The base area number indicates how many square metres of building area are permissible per square metre of plot area. The permissible floor area is the proportion of the building plot that may be covered by buildings. The area of the building plot that lies in the building land and behind the street boundary line defined in the development plan is decisive for determining the permissible floor area. Balconies, loggias, terraces and ancillary facilities are not counted towards the permissible floor area.
For a multi-storey development in a pure residential area, a floor area ratio of 0.4 is specified. If the plot is 1,000 sqm, the built-up area, i.e. the floor area of the residential building, may be 400 sqm.
Calculation of the GRZ:
Plot x floor area = permissible floor area of the building