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

Here are the drafts from provider F: Unfortunately, he has made the living room significantly smaller; the original width would require a steel beam, which would make the offer even more expensive (provider F is already the more expensive of the two). The door to the basement stairway disappears at the ground floor stairs, as does the wall around the stairs. We have not yet received any plans from provider G, but we have the verbal assurance that he does not need to make any wall thicker than we planned from a structural perspective. We are now having both offers/construction service descriptions reviewed by an expert, and then we will see who is cheaper purely in terms of numbers.

If the area on the ground floor is eliminated, the stairwell in the basement counts as part of the heated building envelope and must be insulated accordingly,...

It is strange to see how many people still plan a staircase to an unheated basement, or even garages inside the house.

Then the basement is apparently already sufficiently insulated anyway, since no provider mentioned it. Could that be the case with KFW 55, or what should I pay attention to?

None of this is visible in the drawing. Where is the insulation on the wall, the edge insulation, the note on the Ud value of the doors,... You will see it at the latest in the thermal protection calculation, because every thermal bridge must be documented there, which is a very large effort. The optimized thermal bridge surcharge with equivalence verification cannot be given in this way.

Thank you for the note, I will bring it up. The day after tomorrow, I'm going to the stair builder first, then I will see if the staircase is okay or maybe too steep.

Even in your drawings, the staircase and the area in front of it did not look exactly spacious. In the drawing from Anbieter F, it looks even tighter. Have you had the rise of the staircase measured and tried to use a similar staircase for comfort reasons, etc.?