Fire Resistance Level ("FRL")

Australian Standard AS 1530.4 defines Fire Resistance Level ("FRL") by three measurements, measured in minutes as;

• structural adequacy is the ability of a structure to maintain its stability and load bearing capacity during a fire;
• integrity is the ability to resist the transfer of flames and hot gases from part to another; and
• insulation is the ability to contain temperatures and stop heat transfer between zones.

FRL is denoted as in the form (Structural Adequacy / Integrity / Insulation) measured in minutes. 

For example a wall with a FRL of (90/90/90) has following attributes;

• Structural Adequacy = 90 Minutes
• Integrity = 90 Minutes
• Insulation = 90 minutes

Many passive fire elements are described by their fire resistance level such as fire doors, fire pillows and the like.