2 semi-detached houses, one of which is a semi-detached house with a granny flat

Hello, I have a question: is it possible to build 2 semi-detached houses attached to each other, where an accessory apartment is built into one semi-detached house and a basement is built into the other. We have a bigger problem here finding a suitable building plot where a 3-family house can be built. Thank you in advance for the information.

It depends on what is stated in the development plan. It should specify how many residential units are allowed.

I am currently a bit at a loss as to what I might have left unclear in (?)

where in one semi-detached house a granny flat is built in and in the other a basement is built in.

Do you mean both with basements, one utility and one living basement? - if the granny flat is supposed to be above ground, I already said at the above-mentioned place that I see this half having to become wider.

One with and one without a basement is unproblematic if you build both halves and that "at the same time" (= in one construction phase). Technically, this is practically not much different from a partial basement.

As far as I know, only the development plan should specify the number of residential units allowed, as mentioned. Semi-detached houses are also not always permitted.

If allowed, also pay attention to the prescribed number of parking spaces, whether you can even fit them on the property.

It depends on what is stated in the development plan. It should indicate how many residential units are allowed.

We do not have a building plot yet, this would just be the question whether a granny flat can be built in one semi-detached house and not in the other.