Floor plan design for a single-family house 230-235 m² on two full floors

Anyway, but if the initial calculation here is based on 18 cm thickness and ends up being 25 cm

Then that also has an impact on the staircase, which in the last draft also looks relatively short and therefore steep to me.

And if the ceiling height in all floors is to remain the same, the ridge height must increase... When that is maxed out, there's a problem, right?

Above all, for a room of approximately 12 x 7 m, you should plan for at least 2.60 m ceiling height, preferably 2.80 m, or the parking deck look is perfect. Which in turn looks unpleasant in small rooms.

Then that also has an impact on the staircase, which looks relatively short and thus steep to me in the last draft as well.

With 3.6 sqm, it is definitely too long, too narrow, or both ;)

The provider says that all offers are also statically calculated beforehand. Although I myself cannot really imagine that it is completely calculated already during the offer creation, I assume from the reputation and the high quantities that the statements are serious and that a living room of this dimension should not be a problem if such magnitudes are already found in the catalog. If it is offered to us like this and we also sign it like this, the financial risk should no longer lie with us. In relation, the floor seems to me to be the significantly greater cost risk than the ceiling, as one sometimes reads about unexpected additional costs of 50,000 euros and more...

But often there is a clause about additional costs due to statistical calculation in the small print