Guide
Area metrics in public planning law
Floor area ratio and site coverage in Berlin: what investors need to know
Site coverage ratio and floor area ratio determine how much can be built on a plot, and therefore its value. We explain these metrics and the difference between zoning plans and Section 34 BauGB in Berlin.
Peter Guthmann
Area calculations are a frequent source of misunderstanding in real estate. Whether buying a plot, planning a development or assessing a property valuation, two metrics define the maximum buildable volume and therefore the value of a site: the site coverage ratio (Grundflaechenzahl, GRZ) and the floor area ratio (Geschossflaechenzahl, GFZ).
Site coverage ratio (GRZ)
The GRZ specifies how many square metres of ground floor area may be built per square metre of plot area. It is set in the zoning plan (Bebauungsplan). A GRZ of 0.4 on a 1,000 sqm plot means the footprint of all structures may not exceed 400 sqm.
The calculation includes not only the main building but also ancillary structures such as garages, driveways and sealed terraces. The GRZ is therefore also a measure of soil sealing, affecting the design of outdoor areas and parking requirements.
Floor area ratio (GFZ)
For economic assessment, the GFZ is often the more relevant metric. It defines how many square metres of gross floor area are permitted per square metre of plot area. Gross floor area is the total area of all full storeys, measured at the building's external dimensions. A GFZ of 1.2 on a 1,000 sqm plot permits 1,200 sqm of gross floor area.
This number directly determines the sellable or lettable volume of a project. A higher GFZ allows more residential or commercial space. Note that the exact definition of a full storey may vary between state building codes.
Berlin's special case: zoning plan vs. Section 34 BauGB
Berlin's planning law framework is historically divided. In large parts of West Berlin where no modern zoning plan exists, the 1960 land use plan (Baunutzungsplan) often still applies. In East Berlin, Section 34 of the Federal Building Code (BauGB) frequently applies pending the adoption of new binding development plans.
What Section 34 BauGB means for investors
Section 34 BauGB governs development within built-up areas. A new building must fit into its immediate surroundings in terms of type and scale of use, building method and covered plot area. Fixed metrics like GRZ and GFZ do not apply here; instead, the surrounding development serves as the reference.
This creates flexibility but also planning uncertainty. In boroughs under development pressure such as Neukoelln, a thorough analysis of neighbouring buildings is essential to realistically assess a site's potential. An early preliminary building enquiry at the borough office is advisable in such cases.