Floor plan: Semi-detached house 8x12m. Opinions and creative ideas welcome :-)

Oh yes, and you probably meant Kwai. No, with garlic pills Ilja Rogoff - that's some kind of faction thing, I think: Geha vs. Pelikan

Lamy!

By the way, a house also counts as a DH if the garages are attached.

I don’t understand that. Do you mean now, if the garages are then also necessarily connected to the house? Then you could completely separate the building structures and just put a double garage in between?

I don't understand that. Do you mean now if the garages then must additionally be connected to the house? Then you could completely separate the building structures and just put a double garage in between?

Simple attic apartment is not possible. But two separate ones. The connection only needs to be there, possibly with fire protection insulation in between, no idea. Legally it is then considered a semi-detached house, which can be submitted like that to the building authority. There are enough houses built that way as semi-detached houses/double houses. Even my parents took this crutch on a plot for their single-family house in the 70s with their neighbors: both double garages are placed offset next to each other, both houses are recognizable as single-family houses, legally applied as semi-detached houses. I only mention it because it makes sense here due to the window issue.

I mention it only because it is relevant here due to the window issue

And I am only asking because my niece would like to build a house next to her mother's house. They said an extension would be allowed but not a detached house. Now I wonder if it would count as an extension by using this crutch?

Even my parents used this crutch on a property for their single-family house in the 70s along with their neighbors: both double garages are staggered next to each other, both houses are clearly recognizable as single-family houses, legally applied as semi-detached houses.

I wonder if this trick still works today and in all federal states?
By a semi-detached house, I understand the obligation to build an attached house on one side / boundary development / building line – being able to fulfill that with an (additionally privileged with regard to distance) outbuilding makes me have doubts. What does say about that?

What does @Escroda say about this?

He harbors similar doubts but has to admit that he has not fully grasped the context and cannot provide reliable information without knowledge of Yvonne's parents' construction project and the preceding ten pages. If a planning law opinion is desired, I will read through the thread from the beginning at some point.