Understanding Fire Resistance Levels: What NSW Homeowners Need to Know
When it comes to fire safety in construction, the terms “fire rating” and “fire resistance level” (FRL) are often used interchangeably, but they represent different concepts. In NSW, it’s crucial to understand the precise meaning of FRL and how it impacts your property, particularly regarding fire doors and other passive fire protection measures.
What is a Fire Resistance Level (FRL)?
The term “fire resistance level” refers to a specific standard used to evaluate how well a building element can withstand fire. The Building Code of Australia specifies this through the FRL, which is expressed as a combination of three distinct components: Structural Adequacy (SA), Integrity (INT), and Insulation (INS).
Here’s what each component means:
- Structural Adequacy (SA): This measures how well a building element can support its load during a fire. For example, wall systems must maintain their load-bearing capacity. However, door and frame systems typically do not bear loads and thus do not have a structural adequacy rating.
- Integrity (INT): This assesses whether the building element can prevent the passage of flames and hot gases. It does not measure smoke leakage, which is a separate consideration.
- Insulation (INS): This measures how well the temperature on the non-exposed side of the fire-resistant barrier remains controlled. Essentially, it evaluates the heat transfer through the barrier.
An FRL value might be expressed as 60/60/60, indicating that the building element passed the fire test criteria for 60 minutes in each of the three categories (SA, INT, INS).
How Fire Testing Works
Fire testing involves exposing a test specimen, representative of the final installation, to controlled time and temperature conditions. The specimen is subjected to standard heating conditions and pressure differentials to measure its performance across the three FRL components.
Understanding Failure Criteria
According to AS 1530 Part 4, the test determines whether the building element meets the required FRL criteria. Here’s how failures are assessed:
- Structural Adequacy: Failure occurs if the test specimen collapses or deflects beyond acceptable limits. For doors and frames, which don’t support structural loads, this component is typically not applicable.
- Integrity: Failure is indicated by continuous flaming on the non-fire side, excessive gaps in the furnace, or ignition of the cotton wool pad used in the test.
- Insulation: Failure occurs if the temperature on the non-fire side exceeds allowed limits, as measured by thermocouples.
It’s important to note that when we talk about a “fire rating” of a door or wall, we’re often referring to the integrity component. For example, a door with a 2-hour fire rating typically means it has an integrity rating of 120 minutes, and might be denoted as -/120/30. The dash signifies that structural adequacy is not a relevant factor for that door.
Understanding FRLs helps ensure that your property is adequately protected and compliant with fire safety standards. As regulations evolve, staying informed will help you make the best choices for your building’s fire safety.
For more information regarding fire rated products consider contacting your local council, engineer, builder or locksmith.
Samual Pierce.
