Bygningsreglementet Guidance Chapter 5 (Fire) – Annex 3: Pre-accepted solutions for offices
This document is Annex 3 of the guidance to Chapter 5 (Fire) of the Danish Building Regulations 2018 (BR18). Issued by the Danish Authority of Social Services and Housing (Bolig- og Planstyrelsen), version 1.2 dated 29-10-2021 provides technical standards for fire safety in office buildings. It defines the regulatory requirements for new construction, extensions, and changes in use for office environments within the Danish legal framework.
The scope of this document is limited to building sections categorized under Application Category 1 (Anvendelseskategori 1) and Risk Classes 1-3 (Risikoklasse 1-3). It governs internal layouts including cell offices, open-plan offices (storrumskontorer), and supporting functions such as meeting rooms, archives, and server rooms. The document details pre-accepted solutions for evacuation, structural fire resistance, and fire spread prevention, while referencing specific fire classes like EI 60, REI 120, and A2-s1,d0.
The following sections outline the specific technical requirements for escape routes, compartmentalization, and fire safety installations based on the official guidelines for office buildings.
Classification and Building Categories
Buildings must be categorized into specific application and risk classes to determine the applicable fire safety measures under BR18 § 493. This annex specifically applies to:
- Application Category 1: For building sections where users are familiar with escape routes and can bring themselves to safety independently, without sleeping accommodations.
- Risk Classes 1-3: Defined by the height of the top floor and the total area. Risk Class 3 applies to buildings where the top floor is between 9.6 m and 45 m above terrain.
- Fire Classes 1 and 2: Pre-accepted solutions in this annex satisfy requirements for projects in these fire classes when followed in their entirety.
Evacuation and Escape Route Design
Escape routes (Flugtveje) must ensure that persons can leave the building safely. The design must account for the number of persons and the travel distance to the nearest exit.
- Travel Distance: The maximum travel distance in a fire cell is 45 m. This can be increased to 60 m if the building is equipped with an automatic fire alarm (ABA) or an automatic sprinkler system.
- Ceiling Height: A minimum free height of 2.1 m is required in escape route corridors and stairs.
- Width Requirements: Doors in common access routes must have a minimum free width of 0.77 m. Corridors must be at least 1.3 m wide and stairs at least 1.0 m wide.
Fire cells with more than 50 persons or areas exceeding 150 m² generally require at least two independent exit doors. For smaller units under 150 m² with good visibility, a single exit may be acceptable if rescue openings are present.
Fire Compartmentalization and Construction
Buildings are divided into fire cells (Brandceller) and fire sections (Brandsektioner) to limit the spread of fire and smoke. Structural elements must maintain stability for a specified duration.
- Fire Sections: Must be separated by building components with a fire resistance of at least EI 60 / A2-s1,d0.
- Fire Walls: Buildings placed closer than 2.5 m to a property line must be constructed with a fire wall of at least REI 120 / A2-s1,d0.
- Doors: Doors in fire section walls must generally be class EI2 60-C, while doors between fire cells and escape corridors are typically class EI2 30-C or EI2 30-M.
Frequently Asked Questions
What is the maximum travel distance to an exit in an office building?
The maximum travel distance is 45 m, but it can be extended to 60 m if the building has automatic fire alarms or sprinklers.
When does an office room require two exits?
A room generally requires two exits if it is designed for more than 50 persons or if the fire cell exceeds 150 m².
What is the required fire resistance for doors in fire section walls?
Doors in fire section walls must meet class EI2 60-C (previously known as BD-dør 60).
What is the minimum ceiling height for escape routes?
The minimum free ceiling height in escape corridors and stairs is 2.1 m.
Is an automatic sprinkler system mandatory for all office buildings?
No, it is typically required for buildings with a floor area over 2,000 m² and a top floor height exceeding 22 m, unless specific compartmentalization rules are met.
What are the dimensions for rescue openings in offices?
The combined width and height must be at least 1.5 m, with a minimum height of 0.6 m and a minimum width of 0.5 m.
