(PE). Some products use a mixture of PE and non-combustible fillers to enhance the fire performance of ACP. The core material in ACP make them extremely lightweight and cheaper compared to solid metal panels. ACP are available in a wide range of colours and surface finishes, which can aesthetically transform an old building into a modern version of itself. Insulated sandwich panels (ISPs) have

similar components as ACP but are often much thicker due to the insulation material that forms the core of the product, as shown in Figure 2. The insulation material can vary between products; some consist of non- combustible materials, such as mineral wool, while the more common products use lightweight polymer, such as expanded polystyrene (EPS) and polyisocyanurate (PIR) as the core material. ISPs come in a wide range of thicknesses from 20 mm to 300 mm. ISPs are often used as the main component of external walls on buildings to meet insulation performance requirements.

Risk Identification In Australia, most states have approached this problem by conducting a survey of all their assets to identify buildings with combustible composite cladding or other combustible wall components. Once identified, fire safety engineers are often engaged to inspect these buildings and carry out detailed risk assessments. Figure 3 shows the risk assessment process. Typically, a physical site inspection is carried out to determine the extent of the cladding and identify characteristics of the subject building. During a site inspection, a fire safety engineer identifies potential ignition sources such as nearby parked vehicles, adjacent buildings, openings and electrical outlets in the external walls, smoking areas, etc.

Expanded Polystyrene (EPS)

indicate that it is likely to be combustible. Figure 6 shows photographs from a site inspection where exposed core materials of the façade were found. Immediate and conservative interim

Steel sheets

Figure 2. A hole drilled in an insulated sandwich panel during an invasive inspection showing an EPS core.

Figure 4 shows nearby parked vehicles in close proximity with combustible façade on an acute services building at a large hospital. Although the combustible façade is installed on the exterior of buildings, it is necessary to carry out an inspection of the interior as well. Figure 5 shows a room originally intended for liquid nitrogen storage being used as a general storage room. Since this room was originally intended to store gas cylinders metal louvres were provided in the external wall for ventilation purposes. However, the general storage of

combustible increased the risk of fire occurring and the louvres provided a direct pathway for fire to spread to the combustible façade. A fire originating from this room was one of the fire scenarios assessed for this hospital. During a site inspection, it is often beneficial to make a preliminary determination whether or not the façade system has a polymeric core, which would


Combustible façade identified? Yes

Identify ignition sources and likely fire scenarios Fire assessment risk

Remediation Is the risk level acceptable? Yes STOP Figure 3. Risk assessment process. IFHE DIGEST 2020

measures can then be implemented while material testing is carried out to gather more information regarding the façade system. Information regarding the combustibility of the cladding material is required in order to determine whether or not ignition of the cladding is possible and the extent of flame spread. It is important to understand that small-scale testing of the cladding material cannot provide accurate information regarding how a fire involving the façade system will behave. If more information regarding expected behaviour of façade system is required, large-scale tests are recommended. However, this can be difficult without a supply of approximately 30 m2

of the original

cladding and external wall materials. Where ACP is installed as part of the

wall, the combustibility of insulation and sarking will influence how a fire will behave. Unless the cladding is installed on top of a non-combustible or fire-rated wall system, it is important to assess the combustibility of individual components such as the insulation and sarking materials that make up the external wall as well.

In addition to information regarding the

potential ignition sources and façade system, it is also important to collect information such as the building fire safety systems.

Risk Assessment After information is gathered from a site inspection, a risk assessment can be carried out. The overall risk level is determined by the likelihood and consequence of several credible fire scenarios. The likelihood is determined by identification of the ignition sources near the combustible façade. Any fire safety features in the building such as an automatic sprinkler system will also affect the risk of ignition from interior of the building. Ignition of façade containing combustible components can be generally characterised as follows:2 l Interior fire spreading to external façade via openings such as windows, internal cavities and concealed spaces.

l Exterior fire impinging on the surface of the external façade.

l Exterior fire nearby igniting the external façade through radiant heat only.

The consequence of a fire involving the façade is a complex process that requires an assessment by a suitably qualified fire safety engineer. A combustible façade system installed on a building does not always result in high risk rating. The extent


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