Learn more about ACP and EPS
Aluminium composite panels (ACP)
An aluminium composite panel (ACP) is made up of two thin aluminium sheets bonded to a polymer core. It is the polymer core that makes this product dangerous in a fire.
Typically, these panels span two to six metres in length and are 600mm to two metres wide. They do not generally add to the structural integrity of a building, though may contribute to energy efficiency and weatherproofing.
The highest-risk ACP products have a 100% polymer core – usually polyethylene (PE) – which is often black. The VBA has noticed this variety of cladding was mostly used on buildings constructed before 2012 and is less prevalent on recently constructed buildings.
Aluminium can be used in a process known as ‘coil coating’, which allows for a vibrant range of colour options and provides excellent corrosion resistance. Aluminium composite panels are also cheaper than solid aluminium products and they can allow architects to design curved buildings that are not as easily achieved with steel, masonry or glass materials.
However, aluminium has a low melting point of around 660°C. In a fire, temperatures will be around 800°C to 900°C, which will melt the aluminium skin of the panels and can expedite the ignition of the core.
Expanded polystyrene (EPS)
Expanded polystyrene (EPS) is another type of cladding that is combustible and increases the likelihood of fire spreading more quickly, as it may shrink, melt or ignite when exposed to elevated temperatures.
Used widely in the building industry in Victoria over the past 20 years because of its low cost, lightweight and insulating properties, EPS is typically covered with render and appears as rendered concrete.
Polystyrene is a thermoplastic and has a very poor reaction to fire. Chemical fire retardants may be added to expanded polystyrene; however, they do not prevent combustion from a large fire source and they may also leach over time. As a result, it presents an increased risk of fire spread particularly in multi-storey buildings (class 2 buildings), therefore, it is now prohibited for use as external wall cladding on class 2 building work in connection with Type A and Type B construction in Victoria.