Reaction to fire classification
| Class | Reaction to fire | Flashover in | Additional classes |
| A1 | No contribution to a fire | No | None |
| A2 | No significant contribution | No | Production of smoke & flaming droplets or particles |
| B | Very limited contribution to fire growth | No | Production of smoke & flaming droplets or particles |
| C | Limited contribution to flashover | Flashover after 10 mins | Production of smoke & flaming droplets or particles |
| D | Contribution to flashover | Flashover between | Production of smoke & flaming droplets or particles |
| E | Significant contribution to flashover | Flashover before 2min | Production of flaming droplets or particles. (Smoke release is expected to be substantial) |
| F | Not tested or incapable of achieving Class E | No performance determined |
Materials with good reaction to fire properties achieving classes A1, A2 or B would not be expected to flashover. Rockwool stone wool is classified as A1, the safest of the seven Euroclasses. Non-combustible in nature, Rockwool can withstand temperatures in excess of 1000°C without melting, will only produce insignificant quantities of smoke and no burning droplets.
