Floor plan planning shortly before submitting the building application

because otherwise, apart from the mentioned two-story new building, there are only single-story houses with pitched roofs.

Then I would base the following comparison criteria on: regarding the total height, orientation to the wall height / eaves height of the two-story houses, and regarding the height of the ground floor, orientation to the room heights of the single-story houses.

I am afraid it has to be brought to a normal traditional story height,

There is no such thing as normally traditional: you cannot expect modern floor constructions from you to have their insulation thickness deducted from the clear room height; with regard to different screed thicknesses in underfloor heating, that can be expected more.

Personally, clear heights of 260 cm on the ground floor and 240 cm on the upper floor would be nothing too little.

However, I assumed the basic dimensioning was clarified during the preliminary inquiry; with the actual application, that should no longer pose any obstacles.

Would be just as big a compromise as reducing the ceiling height.

If both compromises weighed equally, the flat roof would be the more expensive option. Also more expensive than your previously planned roof.

Lower ceiling height -> less masonry, less plaster, less facade... each material and labor. So it would be cheaper than the current solution.

Ultimately, I would wait to see what the authorities and the architect say. It only makes limited sense to worry without facts. Have the planner give you several options, you won’t have to decide spontaneously, but will have time to weigh the options. What I mean is: don’t stress yourself out, it will work out! [emoji4]

That is an important argument. It is interesting how much cheaper it becomes when the building is lower.

One can only hope that the [GU] passes on the cost reduction in such cases one to one. In principle, we can't do anything about it since the contract is already signed. No matter what reduction is proposed, it will have to be accepted. Apart from the fact that there will certainly be additional architect fees, maybe additional structural engineer fees, which presumably have to be paid separately.

So in my rental apartments I have always had about 2.45m clear height, and even in our 36m² living/dining room I do not find the height oppressive

We also have 2.45 in the [Kochessbereich], but in return an air area in the [WZ] as compensation. Everywhere on 60 sqm that would probably be a few cm too low for me. However, in the bedrooms, which are not that big either, you can again do without a few cm - personally, 2.40 would be enough for me there.

As the saying goes, "the sky is the limit for man's will." We only have 2.45-meter ceilings, I am 1.86 meters tall, and I don't find the ceiling height oppressive at all. It would be fine if we wanted to lower them, but then with a 2.60-meter ceiling, after lowering it there would only be a 1.45-meter ceiling left.

With higher ceilings, I would have to get a step ladder for every little task, which I would find much more annoying.