Aluminium Cladding & Fire Safety: What It Means for Hoardings
Aluminium Composite Panels (ACP) are not only widely used in permanent building facades but also play a crucial role in temporary structures like construction hoardings. Their lightweight nature, ease of installation, and sleek appearance make them a popular choice for site perimeter enclosures and marketing displays. However, when ACP hoardings incorporate a polyethylene (PE) core, they may introduce significant fire risks—especially in public or high-footfall areas. Addressing flammability concerns through the use of non-combustible materials is fundamental to ensuring both compliance and operational safety in modern hoarding systems.
Understanding the Fire Hazards of ACP Cladding
Aluminium composite cladding (often referred to as ACP, ACM, or aluminium composite board) is a widely used facade material composed of thin aluminium sheets bonded to a core material. In many instances, this core consists of polyethylene (PE), a type of plastic. While aluminium itself does not burn, under fire conditions the thin metal sheets can heat and melt, exposing the flammable plastic core beneath. Once exposed, the PE core can ignite and burn rapidly, making ACP cladding with PE cores a significant fire hazard.
One way to understand the danger is by comparing the cladding to fuel. Experts have noted that polyethylene is essentially a solid petroleum product. When it burns, it releases enormous heat—1 square meter of PE core panel can emit as much energy as about 3 litres of petrol. In the Grenfell Tower disaster, researchers estimated that the building’s cladding panels had a combined energy potential equivalent to 12,000 litres of petrol. This means a high-rise wrapped in PE-cored panels is like a building covered in fuel. The onset of a fire poses a significant threat with potentially disastrous outcomes.
Several characteristics of ACP with PE cores contribute to fire spread:
- High Heat Release: Polyethene has a high combustibility ratio—it produces far more heat than what’s needed to ignite it. A fire becomes self-propagating once the central material is alight.
- Melting and Dripping: As the plastic heats, it melts and drips. On a vertical façade, melting plastic can carry flames downward to lower floors while the fire simultaneously spreads upward, effectively spreading fire in multiple directions.
- Chimney Effect: ACP panels are often fixed to walls with a gap (cavity) behind them for insulation and ventilation. In a fire, this gap can act like a chimney, funnelling hot gases and flames upward. Flames can leap up the cladding’s interior cavity and even re-enter upper storeys through windows, bypassing the building’s internal fire barriers.
- Aluminium Conductivity: Aluminium is a good conductor of heat. Fire-induced heat can be efficiently conducted to other components within the panel system. The metal may not burn, but it can spread heat, and if it warps or falls away, it exposes more of the flammable core.
Safer Hoarding Materials
To mitigate fire risks associated with traditional ACP hoardings, several fire-safe alternatives are available:
- Fire-Retardant PVC Panels: These panels are treated with fire-retardant additives during manufacturing, enhancing their resistance to ignition and flame spread. They are lightweight, durable, and suitable for various hoarding applications.
- Steel Composite Hoarding: Steel-faced panels, such as the Hoardfast Firescreen, offer a 60-minute fire rating. Constructed with a mineral wool core and steel facings, they provide robust fire protection and are ideal for both internal and external hoarding needs.
- Fire-Retardant Treated Timber: Timber hoardings treated with fire-retardant chemicals reduce combustibility and slow flame spread. This treatment enhances the safety of traditional wooden hoardings without compromising their structural integrity.
We ensure that all printing on these fire-safe materials is conducted using compatible, non-combustible inks and substrates, maintaining the integrity of the fire-resistant properties while delivering high-quality visual outputs.
Permanent Façades vs Temporary Hoardings
Aspect | Permanent Façades (Building Cladding) | Temporary Hoardings (Construction Site Barriers) |
Height & Vertical Spread | High-rise buildings allow flames to spread upward rapidly, creating a chimney effect. | Hoardings are usually a few meters high, limiting vertical fire spread. |
Occupancy & Exposure | Fire in cladding endangers people inside buildings, with the potential for fire penetration into occupied spaces. | Hoardings are freestanding, so fire risks are mainly to nearby property or people in the immediate vicinity. |
Material & Area | Façade cladding covers large areas, creating a significant fuel load. | Hoardings use less material and often incorporate non-combustible materials like steel or treated timber. |
Regulatory Oversight | Subject to strict regulations (e.g., BS 8414, Building Regulations) for permanent structures. | Covered by general health and safety laws, risk assessments are required under the Regulatory Reform (Fire Safety) Order 2005. |
Duration of Use | Permanent, exposed to weather and wear for decades. | Temporary, typically in place for a few months or years during construction. |
Fire Risk Mitigation | Stricter regulations post-Grenfell focus on non-combustible materials and fire barriers. | Temporary hoardings may use fire-retardant materials or non-combustible panels where the risk is higher. |
Making Buildings Safer: Fire-Safe Cladding and Future Steps
The key takeaway from the ACP cladding issue is the importance of using non-combustible materials for building exteriors to prevent rapid fire spread. Here are the key steps to ensuring safer buildings—from material selection to implementing effective building site hoarding that can inform and protect during construction or refurbishment phases.
- Non-Combustible Cladding: Builders now use solid aluminium panels, mineral-core panels rated A2, fibre cement, terracotta tiles, and brick slips, all of which don’t ignite like PE-core ACP. Had Grenfell been clad with these materials, the fire would have been contained to the initial flat.
- Fire Barriers: Modern façades incorporate fire-stopping barriers to prevent flames from spreading within the cavity. Post-Grenfell, greater scrutiny ensures these barriers are properly installed.
- Strict Testing and Compliance: All cladding must undergo fire tests like BS 8414 to ensure fire resistance. Combustible materials must prove they can contain fires. PE-core ACPS no longer meet the standard.
- Regulatory Enforcement: The Building Safety Act 2022 established a new Building Safety Regulator to enforce stricter safety standards, ensuring thorough checks are made on materials used in new builds.
- Cladding Remediation: There is a nationwide effort to replace unsafe cladding on older buildings. While costly and disruptive, this remediation is essential for safety.
- Cultural Shift: Fire safety now receives more attention throughout the construction process. Public awareness has increased, ensuring developers and authorities prioritise fire-safe materials.
By using non-combustible materials and implementing stricter regulations, buildings are becoming safer, and fire risks are significantly reduced.
Conclusion
The construction industry now prioritises non-combustible materials, with updated standards like BS 8414 ensuring safer buildings. While temporary hoardings made of ACP pose a lower risk, they still require careful fire safety practices. By adhering to these regulations, we can prevent future disasters, protecting both property and lives. The ongoing regulatory improvements are making UK buildings safer for everyone.
Looking to ensure your construction site is not only secure and compliant but also visually striking?
Explore our range of fire-safe printed hoarding solutions. We specialise in delivering high-quality, customisable hoardings that meet stringent safety standards, ensuring your project stands out while prioritising safety.
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