Does aluminium decking get hot? As the summer sun gets nearer, heat on decks is a common concern but shouldn’t cause problems

A common question that we are often asked is; “Does aluminium decking get hot?”, and the answer is actually relatively complex.

First and foremost, any material that is exposed to sustained, direct sunlight will “get hot”. We’ve all walked barefoot on paving, tarmac or sand and been surprised at how hot it can get in the height of summer. The same applies to decking, whether it’s aluminium or timber or composite deck material.

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The key consideration, then, should be; “Once hot, how long does aluminium decking retain heat?”, and the facts are reassuring. Aluminium is an exceptionally effective thermal conductor, with a thermal conductivity value of around 235 Watts per Kelvin per meter for pure aluminium.

This compares to steel’s much lower 45 W/K/m. Aluminium alloys can have lower thermal conductivity than pure aluminium but still significantly higher than steel. Aluminium’s high thermal conductivity means, then, that aluminium much more rapidly sheds heat than steel does.

When we look at other common decking materials, though, the difference is even starker. Timber has a thermal conductivity of around only 0.15 W/K/m while composite material has a value of approximately 0.30 W/K/m!

These very low thermal conductivity values mean that timber and composite decking will hold heat for a comparatively long time, while aluminium decking will quickly cool down.