160 sqm two-storey single-family house - second attempt

I based it on a step depth of 26cm and a rise of 262.5/15=17.5cm. The staircase descent would be offset by one step, meaning the last top step would already be above the hallway. Thus, with 15 steps, I arrive at an effective length of 14*26=364cm. The house is 10.49m, minus 2*36.5cm exterior walls, one 18cm interior wall, as well as the staircase of 364cm and the living room of 4m, leaving twice 97cm for the areas in front of and behind the staircase. I had asked if that would be too tight and it was each time denied. And how 26/17.5 feels, we want to find out the day after tomorrow at the staircase builder. Also, from when it becomes too steep for us, so that we possibly still find room for the tight areas.

15 risers at 17.5 cm are only 262.5 cm ... but the story height is probably at least 285 cm, since the ceiling and floor construction of the upper floor must also be overcome. A builder etc. should know that. And, in (one should have read it ) typical stair dimensions are provided at the end of the first post.