Building an end terraced house - Which technical requirements should be considered?

It's funny that three parties can't even manage to find a compromise for a uniform appearance and size, at least in terms of external style. The variety of possibilities, due to everyone insisting on their favorite, results in an absurdly ugly overall building.

As a city, I would only award such projects to developers.

It's not that far yet. The awarding hasn't happened yet. You only know afterwards who the other builders of the housing group are.

It's stated in the development plan:

In WA1 and WA3, the following roof types are permitted:
- Gable roofs, tent and hip roofs: up to a max. roof pitch of 40°.
- Shed roofs: up to a max. roof pitch of 15°.
- Flat roofs: up to a max. roof pitch of 10°.

In practice, however, it makes sense to build the group of three with the same roof type.
Technically, different roof types are possible, but this is certainly not desired. The development plan allows it for now.

I had seen that too. I just wasn't aware whether it is actually allowed to build three different houses.

Honestly, I don't believe that a configuration of, for example, a saddle roof, a flat roof, and a hip roof will be approved. Possibly will find the decisive passage in the plan.

you are misunderstanding the situation. He doesn't know who his neighbors will be. Applying now with two friends/acquaintances at the same time is the city's dream scenario but goes against reality. Additionally, I personally wouldn't necessarily want to move next to friends/acquaintances.

@TE I think you will have to wait to see if or until you get a plot, then you will probably be informed who the other two are. A basic roof shape will probably be agreed upon then. A basement will also need to be clarified. Ideally, it would be a developer, but I also know it from here with different ones. Everything is possible.

I don't know how scarce the building land is there. But if I'm given preference by applying together with 2 others, then I'll probably find those 2 somehow.

The classic case is that one person starts without a basement and the neighbor wants to have one later. This is always a problem point with terraced houses that should/must be coordinated in advance.

The whole thing is always difficult; ideally, you really build with the same "developer" or something similar. I experienced it myself, a good acquaintance (he is an architect himself) found a building gap in a new development area and built the missing second half of the semi-detached house there. As an architect, he naturally has certain standards and was also unlucky that the second builder proceeded more according to the motto "cheap rather than good." So he has a nice even exterior plaster, while the neighbor’s is crooked and bumpy (you can especially see it well at the joint).

So ideally, you coordinate in advance!

is supposed to be voted on

But not must. At least the present BP is not restrictive in this regard at all.

Honestly, I don’t think that a constellation of e.g. a gable roof, a flat roof, and a hipped roof will be approved.

When I look at an older REH area (from the 60s) here, it was at first very, very uniform (with gable roofs).
In the meantime, it looks as colorful as possible. One has added a story (with a different roof shape), another has only installed dormers, the third insulated the exterior facade.

And when I look along the village street, most houses (all practically one big group of houses) have nothing in common.