Reaction to fire

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.

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.

The European standard series for the fire classification of construction products and building elements. Part 1 covers reaction to fire (the Euroclass system), Part 2 covers fire resistance, and Part 5 covers the external fire performance of roofs, giving classifications such as Broof(t4).

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 It has largely been superseded in UK regulation by the European EN 13501 classifications, but is still referenced in older specifications and certificates.