Composite decking in the sunshine

Does composite decking expand and contract?

For over 20 years the team at Ecodek have been working with wood composite materials to design and manufacture deck boards that can withstand the extreme temperatures. Even so, composite decking can still expand and contract. However, if fitted correctly, this will not cause a problem. In this blog we look at how and why this expansion and contraction occurs.

Why does composite decking expand and contract?

Composite deck boards contain plastic (in Ecodek’s case this is recycled) and wood fibres, which are both sensitive to changes in temperature. So when a board gets hot in warm weather it will slightly expand – this is called thermal expansion. As a board cools, it will contract.

Ecodek boards are designed to withstand thermal expansion – they’re engineered to expand and contract. The level of expansion and contraction is within a known tolerance and our boards are manufactured to deal with this. Therefore the structural integrity e.g the strength, durability or longevity of the boards is not compromised.

Does composite decking expand when wet?

No, unlike timber decking, composite decking does not expand when wet. Wood is very much affected by moisture absorption. When boards are wet and freeze, this can cause them to splinter and crack. When temperatures are high and the boards dry out they will quickly contract and can shrink and warp. Moisture absorption is a key reason why timber decking does not last and often needs replacing in a few years.

Rain on a wooden deck leading to expansion

Installing composite decking to allow for expansion and contraction

In order to mitigate the effects of composite decking expansion and contraction it is critical that the boards are installed correctly.

To counteract the effects of expansion and contraction, you should always leave an appropriate gap – as specified by the manufacturer – between your boards when installing. This will ensure that there is sufficient space between your boards for them to expand and contract without negatively impacting the integrity of your decking.

For more information on installing Ecodek boards, please download our installation guides, or call our expert, friendly team today on 01978 667 840 .

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