Fire classification (Dutch: brandklasse) is a standardised system that rates how building materials react when exposed to fire, ranging from non-combustible (A1) to highly flammable (F). The European classification system, defined in EN 13501-1, is used across the EU to ensure consistent fire safety standards.
The European fire classification system
Building materials are tested and assigned one of seven main classes:
| Class | Description | Examples |
|---|---|---|
| **A1** | Non-combustible, no contribution to fire | Natural stone, concrete, steel, ceramic tiles |
| **A2** | Non-combustible with minimal organic content | Mineral wool insulation, plasterboard |
| **B** | Very limited contribution to fire | Some fire-retardant treated timber, high-performance wall panels |
| **C** | Limited contribution to fire | Certain wood-based panels with treatment |
| **D** | Acceptable contribution to fire | Untreated timber, some wood-based boards |
| **E** | Significant contribution to fire | Some plastic insulation boards (e.g., untreated EPS) |
| **F** | No performance determined / highly flammable | Unclassified materials |
In addition to the main class, materials receive supplementary ratings for smoke production (s1, s2, s3) and burning droplets (d0, d1, d2). A full classification might read “B-s1, d0” — meaning very limited fire contribution, low smoke, and no flaming droplets.
Why fire classification matters
Building regulations specify minimum fire classes for materials used in different parts of a building. Escape routes, facades, and fire compartment boundaries typically require higher-rated materials (A1, A2, or B), while less critical areas may accept class D or E materials. Choosing the wrong fire class can lead to permit refusal or, worse, a fire that spreads rapidly.
Application in construction
Architects and specifiers must verify the fire classification of every material used in the building envelope, interior finishes, and insulation layers. Manufacturers provide test certificates and declarations of performance that state the fire class. During construction, substituting a specified material with one of a lower fire class is not permitted without recalculating the fire safety design.
Related terms
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