Building density

Building Density - Building density describes the ratio of the built-up area or floor area to the total lot area. It is defined in the zoning plan by metrics such as the floor area ratio (FAR), the floor space index (FSI), and the building mass index (BMI). Building density determines how intensively a property may be developed and is one of the most important factors in property valuation.

Key Figures for Building Density

The BauNVO defines three key figures:

• Floor Area Ratio (FAR): Indicates what proportion of the lot area may be built upon. An FAR of 0.4 means: On a 600-m² lot, a maximum of 240 m² may be built upon. The maximum values under the BauNVO range from 0.2 (small settlement area) to 1.0 (core area). Garages, parking spaces, and ancillary facilities may exceed the GRZ by up to 50% pursuant to § 19(4) BauNVO, but only up to a maximum GRZ of 0.8.
• Floor Area Ratio (FAR): Indicates the ratio of the total floor area of all full stories to the lot area. A GFZ of 0.8 for a 600 m² lot allows for 480 m² of floor area-roughly a two-story house with 240 m² per story. Basements are not included in this calculation if the floor is more than 1.4 meters below ground level.
• Building Volume Ratio (BMZ): Primarily used for commercial buildings and high-rises, this ratio expresses the building volume in cubic meters relative to the lot area. A BMZ of 3.0 for a 1,000 m² lot allows for 3,000 m³ of building volume.

In addition, the zoning plan specifies the number of full stories (e.g., maximum II + D = two full stories plus an attic) and the height of the structures (ridge and eave heights in meters above ground level). This combination of GRZ, GFZ, and number of stories defines the framework for the architecture and the maximum achievable living space.

Significance for Property Value and Planning

Building density is a primary value factor: A property with a floor area ratio (FAR) of 1.2 is significantly more valuable than one with an FAR of 0.4 in the same location because more rentable or saleable space can be created. Investors often calculate property value as residual value-based on the achievable sales proceeds of the finished property minus construction costs, ancillary costs, and profit margin. The higher the permissible floor area ratio (FAR), the more revenue can be generated and the higher the residual value of the property.

For those planning to build their own home, the GRZ determines the maximum floor area of the house and thus the floor plan design. The GFZ specifies how much total living space is feasible-for a two-story house with a converted attic, the sum of all floor areas must remain within the GFZ. An independent architect can quickly determine, based on the GRZ and GFZ, whether a specific floor plan is feasible on a given lot.

Development Density and Redensification

In cities with tight housing markets, such as Nuremberg, the redensification of existing residential areas is a political goal. Municipalities increase the permissible floor area ratio (FAR) through zoning plan amendment procedures to enable more housing-for example, by adding stories to existing buildings or filling vacant lots. Property owners living in an area where a zoning plan amendment with a higher FAR is being pursued should follow the ongoing public participation process. An increase in density significantly raises property values-and enables redevelopment measures that would not be feasible without the higher floor area ratio.

Practical Tip for Property Owners in Nuremberg and Franconia

We recommend that property buyers in the Nuremberg metropolitan region not only review the zoning plan before purchasing but also specifically calculate the maximum floor area. In many new development areas in Nuremberg-such as Kornburg-Nord or Tiergarten-the floor area ratio (FAR) and floor space index (FSI) are comparatively low (FAR 0.3-0.4, FSI 0.4-0.6). Check whether your desired floor plan is feasible under these specifications. In existing areas, it’s worth looking at unused density values-a lot with a floor area ratio (FAR) of 0.8 that is currently occupied only by a single-story bungalow offers significant potential for densification and thus latent value that a knowledgeable buyer can capitalize on.

Frequently Asked Questions

What happens if the building density is exceeded?

Exceeding the floor area ratio (FAR) or floor space index (FSI) specified in the zoning plan renders a construction project inadmissible-the building permit will be denied. In exceptional cases, an exemption may be granted under Section 31(2) of the German Building Code (BauGB) if the fundamental principles of the plan are not affected and atypical circumstances exist. If construction proceeds beyond the permitted density without a permit, a construction freeze and a demolition order may be imposed. The developer bears the demolition costs alone-a cost risk that can quickly reach five figures for a multi-family home.

Do garages and ancillary facilities count toward the floor area ratio (FAR)?

Yes, garages, parking spaces, and their access roads, as well as ancillary facilities as defined in Section 14 of the Federal Building Code (BauNVO), are included in the calculation of the floor area ratio (FAR). However, the BauNVO allows the FAR to be exceeded by up to 50% for these ancillary facilities-but only up to a maximum FAR of 0.8. In practice, this means: With a set GRZ of 0.4, the floor area-including the garage and terrace-may be expanded up to a GRZ of 0.6. We recommend carefully coordinating the calculation of floor area utilization with the architect to avoid surprises during the approval process.

Can the municipality increase the building density retroactively?

Yes, through an amendment to the zoning plan, the municipality can set higher FAR and floor area ratio (FAR) values. This often occurs as part of redensification strategies in existing residential areas or when designating new development zones. The process requires public participation and a balancing of public and private interests pursuant to Section 1(7) of the German Building Code (BauGB). Property owners benefit from an increase in density through rising property values. Anyone who learns early on about a zoning plan amendment process in their neighborhood should actively represent their interests during the public participation phase.

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