Aluminium sheets with fire protection requirement

Aluminium sheets are used in a wide variety of application areas – from building services and mechanical engineering to architecture. However, as soon as fire protection requirements come into play, the choice of the right material is decisive. Aluminium behaves differently in the event of a fire than many other materials and – with the right design – can make a significant contribution to safety.

The relevant standards such as DIN EN 13501-1 and DIN 4102, which govern fire behaviour and building material classes, should be taken into account as early as the planning phase. Depending on the design, aluminium can meet the highest requirements up to A1 (non-combustible). In addition to its chemical stability, it offers clear advantages: low weight, high dimensional stability, no smoke development and complete recyclability. The material thus combines technical safety with sustainable use of resources.

Fire behaviour of aluminium

Heat radiation and adjacent materials

In the event of a fire, aluminium radiates a large proportion of the absorbed heat energy back out thanks to its high thermal conductivity and shiny surface. However, this heat radiation can cause neighbouring materials, in particular plastics or painted components, to heat up or ignite more quickly. It is therefore important to allow for sufficient clearances and thermal separations in the design. In sensitive areas, the use of heat shields or insulation layers between aluminium and combustible components may also be necessary.

Aluminium has a very high thermal conductivity, which means that heat spreads quickly across the entire sheet in the event of a fire. This prevents local overheating, but can at the same time cause adjacent components to be heated more quickly. The melting point is around 660 °C, a temperature that is frequently reached in building fires.

Unlike many plastics or composite materials, aluminium itself does not burn. It develops no toxic gases and does not contribute to the fire load. Instead, it melts and loses its mechanical strength in the process. This behaviour must be taken into account in load-bearing structures – for example in façades or machine enclosures. What is decisive is that the design is engineered so that stability is maintained even at elevated temperatures.

The natural oxide layer that forms in air additionally protects the metal against reaction with oxygen. As a result, aluminium remains chemically stable even under intense heat and does not ignite flames.

Influence of alloy and component thickness

Fire behaviour can vary depending on the alloy. High-strength aluminium alloys with a magnesium or silicon content show a faster loss of strength as the temperature rises than pure aluminium variants. The material thickness also influences the behaviour: thicker sheets require more energy to heat up and thus delay the critical point of melting.

Standards and classification according to EN 13501-1

Example from practice: manufacturers such as Alucobond® or Reynobond® offer different variants with clearly defined fire classes – such as Alucobond A2 (A2-s1, d0) for non-combustible façade panels or Reynobond FR (B-s1, d0) for flame-retardant applications. These classifications are based on tested test certificates according to EN 13501-1 and make it easier for planners to select suitable materials.

For construction products in Europe, DIN EN 13501-1 is the central test standard for fire behaviour. It assigns materials to classes A1 to F – from non-combustible to easily flammable.

Fire class	Meaning	Example
A1	non-combustible	Pure aluminium, untreated
A2	non-combustible with low smoke development	Aluminium composite panels with mineral core
B	flame-retardant	powder-coated aluminium sheets
C–E	normally to easily flammable	Composite panels with polymer core

For use in public buildings, corridors or façades, at least class A2-s1, d0 is often required. This combination stands for low smoke development (s1) and no burning droplets (d0). Depending on the coating and construction, aluminium can meet these requirements without difficulty.

Further standards and regulations

In addition to EN 13501-1, national regulations are also relevant, such as DIN 4102 (building material classes A1–B3) and ETAG 006 for façade elements. For industrial installations, VdS guidelines or special certifications for machine enclosures are also added.

Flame-retardant and non-combustible variants

Pure aluminium is fundamentally non-combustible. Nevertheless, many construction products contain additional layers or core materials that influence fire behaviour. Aluminium composite panels (ACM) in particular consist of two thin aluminium cover layers and a core material.

• PE core (polyethylene): easily flammable, no fire protection classification
• FR core (Fire Resistant): flame-retardant, usually class B-s1, d0
• A2 core (mineral-filled): non-combustible, class A2-s1, d0

Manufacturers label tested products accordingly, so that planners and buyers can recognise the fire class directly.

Coatings and surfaces

Coatings have a significant influence on fire behaviour. Anodised aluminium sheets are considered non-combustible, as they have a pure metal surface. Powder coatings based on epoxy or polyester can – with the right formulation – meet the requirements of DIN 4102 B1 (flame-retardant).

Ceramic coatings or inorganic paint systems offer additional protection, as they release no volatile substances in the event of a fire and reduce heat transfer.

Fire protection coatings

For safety-relevant applications, special intumescent fire protection coatings are used. These foam up when exposed to heat, form an insulating foam layer and delay the heating of the metal. As a result, the stability of the structure is maintained for longer.

Combination with other materials

Material combination	Typical area of use	Fire behaviour	Assessment
Aluminium + steel	Load-bearing façade profiles	very good, both non-combustible	safe, high temperature resistance
Aluminium + plastic (PE)	Composite panels, decorative panels	critical, PE combustible	only conditionally suitable
Aluminium + mineral core (A2)	Façades, building services	non-combustible, no smoke development	optimal for high fire protection requirements
Aluminium + wood	Interior cladding, design applications	wood flammable	only suitable with additional protective coating
Aluminium + insulation material (rock wool)	Sandwich panels	flame-retardant to non-combustible	ideal for industry and building services

In practice, aluminium is often combined with other materials – such as steel, glass, insulation materials or plastics. What is decisive here is that the overall structure complies with the required fire protection rating. A non-combustible metal can lose its positive effect if it is bonded or screwed to easily flammable materials.

Composite systems with a mineral core, ceramic panels or non-combustible insulation materials are considered the safest solution. In building services, aluminium sandwich panels with a rock wool-filled core are also used, which achieve excellent results in the EN 13501 test.

Areas of use in building services and industry

Aluminium with a tested fire classification is used in many industries:

• Façade construction: Non-combustible aluminium composite panels with A2 core for high-rise and office buildings
• Interior fitting: Wall and ceiling cladding in escape and rescue routes
• Building services: Ventilation ducts, air conditioning ducts, cladding of technical rooms
• Mechanical engineering: Fire protection cladding, enclosures and control cabinets
• Transport technology: Trains, buses and ships – a combination of low weight and fire protection performance

Requirements in public buildings

The Model Building Code (MBO) as well as the individual state building codes in Germany prescribe strict fire protection requirements that vary depending on use, building class and number of people. Public buildings such as schools, hospitals, authorities or event venues are subject to particularly high safety standards. In these areas, materials must generally be non-combustible (A1/A2) or at least flame-retardant (B1).

In addition, smoke development plays a decisive role, as smoke gases are responsible for the majority of injuries in the event of a fire. The classification s1 (low smoke development) is therefore preferentially required. In escape and rescue routes, no burning droplets (d0) may occur.

The installation location is also decisive: while non-combustible materials are prescribed for load-bearing and room-enclosing components, flame-retardant aluminium composite panels may be sufficient in decorative areas, provided they meet the building authority approvals.

For verification, planners and building owners must submit test certificates, CE markings and fire protection reports in order to document the conformity of the products used with the building regulations.

Test methods and certification

Fire behaviour is determined using standardised test methods:

• EN ISO 1716: determination of calorific value for classification in A1/A2
• EN 13823 (SBI test): behaviour under the fire of a single burning item
• EN ISO 11925-2: ignitability by small flames

The parameters s (smoke development) and d (droplet behaviour) are derived from the results. Only tested products may be labelled with their classification (e.g. A2-s1, d0).

Practical recommendations for designers and buyers

• Check certificates: only use products with a valid test certificate.
• Assess combinations: test materials in composite systems for their overall class.
• Take processing into account: welding, bonding and painting processes can influence the classification.
• Simulate heat influence: during CNC machining and powder coating, no layer damage may occur.
• Provide documentation: all fire protection verifications must be available for acceptance inspections.

Sustainability and recycling

Compared with primary production, recycling aluminium saves up to 95 % of energy and reduces CO₂ emissions by around 90 %. Aluminium is therefore one of the most resource-efficient materials in the metal sector. Today, over 75 % of all aluminium ever produced comes from recycled sources – a decisive contribution to sustainability in construction and industrial manufacturing.

A further advantage of aluminium is its excellent recyclability. Even after thermal exposure, the metal can be melted down again without any loss of quality. Unlike composite materials with polymer content, no toxic residues are produced.

In modern building concepts, this plays a dual role: safety in the event of a fire and recyclability in the life cycle. Aluminium combines both aspects and enables durable, sustainable structures.

Future prospects: fire protection and smart materials

The European Union is currently working on the revision of the Construction Products Regulation (CPR), which also provides for stricter requirements for the fire protection of light metals and composite materials. In future, digital product passports are to be mandatory in providing information on fire behaviour and recycling potential.

At the same time, research projects such as FireLight or ALU-SAFE are promoting new approaches to improving the thermal stability of aluminium alloys and their coatings. The aim is to develop materials that exhibit higher temperature resistance and lower smoke development without accepting weight disadvantages.

New developments focus on intelligent material systems that can adapt their behaviour. These include:

• Sensor-integrated aluminium sheets that report temperature rises at an early stage.
• Nanocoatings that neutralise fire gases.
• Hybrid systems with automatic foaming when exposed to heat.

In the long term, such innovations could help to make fire protection even more precisely controllable and to significantly reduce the consequences of fire.

In conclusion

Currently, aluminium alloys of the 5000 and 6000 series in combination with mineral-filled cores (A2) and ceramic or anodised coated surfaces are considered optimal for applications with high fire protection requirements. These systems combine high dimensional stability with excellent fire behaviour and are at the same time low-maintenance and recyclable.

Aluminium sheets with fire protection requirements offer a combination of lightness, stability and safety. Through suitable alloys, mineral cores and tested coatings, they achieve fire classes from A1 to A2 and thus meet the requirements of modern construction and industrial applications.

Careful material selection is decisive – matched to the area of use, standard requirement and processing. This ensures that aluminium not only convinces through its mechanical properties, but also offers maximum safety in an emergency.

Plan safely and in compliance with standards: get advice on the suitable aluminium sheet with fire protection requirements or configure your cut directly online.

Frequently asked questions about aluminium sheets in fire protection

Which fire class applies to aluminium? Pure aluminium is non-combustible and corresponds to class A1 according to EN 13501-1.

How do aluminium composite panels behave in the event of a fire? That depends on the core material. Mineral-filled cores achieve A2, PE cores are combustible.

Which coating is the safest? Anodised or ceramic-coated surfaces are considered particularly resistant to fire.

How is the fire class tested? Through standardised tests such as EN 13823 (SBI) and EN ISO 1716, which assess smoke and heat development.

Can aluminium conduct heat and thus intensify fires? Aluminium conducts heat very well, but does not contribute to flame formation. It can deform or melt, but remains chemically stable.