Fire Resistance Rating

A fire resistance rating states how long an element held back fire under standardised test conditions. FD30 and FD60 denote thirty and sixty minutes for door assemblies; walls and floors are rated on the same principle, usually expressed against integrity, insulation and load-bearing capacity.

A rating belongs to an assembly

This is the point most often lost. A rating is not a property of a door leaf, a wall board or a seal considered on its own — it was achieved by a specific combination of components installed in a specific way. Substituting a component, or installing it differently from the tested detail, means the rating no longer describes what is actually in the building.

Where the rating comes from

Required ratings follow from the building's fire strategy and the guidance applicable to its use and height — they are not chosen on site. Where a building's use has changed, the ratings originally specified may no longer match what the building now needs, which is a question for a fire risk assessment rather than for maintenance.

Evidence

Rated products carry identification, and that identification is what allows an assembly to be verified later. Where labels or plugs are missing, the honest position is that the rating cannot be confirmed, and that is what should be recorded — not an assumption in either direction.