Does Composite Decking Expand?

January 2024
Anton White

Composite decking, a popular alternative to traditional wood decking, has unique characteristics that raise important questions for homeowners and builders alike. One such question is: does composite decking expand?

The answer is yes, it does. However, the extent and implications of this expansion are nuanced and worth exploring.

In this article, we delve into the reasons behind the expansion and contraction of composite decking, the factors influencing these changes, and the practical considerations for installation and maintenance.

By understanding these aspects, you can ensure the longevity and aesthetic appeal of your composite deck.

What this article covers:

Does Composite Decking Expand and Contract?

Yes, composite decking both expands and contracts, a fact we at Ovaeda have observed through extensive testing and real-world experience.

This isn't a flaw, though, but a natural aspect of composite decking materials. Understanding and accommodating this behaviour is crucial for a deck that's not only visually appealing but also resilient and enduring.

Why Does Composite Decking Expand And Contract?

The expansion and contraction of composite decking are rooted in its composition. Made from a blend of wood fibres and plastics, these materials are inherently responsive to temperature fluctuations.

When the thermometer climbs or falls, the decking reacts by expanding or contracting. This reaction is a fascinating interplay between the natural and synthetic components of the decking, a phenomenon we've closely studied over the years to ensure the best performance of our products.

What Causes Composite Decking To Expand?

According to our research, heat is the primary catalyst for the expansion of composite decking. On warm, sunny days, both the plastic elements and the wood fibres within the decking start to expand.

This expansion is a natural response to the increase in temperature. The extent of this expansion can vary, influenced by several factors.

The type of plastic used in the composite mix, for instance, can affect the rate of expansion. Similarly, the density and type of wood fibres play a role.

In our experience, higher-quality decking materials and heat resistant composite decking tend to have more controlled and uniform expansion rates. We've seen various degrees of expansion across different products, but with proper installation and spacing, this is a manageable aspect of composite decking.

We always recommend choosing a high-quality composite decking material. This not only makes a difference in the rates of expansion but also when it comes to composite decking fading.

What Causes Composite Decking To Contract?

Contraction occurs when temperatures drop, particularly affecting the plastic components of composite decking. As the weather cools, these materials tend to shrink. This contraction is as natural and expected as expansion.

does composite decking shrink

During installation, it's important to consider this characteristic to avoid potential problems like buckling or the creation of gaps between boards.

The rate of contraction can be influenced by external factors such as ambient moisture levels and the specific blend of materials used in the decking. High-quality composites are designed to minimize these changes, ensuring stability and longevity.

Cooler and wetter weather can also make composite decking slippery in winter under certain conditions, so make sure to be mindful.

Why Is It Important to Keep Composite Decking Expansion and Contraction in Mind?

When it comes to installing composite decking, paying attention to expansion and contraction is crucial. It's not just a minor detail; it's a key aspect that can significantly impact the safety, durability, and overall appearance of your deck.

Safety First

First and foremost, safety is a major concern. If decking boards are installed without proper spacing to accommodate expansion and contraction, they can push against each other.

This pressure can cause the boards to warp, lift, or even create trip hazards. Especially in areas where foot traffic is high, ensuring that each board has enough room to move is essential for maintaining a safe, flat surface. 

Durability And Longevity

Durability is another critical factor. A deck is an investment, and naturally, you want it to last. When expansion and contraction are not taken into account, composite decking warping is a possibility and the boards can start to crack or split over time.

does composite decking expand and contract

This not only affects the deck's appearance but also its structural integrity. By allowing for these natural movements, you're essentially extending the life of your deck, ensuring it remains strong and intact for years to come.

Aesthetics And Appearance

The overall look of your deck is also at stake. Improper installation can lead to unsightly gaps or, conversely, boards that are squeezed too tightly together. Both scenarios can detract from the clean, smooth look of your decking.

By accounting for expansion and contraction, you maintain the aesthetic appeal of your deck, keeping it looking as good as new.

Avoiding Costly Repairs

Ignoring expansion and contraction can lead to costly repairs down the line. If boards warp or crack, replacing them can be expensive and time-consuming. It's much more efficient to install the decking correctly from the start, with an understanding of how the materials will behave in different temperatures.


While composite decking does expand and contract, this shouldn't be a cause for concern. With the right installation techniques and a bit of know-how, you can enjoy a stunning, durable deck that withstands the test of time and the whims of the weather.

At Ovaeda, we're committed to providing you with not just decking solutions, but also the knowledge to make the most of them. So if you're looking for composite decking that's built to last no matter the temperature, we've got you covered.

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