Fire resisting when referred to a building element implies that the element has a validated FRL (FIRE RESISTANCE LEVEL).
As defined in Part 1 of the Building Code under INTERPRETATION, fire resisting construction (SPECIFICATION C1.1) has a direct relationship to the types of construction referred to in Part C1 / Table C1.1 namely ‘Deemed to Satisfy Provisions’ within the ‘Fire Resistance and Stability’ section. Functionally, fire resisting construction is used in the makeup of a building element in order for them to maintain their structural stability, integrity and insulation criteria during a fire emergency. This allows occupants to escape, buildings to remain structurally sound (and not damage other property) and for fire fighting services to intervene to perform their duties.
Fire resisting construction can also relate to a particular material or product that is impervious or resistant to fire, and which can ensure that a fire resistant element of building construction continues to perform its function of carrying a load or providing a separating fire or smoke barrier. It does this for a predetermined period of time and specific heating curve (CELLULOSIC FIRE CURVE or HYDROCARBON FIRE CURVE).
Fire resisting construction should not be confused with flame or fire retarded construction where a material or product is combined with fire retarding ingredients designed to retard ignition of combustible materials. Typically a flame or fire retarded construction might be simply tested to a test which will qualify its ‘Early Fire Hazard Properties’ identified by ignitability, spread of flame and smoke evolved indices. Whilst a fire resistant construction will be tested to a far more stringent requirement such as BS 476 Part 20 or AS 1530 Part 4.