The Grenfell Tower fire in 2017 and the Lacrosse building fire in Melbourne in 2014 exposed a systemic failure in how aluminium composite panels were specified and installed on multi-storey buildings. Australia's regulatory response has been measured but firm. Under NCC 2025, the rules governing external wall cladding on Type A and Type B construction are more explicit than ever, and the consequences of non-compliance extend well beyond a defect notice.
This post covers the core requirements: what the NCC prohibits, how combustibility is tested under AS 1530.1, which materials satisfy the non-combustible requirement, and what a compliant facade system looks like under the current weatherproofing and installation standards.
Why ACP Became a Problem
Aluminium composite panels are a sandwich product: two thin aluminium skins bonded to a core material. The core is where the risk sits. Panels with a polyethylene (PE) core contain up to 100 percent combustible material between those skins. In a fire, the aluminium faces offer almost no resistance. The PE core ignites, melts and drips burning material down the facade, spreading fire vertically at a rate that suppression systems are not designed to handle.
The problem was compounded by substitution during procurement. Panels specified as fire-rated or FR-grade were sometimes replaced with cheaper PE-core alternatives on site, without the change being flagged to the certifier or fire engineer. Laboratory testing of panels removed from Australian buildings after 2017 found PE-core product installed on buildings where FR-core had been specified.
The Aluminium Composite Panel (ACP) with a polyethylene core above 30 percent by volume is now banned from use as external cladding on buildings required to have non-combustible external walls. That prohibition applies to the majority of Class 2 to 9 buildings in Australia.
NCC 2025: The Non-Combustible Wall Requirement
The NCC applies different construction type requirements depending on building class, rise in storeys and floor area. Type A construction applies to the tallest and largest buildings; Type B sits below that. Both require external walls and their components to be non-combustible, with limited and defined exceptions.
Under NCC 2025 Volume One, the relevant performance requirement is that external walls must not contribute to fire spread. The deemed-to-satisfy pathway requires that materials used in external walls of Type A and Type B buildings satisfy the definition of non-combustible as established by AS 1530.1.
The standard also addresses the full wall assembly, not just the cladding panel in isolation. Insulation, cavity barriers, fixings, sealants and substrate materials are all part of the picture. A non-combustible panel fixed over a combustible insulation layer with no cavity barriers does not constitute a compliant system.
AS 1530.1: What Non-Combustible Actually Means
AS 1530.1 is the Australian Standard for combustibility testing of building materials. It uses a furnace test: a sample of the material is placed in a tube furnace at 750°C, and the test measures temperature rise, sustained flaming and mass loss. A material passes as non-combustible if it does not cause the furnace temperature to rise more than 50°C above the initial temperature, does not sustain flaming for more than 10 seconds, and does not lose more than 50 percent of its mass.
Two points matter for specifiers and certifiers.
First, the test must be conducted on the actual product as supplied, not on a representative sample or a similar product from the same manufacturer. A NATA-accredited laboratory must conduct the test and issue the report. Manufacturer data sheets that reference AS 1530.1 without a NATA-accredited test report attached are not sufficient evidence of compliance.
Second, composite and laminated products are tested as a whole assembly, not as individual layers. A panel with two aluminium faces and a mineral fibre core must be tested as that complete panel. If the manufacturer substitutes the core material or changes the face thickness, the original test result no longer applies.
For procurement, this means requesting the current NATA test certificate for the specific product code being supplied. If the product has changed since the certificate was issued, a new test is required.
Materials That Satisfy the Non-Combustible Requirement
Several common facade materials satisfy AS 1530.1 without complex testing arrangements:
- Solid aluminium (not composite): Aluminium sheet or extrusion with no core material passes AS 1530.1. It is used in rain-screen cladding systems, louvres, fins and feature elements.
- Steel: Both zinc-coated and COLORBOND steel satisfy the non-combustible requirement. Steel facade panels, profiled wall cladding and pressed metal cladding are all viable options for Type A and B buildings.
- Masonry: Brick, blockwork, stone and concrete are non-combustible by nature and have always been the baseline for compliant external walls.
- Fibre cement: Most fibre cement products pass AS 1530.1, but specifiers should verify with a current NATA test report rather than assuming compliance.
- ACP with a non-combustible mineral core: Panels with a mineral fibre or aluminium honeycomb core, tested and certified to AS 1530.1, remain available. The FR designation used by some manufacturers does not automatically mean the product passes AS 1530.1; the test report must confirm it.
For steel facade systems in particular, profiled steel wall cladding from manufacturers such as Lysaght, Stramit and Fielders is routinely used on commercial and industrial buildings and satisfies the non-combustible requirement. The product is available in COLORBOND and ZINCALUME substrates, cut to length, and can be fixed mechanically to steel or timber framing.
NCC 2025 and System Weatherproofing: AS 4284 and Cavity Design
NCC 2025 places greater emphasis on the facade as a system rather than a collection of individual products. Two areas where this is most apparent are weatherproofing performance and cavity design.
Weatherproofing Under AS 4284
AS 4284 is the Australian Standard for testing building facades. It covers air infiltration, water penetration and structural performance under static and dynamic pressure. NCC 2025 references facade weatherproofing performance requirements that align with AS 4284 test methods, particularly for Class 2 to 9 buildings where the facade is a primary barrier against water ingress.
For specifiers, this means the facade system including panels, joints, sealants and flashings must be designed to meet the wind pressure and water penetration requirements applicable to the site. A panel that passes AS 1530.1 but is installed with inadequate joint sealant or missing flashings at penetrations does not constitute a compliant installation.
Sealant selection matters. Silicone and polyurethane sealants used at panel joints must be compatible with the substrate, rated for UV exposure and applied to clean, primed surfaces. Sealant failure at panel joints is one of the most common causes of water ingress in facade systems, and it is largely preventable through correct product selection and application.
Drained and Ventilated Cavities
NCC 2025 reinforces the requirement for drained and ventilated cavities behind cladding systems on masonry and framed walls. The cavity serves two functions: it allows any water that penetrates the outer cladding layer to drain away before reaching the structural wall, and it allows moisture vapour to escape rather than accumulating in the wall assembly.
For rain-screen cladding systems, the cavity depth is typically 20 to 40 mm, maintained by vertical battens or top-hat sections fixed to the primary structure. The cavity must be open at the bottom for drainage and at the top for ventilation, with insect mesh to prevent entry of pests and debris.
Cavity barriers are required at each floor level and around window and door openings to prevent the cavity from acting as a flue in a fire event. This is a point of frequent non-compliance in older buildings and one that certifiers should check carefully on new work.
Mechanical Fixing of Panels
NCC 2025 is explicit that external cladding panels on Type A and B buildings must be mechanically fixed, not adhesively bonded as the primary fixing method. Adhesive bonding is not acceptable as the sole means of attachment for facade panels on buildings where non-combustible construction is required.
Mechanical fixing means screws, rivets, clips or bolts that connect the panel to the supporting structure through a physical fastener. The fixing pattern, fastener type and pull-out capacity must be designed to resist the wind loads applicable to the site and building height, in accordance with AS/NZS 1170.2.
For steel cladding systems, self-drilling fasteners into steel framing or purlins are the standard approach. Fastener class must match the corrosion exposure category of the site; coastal and marine environments require Class 4 or stainless steel fasteners.
Practical Checklist for Specifiers and Certifiers
Before signing off on an external wall system for a Type A or B building, the following should be confirmed:
- The cladding panel has a current NATA-accredited AS 1530.1 test certificate for the specific product being supplied.
- The insulation, cavity barriers and any other materials within the wall assembly have also been assessed for combustibility.
- The facade system has been designed to meet the weatherproofing requirements of AS 4284 for the applicable wind region and building height.
- A drained and ventilated cavity is provided, with cavity barriers at each floor level and around all openings.
- All panels are mechanically fixed with fasteners of the correct corrosion class for the site.
- Substitution controls are in place during procurement and construction to prevent PE-core ACP being installed in place of specified product.
Steel Cladding as a Compliant Option
For builders and specifiers looking for a non-combustible wall cladding that is straightforward to procure and install, profiled steel wall cladding is worth considering. Products like Lysaght Monoclad and corrugated steel wall sheeting are non-combustible, available in a wide range of COLORBOND colours, and can be cut to length for the job. They are mechanically fixed, compatible with drained cavity construction, and have a long track record on commercial and industrial buildings across Australia.
ACS supplies steel wall cladding, flashings, top-hat sections and fasteners for facade and wall applications, with cut-to-length service and delivery nationwide. For large or commercial orders, a quote can be requested directly through acsupplies.com.au.
The regulatory environment around combustible cladding is not going to ease. If anything, NCC 2026 and subsequent editions are likely to tighten requirements further as the industry works through the legacy of non-compliant installations on existing buildings. Getting the specification right at the design stage, and verifying compliance at procurement and installation, is the only way to avoid the liability that comes with a non-compliant facade.