered generally due to energy calculations, window areas etc., but maybe you still have a few ideas: What other options do you see for the wall structure to achieve at least KfW55 without producing significantly more wall thickness?

Keep in mind "Des 11anten Steinemantra" (since yesterday also available at baulotse-hoffmann dot de). Take the wall structure with which the builder has the most experience. Everything else is primarily, as Rolf Miller so nicely puts it.

Subsequent division into two/three units. Unfortunately, our current staircase concept is only conditionally suitable for later dividing the house into several units. Do you have any spontaneous ideas on how this could be accomplished?

With a six-year-old eldest and a one-year-old youngest child, my solution for a division is quite clear: just part with the whole house as soon as the kids have completely moved to their study locations. Then the house is at a sought-after age, and in the narrow segment "houses for people with four children," you yourselves will know best how quickly the market absorbs properties.

Nice that the story is continuing. The drawing style of the sketch looks familiar to me. ;)

Yes, I think so too! Thanks to your puzzle from 5 months ago :-) thanks again for your tip! So far, a complete success story! Best regards, Stephan

Are all the cellar rooms upstairs?

How critical do you see a staircase without natural light (except through windows on the 2nd floor)?

Basically, the staircase as a "dark hole" is naturally not very desirable, but I think it won't be too bad in your case. Besides, you still have options to improve it overall, for example if you make the (lower) staircase entrance a bit more open by shortening the adjacent wall/parapet. If you then also widen the first two steps, the staircase will integrate better into the hallway and become more open overall with more obliquely falling light. That should work on the ground floor and the upper floor. On the upper floor, this would have the positive effect of mitigating the tunnel-like character in the children's bathroom.

Are all the basement rooms "über"?

What exactly do you mean by "über"? As in unnecessary? How do you come to that? Because of the room layout? Regards, Stephan