Low ridge height results in a low knee wall

@ 11Ant: thanks. Try:

Development plan/restrictions
Plot size: 520
Slope: no
Site coverage ratio
Floor area ratio: 0.35
Building window, building line and boundary: 17 wide * 14m deep
Edge development
Number of parking spaces: 3m distance from street to building window
Number of floors: I
Roof shape: gable roof or hip roof, between 30° and 45°
Stylistic direction
Orientation
Maximum heights/limits: 7.20 ridge height from top edge of finished floor; floor height max. 0.50 above reference point street crown
Further requirements: dormers max. 3m wide, color of tiles, 2 apartments allowed, open construction method (What is that?), detached and semi-detached houses

Builders’ requirements
Stylistic direction, roof shape, building type: "country house"... later separable 2nd apartment would be good
Basement, floors: basement yes, 1.5 floors.
Number of persons, age: 2 persons 60+
Room requirements on ground floor, upper floor: best possible utilization
Office: family use or home office? No
Guest bedrooms per year: 4* 3 persons
Open or closed architecture
Conservative or modern construction method
Open kitchen, cooking island: kitchen open to dining area, from there open to living room
Number of dining places: 6
Fireplace: no
Music/stereo wall
Balcony, roof terrace: no
Garage, carport: 2
Utility garden, greenhouse: no
Further wishes/special features/daily routine, gladly also reasons why this or that should or should not be: everything "from a single source," no own work, ready-to-move-in finishing (move in with furniture = move-in ready as if I were a tenant).

House design
Who planned it: contacted / written to prefabricated house manufacturer
-planner of a construction company
-architect
-do-it-yourself
What do you especially like? Why?
What do you not like? Why?
Price estimate according to architect/planner: my estimate 2,200 EUR/sqm living space = 400k excluding land
Personal price limit for house, incl. equipment:
Preferred heating technology: no photovoltaic. Heat pump with active cooling. Room temperature individually controllable. Good sound insulation.

If you have to give up, which details/extensions
-can you do without: 1 garage
-can you not do without:

Why did the design turn out as it is now? e.g.
Standard design from planner?
Which wishes were implemented by the architect?
A mix of many examples from various magazines...
What makes it particularly good or bad in your eyes?

Is 400k your limit? If yes, you won't be able to fully utilize the building allowance anyway

As you describe it, one should actually advise you to stay. However: if your nice landlords inherit or sell, you might already feel too old to make the jump (?)

My experience: there is no carved-in-stone right like tenancy law, I consider fear of changes in ownership unfounded.

"Making the jump" is a nice euphemism for the smallest apartment you will ever have. It will be a condominium that you did not buy yourself. ***Sarcasm off***

By the way... that's exactly what my daughter, who has turned into a city person, said. She now thinks it's great to spend a weekend in the countryside.... it smells so wonderful of horse manure.... ))

Is 400k your limit?
If yes, you won't be able to fully utilize the building plot anyway

No, not the limit; that was the calculation: 2,200 * 180 sqm. I am contributing the land.
The 2,200 was thrown my way by a prefabricated house manufacturer as "move-in ready." We'll still see if that actually works out afterward. Or do you think that is already a beautified figure or will be unrealistic?

That's not wrong, but a basement is not included yet ... Prefabricated house providers usually offer starting from the foundation slab

open construction (What is that supposed to be?)

The "o" in the development plan means both detached as well as entire rows of houses / terraced house blocks; as opposed to perimeter block development. "Open" is also legally defined if there is a gap in the house front after 50 meters. So except for major city streets, "o" is practically the norm.