Fibre Reinforced Facade Encyclopedia: Materials
An aluminium composite panel is a flat sandwich sheet of two thin aluminium skins, usually 0.5 mm each, continuously bonded to a core between 2 and 4 mm thick, most often at an overall thickness of 4 mm. It is called ACP in Australia and the UK and aluminium composite material, or ACM, in North America. The skins provide the finish, the weather face and the coating system; the core provides the stiffness that lets a 0.5 mm skin behave like a flat sheet, and it also decides almost everything about how the panel behaves in a fire.
In a 4 mm aluminium composite panel the two aluminium skins are 1 mm of the total and the core is 3 mm. The skins are identical across every grade on the market. What separates a restricted panel from a compliant one is the composition of the 3 mm in the middle.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Overall thickness | 3, 4 and 6 mm; 4 mm is standard | Skins 0.5 mm each, core 2 to 5 mm |
| Skin alloy | 3000 or 5000 series aluminium, 0.5 mm | Coil coated before lamination |
| Coating | PVDF or FEVE, 25 to 35 microns | Determines colour retention and warranty period |
| Weight, polyethylene core | about 5.5 kg/m² at 4 mm | Lightest grade; core density about 950 kg/m³ |
| Weight, mineral filled core | 7 to 8 kg/m² at 4 mm | Mineral filler raises core density substantially |
| Core, PE grade | Unmodified polyethylene | Gross calorific value of polyethylene about 46 MJ/kg |
| Core, FR grade | About 70% mineral filler by mass | Fire retardant grade; most versions still test as combustible |
| Core, A2 grade | About 90% mineral filler by mass | EN 13501-1 A2-s1,d0 where the specific panel is tested |
| Sheet format | Up to about 1,600 mm wide and 6,000 mm long | Routed and folded into cassettes on site or in the workshop |
| Thermal expansion | about 24 x 10⁻⁶ per °C | Aluminium governs; joints and slotted fixings absorb the movement |
How the panel is made and used
Two coils of coil coated aluminium and a core material are fed through a continuous lamination line, bonded under heat and pressure with a thermoplastic or thermoset adhesive film, and cut to sheet. The result is flat, light, dimensionally stable and easy to fabricate: the rear skin and core can be routed in a V groove so the panel folds up into a tray with returns, and the tray is riveted or hooked onto a rainscreen substructure.
That fabrication method is why the material became so widespread. It gives a crisp flat metal appearance at a fraction of the weight and cost of solid aluminium plate, and it is cut and folded from flat sheet without pressing or welding.
The three cores
Polyethylene core, usually marked PE. The core is unmodified thermoplastic polyethylene with little or no mineral content. It is the lightest, cheapest and flattest grade and has essentially no fire retardancy. Polyethylene is a hydrocarbon with a calorific value in the region of 46 MJ per kilogram, comparable with heating oil.
Fire retardant core, usually marked FR. Mineral fillers, commonly aluminium trihydrate, are loaded into the polymer to about 70 percent by mass. The filler releases water when heated and reduces heat release, but the core still contains a substantial organic fraction and most FR grades are reported as combustible in a furnace test.
Limited combustibility core, usually marked A2. Mineral filler is raised to about 90 percent by mass, leaving a small polymer binder fraction. Tested panels of this construction are commonly classified A2-s1,d0 under EN 13501-1, which is the limited combustibility class rather than the fully non-combustible A1 class. In Australia an A2 cored panel still has to be assessed against AS 1530.1 or against the bonded laminate provisions of the NCC for the specific panel.
Why the polyethylene cored panel failed
A panel that is 75 percent polymer by thickness, hung on a ventilated cavity, behaves very differently from the same polymer in a small specimen. Under facade fire exposure the polyethylene softens, melts and flows, the aluminium skin delaminates and opens, and the molten polymer becomes a fuel source distributed up the elevation. The cavity behind a rainscreen accelerates the process by feeding air and drawing flame vertically, and the cassette form concentrates burning material at the edges and drips it down.
Small-scale reaction-to-fire tests on the composite sheet did not predict that behaviour reliably, because a specimen in a laboratory rig neither melts out nor benefits from a chimney. Serious facade fires in Melbourne in 2014 and London in 2017 demonstrated the gap between the small-scale result and the built outcome. The regulatory response was to move the evidence base to full-scale facade tests, AS 5113 in Australia and BS 8414 assessed against BR 135 in the UK, and to restrict the material directly.
This is a history about a core material and a system, not about a brand. Panels of the same designation were supplied by many manufacturers, and the same sheet used on a low-rise signage or soffit application was never subject to the provisions that apply to the external wall of an apartment tower.
Bans, restrictions and audits
In Australia the restrictions were imposed state by state rather than nationally. New South Wales prohibited, under the Building Products (Safety) Act 2017, aluminium composite panels with a core of more than 30 percent polyethylene by mass in the external cladding of certain classes of building, by a ministerial declaration effective from August 2018. Victoria and Queensland introduced comparable restrictions alongside statewide audit and rectification programs, Queensland requiring owners of certain buildings to complete a combustible cladding checklist. Coverage, building classes and deadlines vary by state, so the governing instrument is the state one, not the NCC alone.
In England, Regulation 7(2) of the Building Regulations, introduced in December 2018, required materials in the external walls of relevant buildings above 18 metres to achieve European Class A2-s1,d0 or better, with a narrow list of exemptions. A 2022 amendment lowered that threshold to 11 metres and extended the building types covered. Separately, government screening and remediation programs targeted buildings identified as having unmodified polyethylene cored ACM systems.
What compliant alternatives look like today
- A2 cored aluminium composite panel, where the tested classification satisfies the relevant jurisdiction and the whole system, including cavity barriers and insulation, is assessed together
- Solid aluminium plate, typically 3 mm, at 8 to 9 kg per square metre, giving the same flat metal language without a core
- Fibre reinforced cement sheeting, which the NCC names among materials that may be used where a non-combustible material is required
- Glass fibre reinforced concrete, which can hold an AS 1530.1 result of Not Deemed Combustible and adds moulded geometry that sheet products cannot produce
- Terracotta, stone, glass and metal rainscreens on the same substructure grid
Where the design needs deep relief, double curvature or spans that sheet metal cannot hold, fibre reinforced polymer is the remaining option and it takes a different route. FRP is a polymer composite and is not non-combustible; on a Type A or Type B building it is delivered as a Performance Solution supported by a full-scale AS 5113 test and a fire engineer’s assessment. That is a different pathway from an A2 panel, not an equivalent one, and it belongs in the concept stage discussion rather than the submission.
Standards and references
- AS 1530.1 (combustibility) and NCC 2022 Volume One C2D10, C1V3 and Specification 7, including the bonded laminate provisions (check the edition adopted in your jurisdiction)
- AS 5113 (full-scale facade fire test)
- EN 13501-1 (reaction to fire classification), EN ISO 1182 and EN 13823
- UK Building Regulations Regulation 7(2) and Approved Document B, Volume 1
- NSW Building Products (Safety) Act 2017 and the ministerial use ban declaration of August 2018
- Queensland Safer Buildings combustible cladding checklist process; Victorian Cladding Safety Victoria program
- ASTM E84, ASTM E136 and NFPA 285 (US)
- AS/NZS 1170.2 (wind actions) and AS 4284 (facade testing)
Related terms
Questions specifiers ask
What is an aluminium composite panel made of?
Two aluminium skins, usually 0.5 mm each, continuously bonded to a core 2 to 4 mm thick. The core is either unmodified polyethylene, a mineral filled fire retardant compound at around 70 percent filler, or a limited combustibility compound at around 90 percent filler.
What is the difference between PE, FR and A2 core?
Filler content by mass. PE has effectively none, FR around 70 percent and A2 around 90 percent. As filler rises, heat release falls, weight rises and the panel becomes stiffer and harder to fold. Only A2 construction reaches the European limited combustibility class.
Is aluminium composite panel banned in Australia?
Not as a product type. Several states prohibited panels with a core of more than 30 percent polyethylene by mass on specified classes of building from 2018. A2 cored panels that hold the required classification are still used. The applicable restriction is the state instrument, not the NCC alone.
Is an A2 cored panel non-combustible?
A2-s1,d0 under EN 13501-1 is the limited combustibility class, one step below A1. In Australia the panel has to be assessed against AS 1530.1 or the NCC bonded laminate provisions for that exact panel, so ask for the Australian report rather than relying on the European classification.
How much does an aluminium composite panel weigh?
About 5.5 kg per square metre at 4 mm with a polyethylene core, and 7 to 8 kg per square metre at 4 mm with a mineral filled core. Add 5 to 15 kg per square metre for the substructure, brackets and cavity barriers.
What should replace a polyethylene cored facade?
It depends on the appearance being matched and the structure available. A2 cored panel, solid aluminium plate and fibre reinforced cement sheeting are the closest flat-sheet replacements. Glass fibre reinforced concrete adds moulded geometry with a non-combustible pathway where tested. FRP covers geometry the others cannot, through a Performance Solution rather than the Deemed-to-Satisfy route.
Recladding an aluminium composite panel facade and need moulded geometry as well as a compliance pathway? ShapeShell-RC is our glass fibre reinforced concrete system, tested by Ignis Labs as Not Deemed Combustible under AS/NZS 1530.1. See ShapeShell fire test data
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.