Floor plan house with granny flat - improvement suggestions?

That is of course cleverly solved – I hadn’t noticed it that way at all. I will discuss it with my husband tonight.
Unfortunately, as always, there are also a few disadvantages to this plan; 1. We lack a utility room upstairs and the brother’s shower bathroom is located inside (without a window).

Well, if due to the requirements-budget-situation the jack of all trades finds no place, one might consider taking the jack of all trades without eggs. Still better than no pig at all... ;)

Unfortunately, as always, there are also a few disadvantages with this plan; 1. We lack a utility room upstairs and the brother's shower bathroom is internal (without a window).

That's not a problem: Your en-suite bathroom will be given to the brother (entry from his room) and the internal brother's bathroom will become the utility room. Then you'll just share a bathroom again with your children, where I had actually planned the washing machine (because only 3 people instead of 5 would need to use it) and there would be space for ironing in your large bedroom.

Unfortunately, that is no longer an option because we simply will not get another plot of land.

If I remember correctly, you obtained the plot through an allocation procedure with your own selection, after being drawn among the circle of the privileged. I would be surprised if the current phenomenon of returned draws did not affect your building area. It should be possible, if one is returned, to communicate your wish to exchange to the municipality. Or one could look around the area where such withdrawals have occurred.

By the way, I imagine that at the time we only discussed the selection based on the usual aspects (orientation, access location, neighborhood). I don’t recall any mention of considering (inconsistently designed) multigenerational living, even though it proves to be a major incompatibility factor for the selected plot.

I like this plan quite a bit – especially because the house is pretty compact, which also leaves a bit of garden. The idea of the staircase that leads directly from the living room to the garden is also good. It is also good that there is only one entrance to the house, which saves space again and also gives us a shorter path from the garage to the house.

I would also find the compromise of having the family go upstairs and access the garden via the balcony acceptable. You could make the outside staircase a bit wider so it looks more inviting or maybe have a different shape than an L or something like that. First, you would have to define the seating area and where it should go.

What I do miss, however, is a small storage room on the upper floor. Could you please provide the dimensions of the individual rooms?

Yes, you still need the space under the roof as a storage room. The roof is going on anyway. A second staircase all the way up in the stairwell would probably make sense and depending on the design might still be affordable. As long as everything is kept simple, you can still gain storage space there. But you have to be careful, as it is not insulated. There are already the latest findings with special vacuum boxes and the like. I just read about that somewhere in the neighboring thread. Unfortunately, I can’t provide all the dimensions because my software can’t do that. An architect would probably get somewhat different values anyway, since I use a general wall thickness of 20cm inside and 40cm outside. He would be more precise there.

BTW; are you an architect?

No. All designs are proposals for professionals to check feasibility, statics, and so forth. Nevertheless, I would still like to show a craft proposal that completely neglects the desire for a garden and instead prioritizes living on the ground floor: The goal here was to keep the total square meters within limits while still having acceptable room dimensions. However, the roof on the ground floor is probably quite costly, so it remains just a bit of play.

since the wall thicknesses are generally 20cm inside and 40cm outside for me

The house is planned with 49cm. Just for your information :)

The house is planned with 49cm. Just so you know :)

That is correct, and the interior walls are 11cm, except for the apartment partition wall, which is 30cm thick.