It's stated in the development plan:
In WA1 and WA3, the following roof types are permitted:
- Gable roofs, tent and hipped roofs: up to max. 40° roof pitch.
- Shed roofs: up to max. 15° roof pitch.
- Flat roofs: up to max. 10° roof pitch.
In practice, however, it is advisable to build the group of three with the same roof type.
Technically, different ones are also feasible, but this is certainly not desired. Nevertheless, the development plan allows it for now.