What is the Baumassenzahl (BMZ)?
The Baumassenzahl (BMZ) is the building-mass factor: it states how many cubic metres of building volume are permissible per square metre of plot area. It is used chiefly in commercial and industrial zones, where storey counts say little about single-volume halls or high-bay warehouses. A BMZ of 9.0 allows 9,000 m³ on a 1,000 m² plot. Mapular compiles BMZ reference values from all 16 federal states into one consistent layer.
How does the BauNVO define the Baumassenzahl?
Legal status
Reference data
An authoritative input for analysis and screening. It carries no legal effect of its own.
The BMZ is one of the indicators of the "Maß der baulichen Nutzung" in Sections 16 to 21a BauNVO. Section 21 BauNVO defines it as the permissible building mass in cubic metres per square metre of plot area, calculated from the external dimensions of the building. Planning practice applies the BMZ mainly in commercial and industrial areas, where floor-based indicators like the GFZ do not describe the built volume meaningfully. Binding values are set in municipal development plans.
What this means for you
If you develop or evaluate industrial, logistics or production sites, the BMZ is your density figure: multiply plot area by BMZ for a first estimate of permissible volume, hall heights included. BMZ reference values let you compare commercial land nationwide. Binding figures for a concrete project must still be verified against the local development plan.
Which attributes does the BMZ layer contain?
BMZ value
The building-mass factor recorded for the area, for example 9.0, expressed as permissible building volume in cubic metres per square metre of plot area.
Reference geometry
The polygon of the area or zone the value applies to, delivered in consistent geometry across all federal states.
Federal state
The Bundesland the record belongs to, so you can filter, compare and report by state.
Classification
A harmonised classification of the record within Mapular's catalog schema, making values comparable across state boundaries.
The BMZ is defined federally in the BauNVO, so the indicator itself is uniform across Germany. The differences lie in the source data: each of the 16 states publishes its planning data in its own formats, models and depth of detail. Mapular harmonises these publications into one schema so BMZ values are comparable across state lines.
What can you do with Baumassenzahl data?
- Logistics and industrial site screening: rank commercial plots across Germany by permissible building volume before engaging engineers, brokers or legal counsel.
- Volume feasibility: estimate achievable hall or plant volume from plot area and BMZ, early in the process and without reading development-plan PDFs.
- Zone comparison: benchmark industrial and commercial areas across municipalities and all 16 federal states to prioritise expansion or acquisition markets.
- Data products: integrate a nationwide building-mass indicator into site-selection tools, valuation models and industrial real estate platforms from one consistent layer.
Where does the BMZ data come from?
Compiled from official state publications and planning data into one consistent layer: harmonised geometry, one schema, one delivery for all of Germany.
Which federal states does the BMZ layer cover?
The BMZ layer covers all 16 German federal states in one consistent schema. Because the indicator concentrates in commercial and industrial zones, coverage is naturally densest where such areas exist, but every state is included.
Coverage by federal state
- BBBrandenburgAvailable
- BEBerlinAvailable
- BWBaden-WürttembergAvailable
- BYBavariaAvailable
- HBBremenAvailable
- HEHesseAvailable
- HHHamburgAvailable
- MVMecklenburg-Western PomeraniaAvailable
- NILower SaxonyAvailable
- NWNorth Rhine-WestphaliaAvailable
- RPRhineland-PalatinateAvailable
- SHSchleswig-HolsteinAvailable
- SLSaarlandAvailable
- SNSaxonyAvailable
- STSaxony-AnhaltAvailable
- THThuringiaAvailable
Where the federal state publishes this layer, we carry it: 16 of 16 federal states today. Where it doesn't, we say so.
Coverage gap
Your region of interest isn't covered?
Coverage follows what each state and municipality has actually digitised, so there are real gaps, and they are not always where you would expect. Tell us the region and the layer you need and we will look into what can be sourced for it, including data we do not list today.
Tell us what you needHow do you get access to the BMZ layer?
One unified dataset: Ready for direct integration into your GIS, CAD, or BI tools. Standard formats, documented schema.
Mapular Explorer: Instant planning interface, no GIS setup required. Filter, analyse, and export from your browser.
Frequently asked questions about the Baumassenzahl
What does a Baumassenzahl (BMZ) of 9.0 mean?
A BMZ of 9.0 means that up to 9 cubic metres of building mass are permissible per square metre of plot area. On a 10,000 m² commercial plot, that allows up to 90,000 m³ of built volume: enough to compare hall concepts and site options long before any detailed design work begins.
When is the BMZ used instead of the GFZ?
The Baumassenzahl is used mainly in commercial and industrial zones. A single-volume logistics hall or a high-bay warehouse has few storeys but enormous volume, so a floor-based indicator like the Geschossflächenzahl (GFZ) says little about it. The BMZ, defined in Section 21 BauNVO, measures density in cubic metres and describes such buildings meaningfully.
Is Mapular's BMZ data legally binding?
No. Mapular's BMZ layer provides reference values compiled from official state publications and planning data. The legally binding building-mass factor for a specific plot is set in the municipal development plan. Use the layer to screen and compare industrial and commercial sites, and verify individual values before binding project decisions.
Which federal states does the BMZ layer cover?
Mapular's BMZ layer covers all 16 German federal states in one consistent schema. Since the indicator is set mainly for commercial and industrial areas, records cluster in those zones, but every federal state is represented, making genuinely nationwide comparisons of commercial land possible.
How is building mass calculated for the BMZ?
Under Section 21 BauNVO, the building mass is calculated from the external dimensions of the building and expressed in cubic metres. The Baumassenzahl then relates this volume to the plot area: BMZ equals permissible building mass per square metre of plot. This makes it the volume counterpart to the floor-based GFZ.
Who typically needs BMZ data?
BMZ data is most valuable for logistics and industrial developers, corporate site-selection teams, appraisers of commercial land and platforms serving industrial real estate. Anyone who needs to know how much volume a commercial plot can legally carry, before commissioning planners, benefits from nationwide, comparable BMZ reference values in one layer.