Glossary
FRL
Plain-Language Definition
Fire Resistance Level — a rating expressed as three numbers (e.g., 120/120/120) indicating the time in minutes a building element can maintain: structural adequacy / integrity / insulation during fire.
Technical Context
The three components: Structural Adequacy = load-bearing capacity, Integrity = prevents passage of flames and hot gases, Insulation = limits temperature rise on unexposed face. FRL is determined by fire testing per AS 1530.4, BS 476, or ASTM E119. Common FRLs: fire-rated wall 120/120/120, fire door 60/60/30 or 120/120/30, fire-rated column 120/-/-.
Why It Matters
FRL ensures that structural elements, walls, and doors maintain their fire-separation function long enough for evacuation and firefighting. A column with inadequate FRL may collapse during fire, causing progressive structural failure. FRL requirements are specified by building codes based on building height, use, and compartment size.
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