Capped vs Uncapped Composite Decking

If you're currently weighing up your options for a new decking installation, you’ll already know there’s no shortage of choice out there. And if you’ve joined the thousands of UK customers considering the advantages of composite decking, there’s a good chance the terms ‘capped’ and ‘uncapped’ composite have reared their heads once or twice during your research.

But what do these terms actually mean?

The good news is that this article will walk you through everything you need to know, helping you to ensure you’re fully up to speed and feeling confident as you plan your project.

From explaining what’s meant by capped and uncapped composite decking to comparing cost, performance, maintenance, aesthetics and more, we’ll cover it all. And yes, we’ll also answer the big question: do these differences really matter? (Short answer: yes, they do.)

According to the Oxford English Dictionary, the word ‘composite’ refers to something made from “several different things, parts or materials”.

And in the case of composite decking, the boards are exactly that. While traditional wood decking boards are cut from solid timber, modern composite boards, also known as wood plastic composites or WPC, are usually made from a mixture of plastic and natural wood fibres.

Boards also contain bonding agents that bind the materials together, along with pigments that allow manufacturers to produce decking in a wide choice of colours.

At Cladco, we offer two types of composite decking: Signature (uncapped) and ProDeck (capped). Both are made from recycled plastic and recycled hardwood fibres, and are excellent, reliable choices. Signature composite decking offers superb value, while ProDeck's capped design adds improved long-term performance and reduced upkeep.

Now that we understand what composite decking is, we can start to focus on what capped and uncapped decking boards are and why the distinction really matters.

When it comes to composite products, such as decking and cladding boards, the term ‘capped’ refers to the durable protective shell-like surface layer. Think of it like the thin layer of enamel on your teeth. 

This capped surface usually takes the form of a strong polymer coating, designed to provide additional protection from everyday wear and tear, such as scrapes and scratches. Not only that, but capped composite boards also offer enhanced resistance to staining, colour fade, mould growth and water absorption.

And it’s not all about protection. Many homeowners would rather spend their spare time enjoying their decking rather than having to worry about the arduous process of sanding, staining or oiling boards, as you have to with wood decking. With capped composite decking, you can enjoy a low-maintenance alternative to timber, which, aside from a quick wipe clean with warm, soapy water now and again, requires little effort to look after.

These advantages help explain why the popularity of capped composite decking has continued to grow over recent years, even in a market where timber has long been the go-to choice.

How long does capped composite decking last?

Ultimately, the lifespan of any decking board depends on several factors, including the quality of the materials used, where the boards are installed, and how they’re maintained over time. In terms of Cladco’s range of capped composite decking boards, our ProDeck range is expected to far outlast the warranty of 15 years, provided the boards have been installed as advised in our installation guide.

It’s important to stress that while many manufacturers make confident predictions about the longevity of their decking boards, since composite decking has only been widely available in the UK for around 12 years, it is hard to truly know how long the boards will last. So it’s worth bearing this in mind when making your final decision.

After learning about capped boards, you can probably already work out what uncapped composite decking is. And you’d be right. It really is as straightforward as it sounds.

An uncapped board is a composite decking board made from a mixture of plastic and wood fibres, but without the protective polymer cap.

If you’re reading this and thinking, “Hang on. Why wouldn’t I want a protective cap if it offers extra protection?” the answer is simple: cost.

Per square metre, uncapped composite decking will typically cost around £10 to £15 less than its capped alternative. While this may not sound like a huge difference on its own, if you’re working on a large decking project, those costs add up quickly, making uncapped composite a very appealing choice for many.

Not only do uncapped boards look great and come in a wide range of colours, but they are often made using the same materials as their capped counterparts. The only real difference is the absence of the extra layer.

This is where the limitations begin to show. Because the boards are uncapped, you’ll need to stay on top of cleaning to prevent the build-up of dirt, causing potential stains and general deterioration. Uncapped composite is more susceptible to moisture, colour fade and staining.

Whether it’s spilt drinks, food and sun cream or marks from tree sap, leaf litter or algae, uncapped decking needs prompt cleaning to keep it looking its best. This applies even during the winter months when your garden decking may be the last thing on your mind.

How long does uncapped composite decking last?

It won’t come as much of a surprise to learn that capped composite decking has a longer life expectancy than uncapped composite decking. As previously mentioned, the life expectancy of your decking comes down to several factors, such as how well it’s looked after, where it is installed and what materials are used to manufacture the boards. At Cladco, our uncapped Signature composite decking range is expected to far outlast its 10 year warranty, providing the decking is installed as advised in our installation guide.

As mentioned earlier, when discussing the lifespan of capped and uncapped composite boards, it’s important to remember that composite decking is still a relatively new material in the UK. The full longevity of the composite is yet to be truly known. For this reason, companies offering 25 year warranties may be doing so without real-life evidence to support their claims. Something worth bearing in mind.

As with most products that offer added features, capped composite is generally more expensive than uncapped decking, making uncapped a great choice for budget-conscious homeowners. We’ve already looked briefly at the differences in cost per square metre, but to give a clearer comparison, let’s look at Cladco’s own ranges: Signature and ProDeck.

Based on 2.4m boards with a coverage of 0.36m², our uncapped Signature composite decking costs around £14 per board, which works out at roughly £39 per square metre.

Cladco’s capped ProDeck composite decking costs around £18 per board, coming to approximately £50 per square metre.

While capped composite is the more expensive option upfront, this doesn’t tell the whole story. Once you factor in expected lifespan and the long-term cost and effort involved in keeping the boards clean, the comparison shifts.

Capped composite requires far less maintenance throughout the year, which not only saves time but also reduces maintenance costs and the frequency you need to buy cleaning or colour-restoring products. Uncapped decking boards, on the other hand, tend to weather more quickly, so they may require more investment to maintain.

So, if you’re planning a composite decking installation for your forever home and want a material that will last many years, the cost per year of use brings the two options much closer than you might first expect.

When it comes to aesthetic appeal and appearance, many composite decking boards, including our Signature and ProDeck ranges, feature a dual-sided design. One side features a grooved surface, while the other often has an authentic woodgrain-effect finish. This means that, depending on which side you install facing up, you can achieve a different look for your project.

In terms of the differences between capped and uncapped boards, capped decking, such as ProDeck, tend to have a slightly smoother surface texture because of the added polymer shell. This gives capped boards a more premium feel, though both types offer a clean and attractive finish.

Both capped and uncapped decking boards come in a wide variety of colours, too. While traditional wooden decking requires staining or painting to achieve the look you want, with composite decking, the colour pigments are added to the boards during the manufacturing process. This means you can choose from classic earthy tones like teak and sandstone, or more contemporary shades, including light grey and charcoal.

Capped Composite Decking

If you’ve reached this section and are now starting to feel convinced that a capped composite is the right option for you, firstly, good choice! But it is also important to look at some of the limitations or potential problems that customers sometimes encounter when installing capped composite decking boards.

As we covered in the aesthetics section, the protective shell on capped boards gives them a smooth, premium finish that feels comfortable underfoot. However, on some capped products, this smoother surface can become slippery when wet. This is more noticeable in busy walkways or when the smoother woodgrain-effect surface is used instead of the narrow grooves, which offer improved traction.

At Cladco, this isn’t an issue you need to worry about. Our ProDeck boards are independently tested for slip resistance and achieve a low-slip rating even in wet conditions, provided they’re installed with the grooves running perpendicular to the direction of travel. For context, anything scoring above 36 is classed as having ‘low slip potential’. After eight rounds of testing in wet conditions, ProDeck achieved a mean score of 43 when measured across the grooves. If you’d like to see the full results, all product certifications are available to view all our product certifications in our accreditation section.

Another issue that can occur, although it is rare, is delamination, which is where the protective cap starts to separate from the composite core, leaving areas of the board exposed to the elements. Again, this is not something you need to worry about with Cladco ProDeck composite decking boards, but it is worth bearing in mind if you are considering cheaper or lower-quality capped composite boards.

Uncapped Composite Decking

Without the protective cap, uncapped composite decking boards are more prone to issues such as colour fade and water staining. They can also be more susceptible to mould and algae growth, which means more frequent cleaning throughout the year is required to prevent staining and reduce the risk of slipping.

Below are some of the most common environments we see here in the UK. Each comes with its own set of conditions to think about when choosing your decking, so you can be confident your deck will perform at its best.

High rainfall

We all know it. The UK gets plenty of rain. But what about the areas considered the wettest in the UK? In consistently wet climates, capped decking is by far the best choice, thanks to its improved resistance to water saturation and water marks. ProDeck, for example, is manufactured to ensure zero water absorption.

Frost-prone areas

During cold snaps, your decking will naturally be affected by temperature changes. Capped boards are more resistant to expansion and contraction caused by fluctuating temperatures, making them a strong option in frost-prone regions. However, it’s important to remember that any decking surface, whether that's capped, uncapped or even timber decking, can become slippery in icy conditions, so caution is always advised.

Damp and shaded spaces

Both capped and uncapped boards are designed to cope with general dampness and shaded conditions. The main difference here comes down to maintenance.

If you choose uncapped boards for a shaded area, you’ll need to stay on top of cleaning, as algae and dirt can build up more easily. Because shaded spaces take longer to dry out, the boards are exposed to moisture for longer periods, which increases the likelihood of water marks and gradual moisture absorption if not regularly maintained.

Capped decking boards handle slow-drying environments more effectively thanks to their protective surface, but uncapped boards are still a perfectly suitable option if you don’t mind the extra upkeep.

Sunny areas

While both capped and uncapped boards are suitable for sunny spaces, it's important to remember that colour fade is more likely in these conditions, especially with uncapped boards. This is completely natural and common among all composite decking boards, albeit to varying degrees.

It’s simply the natural wood fibres reacting to UV rays. It isn’t a sign of a faulty product, and if you want to learn more about this natural colour fade, you can read this helpful article on the subject. 

Capped composite boards are designed to retain their colour for longer and offer better resistance to fading, such as Cladco's ProDeck board, which has exceptional resistance to the effects of fading.

Where things become more noticeable is in partially shaded areas. Any parts of your decking that receive less direct sunlight, whether from furniture, planters, railings, overhanging trees or nearby buildings, will fade at a slower rate than surrounding boards exposed to direct sun.

• If your decking is permanently shaded in certain spots, both uncapped and capped composite is a great modern choice. Capped composite, however, is the better option overall, as it helps maintain a more consistent fade level across the whole deck and will require less maintenance.
• If your deck is temporarily shaded, for example, caused by outdoor furniture or movable planters, both capped and uncapped boards work perfectly well. If you opt for uncapped boards, you’ll want to make sure you move items around from time to time so the entire surface gets equal exposure and fades more evenly.

Coastal locations

Living near the coast brings a few extra considerations. Sea air contains higher levels of salt, which act as a corrosive and put extra stress on outdoor materials, including composite decking.

And, of course, seagulls will do their best to leave their mark (we won’t go into more detail than that!). This is where capped composite really helps, as its more stain-resistant surface makes clean-up far easier, a definite advantage in coastal gardens.

Overall, capped composite decking is the tougher, lower-maintenance option in these environments thanks to its protective surface. Uncapped composite can still be suitable, but you’ll need to be quick to react and more thorough with cleaning to stay ahead of salt deposits and any “souvenirs” left by the local wildlife.

High footfall (Commercial)

In commercial settings, such as outdoor seating areas at cafés, bars, restaurants and pubs, it’s important to think about how much foot traffic your decking will face and how much daily wear and tear it will need to withstand. An outdoor deck in a busy bar can experience, in a single evening, the same level of use that a domestic garden deck might see over the course of an entire year, so durability and longevity become key priorities.

Capped composite decking is well-suited to commercial environments thanks to its protective surface layer, which helps shield the boards from the bumps, scrapes and general impact that come with heavy use. Taking our ProDeck range as an example, its strong core design, combined with superior structural integrity and load-bearing capacity compared to uncapped decking, makes it a quality decking material, more than capable of handling high-traffic spaces.

At Cladco, we also offer an uncapped Signature composite decking board with a solid core. Its solid construction provides enhanced strength and load-bearing capacity compared to our hollow-core board of the same Signature range, making it a more durable option for commercial settings. While it won’t offer the same level of protection against stains, bumps and scrapes as a capped board like ProDeck, it still delivers strong structural performance where it’s needed most.

The good news is that whether you opt for uncapped or capped composite decking, both follow a very similar installation process. The main difference between the two is the accessories used, such as the specific fixings and clips required for each range.

Both our Signature and ProDeck boards have their own compatible clips, such as starter clips, T-clips and hidden clips, along with trims and bullnose boards designed specifically for their profiles. For example, a Signature T-clip isn’t suitable for a ProDeck board, and vice versa.

Beyond this, the installation requirements are largely the same. Both ranges need to be installed on a suitable subframe with correct joist spacing, expansion gaps and ventilation beneath the deck. A slight fall should also be incorporated into the subframe to encourage water runoff. As long as these principles are followed, the installation process for capped and uncapped decking is virtually identical.

If you’d like a more in-depth look at either decking type, why not explore our Help & Advice section? It’s full of useful tips, FAQs and detailed installation guides for both of our composite ranges. You’ll find plenty of step-by-step guidance to help ensure a professional, trouble-free installation.

Like any outdoor surface, decking has a lot to contend with, from wind, rain and frost to spills, scrapes and everyday use. Your boards naturally face a variety of challenges throughout the year. To keep your decking looking its best for as long as possible, a little regular care goes a long way. The amount of maintenance required, however, depends on the type of decking you install.

As we’ve covered, uncapped composite needs more frequent cleaning due to the absence of an additional protective surface layer. This usually means regularly sweeping away leaves, dirt and debris, then washing the surface with a mix of warm water and a domestic detergent, using a cloth or mop. Capped boards will still need to be cleaned, but thanks to their protective coating, they won’t demand quite the same level of attention. This makes capped composite decking the ideal choice if you want a low-maintenance choice.

Specialist composite decking cleaners can also be used, instead of domestic detergents, on both capped (ProDeck) and uncapped (Signature) boards to help maintain their appearance. The same goes for revivers, such as composite wood finishes, which are designed to freshen up colour and add extra protection. Because capped boards have much higher resistance to fading, treatments like these won’t be needed as often. For uncapped boards, however, a reviver is a great way to breathe new life into your deck and help protect it for the seasons ahead.

Composite decking boards are typically manufactured from a blend of responsibly sourced recycled wood fibres and post-consumer plastics. By reusing these materials and giving them a new purpose, they are diverted from landfill and used to create a durable, long-lasting product. This recycled core is what makes composite decking a more sustainable choice compared to alternatives made entirely from PVC or hardwood that has been treated with toxic and harmful chemicals.

While the core of a capped composite board is sustainable, the polymer cap that protects its surface does complicate things slightly at the end of the board’s life. Before a capped board can be recycled, this protective layer needs to be removed, which is a time-consuming process that some local authorities and recycling centres simply do not offer. Uncapped boards, by comparison, are generally simpler to recycle as they don’t require this extra removal step.

And if sustainability is a key concern for your upcoming decking project, you can take a look at our article on Cladco's eco-friendly decking for more information on the various options available to you.

If cost is your main deciding factor and you want a good-looking deck for a typical domestic outdoor space, uncapped composite is a great fit. It’s ideal for open, sunny spaces and suits homeowners who don’t mind carrying out regular cleaning to keep staining and algae at bay.

If you’d prefer the most durable finish and want something that requires the least ongoing maintenance, especially in wet, shaded, coastal or high-footfall areas, then capped composite is the stronger long-term choice. It offers better colour stability, zero water absorption, enhanced UV protection and a finish that stays looking newer for longer.

As this article has hopefully shown, there are plenty of reasons why composite decking has become such a popular choice in the UK, especially when compared to traditional timber decking. Whether your priorities are cost, appearance, performance or longevity, both capped and uncapped boards bring something different to the table.

Capped composite comes out on top in most side-by-side comparisons, but it’s worth noting that uncapped boards still offer a great-looking, more affordable alternative, with the added benefit of being easier to recycle at the end of their life.

If you feel capped composite is the right fit for your project, you can explore our ProDeck range. And if uncapped sounds more like your style, our Signature boards are well worth a look.

Whichever option you choose, it’s always a good idea to take your time and do a little research. If you’d like any extra help along the way, you’ll find plenty more information on our website, or you can give our friendly team of decking experts a call on 01837 659901. And if you want to see the boards up close before making your decision, we also offer samples of all our Cladco decking ranges.