The Importance of Fire Resistance Level (FRL) in Building Safety
Fire poses a serious threat to both life and property. Without adequate fire safety measures, it can spread rapidly, compromising structures and endangering occupants with toxic fumes.
To address this, various methods have been developed over the years to prevent and control fires. A critical approach is the use of building materials with passive fire protection properties. Although no material is completely fireproof, some systems can withstand fire for a specified duration, making fire resistance ratings essential.
Life Safety: The main goal of FRL is to protect occupants by providing enough time for safe evacuation and fire suppression.
Property Protection: Fire-resistant materials help contain fires, limiting spread, reducing property damage, and lowering repair costs.
Compliance: Building codes often require specific FRL standards for different structures. Adhering to these ensures safety and provides peace of mind for occupants and owners.
Insurance and Liability: FRLs can influence insurance coverage and premiums. Effective fire resistance measures can reduce damage risks, lower insurance costs, and minimize legal liability in the event of a fire.
FireSafe’s Role in Meeting FRL Standards
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FireSafe stands out in todayโs competitive market with advanced technology and expertise. Our products offer a reliable, cost-effective alternative to existing fire protection solutions, ensuring FRL compliance without compromising on quality or performance.
What is Fire Resistance Level (FRL)๏ผ
Definition of Fire Resistance Level (FRL)
Fire Resistance Level (FRL) measures how long a building component, such as a wall or door, can resist fire. Required by the Building Code of Australia (BCA) for multi-storey buildings, FRL is defined by AS 1530.4, assessing structural adequacy, integrity, and insulation in minutes.
This standard, AS 1530.4-2014, mainly evaluates the fire performance of materials, components, and structures. The materials it encompasses include, but are not limited to:
- Masonry (brick, concrete block, stone)
- Concrete (precast, cast-in-place, reinforced)
- Steel (structural, composite)
- Timber (solid, laminated)
- Gypsum board and plasterboard
- Insulation materials (mineral wool, glass wool, foams)
- Fire-resistant glass
- Fire doors and windows
- Fire-stopping and penetration seals
FRL Rating System
FRLs are expressed in a format that indicates the fire resistance duration of a component in three key aspects: structural adequacy, integrity, and insulation. Typically, FRLs are written as X/Y/Z, where:
- X represents the duration for structural adequacy.
- Y represents the duration for integrity.
- Z represents the duration for insulation.
For example, an FRL rating of 90/60/30 means that a building element must maintain its structural adequacy for 90 minutes, integrity for 60 minutes, and insulation for 30 minutes during a fire.
Components of Fire Resistance Level (FRL)
Structural Adequacy
Structural adequacy measures how long a building element can withstand loads when exposed to fire, ensuring the structure remains stable and safe for occupant evacuation.
For example, in a fire, the temperature rise causes metal load-bearing elements to soften until they can no longer support the applied loads. The time it takes for the element to reach failure under these conditions defines its “structural adequacy.”
Non-load-bearing elements do not require this parameter, so you may see FRL expressed as -/Y/Z. This indicates no requirement for structural adequacy, which is common for elements like doors in fire-rated walls. For instance, a door in a firewall might have an FRL of -/60/30.
Integrity
Integrity measures how long a building element can remain intact during a fire, focusing on preventing the passage of flames and hot gases through cracks or burn-throughs. This ensures that fire compartments remain sealed, limiting the spread of fire and smoke to adjacent areas.
For example, in a firewall, the side exposed to fire heats up more quickly than the non-fire side, leading to uneven expansion. This can cause the wall to buckle and crack, allowing hot gases and flames to pass through, and compromising the integrity of the fire barrier.
This parameter applies only to elements that separate fire compartments, like firewalls, and does not apply to load-bearing elements that are fully exposed to fire. Therefore, the FRL for load-bearing elements is often expressed as X/-/-, indicating that they do not require integrity or insulation ratings.
Insulation
Insulation measures how long a building element can resist heat transfer during a fire, ensuring that the temperature on the unexposed side remains below specified limits. This helps prevent adjacent materials from catching fire, providing a safer environment for evacuation and firefighting. Typically, failure occurs when the temperature on the non-fire side reaches 180ยฐC.
Insulation applies to elements with a barrier function and, like integrity, is not usually required for load-bearing elements such as columns. Insulation is often the most challenging criterion to meet, and many components will fail in insulation before integrity or structural adequacy. As a result, insulation values are often lower, leading to requirements such as 120/60/30.
The Role of Architects in Considering FRL
Methods to Achieve 60-Minute Fire Resistance
A 60-minute fire-rated board can withstand fire for a full hour, making it ideal for buildings where occupants may need extra time to evacuate, such as hospitals and schools. In the UK, residential ceilings typically require at least two layers of fire-rated plasterboard to achieve the necessary 60-minute fire resistance. Additionally, areas like stairwells, elevator shafts, corridors in multi-storey buildings, and rooms containing flammable materials or equipment also need to meet this fire rating.
While higher-rated panels (90, 120, 150, 180, or 240 minutes) are available, they can still be used in applications requiring a 60-minute fire rating. These panels provide greater fire resistance and can offer extra protection and peace of mind during a fire emergency.
The main products available on the market that provide 60-minute fire protection include:
- 15mm (minimum) fire retardant boards;
- 10-15mm vermiculite spray; and
- 1-2mm intumescent coating with a 50mm gap for expansion.
Thickness and Clearance Requirements
Building designers must consider the specific thickness and clearance requirements for different fire protection methods. For example, when specifying fire-retardant panels or applying intumescent coatings, it’s crucial to determine the correct thickness to achieve the required FRL. Additionally, adequate clearance for intumescent materials should be factored into the design to prevent issues during a fire.
Collaboration with Fire Protection Engineers
Architects should collaborate closely with fire engineers throughout the design process. Fire engineers have the expertise to assess fire risks and recommend suitable FRLs for various building components. Involving fire engineers early on ensures that the design meets fire safety codes and standards, reducing the risk of costly redesigns later.
Integration of fire protection measures
Considering FRL involves seamlessly integrating fire protection measures into the design of a building. This includes identifying areas that require enhanced fire resistance, such as firewalls, doors and structural elements. Architects must ensure that these elements are placed in appropriate locations within the overall design to provide effective separation and fire protection.
Building Code Compliance
Architects must thoroughly understand the Building Code of Australia (BCA) requirements for FRLs. Staying up-to-date with relevant codes and standards enables architects to design buildings that meet or exceed the required FRLs. This compliance ensures occupant safety and streamlines the approval process with fire engineers and building surveyors.
Ensuring Fire Rating Compliance and Safety
Adequate fire protection is crucial to your building’s structural integrity. During the planning and design stages, architects and designers may lack specific expertise in passive fire protection systems. While they can specify the necessary codes, ensuring that these solutions are integrated into the building plans requires a specialist in passive fire protection. Engaging a specialist early ensures that fire protection details in the drawings are clear and accurate, and that the specified products have been adequately tested.
It’s also essential to have the correct supporting documentation from the start, demonstrating compliance with the required Fire Resistance Level (FRL) and Building Code of Australia (BCA) guidelines. This documentation confirms that an accredited installer has implemented the system according to product test reports and the manufacturer’s technical data sheets.
If you have questions about FRL or fire protection products, Firesafe’s team of experts is available to assist with all your passive fire protection needs.
FAQ
How Is Fire Resistance Measured?
Fire resistance is measured using standards like ASTM E119 and ANSI/UL 263. These standards evaluate fire resistance ratings in hours by exposing construction assemblies to a standard time-temperature curve in a controlled test furnace. The tests assess the assembly’s ability to maintain structural integrity, limit temperature rise, and prevent flame passage, ensuring reliable performance under fire conditions.
What is Fire Resistance Rating (FRR)?
Fire Resistance Rating (FRR) measures the fire resistance of a material or assembly. Although FRR and Fire Resistance Level (FRL) are often used interchangeably, there is a distinction: FRR is the target fire resistance value set by a fire design engineer, while FRL is the actual value achieved through testing.
Fire ratings are determined using tests such as ASTM E-84 and ASTM E-119. ASTM E-84 measures flame spread and smoke development in materials, indicating how quickly fire spreads and the amount of smoke produced. ASTM E-119 assesses the fire resistance of structures by evaluating their ability to maintain integrity and prevent flame passage under fire conditions.
What Is Level 3 Fire Rating?
A Level 3 fire rating, also known as a Class C fire rating, corresponds to a flame spread rating between 76 and 200. This rating applies to materials like plywood, fiberboard, hardboard siding panels, and fast-burning woods. It indicates the material’s ability to resist fire spread, helping ensure that buildings meet safety standards.
What Is FRL 90 for a Material?
FRL 90 for a material means that during a standard fire test, the material will maintain stability, integrity, and insulation for 90 minutes in each category, expressed as 90/90/90.