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Compliance with the fire behaviour of building materials is related to performance of standard issued by the British Standards Institution tests described in British Standards BS 476: part 3 to 31.

The reaction to fire tests classify the material in 4 categories from class 1 to class 4 connected with the 1.5 min and final flame spread according mainly to the BS 476-7 -surface spread of flame testing method (and to BS 476-6) fire propagation test- (see table below). 

Table 1: BS 476 Fire classification 

ClassBS 476-7
Maximal final flame spread
Limit mm
BS 476-6
Flame spread index FPI
1165 Rooms
Circulation spaces within dwellings
I.E. class 0 according to
BS 476-6
Other circulation spaces, including the common areas of flats and maisonettes
3710 Small rooms of area not more than 4m2 in a residential building and 30m2 in a non-residential building
4Exceed class 3  

Subpages (2): BS 476-6 BS 476-7