When choosing between the different types of decking materials, there are many different factors to consider.
How long will the boards last? How much maintenance will they require? Are they susceptible to mould and rot?
These are all important things to think about whilst you make your decision, but there is another important question that can sometimes be overlooked.
How much does the decking material expand and contract?
In this article, we’ll take a look at how much composite decking expands and contracts, and what effect that can have on your decking boards. We’ll also examine the other types of decking material to see how they compare to composite when it comes to expansion and contraction.
What Is Composite Decking?
Composite decking is made using recycled wood fibres, plastic polymers, and a bonding agent. This mixture of composite decking materials is melted through a process of co-extrusion and then passed through a ‘die’ in order to shape it into composite deck boards.
Due to the materials used to make it, composite decking is far more durable than wood decking and is also very resistant to damp, rot, and insects. This gives it great longevity meaning that composite decking boards last a lot longer than wooden decking boards.
As they need to be replaced less often and are made with recycled materials, composite deck boards are also environmentally-friendly. Our composite decking products are made with up to 95% recycled materials and FSC-certified wood.
Composite also requires far less maintenance than traditional wooden boards and doesn’t need to be stained, painted, or sealed. This means that installing a composite deck will save you time and money in the long term.
Why Does Composite Decking Expand and Contract?
Composite decking expands and contracts as temperatures fluctuate. Both plastic and wood flex a certain amount when temperatures rise or drop. Wood expansion and contraction are also affected by how much moisture has been absorbed by the decking boards.
As composite decking boards are very water-resistant, they don’t tend to absorb moisture easily. This means that the main factor affecting contraction and expansion in composite deck boards will always be temperature.
Although uncapped composite boards are resistant to water absorption, capped decking boards are even more so. However, this doesn’t have much of an effect on the rate of expansion and contraction.
The small amount of water that can be absorbed by uncapped boards does not cause them to expand and contract more than capped boards.
What Causes Composite Decking To Expand?
When temperatures rise, composite decking experiences thermal expansion. This causes the boards to expand slightly during warm weather.
Quality composite decking is designed to have enough flexibility to withstand these expansions without the integrity of the boards being compromised. This means that periods of thermal expansion will not reduce the lifespan of composite decking or make it less durable.
Unlike wooden boards, composite deck boards don’t expand when they get wet. This is one of the many benefits of composite as a material when compared to natural wood or pressure-treated wood.
Although thermal expansion shouldn’t be much of an issue, there are some ways of mitigating it. For example, if your boards are a dark colour, they will absorb heat more quickly and expand slightly more than if they were a lighter colour.
What Causes Composite Decking To Contract?
Composite decking contracts when exposed to low temperatures. This is often referred to as shrinkage and is caused by the cells in the wood fibres and plastic pulling closer together.
Contraction occurs within a known tolerance, and composite boards like ours are manufactured to withstand contractions within these tolerances.
As composite decking is water-resistant it doesn’t experience the same rates of contraction as wooden boards do during low temperatures. Wood decking absorbs water which then freezes, causing it to contract much more significantly than composite does.
Does It Matter If Composite Decking Expands and Contracts?
So, we’ve established why and how composite decking expands and contracts. You may now be wondering if this actually matters.
As the rate of contraction and expansion in composite decking materials is fairly minimal when compared to other materials, it may seem like a trivial issue. However, there are still several things that will be affected by the slight contraction and expansion of composite boards.
Safety
One thing that may be a concern due to expansion and contraction is safety. If nails and screws are used to secure decking boards in place, then there is a risk they will be loosened by expansion and shrinkage.
This may cause damage to the boards and could also be a safety concern if the nails or screws are out of place. This may make the boards less secure and could also pose an injury risk.
If the screws and nails are fully intact and secure, this shouldn’t be much of an issue. However, the best way of removing this risk is to use grooved decking boards.
Grooved decking boards don’t require nails or screws to be secured in place. Instead, they are secured using hidden fasteners and clips. These are designed to withstand expansion and contraction and won’t pose any safety risks.
Installation
Another factor that may be affected by contraction and expansion is the installation process. A small amount of shrinkage won’t be an issue, but expansion can make the installation process difficult.
If the boards expand, they become harder to cut to the right size as the measurements will be slightly off. This means that it’s best to install composite boards when temperatures are lower, such as early in the morning.
If temperatures get too high whilst installing the boards, you should pause the process and start again the next morning.
Proper Deck Board Spacing
As composite boards expand and contract, proper deck board spacing is very important. Many people install decking with the boards touching each other as they think it looks more aesthetically pleasing.
However, failure to leave the right amount of space in between them can have several negative consequences.
Contraction
If the boards are too far apart, the gaps will become even bigger when they contract during low temperatures. This can be a safety hazard for people walking across the deck.
Expansion
If the boards are too close together, friction could damage the boards when they expand during high temperatures. In some extreme cases, this could lead to the boards warping, twisting, splitting, cracking or even rising away from the substructure.
The correct amount of space that should be left in between the boards during installation is between 3mm and 6mm. This will ensure that your boards can withstand the pressures of contraction and expansion, which will help to maintain their durability and longevity.
How Does Composite Decking Compare To Other Decking Materials?
Although composite decking is prone to expansion and contraction, it performs better when it comes to this metric than many other types of decking.
How much a particular type of decking expands and contracts may not be one of the first things you consider when choosing decking, but it is important.
Let’s take a look at the three other most popular types of decking, which are wood, UPVC and aluminium, to see how they compare to composite when it comes to contracting and expanding.
Wood
Wood is the decking material that is most affected by contraction and expansion. The main reason for this is that it absorbs a lot of water. The only way of mitigating this is to seal and re-seal wooden boards annually to try and limit their rate of water absorption.
During low temperatures, the water inside wooden boards freezes, causing them to expand. This leads to splintering and cracking. When temperatures are high, the water inside the boards quickly evaporates, which causes them to contract.
This is one of the reasons that wooden decking has such poor longevity. After a few years of hot summers and cold winters, the boards will most likely be splintered, cracked and warped. This means they will either need to be repaired or replaced, which is costly and time-consuming.
If the boards are left in this condition, they will quickly become an eyesore and will also start to be hazardous. Split and splintered wooden decking can result in sharp edges which pose a safety risk.
UPVC
UPVC decking is made of 100% plastic which means it contracts and expands far less than wood decking. However, as with composite boards, UPVC boards will still expand and contract slightly depending on the temperature.
The main method of accounting for this in UPVC decking is the same as it is for composite. The right amount of spacing in between the boards is vital to ensure that they don’t become damaged or unsafe when they expand and contract.
Lighter-coloured boards will absorb less heat during warm weather. Divider or splitter boards can also be placed in between the boards to prevent any friction from occurring when they change size.
Aluminium
Aluminium decking doesn’t experience much contraction or expansion in response to temperature changes. For this reason, it is used in the construction of structures where warping and bending cannot be risked.
Unlike a composite decking board, an aluminium board doesn’t need to have a space between it and the next board to avoid damage. Aluminium decking boards can safely be in contact with each other even during high temperatures.
This is one of the reasons that aluminium decking has such longevity and rarely needs to be replaced. However, there are many other downsides to aluminium as a decking material when compared to composite.
FAQs
What happens if I install composite boards without leaving a gap between them?
If you install composite boards without leaving any gaps between them, they can be damaged when they expand and pose a safety risk when they contract. Improper deck board spacing will also mean that water can’t drain away from the boards properly.
Do I need to leave a gap between a composite deck and my house?
When installing a composite deck, you should leave a gap of between 5mm and 15mm between the edge of the deck and your house. This will allow proper water drainage to occur during wet weather, as well as proper drainage of meltwater from snow.
Do composite deck boards warp?
It’s highly unlikely that composite boards will warp as they are very water-resistant, unlike wood decking. However, they can sag or buckle if the right amount of space isn’t left between them during installation.
How long does a composite deck last?
Generally, composite decks should last between 25 and 30 years. There is no maintenance required in order to maintain their longevity, and the lifespan won’t be affected by the minimal amount of shrinkage and expansion that occurs due to weather conditions.
Final Thoughts
Although composite decking does expand and contract, it shouldn’t be much of an issue as long as the boards are installed properly with the right amount of spacing.
When compared to other decking materials such as wood, composite has a clear advantage due to its water resistance. This means that shrinkage and expansion are fairly limited and won’t reduce the longevity of the boards.
In climates where temperatures fluctuate constantly, such as the UK, this is an important factor to consider. Clearly, composite decking is one of the best choices when it comes to contraction and expansion.
Comments (27)
“Great article! It’s important to consider all aspects when choosing a decking material, including how much it expands and contracts. The information provided about composite decking’s durability and resistance to elements is helpful. I’m curious about the purchasing process for this product and would love to hear more about it. Overall, this article has given me a better understanding of composite decking and its benefits. Thank you for sharing!”
“Great article on the important factor of expansion and contraction in decking materials. It’s often overlooked but can have a big impact on the longevity of your deck. I appreciate the comparison between composite and other materials, and it’s clear that composite is a durable and low-maintenance option. I’m now curious about how to purchase composite decking and will be looking into it further. Thanks for the informative read!”
“Great article on the importance of considering expansion and contraction when choosing decking materials. I found it very informative and it’s definitely something to keep in mind. I’m curious about the purchasing process for composite decking – is it readily available or do you have to order it? Overall, a helpful and well-written piece.”
“Great article! I never considered how much decking material can expand and contract, but now I know it’s an important factor to consider. I appreciate the breakdown of composite decking and its durability compared to other materials. I’m curious about purchasing composite decking now, but I’m not sure where to start. Maybe some tips on where to find reputable suppliers or brands would be helpful. Overall, very informative and well-written piece.”
This article provides valuable information on an often overlooked aspect of choosing decking materials – expansion and contraction. It’s important to consider this factor in order to ensure the longevity of your decking boards. Composite decking seems to be a durable and low-maintenance option, but I would like to know more about where to purchase it and what other customers’ experiences have been. Overall, a helpful read for anyone considering composite decking.
“Great article on an often overlooked aspect of choosing decking materials – expansion and contraction. It’s important to consider this factor, especially in areas with extreme weather. I appreciate the comparison of composite decking to other materials and the explanation of its durability. I’m now curious about how to purchase composite decking and will do some further research. Thanks for the informative read!”
“Great article! I never thought about the expansion and contraction of decking materials before. It’s definitely an important factor to consider when making a decision. I’ve been considering composite decking for its durability and resistance to rot, but I’m curious about the purchasing process. Any tips or recommendations? Thanks for the informative read!”
As an expert in composite building materials, I can attest to the importance of considering expansion and contraction when choosing a decking material. While factors like durability and resistance to rot are crucial, the potential for expansion and contraction can greatly impact the longevity and overall performance of your decking boards.
Composite decking, with its unique combination of recycled wood fibres, plastic polymers, and bonding agents, is known for its durability and resistance to moisture and insects. However, it is important to note that even composite decking can expand and contract due to changes in temperature and humidity. This can lead to warping, buckling, and even cracking of the boards over time.
In comparison, traditional wood decking is more prone to expansion and contraction, which can result in splinters, warping, and overall deterioration. Other decking materials, such as PVC and aluminum, may have less movement but can still be affected by temperature changes.
Therefore, when considering all the factors in choosing a decking material, it is crucial to also factor in the potential for expansion and contraction. Composite decking, with its impressive durability and resistance to moisture and insects, is a great option for those looking for a low-maintenance and long-lasting decking material. However, proper installation and maintenance are still key to minimizing the effects of expansion and contraction.
Overall, it is important to thoroughly research and consider all aspects of a decking material before making a decision. As an expert in composite building materials, I highly recommend taking into account the potential for expansion and contraction to ensure the best performance and longevity of your decking boards.
“Great article! I never considered how much decking materials can expand and contract. This is definitely an important factor to consider when making a decision. I appreciate the comparison between composite and other materials. I’m interested in purchasing composite decking, but I’m not sure where to start. Any recommendations on where to buy it? Thank you for the helpful information!”
This article is a great resource for anyone considering composite decking. It covers an important aspect that is often overlooked – how much the material expands and contracts. It’s helpful to see a comparison with other types of decking as well. However, I have a question about purchasing composite decking. Do you have any tips or recommendations on where to buy it? Thank you for the informative article.
“Great article on the important factor of expansion and contraction in decking materials. It’s often overlooked but can have a big impact on the longevity of the boards. I appreciate the comparison to other types of decking and the explanation of how composite decking is made. I’m now considering composite for my own deck, but I’m wondering where I can purchase it. Any recommendations or personal experiences with purchasing composite decking would be helpful. Thanks!”
This article provides valuable information on an often overlooked aspect of decking materials – their expansion and contraction. It’s important to consider this when making a decision, and this article does a great job of comparing composite decking to other materials. I would love to know more about where to purchase this product and how to ensure I’m getting the best quality. Thank you for sharing this informative piece.
“Great article on the often overlooked aspect of decking material – expansion and contraction. As someone who is currently in the process of choosing decking for my backyard, this was very informative. I appreciate the comparison to other materials and the explanation of how composite decking is made. My only question now is where can I purchase this durable and resistant product? Thank you for shedding light on this important factor in decking decisions.”
This article provides valuable information on an often overlooked aspect of choosing decking materials – expansion and contraction. It’s important to consider this factor in order to ensure the longevity of your deck. I appreciate the comparison of composite decking to other materials and the explanation of its durability and resistance to common issues like rot and insects. I would love to know more about where and how to purchase this type of decking.
“Great article on the important factor of expansion and contraction in choosing decking materials. As someone considering composite decking, I appreciate the explanation of the materials and their durability. However, I’d love to know more about how to purchase this type of decking and if there are any specific brands or factors to consider. Overall, a helpful and informative read for anyone in the market for decking options.”
Thank you for your comment! As an expert in composite building supplies, I can assure you that choosing the right decking material is crucial for long-term durability and performance. In terms of purchasing composite decking, I would recommend looking for reputable brands that offer a warranty and have a proven track record in the market. It’s also important to consider factors such as the type of composite material used, the color and texture options, and the overall maintenance requirements. Overall, I’m glad you found this article helpful and informative in your search for the perfect decking option.
“Great article on the importance of considering expansion and contraction when choosing decking materials. I’ve been considering composite decking for its durability and resistance to rot, but wasn’t aware of how much it can expand and contract. It would be helpful to know where to purchase this product and if there are any specific brands that have better expansion and contraction properties. Overall, a valuable read for anyone looking to invest in a long-lasting decking option.”
Thank you for your comment! As an expert in composite building supplies, I can definitely attest to the importance of considering expansion and contraction when choosing decking materials. Composite decking is a great option for its durability and resistance to rot, but it’s important to also take into account its expansion and contraction properties.
In terms of where to purchase composite decking, there are many reputable suppliers that offer a variety of brands with different expansion and contraction properties. It’s always a good idea to do your research and compare different brands to find the best fit for your specific project. Some popular brands known for their minimal expansion and contraction include Trex, TimberTech, and Fiberon.
Overall, I agree that this article is a valuable read for anyone looking to invest in a long-lasting decking option. It’s always important to consider all factors when making a decision, and understanding how a material will react to changes in temperature and weather is crucial for ensuring a successful and long-lasting project. Thank you for sharing your thoughts and bringing attention to this important aspect of decking materials.
“Very informative article! I never thought about how much decking material expands and contracts until now. It’s great to know that composite decking is not only durable and resistant to rot, but also has minimal expansion and contraction. This definitely makes it a top contender for my decking choice. I’m curious about purchasing composite decking, do you have any recommendations on where to buy it? Thanks for the helpful information!”
“Great article on composite decking and its expansion and contraction properties. It’s definitely an important factor to consider when choosing decking materials. I’m curious about purchasing composite decking – do you have any recommendations or tips on where to buy it? I’ve heard great things about its durability and resistance to rot and insects. Looking forward to your insights!”
“Great article on the importance of considering expansion and contraction when choosing decking materials. I’ve been researching composite decking and this was really helpful in understanding its durability and resistance to elements. I’m curious about the purchasing process for composite decking, as I’m looking to invest in a long-lasting option for my deck. Thanks for the informative read!”
“Great article on an important factor to consider when choosing decking materials. I appreciate the comparison between composite and other types of decking in terms of expansion and contraction. However, I am curious about the purchasing process for composite decking. Is it widely available and easy to find? Any tips on where to purchase it? Thanks for the informative read!”
“Thank you for this informative article on composite decking expansion and contraction. It’s often overlooked but an important factor to consider when choosing decking materials. I appreciate the comparison to other types of decking and the explanation of how composite decking is made. I’m now curious about how to purchase composite decking and will do further research. Overall, great job on breaking down this important aspect of decking materials.”
“Great article on the importance of considering expansion and contraction when choosing a decking material. I appreciate the comparison to other types of decking and the explanation of composite decking’s durability. I’m curious about where to purchase this type of decking and if there are any specific brands or factors to consider when making a purchase. Overall, a helpful and informative read for anyone in the market for decking.”
“Great article on the important factor of expansion and contraction when choosing decking materials. It’s reassuring to know that composite decking is not only durable and resistant to various elements, but also has minimal expansion and contraction. As someone looking to purchase decking, I appreciate the comparison to other materials and the explanation of the manufacturing process. This has definitely helped me in making my decision. Thank you for the informative read!”
This article provides valuable information about the expansion and contraction of composite decking, which is an important factor to consider when choosing the right decking material. It also compares composite decking to other types of decking materials in terms of durability and resistance. However, I have a question about purchasing the product. Can you provide any tips or recommendations on where to buy high-quality composite decking? Thank you.
“Great article on the often overlooked aspect of expansion and contraction in decking materials. As someone who is considering composite decking for my own home, I found this information very helpful. However, I’m wondering where I can purchase this type of decking and if there are any reputable brands you can recommend. Overall, a well-written and informative piece. Thank you for shedding light on this important factor in decking material decision-making.”