Fire performance classes

The reaction to fire performance of timber cladding is defined under EN 13501-1, and construction products are assigned a Euroclass rating under this system. The Euroclass system comprises ratings from A - F, and describes characteristics such as flame spread, ignitability, heat release, smoke production, burning droplets etc. The ratings system and examples of each category can be found in the table below.

Classification	Definition	Description	Examples
A1	Non-combustible	No contribution to fire	Glass/ Stone/ Concrete
A2	Limited combustibility	Very limited contribution to fire	Gypsum Boards with thin coverings (eg paper faced)
B	Combustible	Limited contribution to fire	Some flame retardant treated wood products*
C	Combustible	Minor contribution to fire	Some flame retardant treated wood products*
D	Combustible	Medium contribution to fire	Most wood based panels over 390kg/m³ in density*
E	Combustible	High contribution to fire	Some wood panel systems/ Plastic based insulation/ Composites
F	Unclassified	Not tested	N/A

Within the fire performance classes described above, further limitations of smoke and burning droplet production are taken into account in certain situations. This is normally applied to Euroclass A-D categories in specific circumstances, and would be written in the format Euroclass B-s1, d0.