Reading and Understanding a Development Plan: GRZ, GFZ, Building Line and Exemption
How big, how tall and in what form you may build is set by the development plan. This guide explains the most important stipulations, from the site coverage ratio (GRZ) and floor space ratio (GFZ) to full storeys, building line and roof shape. Plus: the difference between textual and graphic stipulations and the exemption under Section 31 BauGB.
The development plan (Bebauungsplan) determines whether and how you may build on your plot – yet to a layperson the document, made up of a plan drawing, abbreviations and legal paragraphs, seems puzzling at first. Anyone who can read and understand the development plan can tell, even before buying the plot, how large, how high and in what form the desired house may actually turn out. This guide explains the most important stipulations such as the site occupancy index (GRZ), floor space index (GFZ), full storeys, building boundary (Baugrenze), building line (Baulinie) and roof shape, distinguishes textual from graphic stipulations and shows when an exemption under § 31 BauGB is possible and how the unplanned built-up area (Innenbereich) under § 34 BauGB is set apart from it.
What is a development plan and what is it for?
Short answer: A development plan – B-Plan for short – is a binding statute of the municipality that governs, for a particular area, how it may be built on. It determines which type of use is permissible, how much area may be built on, how high and in what form building must take place, and exactly where on the plot the building may stand. The plan is divided into a graphic part, the plan drawing, and a textual part with the stipulations. For builders it is the central basis of all: only what the development plan permits is readily eligible for a permit. So always check the B-Plan before buying the plot.
The development plan applies the framework of building law concretely to your plot. It is based on the German Building Code (Baugesetzbuch) and the Land Use Ordinance (Baunutzungsverordnung) and is adopted by the municipality. You can inspect it at the building office or often online via your municipality's geoportal. Anyone considering a plot should check the B-Plan together with the extract from the register of building encumbrances (Baulastenverzeichnis) and the land register. Fundamental notes on selecting a plot are given by the guide to plot assessment. You can find the legal text in the German Building Code (BauGB).
GRZ and GFZ: how much you may build
Short answer: The site occupancy index (Grundflächenzahl, GRZ) and the floor space index (Geschossflächenzahl, GFZ) determine how much you may build on a plot. The GRZ states what share of the plot may be built over: a GRZ of 0.3 means that 30 percent of the plot area may be covered by the building. The GFZ describes the ratio of the total floor area to the plot area: a GFZ of 0.6 allows a total of 300 square metres of floor area on a 500-square-metre plot. Together, both figures cap the possible building mass. Ancillary installations such as garages and terraces may exceed the GRZ additionally under certain conditions.
Sample calculation for a 500 m² plot
| Figure | Value | Permitted | Meaning |
|---|---|---|---|
| GRZ | 0.3 | 150 m² buildable | footprint of the building |
| GFZ | 0.6 | 300 m² floor area | sum of all full storeys |
| GRZ + ancillary installations | up to 0.45 | up to 225 m² | garage, access, terrace |
Think of GRZ and GFZ together
GRZ and GFZ work together: a low GRZ forces a compact floor plan, while a higher GFZ allows additional storeys. Anyone who brings the figures into the planning early avoids floor plans that later cannot be permitted. Work the values through for your specific plot before you commit to a house type.
Full storeys, height and roof shape
Short answer: Besides the footprint, the development plan governs the permissible height of the building via the number of full storeys, the eaves and ridge height and the roof shape. The number of full storeys determines how many floors are permissible as fully-fledged storeys – a converted loft counts, depending on the height and roof pitch. The eaves and ridge height limit the building height in metres and ensure a uniform street scene. The roof shape often prescribes whether a gable, hip, mono-pitch or flat roof is permitted, often including the roof pitch and ridge direction. These requirements significantly shape the appearance of your house.
The roof requirements in particular are often underestimated: anyone planning a modern flat-roof house where the area only permits gable roofs with a certain pitch has to re-plan or apply for an exemption. The definition of a full storey also varies by state building regulations, so that a knee wall above a certain height turns the loft into a full storey. Clarify these points before you choose a house type from the configurator or from the show homes – this way you avoid nasty surprises in the building application.
Does your desired house fit on the plot?
GRZ, GFZ, full storeys and roof shape decide which house type is eligible for a permit. Compare the offers of several prefabricated house manufacturers free of charge – experienced providers check the development plan and adapt the floor plan and roof to the stipulations.
Building boundary and building line: where the house may stand
Short answer: The building boundary (Baugrenze) and building line (Baulinie) determine where on the plot building may take place and are shown in the plan drawing by special lines. The building boundary marks the outer limit of the building envelope: the building may not exceed it, but need not touch it – so it can be placed anywhere within the building envelope. The building line, by contrast, is mandatory: the building must stand with its exterior wall on it, which creates a uniform building alignment along the street. Both lines, together with the setback areas of the state building regulations, determine the exact position of your house. Subordinate components may exceed the boundaries slightly under certain conditions.
- Identify the building envelope (the area within the building boundaries) on the plan.
- Check whether a mandatory building line prescribes a fixed building alignment.
- Observe the setback areas of the state building regulations in addition to the building envelope.
- Check the position of the garage, carport and ancillary installations on the plan.
- Match the ridge direction and site access with the plot geometry.
Textual and graphic stipulations
Short answer: A development plan consists of two complementary parts: the graphic and the textual stipulations. The graphic stipulations are in the plan drawing and work with lines, colours and abbreviations – here you find the building boundaries, building lines, the type abbreviation of the building area and the figures GRZ, GFZ and number of full storeys. The textual stipulations supplement and specify the drawing, for instance on roof shape, materials, enclosures, rainwater or trees that must be preserved. Both parts apply equally; you have to read them together. The plan symbol ordinance (Planzeichenverordnung) explains which symbol means what.
In practice it is advisable first to study the legend of the plan drawing and then to go through the textual stipulations point by point. Pay particular attention to requirements on façade and roof colours, permitted materials, solar systems, parking spaces and the infiltration of rainwater – such details significantly affect your costs and your design. If questions remain open, a conversation at the building office or a preliminary building enquiry (Bauvoranfrage), which creates clarity about buildability before you submit the complete building application, helps.
Exemption under § 31 BauGB and the built-up area under § 34
Short answer: If your project deviates from a stipulation of the development plan, an exemption under § 31 BauGB may be possible – but only under strict conditions. The basic principles of the planning must not be affected, the deviation must be acceptable in urban-planning terms or avert an unintended hardship, and the neighbours' interests must be preserved. The authority decides on the exemption at its discretion; there is no entitlement. If no development plan exists at all for a plot, but it lies within a coherently built district, admissibility is governed by § 34 BauGB – the project must then fit into the character of the immediate surroundings.
The difference is decisive: in the plan area, the B-Plan lays down the rules exactly, and deviations require an exemption. In the unplanned built-up area under § 34, by contrast, the actual surrounding development counts – the type and extent of use, the construction method and the buildable area are guided by the neighbouring buildings. This opens up scope, but at the same time makes the assessment more difficult and less predictable. Anyone who wants to build outside built-up districts, on the other hand, quickly ends up in the outlying area (Außenbereich) with considerably stricter rules, as explained by the guide to building in the outlying area.
Do not rely on a verbal assurance
An exemption under § 31 BauGB is not a formality and no sure thing. Obtain confirmation of admissibility in writing – ideally via a preliminary building enquiry – before you buy a plot or sign a building contract. A purchase relying on verbal information can become expensive if the authority later refuses the exemption.
Anyone who reads the development plan systematically – first the figures, then the building envelope, then the textual details – can estimate even before the purchase which house is realistically feasible. Check the plan together with an expert and, in case of doubt, have a preliminary building enquiry submitted. This way the unwieldy document becomes a reliable compass for your building project. Which house type comes into question within these requirements is shown by the prefabricated house overview.
Check the plot and development plan together
An experienced prefabricated house manufacturer reads the development plan and matches the floor plan, height and roof shape to it. We put you in touch with suitable providers with transparent fixed prices, free of charge and with no obligation – so that your desired house is also eligible for a permit.
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Compare house prices nowImportant questions briefly explained
The most common price questions around Reading and Understanding a Development Plan – answered concisely by the Prefabricated House editorial team (as of 2026).
