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Layman's Guide to Combustible External Wall Cladding

If you've had your head buried in the sand for the last few years, you'll be asking why a fire engineer is writing about composite wall cladding. Please familiarize yourself with the following news stories and nifty table (original article here) of recent events.

Cladding fire history engineering
Image Courtesy of Nguyen et al.

What is Combustible External Wall Cladding Made Of?

Your typical Aluminium Composite Panel (ACP) comprises two thin sheets of aluminium sandwiching a composite core which is usually Polyethylene (PE) or Ethylene Vinyl Acetate. The concentration of combustible elements in the core of the panel can vary between products so the below guide from the Victorian Building Authority may be helpful.

For ACP you've got four categories as defined by the CSIRO shown in order of most combustible to least:

  • Category A (PE): 30-100% polymer core. Remaining non-combustible

  • Category B (FR): 8-29% polymer core. Remaining non-combustible

  • Category C (A2): 1-7% polymer core. Remaining non-combustible

  • Category D: Fully non-combustible

Why is this important? Anything other than Category D is at risk of some level of fire spread.

Where is Combustible Cladding Banned?

Under the National Construction Code (NCC), external walls of Type A and Type B construction buildings must have external walls which are non-combustible.

While there are several factors that influence the Type of Construction on a building, the below serves as a rough guide noting that some other requirements in the NCC may classify your building as a different Type of Construction.

Speak to your appointed building certifier for a more accurate assessment.

Fire engineers table
Image Courtesy of the ABCB

The intent behind banning of combustible external walls in Type A and Type B construction is to limit fire spread externally in a multi-storey building. Fire safety systems are typically not designed to accommodate fires on multiple storeys.

Why is Combustible Cladding Used?

By now you would agree that having your external wall lined with a panel comprising what is effectively the below constitutes a serious fire hazard.

So why do people do it? Anecdotal evidence provided by architects whom shall remain anonymous indicate the following reasons:

  • The composite core provides insulation which helps meet energy efficiency requirements in the NCC

  • ACP is typically structurally lighter than non-combustible variants of similar shape and size. The structural systems required to support such walls are generally simpler and more cost effective.

  • Money.

Is Your Building at Risk?

Chances are if you're reading this, you've got a building with combustible external wall cladding and want to know what to do about it.

Unfortunately, the construction industry in previous years was not as stringent as it is today in terms of reviewing external wall composition. As such, your building may be non-compliant and at risk of a large loss event in a fire.

Another technicality is that the NCC clauses (C1.9 and C1.14) which require non-combustible external walls and associated attachments were introduced in NCC 2016 Amendment 1. As such, any combustible-clad Type B or Type A construction building under an approval of an older NCC version is at risk of non-compliance and a major loss in fire.

What Are Your Options?

Quite simple actually:

  • Remove and replace the combustible cladding with a non-combustible alternative or;

  • Engage a fire safety engineer to prepare a Fire Engineering Report (FER) containing a Performance Solution to justify its retention (or part thereof).

Who Can Help You Retain Your Combustible Cladding?

In short, no one at an affordable price.

The professional indemnity insurance market has been inundated with such a large quantum of claims over the last few years relating to combustible cladding that they've tightened their terms and conditions for engineering firms.

What does this mean? Many engineering companies can no longer write FERs containing Performance Solutions which justify retention of combustible cladding. There may still be some out there but chances are the fees to write such a report will be exorbitant in order to cover their bloated insurance premiums.


There you have it folks. A simple guide (hopefully) answering your common questions about combustible wall cladding. Have more questions? Reach out to us directly to chat further.


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