Improve floor plan single-family house 1 1/2 stories

hm, how do you imagine the staircase? It floats open in the common room, is that supposed to be?

The staircase must be closed off from the common room, on the side above the stair slope a wall must separate the stairwell from the common room, with some distance because the handrail also needs space. The stairwell belongs to the attic apartment.

You might tolerate a lot for a holiday apartment, but for a family of three I find the upper floor not livable at all. I see no way to run a household. Washing machine? Space for brooms and such? And that would also need to be provided for the holiday apartment.

I'll take a closer look at that. The washing machine for the attic at least fits on the right behind the door between the wall and the bathtub.

Why don’t you just build a standard house where you can section off the staircase to the second residential unit directly at the entrance and then lock a room that would then be accessible from the outside.

That is actually the other alternative I am pursuing. However, the one-and-a-half story prefabricated houses can hardly ever be divided horizontally because it is difficult to fit a bathroom downstairs and a kitchen upstairs. And the prefabricated bungalows can very rarely be divided vertically because they are optimized for their use. And the multi-generation bungalows are above the budget.

The discussion is not worth it.

I also think it's a shame that I'm not an architect. What is a good design in this situation? I have looked at many floor plans here in the forum, but with similar conditions, I had the impression that the discussion always led to building the house directly as a single-family home without dividing it before (or after) the single-family usage. Among acquaintances and friends, however, I see that old houses are divided into several apartments or old houses with several tiny apartments are converted into a single-family home. Only that someone plans it that way right from the new construction seems to be rare.

Does it really have to be a divided house? Wouldn't it also be possible to design the house just for you?

Why are you actually planning to move into the upper floor? I would never voluntarily move in there. Let the vacation guests stay upstairs.

Why don’t you build a house the way you want it in 10 years and rent it out now? The children's room will later be a guest or office room. Total area slightly smaller, but no 2 bathrooms, no 2 kitchens, later no expensive renovation.

What is a good design in this situation?

That might be easier to answer if you also described the desired target state here. Apart from that, the situation is unusual after all, so there will hardly be any comparative examples, and certainly no standard.

Why, too interesting?

No, you really can't finish listing the no-gos. So some prefab house providers also have houses for 2 families in their program. These are marketed under names like generation house or family, etc. You can certainly find something better with those, just to get a first feeling for something like that.