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Can You Put Ice Melt on Composite Decking?
When the British summer finally hits, one of the biggest concerns for homeowners is heat absorption. “Will my new composite deck burn my feet?”
The short answer is: Yes, in direct sunlight, any decking material will get hot.
Whether it is timber, stone, or composite, the laws of thermodynamics apply. If a surface absorbs solar energy, its temperature rises. However, by understanding the factors that drive this heat—density, colour, and core structure—we can engineer a deck that remains comfortable even in a heatwave.
The Data: How Hot Does It Actually Get?
Many people assume timber stays cool while “plastic” composite gets unbearably hot. We looked at the data to see if this is true.
The Test: Materials were exposed to direct sunlight in temperatures averaging 30°C for several hours.
Softwood (Pine/Cedar): Reached 48°C – 69°C
Hardwood (Ipe): Reached 58°C – 60°C (The dense grain helps conduct heat away).
Composite (Capped): Reached 56°C – 65°C
The Engineer’s Verdict: There is a minimal difference between dark timber and composite. Both can reach temperatures that are uncomfortable to walk on barefoot (60°C is the threshold for pain). The difference is that while timber might crack or splinter under this heat, composite will only expand (which is why correct expansion gaps are vital).
The 3 Factors That Dictate Temperature
If you want a cooler deck, you need to manipulate these three variables:
Colour (The Albedo Effect)
This is the single biggest factor. Dark colours absorb light; light colours reflect it.
- Why does this matter? If the surface temperature of your deck is a priority for you, understanding colour selection is crucial.
- The Rule: A Charcoal or Dark Brown board will always be hotter than a Light Grey or Oak board.
- The Science: Just like wearing a black t-shirt on a sunny day, dark pigments absorb the full spectrum of solar radiation. If your deck is South-Facing, we strongly recommend choosing a lighter shade to reflect those UV rays.
Core Structure (Solid vs. Hollow)
The density of the board changes how it stores heat. Put simply, solid boards contain more material in their core, meaning they expand more and hold heat for longer.
- Solid Core: Has a high “thermal mass.” It absorbs heat and acts like a battery, staying hot long after the sun goes down. It also exerts more force when expanding.
- Hollow Core: The air chambers inside the board act as an insulator (like double glazing). This allows heat to dissipate faster, often keeping the surface temperature slightly lower than a solid equivalent.
Exposure & Sunlight Levels
The most obvious factor determining temperature is the level of direct sunlight exposure.
- South-Facing Gardens: Will experience the most intense heat.
- North-Facing Gardens: Will be largely shaded and remain cool.
- Tip: If you have a South-Facing garden, avoid dark solid boards unless you have shading.
How To Manage The Heat
You don’t have to sacrifice your deck choice just because of the sun. Here are the best engineering solutions to manage surface temperatures:
- Use Outdoor Rugs: A simple, stylish rug breaks the path of the UV rays. It provides a “safe zone” for bare feet and pets without blocking the airflow.
- Shade Engineering: Retractable awnings, pergolas, or sail shades are the ultimate solution. By blocking the direct UV path, you stop the heat absorption at the source.
- The “Hollow” Hack: As mentioned above, if you are worried about heat, opt for a Light-Coloured Hollow Core board. This is the coolest possible combination for a composite deck.
Conclusion
All decking materials—even stone and timber—retain heat when exposed to the full blaze of the sun.
- The Myth: “Composite is hotter than wood.”
- The Reality: Dark wood and dark composite reach almost identical temperatures (60°C+).
Our Advice: If you want your family and pets to walk barefoot comfortably in July:
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Choose a Lighter Colour (Light Grey/Oak).
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Consider a Hollow Core board to aid heat dissipation.
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Keep an outdoor rug handy for the hottest days of the year.
By making these smart choices during the design phase, you can enjoy a deck that is durable, splinter-free, and comfortable all summer long.
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