Which house floor area generates which living space?

Hello,

I wonder if it is possible to calculate which floor area for the house one must choose in order to generate a certain living space.

For me, it certainly plays a role that it is to be built as a 1.5-storey house.

For simplicity’s sake, if I calculate with a house of 10x10 meters, then I have a gross area on the ground floor of 100 sqm. If I subtract the exterior walls, about 86.5 sqm remain (9.30x9.30).
I would then have to adjust this value for the interior walls, right? Are there other areas that need to be subtracted? I’m thinking of the staircase, for example.
Let’s assume that of the 100 sqm gross, 80 sqm net remain.
1.5-storey means that max. 75% of the area is allowed to have a room height of 2 meters or more, right?
75% of the 80 sqm would be 60 sqm. -> 140 sqm living space using the example of 10x10 with a 1.5-storey construction method.

You can probably point out several errors that I don’t see. Probably also that the area in the upper floor >1m <2m is missing.

Then I still have to somehow determine my space requirements and reconcile that with the floor area...

Thanks and regards

Our house is rectangular, 1.5 stories, and the eligible living area is approximately 1.35 times the floor area of the outer footprint.

The living area of the attic strongly depends on the knee wall height and roof pitch.
The 75% only matters if, according to the development plan, you are only allowed to build one story.

It is the same with us; we are only allowed to build one story, and the roof angle is quite steeply specified at 43 to 47 degrees. As a layperson and with a pencil on paper, I come to a knee wall of about 100 cm. According to your formula, for example, 9x11 would then result in approximately 133 sqm. 9.3x11.5 would result in 144 sqm. That plus basement and attic studio would, I believe, be the dimension I have in mind.

As a rough rule for floors without sloping roofs: floor area * 0.85 = living area