Single-family house approx. 180 m² - What do you think about that?

No, the side of the stairs (the second half) also needs a boundary to the bathroom, otherwise you will have a triangular peephole into the bathroom.

This refers to (shown in yellow)
however, this wall piece does not need to be "floor-to-ceiling", but can follow the stair steps - if necessary, smoothed with drywall.

What is meant is (shown in yellow) however, this wall section does not need to be "floor-to-ceiling," but can follow the stair steps - if necessary "smoothed" with drywall.

Oh, I see, then everything is clear, it was just not important to me for the representation in the floor plan.

meant is (shown in yellow) however, this wall section does not need to be "floor-to-ceiling" but can follow the stair steps – if necessary, "smoothed" with drywall.

Oh, then everything is clear, it was just not important to me for the representation in the floor plan.

It doesn't matter which version: there will have to be a wall there, and then the bathroom will look different than currently drawn. For me, by the way, this is no longer open for discussion, because, simply put, this is currently a botched stair design that needs to be changed.

I agree that a bathroom pushed under the stairs like a utility room is not the real deal, but even more so an incentive to take the opportunity to think about a more clever and elegant overall solution. The current design is a recognizable evolution as an intermediate step, but I do not yet see the finish line.

Played around a bit more. Maybe the OP can still use some ideas from it.



However, I couldn’t really identify any real advantage compared to the other versions. Also, it will probably be too expensive that way. So I thought, actually the OP has one room too many upstairs despite the set-back upper floor. So why not put the media upstairs and try a simplified version?
Therefore, here is this version: