How safe are powder-coated and anodised finishes in fire?

Fire safety is covered in the UK Building Regulations – and since the Grenfell fire, they’ve been toughened up considerably. 

But what do the fire regulations mean for your choice of coatings? In a large architectural façade project involving lots of materials, this might be low on your priority list. 

Is an anodised finish a fire risk? 

Quick answer, no. It’s an electrolytic process to increase the thickness of the oxide layer that appears naturally on the surface of exposed aluminium. Aluminium is rated A1 - that means it’s non-combustible. So, by default, anodising is too. 

What about powder-coating? 

It can catch fire, but we’re talking about the thinnest of layers (40-60 microns) on a metal surface, so the risk is negligible. But there is a risk, so it’s generally rated A2. 

Is A2 okay? 

Building control and fire officers may approve powder-coating – even if it’s rated A2. It’s important to talk to them first, and liaise with your façade specialist... perhaps even commission fire testing. If that sounds like a hassle, you should know that depending on the thickness of the coating and the shape of the component (even the colour), powder-coating could pass at A1 in a fire test. 

Does coating thickness matter? 

Anything more than 60 microns thick is unlikely to be rated A1 – which could be a problem in maritime locations, where extra protection is required against the corrosive effect of salt spray. Here, anodising may be the better approach. However, it’s still a good idea to talk to building control and fire officers – or ask a façade specialist to do so on your behalf. 

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