Administrative Provisions for Secondary Buildings up to 50 m² – Danish Building Regulations Guidance
The official guidance titled Vejledning om opførelse af sekundær bebyggelse med et samlet areal på højst 50 m2 was updated in January 2021 by the Danish Transport, Construction and Housing Authority (Trafik-, Bygge- og Boligstyrelsen). This document provides the administrative framework for constructing secondary buildings within the scope of the Danish Building Regulations (BR18). It specifies the conditions under which certain structures can be erected without a formal building permit application, provided they comply with the general building right and other relevant legislation.
The scope of the guidance covers secondary structures including garages, carports, sheds, greenhouses, orangeries, and covered terraces. A central threshold is established at a cumulative area of 50.0 m² per plot; buildings exceeding this total always require a permit. The document explicitly defines the permitted use of these structures, emphasizing that secondary buildings must not be used for residential purposes or prolonged stays, even if they meet technical housing standards. It also details specific regulatory domains such as fire safety requirements, distance to boundaries (skel), and the calculation of floor area and plot ratios.
Professional users will find structured criteria for placement on the terrain, fire protection classes such as EI60, and the application of the Fradragsreglen (deduction rule). This reference is designed to assist architects, developers, and property owners in determining whether a project can proceed under simplified administrative rules or requires a full municipal assessment.
Area Calculation and Permit Requirements
The requirement for a building permit is determined by the total cumulative area of all secondary buildings on the property. Existing secondary structures must be included in this calculation regardless of whether they were originally permit-free.
- Permit-Free Limit: Total secondary area must not exceed 50.0 m².
- Ground Level Requirement: Since January 1, 2020, permit-free construction is only applicable to structures placed directly on the terrain; underground constructions require a permit due to structural complexity.
- Integrated Buildings: Garages or carports integrated under the same roof as the primary residence are not considered permit-free secondary buildings and always require a building permit.
Placement in Boundary Zones (Skelbræmmen)
Specific conditions apply when secondary buildings are placed closer than 2.5 meters to the property boundary or a path. These rules serve to prevent nuisance to neighbors and ensure safety.
- Height Limit: No part of the building's outer walls or roof may exceed 2.5 meters above the terrain level.
- Maximum Length: The total length of all sides facing a specific boundary must not exceed 12 meters across all secondary structures on the plot.
- Openings: No windows, doors, or other openings are permitted on sides facing the boundary or path.
- Roof Water: All rainwater must be contained on the property's own ground.
Fire Safety and Protection Standards
Fire safety regulations must be observed to prevent the spread of fire between buildings on the same property and to neighboring plots. Requirements vary based on the distance from the boundary and whether the building is attached to the primary structure.
- Boundary Distance > 2.5 m: Generally, fire safety considerations for walls facing the boundary are not required if the distance exceeds 2.5 meters.
- Attached Structures: If a garage is built against a neighbor's boundary, the wall facing the neighbor must meet at least EI60 [BD-bygningsdel 60] standards, meaning it must withstand heat and flames for 60 minutes.
- Attached to Primary Building: If a secondary building is attached to the main house but not integrated, specific fire protection measures for connecting doors or windows may apply.
The Deduction Rule (Fradragsreglen)
Under the building regulations, a certain amount of secondary building area can be deducted when calculating the total floor area for the plot ratio (bebyggelsesprocent).
- Detached Houses: Owners can deduct up to 50.0 m² of secondary building area per dwelling.
- Terraced and Multi-storey Housing: The deduction limit is set at 20 m² per dwelling for terraced, semi-detached, or multi-storey housing units.
Frequently Asked Questions
Can I use a secondary building for a home office or guest room?
No, secondary buildings are strictly for short-term stays and storage. Use for habitation or prolonged stays, such as a bedroom or dining room, requires the building to be reclassified as a primary residential area and typically requires a permit.
Does the 50 m² limit apply to each individual shed or garage?
No, the 50 m² limit is a cumulative total for all secondary buildings on the property. If you have an existing 40 m² garage, you can only build a 10 m² shed without a permit.
What are the rules for secondary buildings in summer house areas?
In summer house areas, building within 0.0 to 2.5 meters of the boundary is generally prohibited. In the inner zone (2.5 to 5.0 meters from the boundary), secondary buildings can be erected if they meet specific height and length requirements similar to residential boundary rules.
Is a permit required to demolish an old shed?
If the secondary building is not integrated into the primary building and its individual area is 50 m² or less, it can generally be demolished without a permit, but the demolition must be reported to the BBR (Building and Dwelling Register).
How is the 12-meter length rule calculated in the boundary zone?
The rule counts the total length of all secondary buildings located closer than 2.5 meters to a specific boundary. Only the longest side of the building that faces that boundary is included in the cumulative 12-meter limit.
What happens if my project violates a local plan (lokalplan)?
Provisions in a local plan take precedence over the general building regulations. If a local plan sets a lower plot ratio or stricter placement rules, those must be followed even if the building regulations would otherwise allow the project.
