Glossary
FRL (Fire Resistance Level)
Plain-Language Definition
A grading that specifies the time in minutes a building element can withstand fire exposure for structural adequacy, integrity, and insulation, expressed as three numbers (e.g., 120/120/120).
Technical Context
The three numbers represent: structural adequacy (ability to carry load), integrity (resistance to flame passage), and insulation (resistance to heat transfer). Common FRLs include: 120/120/120 for fire-rated walls separating tenancies, 60/60/60 for fire doors in corridors, and 240/240/240 for structural columns in high-rise buildings. Testing is per ISO 834 or ASTM E119. BNBC and NFPA specify required FRLs based on building type, height, and occupancy.
Why It Matters
FRL determines how long building elements will maintain their fire separation function during a fire, directly protecting evacuation time and firefighting access. Incorrect FRLs can lead to fire spread between compartments. During due diligence, verifying that fire-rated elements meet their stated FRL is a critical safety check.
Related Articles
Explore in-depth articles related to this topic in the Knowledge Library.
Search Knowledge Library →