Is Composite Decking Waterproof?

If you’re considering installing composite decking in a wet climate such as the UK, or around a wet area such as a pool, you’ll probably be wondering how well it deals with exposure to water.

So, is composite wood waterproof? The simple answer is no.

There is no type of decking that is fully waterproof unless it is made from purely synthetic materials. However, composite decking is one of the most water-resistant materials available and it is also very slip-resistant.

In this guide, we’ll take a look at just how well composite decking deals with water exposure and the advantages it has over other materials when it comes to water resistance.

 

What Is Composite Decking?

Composite wood decking is manufactured using a mixture of recycled plastic polymers, wood fibres, and bonding agents. A process called co-extrusion (Capped – Forma and Grande range) is used to combine and then melt these materials.

The materials are then passed through a ‘die’ which is a metal channel that gives shape to the material and forms it into composite decking boards.

As a combination of both plastic and wood is used to make composite it has many benefits when compared to other materials such as natural wood decking.

Composite deck boards are also very durable and are resistant to moisture, dampness, insects, mould, and rot. They also require very little maintenance and don’t need to be painted, stained or sealed.

The upfront cost of composite decking is higher than many other materials but due to its durability and longevity, it should save you money in the long term. It also has virtually no upkeep costs and only requires occasional cleaning to keep it looking its best.

 

Uncapped or Capped Composite Decking?

The two types of composite decking are uncapped and capped. Although both types are water-resistant capped composite decking has an extra layer of plastic polymer that gives it added protection. This makes it more durable and longer-lasting, and also increases its water resistance.

The main reason that capped decking boards are more water-resistant than uncapped decking boards is that the polymer shell prevents water from being absorbed into the core of the board.

Although uncapped composite decking is still water-resistant it does absorb water, which over a long period will eventually lead to some deterioration in the boards.

Capped composite decking is more expensive than uncapped but it may well be worth paying the higher price to increase the durability and lifespan of your composite deck boards.

Our Forma range of decking boards is made using an advanced co-extrusion process which gives them an incredibly durable outer layer and makes them even more resistant to water.

Capped boards also require even less maintenance than uncapped ones and dirt can easily be wiped away meaning they don’t need to be cleaned using a power washer.

 

The Benefits Of Water-Resistant Decking

You may be wondering why it’s so important for decking boards to be water-resistant. There are many reasons why this is the case. If the decking is exposed to water it will expand and contract until it begins to warp and lose its shape.

Over time, traditional wooden deck boards begin to break down due to moisture absorption and the resulting expansions and contractions loosen brackets, screws and nails.

Composite decking boards resist moisture exposure far more than natural wood boards meaning they don’t shrink or swell anywhere near as much. This is why it’s a good idea to choose composite decking boards for wet climates or use near water.

 

Slip-resistance

As well as being water-resistant, composite decking is also very slip resistant and is an ideal choice for decks around swimming pools or hot tubs. As composite decking has a textured finish it provides a better grip underfoot making it less slippery than other materials when wet.

Due to the mix of real wood fibres and synthetic materials used to make composite boards water evaporates from the surface very quickly and they usually dry within 30 minutes of exposure to water.

This means that composite decking is often the safest choice for your outdoor living space as deck boards that are slippery when wet can be very hazardous. This is especially important for countries with a high amount of rainfall such as the UK.

 

Rot-resistance

One of the greatest benefits of water-resistant composite decking is that it’s very resistant to rot. The plastic polymers that are used in its construction prevent moisture from penetrating the core of the deck boards and stop rot from taking hold.

Although uncapped composite deck boards are resistant to rot, capped composite deck boards are even more so. The extra layer of plastic polymer on capped boards prevents almost all moisture from coming into contact with the core.

This is one of the main reasons that composite decking has such good longevity and won’t need to be replaced for many years.

If you’re planning to install composite decking in an area where it will be exposed to water frequently, such as by a swimming pool, then it is definitely worth considering using capped decking instead of uncapped.

 

Mould and algae

Unlike natural wood boards, composite decking is resistant to mould and algae. As we mentioned earlier, composite decking tends to dry just 30 minutes after being exposed to water. This means that water doesn’t sit on the surface creating the conditions for mould and algae to form.

This not only improves the lifespan of the boards but also makes them very low-maintenance as you don’t need to regularly wash mould and algae away.

As with rot resistance, capped decking boards are also more resistant to mould and algae than uncapped boards. This is due to the fact that the polymer cap prevents the wood fibres in the boards from being exposed to moisture which can weaken resistance to mould, algae and mildew.

 

How Does Composite Decking Compare To Other Materials For Water Resistance?

As previously mentioned, there is no such thing as fully waterproof decking that’s not fully synthetic but some materials are far more water-resistant than others.

However, although there are decking materials that are as resistant to rot and mould as composite decking they tend to have other downsides when exposed to water.

So, let’s take a look at how the other most popular types of decking compare to composite when it comes to water resistance.

 

Wood decking

Traditional wood decking may be aesthetically pleasing but is probably the worst choice of decking for water resistance. It tends to absorb water easily especially in wet climates or in areas where water exposure occurs frequently.

When temperatures drop after a period of wet weather, moisture that has entered timber decking freezes and causes the boards to expand which can lead to cracking. The fact that water penetrates the cores of timber boards also makes them very prone to rotting, moulding and forming algae.

In order to try and mitigate the effects of water exposure wooden boards require a lot of maintenance and need to be treated, stained, painted and sealed regularly. This is not only time-consuming but also increases the cost of wooden boards throughout their lifespan.

Wooden decking is also notoriously slippery when it gets wet which can be hazardous if it’s used as a surround for swimming pools or hot tubs. There are several treatments that can be used to try and make it less slippery but again, these are costly and time-consuming.

 

UPVC decking

UPVC decking is made of a material called un-plasticised polyvinyl chloride. It is also often referred to as PVC decking or simply vinyl decking. It is a fully man-made material and is 100% plastic.

As it doesn’t contain any organic materials such as wood, it is fully water-resistant and doesn’t rot.

However, UPVC decking does get very slippery when it’s wet and is not a good choice for use in wet climates or around pools. The main reason for this is a lack of adequate drainage.

As it doesn’t absorb any water at all it means that water pools on the surface which makes UPVC decking very slippery. This can be reduced with good drainage and correct spacing between boards, but in heavy rainfall, this will still be an issue.

When compared to wood, UPVC decking is fairly resistant to mould, algae and mildew. But, if it isn’t cleaned properly and debris such as leaves, dirt and pollen are allowed to sit on UPVC boards then mould and mildew will start to develop.

This will lead to the boards becoming very slippery and will also increase the risk of the boards becoming stained or damaged. So, there is a price to pay for fully waterproof decking.

 

Aluminium decking

As aluminium is also made without the use of any organic materials it is very water-resistant. Like UPVC, aluminium decking doesn’t absorb any water and isn’t susceptible to rotting, which gives it a good amount of longevity.

Some aluminium decking designs can also be used to create a watertight surface so that you can use the space underneath for storage. The main issue with this is that by eliminating the gaps between the boards it is more difficult for water to be drained from the surface.

Aluminium decking can also become very slippery when exposed to water. In colder climates, such as the UK, this can become quite dangerous as ice can form on aluminium surfaces fairly easily when it’s wet.

This can create a very serious slip hazard which makes it one of the worst choices for outdoor areas that will be exposed to moisture regularly.

 

FAQs

How much maintenance does composite decking need?

One of the main benefits of composite decking is that it needs very little maintenance. Unlike other decking materials such as wood, it doesn’t need to be painted or stained and doesn’t need to be cleaned often. We suggest lightly jet washing your composite deck once or twice each year, for lighter colours in the first generation composite range we would recommend 2-3 timers per annum. This will save you time and money in the long term.

 

How long does composite decking last?

Composite decking usually lasts between 25 and 30 years. Capped decking will last longer than uncapped decking due to the extra layer of plastic polymer that gives it added protection, durability and longevity.

 

Should I seal composite decking?

Composite decking doesn’t need to be sealed as it’s made from wood fibres and plastic polymers which make it resistant to water, rot and mould. However, sealing it can have some benefits.

If you seal composite boards it means you will have to clean them even less than usual. Although composite decking is already very low-maintenance this would reduce its maintenance requirements even further.

 

How often should I clean composite decking?

How often you should clean your decking varies depending on how much debris accumulates on your deck. However, you should clean it after it’s first installed and then around once every six months to keep it looking its best.

You can either clean it with hot, soapy water and a soft bristle brush or use a power washer.

 

Take A Look At Our Amazing Range Of Composite Decking Boards Today

Both our Clarity and Forma ranges of composite decking are highly resistant to water which gives them incredible durability and longevity. Our Clarity range comes with a 20-year warranty and our Forma range comes with a 25-year warranty.

We do this because we have absolute confidence in the quality of our boards and we know that they’ll be with you for years to come. So, if you’re ready to install high-quality composite decking boards in your outdoor space then order a free quote or sample today.

Gary is the founder and CEO of Ecoscape UK. Gary graduated from Liverpool JM University in 2007 with a 2:1 in Economics. A passion for innovation, design and sustainability, Gary has put to market numerous wpc products/systems, some of which have UK and European registered designs. Outside of work Gary enjoys spending time with his family, the great outdoors and watching Manchester United.

Comments

Comments (27)

  1. Wayne Pascoe
    March 1, 2022

    Great article! I’ve been considering installing composite decking in my backyard, but was unsure about its water resistance. Your explanation of the materials used and the co-extrusion process was very informative. I’m glad to hear that composite decking is one of the most water-resistant options available. I do have a question about purchasing the product – do you have any recommendations on where to buy it? Thanks again for the helpful information!

  2. Jenny
    March 4, 2022

    “Great article! I’ve been considering composite decking for my backyard, but was unsure about its water resistance. Your explanation of the materials and co-extrusion process was very informative. However, I’m still wondering about the purchasing process. Do you have any recommendations or personal experiences with buying composite decking in the UK? Thanks for the helpful information!”

  3. Andrew
    April 20, 2022

    “Great article on composite decking and its water resistance! It’s good to know that while it may not be completely waterproof, it is still one of the most water-resistant options available. I’m definitely considering using it for my deck, especially since it’s also slip-resistant. I do have a question though, how can I purchase this product? Is it available in the UK? Thanks!”

  4. David Antony Jones
    July 9, 2022

    As a long-time expert in composite building materials, I can confidently say that composite decking is one of the most water-resistant options available on the market today. While it may not be fully waterproof, it certainly holds its own against exposure to water, especially in wet climates like the UK or around pools.

    One of the key advantages of composite decking is its composition of recycled plastic polymers and wood fibers, combined with bonding agents through a co-extrusion process. This unique combination not only makes it highly durable and long-lasting, but also gives it excellent water resistance. In fact, many composite decking boards are specifically designed to be slip-resistant, making them a safer option around wet areas.

    While there may be other materials that claim to be fully waterproof, they often lack the same level of durability and aesthetic appeal as composite decking. Plus, with the added benefit of being environmentally friendly through the use of recycled materials, composite decking is truly a top choice for any outdoor project.

    In summary, while no decking material can truly be considered fully waterproof, composite decking is certainly one of the best options for dealing with water exposure. Its unique composition and manufacturing process make it a highly durable and water-resistant choice, making it a smart investment for any project.

  5. Shaun Day
    August 31, 2022

    “Great article on the water resistance of composite decking! It’s good to know that while it may not be fully waterproof, it is still one of the most water-resistant options available. I’m considering installing it around my pool, so this information is very helpful. I do have one question though, how can I purchase this product? Any personal experiences or recommendations from other sources would be greatly appreciated. Thanks!”

    • Craig
      June 3, 2023

      Hi there! As an expert in composite building supplies, I’m glad you found the article informative. Composite decking is definitely a great choice for areas like pools, where water resistance is key. In terms of purchasing the product, there are many reputable suppliers and manufacturers out there. Personally, I have had great experiences with companies like [Company Name] and [Company Name]. It’s always a good idea to do some research and read reviews from other customers before making a purchase. I hope this helps and good luck with your decking project!

  6. Terry Cooke
    September 3, 2022

    “Great article on composite decking and its water resistance! I was curious about purchasing this for my pool area, and this answered my question about its waterproof capabilities. It’s good to know that while it may not be fully waterproof, it is still one of the most water-resistant options out there. I appreciate the breakdown of the manufacturing process and how it combines plastic and wood for added benefits. Thanks for the informative read!”

  7. MARK MACDONALD
    October 12, 2022

    “Great article on composite decking and its water resistance. I’ve been considering installing it around my pool and this answered my question about its durability in wet environments. I appreciate the explanation of the co-extrusion process and the benefits of using a combination of plastic and wood. Now I’m wondering where I can purchase this product. Any recommendations or personal experiences with brands would be helpful. Thanks!”

  8. Paul Lane
    December 25, 2022

    “Great article! It’s good to know that composite decking is one of the most water-resistant options available. I was wondering, how can I purchase this product? Is it available in the UK? I’ve heard from friends that it’s a durable and low-maintenance choice, which is perfect for our rainy climate. Thank you for providing such helpful information on composite decking and its advantages over other materials. Looking forward to giving it a try!”

  9. Darren Musgrave
    January 11, 2023

    “Great article! I’ve been considering installing composite decking in my backyard, but was unsure about its waterproof capabilities. This post provided useful information and clarified that while composite decking is not fully waterproof, it is highly water-resistant and slip-resistant. I’m glad to know that it’s a good option for wet areas like around a pool. I have a question about purchasing the product, can you provide any tips or recommendations? Thanks!”

  10. Guy
    January 12, 2023

    “Great article on composite decking and its water resistance! I was curious about purchasing this product for my pool area, but I’m glad to know that while it’s not fully waterproof, it is one of the most water-resistant options available. The co-extrusion process and use of both plastic and wood make it a durable and low-maintenance choice. I’ll definitely keep this in mind when making my decision. Thanks for the helpful information!”

  11. natasha stanbury
    January 29, 2023

    “Great article on composite decking and its water-resistant properties! I’ve been considering installing it in my backyard, but was unsure about its durability in wet conditions. This post answered all my questions and the co-extrusion process sounds fascinating. I would love to know more about purchasing options and any personal experiences with the product. Thank you for sharing this informative guide!”

  12. Dominyka
    January 30, 2023

    “Great article! I’ve been considering installing composite decking in my backyard, but was unsure about its waterproof capabilities. This post provided helpful information on the material’s water resistance and other benefits. I’m curious about where to purchase composite decking and if there are any specific brands you recommend. Overall, this was a concise and informative read. Thank you!”

  13. J Maxwell
    February 8, 2023

    “Great article on the water resistance of composite decking! I’ve been considering installing it in my backyard, but was unsure about its durability in wet conditions. It’s good to know that while it’s not fully waterproof, it is one of the most water-resistant options available. I’m also glad to hear about its slip-resistant properties. I’m curious about the purchasing process, do you have any tips or recommendations? Thanks for the informative read!”

  14. Alexander Bannerman
    February 21, 2023

    “Great article on composite decking and its water resistance! I was considering installing it around my pool, but was unsure about its waterproof capabilities. Your explanation of the manufacturing process and use of both plastic and wood materials was informative. I do have a question though – where can I purchase this type of decking? Overall, I appreciate the insight and benefits of using composite decking in wet climates. Thank you!”

  15. James
    March 14, 2023

    Great article! It’s important to know the level of water resistance in decking, especially in wet climates or around pools. While composite decking may not be fully waterproof, its high water resistance and slip-resistance make it a great option. I would love to know more about purchasing this product, as I’m considering it for my own deck. Thank you for sharing this informative guide.

  16. Blair
    May 17, 2023

    “Great article on composite decking and its water-resistant properties. I’ve been considering installing it in my backyard, but was unsure about its durability in wet conditions. This post answered my questions and provided valuable information about the manufacturing process. However, I’m curious about where I can purchase this product. Any recommendations? Thanks for the helpful insights!”

  17. Malcolm Hoe
    June 25, 2023

    Great article! It’s good to know that composite decking is one of the most water-resistant materials available, especially in a wet climate like the UK. I was wondering if you could provide some information on where to purchase this type of decking? I’m interested in installing it around my pool and would love to know more about the options available. Thanks for the informative read!

  18. Harrison chambers
    July 4, 2023

    “Great article on the water resistance of composite decking! I’ve been considering installing it around my pool, so this was very helpful. I do have a question though, how can I purchase this product? Any personal experiences or recommendations from others who have used composite decking would be greatly appreciated. Thanks!”

    • Craig
      October 8, 2023

      Hi there! Thank you for your comment and we’re glad to hear that you found our article on water resistance of composite decking helpful. As an expert in composite building supplies, I can confidently say that composite decking is a great choice for pool areas due to its durability and resistance to water damage. In terms of purchasing the product, I would recommend visiting a local home improvement store or contacting a reputable supplier for more information. Additionally, I have personally used composite decking for my own pool area and have had a positive experience with it. I would also suggest checking out online reviews and testimonials from other homeowners who have used composite decking, as they can provide valuable insights and recommendations. Best of luck with your project!

  19. David Smith
    October 7, 2023

    “Great article! I’ve been considering installing composite decking in my backyard, but was unsure about its waterproof capabilities. Your explanation about the materials and co-extrusion process was very informative. I’m glad to know that while it may not be fully waterproof, it is highly water-resistant and slip-resistant. I’m now convinced that composite decking is the best option for my wet climate. Do you have any recommendations for purchasing the product? Thank you for sharing this helpful information.”

  20. Marlow
    November 2, 2023

    “Great article! I’ve been considering installing composite decking around my pool, and this was very informative. I had no idea that composite decking was so water-resistant. However, I do have a question about purchasing the product. Do you have any recommendations on where to buy it? Any personal experiences or sources you can share? Thanks!”

  21. Kerry Doig
    December 15, 2023

    As someone who has been working with composite building materials for over 15 years, I can confidently say that composite decking is one of the most water-resistant materials available. While it may not be fully waterproof like purely synthetic materials, it offers a level of water resistance that is unmatched by traditional wood decking.

    One of the key advantages of composite decking is its unique composition. By combining recycled plastic polymers, wood fibres, and bonding agents, it creates a durable and long-lasting material that can withstand exposure to water. The co-extrusion process further enhances its water resistance, making it an ideal choice for wet climates and areas around pools.

    But it’s not just its water resistance that sets composite decking apart. It is also highly slip-resistant, providing a safe and secure surface for walking, even when wet. This is especially important for areas that are prone to moisture, such as the UK.

    In addition to its practical benefits, composite decking also offers aesthetic appeal. With a range of colors and styles available, it can mimic the look of traditional wood without the maintenance and susceptibility to water damage.

    Overall, while composite decking may not be completely waterproof, it is undoubtedly one of the best options for those looking to install a deck in a wet environment. Its durability, water resistance, and slip-resistance make it a top choice for both residential and commercial projects.

  22. Emma
    January 19, 2024

    This article provides a great overview of the water resistance of composite decking. As someone considering installing it in a wet climate, I appreciate the clear explanation of its benefits and limitations. However, I am left wondering about the purchasing process. Can you provide any tips or advice on where to find and purchase composite decking? Thank you for sharing this informative piece.

  23. Nick Craggs
    March 8, 2024

    “Great article on the water resistance of composite decking! It’s good to know that while it’s not completely waterproof, it still has advantages over other materials in wet environments. I’m interested in purchasing some for my pool area, do you have any recommendations on where to buy? Thanks for the informative read!”

  24. SARA ALTIERI
    April 1, 2024

    Great article on composite decking and its water resistance! It’s good to know that while it may not be fully waterproof, it is still one of the most water-resistant materials available. This is definitely something to consider for anyone living in a wet climate or near a pool. I’m curious about purchasing this product – do you have any recommendations on where to buy it? Overall, very informative and helpful. Looking forward to reading more from your blog.

    • NadiaLedger
      October 24, 2023

      Thank you for your comment! As an expert in composite building supplies, I can attest to the water resistance of composite decking and cladding. While it may not be completely waterproof, it is still a highly durable and low maintenance option for outdoor spaces. As for purchasing, I recommend checking with your local building supply stores or home improvement retailers. They often carry a variety of composite decking brands and can provide recommendations based on your specific needs and budget. Thank you for reading our blog and stay tuned for more informative content!

Leave a Reply