The building planning law basically distinguishes between the inner area and the outer area. The inner area is understood to be those parts of the town which are built up in a coherent manner and which actually have a successive, coherent development which is an expression of an organic settlement structure. Outside areas are the areas outside the coherently built-up districts and outside the scope of (qualified or project-related) development plans (see also "Development Plan; Information" under "Related Topics").
Municipalities can, by statute
- define the boundaries of built-up areas (demarcation statutes),
- define built-up areas in the outskirts as coherently built-up districts if the areas are shown as building land in the land use plan (defining statute),
- include individual areas in the outer area in the built-up districts if the included areas are characterized accordingly by the building use of the adjacent area (Einbeziehungssatzung).
The demarcation statute has only declaratory effect. It shows which properties still belong to the built-up areas and which are already to be assigned to the outer area.
With the help of a demarcation statute, the municipality can define built-up areas in the outer area as coherently built-up districts if the area is shown as a building area in the land use plan. Such a statute is therefore only possible if there is already a corresponding representation in the land use plan and there is actually a certain building context.
The inclusion statute can be used to include individual outdoor areas in the inner area if they are already characterized accordingly by the building use of the adjacent area. When such a character can be assumed depends on the concrete situation in the individual case.
The lawfulness of a designation or inclusion statute requires that it is compatible with orderly urban development, that it does not establish the admissibility of projects subject to a mandatory environmental impact assessment, and that there are no indications that the conservation objectives and the protective purpose of sites of Community importance and European bird sanctuaries within the meaning of the Federal Nature Conservation Act will be impaired.
The bylaws may also contain provisions that regulate the permissibility of construction projects in more detail. The determination and inclusion statutes are drawn up in a procedure regulated by law, in which both the public concerned and the authorities and other public bodies affected are given the opportunity to comment within a reasonable period.