Building window on the corridor map - approval

It depends: some state building codes or development plans allow so-called subordinate components such as bay windows outside the building envelope. If that is the case, however, they still count towards the floor area, thus increasing the scope for a suitable upper floor that should/must not become a full storey.

That is correct and to my knowledge the only way to legally increase the floor area of a ground floor. However, I have not read anywhere that this would turn a two-storey building into a one-storey building.

This results from the mathematics, as previously described. If the ground floor (EG) grows while the upper floor (OG) remains the same, then the ratio shifts in favor of the applicable regulation. The issue with the bay windows (Erkern) only makes sense if the building envelope (Baufenster) - as in this case - is already maxed out. The last option is then to reduce the upper floor (OG) until the permissible ratio is reached.

Basically, you can calculate this on a beer coaster (even if there are already a few marks from the landlord on it), so the persistence of the problem is not really clear to me.

Best regards
Dirk Grafe

Basically, you can calculate that on a beer coaster (even if there are already a few marks from the landlord on it),

Nice hint. Does it help the OP further?

That is correct and to my knowledge, the only way to legally enlarge the floor area of a ground floor. However, I have never read anywhere that this would turn a two-story building into a one-story building.

I think you and @lauroon don’t understand because you haven’t yet dealt with full stories, the definition in the respective state building code, and how they are calculated. Could that be?

For you, is a second floor, an attic with vertical walls, or a city villa a two-story building? Could that be?

Because then I wouldn’t understand it either

I think you and @lauroon don't understand it because you haven't dealt with full floors, the definition in the respective state building code, and how to calculate them. Could that be?

I cannot speak for the OP, I am very familiar with it. Before I switched to the F & B sector, I worked for many years in the construction-related industry. Therefore, I know that Dirk Grafe's comparison is problematic. What he describes is a stepped floor, which is a special form of the second floor and is allowed everywhere the municipality does not exclude it in the development plan. But thanks for questioning!

I cannot speak for the OP, I am very familiar with this. Before I switched to the F & B sector, I worked for many years in the construction-related trade. Therefore, I know that Dirk Grafe's comparison is flawed. What he describes is a setback floor, which is a special form of two-story buildings and is allowed wherever the municipality does not exclude it in the development plan.

But thanks for questioning!

No, I am _not_ just describing the special case of a setback floor, but rather presenting the general regulation. Therefore, there is no flaw, and it can simply be calculated based on the square meter number, regardless of whether it is a setback floor or not.

Best regards
Dirk Grafe