Is a semi-detached house construction allowed?

The scope for interpretation of "subordinate" is then debatable.

... but a building authority is traditionally not eager for discussion. In practice, I expect at least a 60:40 or even 67:33 size ratio between the two residential units – and that is probably not compatible with two couples building together, assuming "equal footing."

The scope for interpretation of "subordinate" is then debatable.

I don't think so. This is a building law term, as I think. Subordinate should also be outbuildings, so in terms of size they should not compete with the main house.

Because in border construction (semi-detached house) there are 2 residential buildings that are built attached to each other.

Then that is a continuous development? Well then, maybe the entire location and development plan will be posted here someday, so we don't have to guess.

Could the floor area ratio also speak against a semi-detached house? Is it known?

Then it is a closed development?

No, I think we already had that topic in the other thread of the OP: a compulsory extension does not yet make a "g", under fifty meters in width a block is still "o".

I googled the term "Untergeordnete Wohneinheit" and also found development plans that speak of a max 60% area of the primary residence... When drawing up the plan, there were 2 semi-detached houses of unequal size, but that was certainly not the authors' intention

No, I believe we already had this topic in the other thread of the OP: a cultivation obligation does not yet make a "g," under fifty meters in width a block is still "o."

Ah yes. Man, why always these little-piece discussions when nothing comes out of it anyway. No development plan, site plan… the OP's last thread is a month old, I would have long since made telephone contact with the building authority as the OP and found out this answer myself - without puzzle tasks. :rolleyes: