Wednesday, 4 April 2018

Don't be scared of aluminium cladding

Despite all the news reports suggesting otherwise, I'm going to argue that you should not be scared of aluminium cladding.

You should not be scared of aluminium cladding because, despite news reports failing to understand the difference, aluminium cladding (which is inert, stable, safe and not flammable) is very different to a type of cladding called Aluminium Composite Panels (ACP) which is the thing implicated in the Grenfell Tower fire, and discussed widely and inaccurately this morning on Radio NZ and elsewhere...

So it's not because reporters are scaremongering. It's because they don't understand the difference between two different things. i.e., between aluminium cladding and Aluminium Composite Panels.

Aluminium cladding is generally a very thick extrusion of solid aluminium often intended to emulate a weatherboard or other timber products, and used with increasing frequency to clad and re-clad houses. It is a non-combustible material. It is perfectly safe. And it is nothing like Aluminium Composite Panels (ACP).

Aluminium Composite Panels (ACP) are a sandwich panel of two very thin layers of aluminium with either polyethylene  or polyurethane in between to give the sheet rigidity. Essentially plastic sandwich, it is used frequently and (until recently) very fashionably on many high-rise and commercial buildings. The problem is not the aluminium however, which is demonstrably safe. It is what's inside the sandwich, which isn't.

Does this difference between two totally different cladding types matter?

Well, it certainly does if you're designing and specifying a building. And it certainly does if you're buying one, or already living in one. As a designer of houses myself, I've already heard from developer clients, who've very happily used aluminium cladding before, that they simply can't use it now: far too much fear in the market. Because buyers just aren't interested in anything at all with the 'A' word; they're not interested because they've been told by (mis)reporters who should read better that "aluminium cladding is dangerous." Reporters who should read better, because the very report from which they're drawing their mis-reporting (which Radio NZ web types have even linked to make it easy for their reporters and sub-editors) speaks only about Aluminium Composite Panels, and not at all about aluminium cladding.

So please, don't be concerned about aluminium cladding -- only about the misreporting of reporters.



  1. I am sorry but you are wrong. Aluminium is combustable, but a lot harder to set on fire than ACPs. HMS Sheffield was lost during the Falklands war because the Exocet's fuel set fire to the aluminium superstructure, and that was a lot thicker metal than cladding.

    1. So you are saying that cladding my house in Aluminium leaves me vulnerable to Exocet missiles?

      I will be sure to take that into account in my insurance premiums.

  2. There are methods by which any metal that oxidizes can be ignited; fire is, after all, merely a runaway exothermic oxidation reaction. The question is whether conditions experienced by the building, during ordinary use, may ignite the material. Aluminum cladding (siding, in the USA) would melt before it burned in most house fires.

    Think of it this way: Does anyone, anywhere, worry about beer cans in their garage igniting? If not, we can dismiss the idea of aluminum cladding being a fire hazard.

  3. For a recent large greenfields development I was involved in we needed to agree to the following condition to get consent:

    "The discharge shall not be from (a) any copper, galvanised, unpainted zincalume or any other unpainted metal roof material, gutters or downpipes or external cladding on any building within the application site."

    This is apparently because runoff from any of these surfaces (including unpainted zincalume) increases the contaminant levels downstream (copper & zinc) and harmful to the aquatic environments.

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