Does Aluminium Decking Get Hot? Comparative heat-testing performed on AliDeck decking boards vs timber and composite boards

Leading the way in the switch to non-combustible balcony materials, AliDeck are committed to having the answers for every question our audience may have.

Large roof terrace decking replacement project completed in Bermondsey, London, as part of refurbishment works for The Hyde Group

One of the most common questions we hear is; “Does aluminium decking get hot?”, and it has often been difficult to give a concise answer.

Aluminium is an excellent conductor and has a high capacity to dissipate heat, boasting a thermal conductivity value of around 235 Watts per Kelvin per meter for pure aluminium and only slightly lower values for aluminium alloys. Traditional decking materials such as timber or composite have significantly lower thermal conductivity values, of around 0.15W/K/m and 0.30W/K/m respectively.

This means that aluminium decking much more readily sheds heat than either timber or composite. While it will get hot, as any material will in direct sunlight, the heat is rapidly dissipated and not built up, leading to cooler temperatures.

Proving the science with practical heat testing

Explaining thermal conductivity properties of aluminium is, of course, an unsatisfactory answer to the question of whether aluminium decking gets hot. We decided that practical testing was required to create a set of data that finally puts the matter to rest.

Aluminium Decking Vs Timber Composite Heat Testing

Two experiments; reflective surface temperature test and material core temperature test

July 2022 saw record temperatures across the South East, the highest the UK has ever seen. This created an optimal time for us to undertake an experiment at our head office in Rochester to answer this question as to whether aluminium decking becomes unduly hot.

We built a simple testing rig, comprised of two 500mm lengths of aluminium decking, two of timber decking, and two of composite decking. Sited in direct sunlight and with measurements taken throughout, the data collected from each test was revealing.

Test 1: Reflective Surface Temperature

Beginning the test by keeping the test rig in the shade for 2 hours to achieve a baseline temperature, we moved the rig into a new location with direct sunlight for the test proper.

Performing regular measurements throughout the day using a laser-gun infrared thermometer, we captured data over three hours before returning the rig to the shade for 15 minutes to measure cool-down.

Does aluminium decking get hot? AliDeck perform heat test and make like-for-like comparison to timber and composite decking


Material Baseline after 2 Hours in Shade After 30 Minutes in Direct Sunlight After 1 Hour in Direct Sunlight After 2 Hours in Direct Sunlight After 3 Hours in Direct Sunlight After 15 Minutes in Shade
Timber 29.7°C 53°C 52.3°C 54.8°C 56.5°C 35.9°C
Composite 29.1°C 53.7°C 54.6°C 57.5°C 58°C 40.9°C
Aluminium 28.9°C 46.4°C 44.6°C 46.3°C 49.3°C 33.9°C
Timber Average in Direct Sunlight 54.15°C
Composite Average in Direct Sunlight 55.95°C
Aluminium Average in Direct Sunlight 46.65°C
Ambient temp 35-38°C
Test Date 19-Jul-22
Location Rochester, Kent
Time at Baseline 10:55am

Test 2: Material Core Temperature test

Again, keeping the rig shaded for a period to start the test at ambient temperature level, moved the rig into the sunlight for one hour.

Using an Elcometer 215 Oven Data Logger, a temperature profiling device used to continuously record material temperature as it passes through our powder-coat oven, we connected probes to all decking materials and recorded temperatures every 5 seconds for the duration of the test.

Further testing on heat performance of aluminium decking versus timber and composite decking, core material temperature measurements reveal compelling data


Material Maximum Temperature recorded during 1 Hour in Sunlight
Timber 37.0°C
Composite 39.3°C
Aluminium 40.9°C
Ambient temp 25°C
Test Date 4-Aug-22
Location Rochester, Kent
Time at Start 11:00am

Aluminium decking does not get significantly hotter than timber and composite decking

The data speaks for itself; aluminium decking was by far the best performing material in the Reflective Surface Temperature test and performed at essentially the same level as composite decking (and only a few degrees above timber decking) in the Material Core Temperature test.

So, we finally have an answer to the question; “Does aluminium decking get hot?”, and that answer is “Not any hotter than timber or composite decking, and it gets cooler quicker too!