What is Fire Rating?
Fire protection systems in commercial buildings are vitally important for saving lives and protecting the building structure in the case of a fire.
What is fire rating?
The term “fire rating” is very broad and can be misinterpreted. Under the National Construction Code, the correct terminology is Fire Resistance Level or FRL. While fire rating plays a part in the various parts of a FRL, the two are not the same or interchangeable.
When it comes to a FRL, it is important to understand what the different components are, how they are determined and the role they play in passive fire protection, particularly in fire doors.
So what is FRL?
The NCC refers to Australian Standard AS 1530.4 , which defines Fire Resistance Level ("FRL") denoted as in the form (Structural Adequacy / Integrity / Insulation) measured in minutes.
- 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.
For example a wall with a FRL of (90/90/90) has following attributes:
Structural Adequacy = 90 Minutes
Integrity = 90 Minutes
Insulation = 90 minutes
What is Passive Fire Protection?
Based on compartmentation of fire and preventing collapse through structural fire resistance, when properly installed and maintained, your building’s passive fire protection can save lives and assets, and the building itself.
Passive Fire Protection involves creating physical barriers which are designed to stop fire from spreading from one building to another, or from one area of a building to another. In Australia, the most popular building materials used for Passive Fire Protection includes fire barriers in the fire-rated ceiling, floor, and fire-rated walls.
What is the failure criteria?
AS1530.4:2014 outlines the passing deviations for the three categories and describes how to test each element.
Structural adequacy fails when the test specimen collapses or when the maximum rate of deflection exceeds prescribed limits.
Integrity fails when one of the following occurs:
- There is continuous flaming on the non-fire side of the test assembly
- Through gap into the furnace exceeds the prescribed sizes
- Ignition of the cotton wool pad test
It is typically the duration of integrity that is mislabeled “fire rating”. If a wall has a fire rating of two hours, it is because the integrity portion of an FRL tested at 120 minutes, ie -/120/120 for non load-bearing walls.
Insulation fails when the thermocouples, or temperature measuring devices on the non-fire side of the test assembly, exceed the prescribed limits.
Solutions for Passive Fire Protection
There are multiple types of lightweight Passive Fire Protection Systems. Those includes plasterboard systems, aerated concrete system, metal-form concrete system. The list below outline some examples of manufacturers in Australia who provide these solutions.
- CSR
- Knauf
- Siniat
- BGC
- Hebel
- Speedpanel
- K8 Supapanel
ArchiEng team of engineers have over 20 years experience designing and specifying these systems to provide a complete solution, incorporating structural, fire, acoustic, thermal and seismic into a single report. Click here to find out more on how we have assisted hundreds of architects and builders in providing these solutions.
Passive Fire Protection Systems Avoid Loss from Fire
The ramifications of a small fire for any building owner are likely to be dire. The potential for loss of life, damage from fire, smoke and water plus loss of business productivity are just the beginning of a long list that could mean total devastation for any business.
By conforming to NCC standards and choosing an experienced team to properly design your passive fire protection systems, business owners can minimise potential loss of life, property damage and more. It is a building owner’s obligation to ensure all fire rated elements are property installed, maintained and checked so that it performs without failure should the need arise.
What is a building certifiers role in Passive Fire Protection of buildings?
A building certifier needs to receive evidence of compliance such as a NATA Accredited Testing Authority report to meet the NCC C3.15a requirements in order to sign-off on a fire rated building. Even if you make changes to any component of an existing fire rated building or fire tested system, you may alter the performance of the system and potentially breach the fire barriers.
It is important to note that whoever has decided to swap materials and deviate away from the intended specification, is responsible for obtaining Evidence of Suitability in accordance to the NCC.
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