Fires can cause horrific damage and are a serious threat to people’s lives. That’s why it’s critical that buildings are equipped with the right passive and active fire protection measures.
Along with fire rated doors, walls and floors, fire rated windows play a significant role in a building’s passive fire protection. By helping reduce the spread of fire and smoke, fire windows help save lives in the event of a fire.
What are fire rated windows?
Fire rated windows are specialised windows that resist the spread of fire. They are used in commercial and residential settings where natural light and vision are important. Particular materials, design and manufacturing techniques are used to make sure fire rated windows meet the relevant Australian Standards according to the Building Code of Australia.
Along with fire rated walls, floors and doors, fire windows are an integral part of a building’s passive fire protection. Passive fire protection prevents the spread of fire and smoke in a building by breaking it into compartments. This helps create safe passageways for people to evacuate and gives more time for emergency services to arrive.
Why are fire windows important?
Modern architecture relies heavily on the use of glass to create attractive and comfortable indoor spaces. Contemporary designs that allow for more natural light and spaciousness are popular by architects and clients alike.
Commercial buildings are required to meet particular standards when it comes to fire safety. Fire rated windows allow architects and builders to achieve both the fire safety standards and the modern architectural look.
As mentioned above, fire windows are an important part of a building’s passive fire resistance. Fire windows help prevent or slow down the spread of fire from one area of a building to other areas. This allows more time and safe passageways for occupants of the building to evacuate. Fire windows also help slow down the destruction of a building, giving the fire brigade more time to control the situation.
How are windows rated for fire resistance?
In Australia, fire windows are given a fire resistance level (FRL) according to the Building Code of Australia. The FRL of a fire window indicates how well it can withstand fire under test conditions. The FRL for any building element is given as three numbers: structural adequacy, integrity and insulation.
- Structural adequacy – this number refers to how long the product can withstand the spread of fire and still remain structurally sound. In other words, how long it can support what it is designed to support. Since windows are not structural building elements, they are not tested for structural adequacy. The FRL for windows is given as “-” for structural adequacy to indicate this.
- Integrity – this number refers to how well the window can prevent the spread of flames and hot gases. Fire rated windows must pass certain criteria in this category.
- Insulation – this number refers to how long the window can prevent the spread of fire due to heat transfer. The window is required to maintain a temperature below 180 degrees C and prevent an average temperature increase of 140 degrees C during the test.
For example, the FRL of a window may be given as -/60/60. This means the window would not be expected to fail for 60 minutes in both the integrity and insulation categories when exposed to fire.
How are fire windows tested?
In Australia, fire windows and other fire safety elements are required to be tested to certain specifications (AS1530.4). The testing helps assess how well the window can prevent the spread of fire, contain smoke and reduce heat transfer. The frame, glass and any other components all need to be tested.
A control fire is used to mimic real fire conditions and the testing continues the duration of the required resistance level. The window is then assessed based on the resistance requirements and given the appropriate FRL. Fire testing in Australia is conducted by accredited authorities and organisations, which are governed by the National Association of Testing Authorities.
Where should fire windows be installed?
Fire windows are designed to be installed where a high degree of protection is required, in exit pathways or where specialised equipment is not able to be protected by sprinklers. They are used in a wide range of applications including residential complexes, homes, offices, shopping centres, schools, car parks etc. Fire windows can be installed in external or internal walls.
What are fire rated windows made from?
Fire windows are made from insulating safety glass and a metal frame which is usually timber, steel or aluminium. The glass for interior applications is usually a clear composite glass. Some designs use at least two float glass panes with transparent, fire resistant layers in between. The glass for exterior applications often has an additional laminated pane which reduced UV degradation of the fire resistant layers.
Advanced technologies make it possible to manufacture attractive fire resistant window frames from a number of materials. Aluminium is lightweight, corrosion resistant and economical. Steel is highly robust, incredibly strong and durable. Fire rated timber is strong and durable, with natural insulating properties.
How do fire glass windows work?
In the case of a fire, the fire resistant glazing and special glass of the window act as a barrier against the spread of fire, heat radiation and smoke. The fire may shatter the float glass pane closest to the flames. The fire resistant layer in the middle foam, creating a heat shield. This heat shield prevents the spread of heat radiation, fire and smoke.
The thickness of the fire resistant layer will determine how long the window will resist the spread of fire for. Common FRLs for fire window are -/30/30, -/60/60, -/90/90 or -/120/120.
When it comes to fire protection, it’s important to get the very best. When looking for fire rated windows, consider if the product meets the building regulations, has been rigorously tested and meets your functional and aesthetic needs.
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