Single-family house or semi-detached house?

My 2 cents ... when you think of a semi-detached house, you should definitely coordinate, because building one after the other surely means additional efforts for the excavation, as safety measures must be taken for the already existing semi-detached house.

... I also see no objection to a joint planner.

There is nothing against it ... but it is not a mandatory requirement. And that's all I'm concerned about.

But if you talk about an emergency landing in relation to a semi-detached house, that says it all.

... building one after the other probably means additional effort for the excavation pit, since securing works would have to be done for the already existing semi-detached house.

No, securing measures would only be necessary if one builds with a basement and the other without. But even that is possible.

... it is possible, but to my knowledge it involves additional effort (compared to the variant of building simultaneously), even when building without a basement, because the floor slab of the second semi-detached house must reach up to the floor slab of the first semi-detached house.

For reasons of soundproofing, the floor slabs should not touch each other directly.

It is just unrealistic. In new residential areas, semi-detached house plots are often sold. Neighbors rarely cooperate in such cases. Usually, they don’t even build at the same time.

Have you ever even built a semi-detached house? There is so much ignorance and speculation in this thread.

Yes, they do not touch. But the excavation pit still generally requires a bit more space than the floor slab, and then the other semi-detached house is there. Therefore, there is usually additional effort.

And I tend to observe that semi-detached houses are mostly built by developers, and then of course both halves at once.