Australian Standards and the National Construction Code (NCC) outline the fire safety measures for construction materials, including plywood, OSB (Oriented Strand Board) and MDF (Medium Density Fibreboard) to ensure public safety. We’ll delve into the key regulations and rules related to fire rated board types used in building construction.
Building materials are classified based on their reaction to fire and fire resistance. While plywood is one of the most widely utilized engineered wood products in construction, MDF and OSB are also commonly used for different applications. Each of materials mentioned has its own fire rating properties, which influence their selection based on the intended use. For example, the fire resistance of plywood is primarily determined by its reaction to fire performance and its ability to contribute to fire spread. Plywood materials are classified based on Fire Resistance Level (FRL) and the Group Number.
Group Number Classification for fire rated materials
The Group Number of a timber material indicates how it behaves in the event of a fire. It is very important to select materials with appropriate fire properties to reduce fire hazards in the building.
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Group 1: Materials that have low flammability and do not contribute significantly to fire growth (in particular, fire-resistant plywood).
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Group 2: Materials with moderate flammability.
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Group 3: Materials with high flammability.
Depending on its composition and density, MDF is generally classified as Group 2/3 material. It tends to be more flammable than plywood but can be treated to improve its fire resistance. Fire-retardant MDF is possible for use in high-risk areas. OSB is also usually classified as Group 2/3, depending on its thickness and the type of adhesive used in its manufacturing process. OSB is usually more susceptible to flame spread in comparison to plywood, making it less preferable in areas where high fire-resistance is critical.
In most buildings, Group 1 materials are used for areas with high fire risk. Fire-treated plywood or fire-resistant coatings can help achieve a better Group classification.
Fire Resistance Levels (FRL) for fire rated plywood
The Fire Resistance Level (FRL) is an essential parameter for understanding how well a material can withstand fire. It defines the material’s ability to resist the spread of flame, heat transmission, and structural collapse. Fire rated plywood, like other building materials, must meet specific FRL standards depending on its application.
The FRL parameter is measured in terms of time (minutes):
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Integrity: How well the material can prevent the spread of flames (minutes).
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Structural Adequacy: How long the material can carry a load in the event of a fire (minutes).
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Insulation: How well the material can prevent heat from passing through to the other side (minutes).
For example, an FRL index of 90/90/90 indicates that the material researched can maintain its structural integrity, prevent fire spread, and block heat transmission for 90 minutes during a fire event.
Fire-Rated Plywood and Treatments
Regular plywood does not usually meet the necessary fire resistance standards for building construction. However, fire rated plywood is available in the Australian market. This plywood types are specially treated with fire-retardant chemicals and intumescent coatings, or made from fire-resistant wood types (Teak, Oak etc.). These treatments reduce the flammability of plywood, helping to delay the spread of flames in the event of a fire.
It's essential to verify that the plywood you use meets the relevant Australian Standards (AS/NZS 3837, AS 1530.3) or European Standards (EN 13501-1, EN 11925-2, EN 13823 etc.).
Building Code of Australia (BCA) and Fire Regulations
The National Construction Code (NCC) dictates the requirements and measures for fire safety in buildings. The code is divided into a few volumes (Volume 1 applicable to commercial buildings and Volume 2 for residential buildings). Different parts of a building require varying levels of fire resistance based on their size, use, and location.
For buildings with high fire risk (for example, residential buildings with multiple floors), the use of fire-rated plywood is often mandated, especially in critical areas such as ceilings, walls, and external cladding (AS 1530 series). Plywood panels used for non-structural applications (like interior cladding) usually have different requirements from structural components like fire doors or load-bearing walls.
In addition to fire ratings mentioned above, Australian regulations increasingly consider the environmental impact of modern construction materials. Using fire rated plywood products that are also certified sustainable provide benefits in eco-conscious building projects. Many companies in Australia now are interested in green-certified fire-treated plywood, which must meet both fire safety and sustainability standards. Wood used for the plywood is often sourced from sustainably managed forests, certified by organizations like the Forest Stewardship Council (FSC). FSC certified plywood ensures that the timber comes from forests that meet stringent environmental, economic, and social standards.
For more information, visit these official sources:
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Australian Building Codes Board (ABCB): www.abcb.gov.au
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Standards Australia: www.standards.org.au
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Fire Protection Association Australia (FPA): www.fpaa.com.au