Floor plan design (semi-detached house of 240 sqm) - experiences?

I have roughly drawn in the windows, I believe I read in the development plan that you have to maintain 1.5m distance to public streets if the driveway is direct. Whether that is correct and realistic, I am unsure.

That can be done like this

I don't understand everything about it.

What don’t you understand about the development plan? You can ask specific questions.

I think going to an architect is necessary. How much should one budget? €6-7k? Or is a “first sketch cheaper”?

If you want to build with a general contractor (GC), then you don’t need a separate architect, since that is included with the GC.
Yes, an employed architect won’t be able to design you an exclusive house now, but that is neither wanted nor possible here.

Ultimately, it can be noted that this is a standard plot with a standard development plan. A standard design is planned on it (just as you have sketched it).
You look for an architect if you have problems or want something more individual, and also if you want to build with individual or own trades.
That is not necessary here.

However, I warn against (this was always mentioned here by ) letting a semi-detached house best be built together by one GC. Although you don’t save much on additional construction costs, a few thousand euros for joint trips, container, and scaffolding orders are already saved. What you save on are construction defects at the joint and strange annex structures when one starts earlier than the other. Even a GC semi-detached house half can be planned individually inside.

Therefore: sit down with the neighbor and agree on the GC.
Inside you can then have individual planning done.

(das hat hier @11ant auch immer erwähnt),

Where has he actually gone?

Where did he actually go?

This will be deleted soon... and that is among other things the reason why he is no longer here.

I do, however, warn (as @11ant has always mentioned here) that it is best to have a semi-detached house built jointly by a general contractor. Although you don't save much on incidental construction costs, you can save a few thousand euros on joint trips, container and scaffolding orders. What you save on are construction defects at the connection and strange annex constructions when one starts earlier than the other. Even a semi-detached house built by a general contractor can be individually planned inside.

Therefore: sit down with your neighbor and agree on the general contractor.
Inside you can then have it planned individually.

More precisely: agree on a common planner, and build together at least up to the finished floor slab/top edge of floor slab; better yet up to the shell construction / topping-out ceremony. After that, the paths can safely diverge.
A part of the quote I have marked in bold.
The two most important points are
1. the coordination of the construction of the buildings at least until reaching ground level, and
2. the "bonding surface" / (nowadays separated) party wall of the two halves
(o.p.)

P.S.:

The house should have 2 full floors + a gable roof and max. FH 11m TH 6.5m SD 20°. 0.4 / 0.7 as area specifications. A garage would be great but I suspect that will be tight.

The plot with 240 sqm and 2 parking spaces as specifications including the development plan.

We are a bit lost and just took an example from the internet that represents the absolute dream. However, that is 174 sqm of living space. How I now come up with a floor plan that ends up between 130-140, I would really need help with that.

BE SURE NOT to try to reduce an overly large template – that can never ever, never, never work, especially not in this category of property, as these houses are planned without even the smallest seam allowance. Because of the SD 20° gable roof, you can only take parts from the inspirational sources "DH of the usual suspects" (see forum search with the keyword "usual suspects" Brale / Hildmann Traumhaus / Tecklenburg / Weisenburger / Wengerter / Werner). Typical models are e.g. 141 SD35, which means offering 141 sqm of living space with the attic studio = parents’ bedroom included under a 35° gable roof for families with three children; because you are supposed to build an SD 20°, the models with PD are not suitable for 1:1 adoption; and the smaller models just under 130 sqm also usually cannot be transferred to you. Otherwise, I am happy to recommend my post "A semi-detached house has TWO halves" to you (where you can also find my "A house-building schedule for you as well: the phase model of the HOAI").