EN 13501

The harmonised European classification of construction products' reaction to fire under EN 13501-1, running from A1 (non-combustible) through A2, B, C, D and E to F, with supplementary classes for smoke production (s) and flaming droplets (d). UK building regulations reference Euroclass ratings for cladding, insulation and internal linings.

How a material or product behaves as a fuel in the early stages of a fire, covering ignitability, flame spread, heat release and smoke production. It is distinct from fire resistance, which concerns how long a complete construction element withstands a developed fire; in Europe reaction to fire is classified under EN 13501-1.

The ability of a complete building element such as a wall, floor or door to withstand a fully developed fire for a stated period while maintaining loadbearing capacity, integrity and insulation (the R, E and I criteria). It is assessed by furnace testing and classified under EN 13501-2, and is distinct from reaction to fire, which concerns surface burning behaviour.

A classification for the external fire performance of roof coverings under EN 13501-5, based on test 4 of CEN/TS 1187, the test method used in the UK. It indicates that the covering resists fire penetration and spread when exposed to external sources such as burning brands, and UK building regulations use it as the benchmark for unrestricted use of roof coverings.

The long-standing British Standard series for fire tests on building materials and structures, including surface spread of flame (Part 7), fire propagation (Part 6) and external fire exposure of roofs (Part 3). It has largely been superseded in UK regulation by the European EN 13501 classifications, but is still referenced in older specifications and certificates.