The "reaction to fire" tests classify the material in 4 categories from In 1, In 2 to Ut 1, Ut 2 (see table below).
Table 1: Norway fire classification | Fire class | Fire test | Details | Fire contribution | | Calorific potential | ISO 1716 Reaction to fire tests for building productsDetermination of the gross calorific value | Determination of the gross calorific value | | | Ignitability of surface material | ISO 5657 (NT Fire 033)
Reaction to fire
Ignitability of building products | Class In 1, Ut 1
or
Class In 2, Ut 2 | Slowly igniting material
Normal igniting material | Fire spreading characteristics of surface materials
| NS-INSTA 412 (NT Fire 004)
Heat release and smoke generation | Class In 1, Ut 1
or
Class In 2, Ut 2 | Slow heat releasing material
Normal heat releasing material | | Smoke production of surface materials | NS-INSTA 412 (NT Fire 004)
Heat release and smoke generation | Class In 1
or
Class In 2 | Slow smoke production
Normal smoke production | | Fire spread of floor coverings | Fire spread and smoke generation. | Class G | | | Smoke production of floor coverings | Fire spread and smoke generation. | Class G | |
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