Existing buildings on plots in a new development plan

Or are there any loopholes in the case of infill development.

Like the amendment of the development plan or something like that?

The city can then easily (with us after coordination in the building committee, etc.) amend the development plan.

"building is not allowed there"

"listen, the development plan doesn’t matter at all ..."

"... in 4 years at the latest they will also be building in the gardens"

A loophole is opened by §31 of the Building Code. However, since the development plan prevents construction twice over (no building plot and no access), there will be explanations in the justification of the development plan, so that the main features of the planning are likely affected and thus the loophole remains closed.

That would no longer be a loophole. The procedure is complex, must be well justified and requires extensive public participation.

It only works smoothly if the public is asleep or fully agrees with the plan.

... is the current legal situation.

... is nonsense.

Four years for a legally binding amendment to the development plan would be very ambitious (well, one does not know whether and how long considerations have been secretly ongoing) and only conceivable without resistance from the public. Since the current development plan does not seem to be that old, nothing substantial will change there in my opinion over the next 20 years.

Another area with the designation "Area without ingress and egress" is located in Plan Street B. This is explained by the fact that the previously developed plots along Heilbrunnstraße should retain their previous accesses for property development – from Heilbrunnstraße – and (precisely) not be burdened with additional traffic on the significantly narrower Plan Street B through new ingress and egress in the rear area. This is also intended to prevent rear development outside the building plots on the areas already developed today along Heilbrunnstraße.

The "prevention" of development on areas outside the building windows probably means exactly what you addressed?

Yes. Since it is explicitly mentioned here that no construction is to take place there, it is IMHO a fundamental aspect of the planning, so that exemptions according to §31 of the Building Code are excluded. For someone wanting to build a garden only the option remains to persuade the municipality to repeal or amend the development plan. Such a fundamental change to such a new development plan is extremely unlikely. And even if it came to that, you could signal strong resistance during the early public participation, so that the municipality is no longer willing to pursue the plan any further.

Absolute certainty only exists, of course, if you acquire all neighboring plots.

This is also intended to prevent rear development outside the building envelopes on the already developed areas on Heilbrunnstraße.

that was a house seller from a large German general contractor who, according to his wording, wanted to take away "the illusion" that nothing will happen there in the next few years.