Does Composite Decking Shrink? What Homeowners Need to Know Before Installation
One of the most common questions homeowners ask before investing in a new outdoor space is simple but important: Does composite decking shrink? It’s a fair concern. Decking lives outdoors, exposed to sun, rain, and fluctuating temperatures, and nobody wants gaps, warping, or movement ruining the finished look.
The good news is that composite decking behaves very differently from traditional timber. While no outdoor material is completely immune to movement, modern composite decking is engineered for stability. Understanding how it reacts to temperature changes, how spacing works, and why correct installation matters will help you build a deck that looks good for years to come.
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Thu, 28 Jul 2026
Does Composite Decking Shrink Over Time?
So, let’s address the question directly: Does composite decking shrink once it’s installed?In short, composite decking does not shrink in the same way natural timber does. Timber boards contain moisture, which evaporates over time, causing noticeable shrinkage, splitting, and cupping. Composite decking, on the other hand, is manufactured from a controlled blend of materials that are designed to be far more dimensionally stable.
That said, composite decking can experience minor expansion and contraction due to temperature changes. This is normal and expected. Unlike timber, this movement is predictable and accounted for during installation, which is why correct spacing is such a critical part of the process.
Does Composite Decking Shrink: What Causes Deck Boards to Move?
All outdoor decking materials respond to environmental conditions. Heat causes materials to expand, while cooler temperatures can lead to slight contraction. Composite boards are designed to handle this movement evenly across the length of the board, rather than shrinking unevenly like wood.
This is why you’ll often hear installers talk about board spacing for deck projects. Spacing allows boards to expand without pushing against each other, reducing stress on fixings and preventing surface distortion. When installed correctly, this movement is barely noticeable and does not affect the overall appearance or performance of the deck.
Does Composite Decking Shrink: Why Board Spacing for Decks Is So Important
Proper spacing for deck boards isn’t just about allowing for temperature movement. It also plays a key role in drainage, airflow, and long-term durability. Without adequate spacing, water can pool on the surface, debris can build up, and boards may experience unnecessary pressure during hot weather. Correct board spacing using composite decking gap inserts ensures rainwater drains away efficiently and allows air to circulate beneath the deck. This helps keep the substructure dry and supports the long lifespan that composite decking is known for.
How Much Gap Between Deck Boards Is Recommended?
A very common follow-up question to “Does composite decking shrink?” is how much gap between deck boards should be left during installation. The answer depends on the specific composite decking system being used and the fixing method. In general, composite decking requires a consistent, small gap between boards to accommodate expansion. Many homeowners also ask how much of a gap between deck boards is needed to avoid future problems. Too little space can cause pressure during warm weather, while too much can affect the deck’s appearance.
This is where planning tools become incredibly useful. The EnviroBuild decking calculator helps you accurately plan board layout, spacing, and quantities before installation, reducing guesswork and helping you get the details right from the start.
Composite Decking vs Timber: Shrinkage Compared
If you’ve ever owned a timber deck, you’ve probably seen firsthand how dramatically wood can shrink over time. Gaps widen, boards twist, and fasteners loosen as the timber dries out. This is one of the main reasons homeowners move away from wood when deciding between decking, paving, or upgrading an existing outdoor area.
Composite decking offers a much more stable alternative. While it still needs correct spacing, the movement is minimal and controlled. When comparing paving or decking, composite decking often sits in the middle ground: more forgiving and warmer underfoot than paving, but far more stable than timber decking. This predictability is a major advantage for anyone looking for a clean, consistent finish year after year.
Pros and Cons of Composite Decking
When weighing up the pros and cons of composite decking, stability is firmly in the “pro” column.
On the plus side, composite decking does not dry out, split, or shrink like timber. It requires less maintenance, holds its shape well, and delivers a more uniform appearance over time. The controlled expansion and contraction mean you know what to expect if the deck is installed correctly.
On the downside, composite decking does require careful installation. Ignoring spacing guidelines or failing to plan board layout properly can lead to issues that are easily avoided with the right preparation.
An Honest EnviroBuild Composite Deck Review: What Homeowners Actually Experience
A review of composite decking EnviroBuild products are available on Google as well as Trustpilot.
Here are what some of our happy customers have to say:
Darren:
“The team at EnviroBuild were really helpful, and sourced everything I needed. In particular Chris James on the sales team, who was able to answer any questions that we had, provide details on the available products and who even managed to get us a little discount. Thanks to his work we even cancelled an existing order with another company and got all we needed through one place at very competitive rates.
We had great service and delivery was excellent too.
We love the composite decking and joists, they are easy to cut and work with and the hidden fixings make it look amazing!
We are hoping to get many years of use out of our garden now without the fear of rotting as our previous wooden deck did.
Big thumbs up from us!”
Victoria:
“This product is fantastic. It has totally transformed my outdoor space and I would highly recommend this over your standard wood decking. I chose to go two tone and put the darker colour around the edges to really set it off. I still have a little more work to complete the garden but am absolutely delighted with how it's come on. Envirobuild are a fabulous company and were very quick to answer my queries when I was designing this project. My decking has gone in over several stages and each time I have found their customer service to be impeccable. You cannot go wrong with Envirobuild!!”
Jaroslaw:
“As always great customer service and great product (Frontier decking) from Envirobuild. Ava from sales department was very helpful (and very patient) :)
I had to change my order couple of times and she was always happy to send me new qoutes and answers all my questions.
Also warehouse collection was arranged smoothly so I didn't waste much time over there.
Keep up good work...”
This reliability and friendly customer service is a big reason why our composite decking continues to grow in popularity for patios, balconies, and garden spaces.
Installation Matters More Than You Think
Even the best materials won’t perform well if installed incorrectly. Understanding the correct spacing, fixings, and layout is essential. Using planning tools like the EnviroBuild decking calculator helps ensure you order the right amount of material and apply the correct spacing from day one. This level of preparation is especially useful if you’re still deciding between decking options, as it allows you to visualise costs, layout, and long-term performance before committing.
Does Composite Decking Shrink? Final Thoughts Before You Build
To come back to the original question: Does composite decking shrink? Not in the way timber does. Composite decking is designed to remain dimensionally stable, with only minor, predictable movement due to temperature changes. By following spacing guidelines and planning your layout carefully, you can enjoy a deck that looks great and performs reliably for years to come. When installed correctly, composite decking offers peace of mind, low maintenance, and a clean, consistent finish that’s hard to beat.
If you’re exploring options for your outdoor space, we provide composite decking, aluminium decking, fibre cement decking, 100% recycled plastic decking, composite cladding, aluminium cladding, composite fencing, porcelain paving, and the substructure systems that support them.
