Composite (WPC) Decking Boards

Find & compare UK's best prices for wood-plastic composite decking

By Michael Watson

Composite decking (also commonly known as ‘WPC’ or ‘Wood-Plastic Composite’) is a recent innovation in the decking industry which affords you the beauty of a modern deck, without the inherent work & maintenance. While it is a man-made material, many decks made with this material are very well made and often have the same authentic, natural look/feel of a hardwood structure. As a result they have become the fastest growing decking material in the industry.

grey composite deck boardsMost composites are hybrid materials, made from a recycled plastic & wood flour mixture. Because they use discarded plastics which have been recycled & wood chippings/sawdust, they are much friendlier on the environment than other types of decking. Most boards are made from Polyethylene or Polyvinyl Chloride.

Before you buy, read our expert facts & opinions so you know exactly what you are buying into. We’ve also sourced the very best prices for comparison in the UK.

In this guide - expert guidance on composite decking boards, including...

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Section 1: Background

The big reason many buy composite decking is for its convenience – with close to zero maintenance once fully installed, it requires the least ongoing care of all the decking types. There is no need to sand & treat the surface regularly as with many wood structures; these boards don’t fade & often require little more than a soap-and-water wash each year. They also come in a variety of styles & colours to match any requirement.

The majority of providers will also manufacture accompanying balustrades, mouldings & railings which will all match with the board colour & styling.

High Cost

Not Eco-Friendly

Easy
Installation

Low
Maintenance

Retailers are so confident in its quality that many composites also come with a guarantee of quality for so many years. Because of the high plastic consistency, this decking is highly resistant to rot & fungus. It’s also incredibly strong. It won’t warp, twist or splinter. It’s resistant to UV rays & won’t fade or turn grey. Because of its composition it’s also resistant to scratches & stains – so you don’t need to worry about what footwear your guests are wearing or what they might drop on your deck!

So is there anything it won’t do? Well, unfortunately all of this does come at a cost. Board-for-board, composite is nearly always more expensive than wooden alternatives. And unlike wooden decking, it can’t be sanded-down & stained a different colour if you one-day decide you’d like a change. Purists might also argue that it doesn’t have the same traditional feel of a wooden structure, but we think it does a pretty good job of it!

For those who want to relax on their deck instead of always work on it – it’s the perfect choice. If you’re happy to part with the extra cash, you won’t be disappointed.

FAQ: How is composite decking made?
Manufacturers generally follow a fairly rigid process when producing their products –

  1. The two main components: wood flour & plastics are first mixed. At this stage, some manufacturers also add their desired preservatives & pigments.
  2. The components are heated together into a doughy mixture and shaped into boards, before being cooled.
  3. To finish the process the boards are then capped; a plastic shell is coated over the boards at just the right thickness. This is sometimes known as co-extrusion.

If you are considering a composite deck, you might also want to consider fully-plastic PVC decking which has many similarities.

Pros
  • Easy ‘soap & water’ maintenance. No need to sand, treat or paint regularly.
  • Long lifespan – usually at least 25 years+
  • Resistant to fading, stains, scratches
  • Won’t rot & resistant to mold & fungus
  • Heat resistant
  • Custom fixing systems make installation easier & reduce wasted materials
  • Often environmentally friendly – few toxins used in production, made from recycled materials
  • Slip resistant – suitable for children & the elderly
  • All boards are defect free – meaning you can use every board
Cons
  • Very high cost in comparison with other options out there
  • Material cannot be recycled once structure is ready to be removed
  • Custom fixing system can add to cost
  • Colour can’t be changed ad-hoc by sanding/staining

What is 'capped composite' decking?

This type of decking is often referred to as being either ‘capped’ or ‘uncapped’. Capping refers to a process some composites go through whereby a plastic coating is added to the boards in order to give added protection against the elements. This protective sleeve isn’t added after the boards have been made, instead it is bonded to the core throughout the manufacturing process.

The name comes from the plastic material added to the boards to yield this extra protection: capstock. Think of this as being like the sugar coating around smarties – it helps to protect the core materials, giving them added protection against UV rays, damp & mold.

Capped materials afford many of the benefits you might get with indoor surfaces such as laminate. They are resistant to spills & stains which can be wiped clean with ease. Often they also make the colour of the wood appear more intense with a cleaner finish.

Some manufacturers completely surround the deck with this protective cover, often leaving the boards clear where fasteners are typically attached. It is most common to leave one side (usually the bottom) uncapped. This allows the underside of the boards to breathe. In the past, composites which have been fully covered in capping have been known to expand & mushroom from the ends of boards. They suck in moisture during wet weather but leave nowhere for the expansion pressure to escape – sometimes leading to the boards expanding out of the ends. Often they wouldn’t return back to normal after drying out & could completely ruin the look of a deck.

Top Tip: Always check that your new boards aren’t capped on all four sides of their boards. Trapping in moisture will likely lead to your boards mushrooming at the ends. Your new boards should either be capped only on one side, or on the top & sides; leaving the bottom with room to expand outwards. This will allow your boards to expand in length and width when wet – and to shrink in both directions when drying out.

While earlier generations of WPC decking were primarily uncapped, the majority of retailers now utilise capping as standard. It’s still best to check before purchasing your boards.

Most retailers claim that capping will significantly increase the lifespan of your structure. Whilst it’s probably a little early to confirm whether this is the case or not, most feedback we’ve heard so far has been wholly positive.

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What’s the difference between ‘solid’ & ‘hollow’ decking?

As well as being ‘capped’, some retailers might also refer to their boards as being either ‘solid’ or ‘hollow’.

Solid composites look more like real wood than the hollow version. They are also heavier & more durable. However this does mean that this material has a tendency to expand & contract to greater levels during times of high moisture & environments where there are big swings in temperatures.

Because hollow boards are less dense, they are more susceptible to damage than solid types. You should take care during the transportation and installation of these boards. However, they are less likely to expand & contract at significant levels like their solid counterparts. And while they are weaker, they are often more affordable than solid types.

Though they are more expensive, generally solid boards are the more popular choice because of their durability & resemblance to real wood.

Section 2: Buying Composite Boards

If you’re looking to buy composite boards, you can either visit a supplier in-store or buy them online. Many local timber merchants won’t sell them so it is often easier to buy them online from a recognised supplier. Remember too that you will nearly always find the better deal online.

Our Best Buys: Composite Decking

We know it can be difficult to know exactly which supplier offers the best deal, especially when all decking boards are different sizes & quality. Most sites don’t make it easy to compare. To help our users, our experts have collected their top suppliers list below, with prices broken down per square metre – so you can see for yourself which websites are truly offering the best deal.

Remember to also use our handy decking calculator – which will help you figure out the quantities of materials you’ll need for your build.

Top Buy

wood n beyond logo

High quality boards with best range of composites on the internet

WOOD N BEYOND – FROM £64.73 PER SQ/METRE

For composites, Wood N Beyond are our undisputed top buy. Their range is the best you'll find online and is priced very competitively (only mildly more expensive than the cheapest on the net). Despite their affordability, the company has a solid reputation for delivering a quality product and excellent customer service.

Delivery usually takes around 3-5 days which is not the best if you're eager to get started, but customers can take advantage of their VIP Delivery service for an extra cost.

Points of Interest

Delivery Time: 3-5 days. VIP delivery available
Quality: Excellent
Customer Service: Good
Product Range: Good

Cheapest Buy

b&q logo

Cheapest composite decking, a decent range & next day delivery

B&Q – FROM £62.22 PER SQ/METRE

If price is the main consideration for your build, you'd be hard pressed to find composite boards at a better price than from B&Q.

Their cheapest boards are available at £62.22 per metre², saving you over £2 per metre² when pitched against the next best offer.

B&Q have a reputation for high quality products and any materials you buy are likely to last a long time. Customers can also benefit from next day delivery but should be wary of their poor customer service record on Trust Pilot ratings.

Points of Interest

Delivery Time: Next day delivery
Quality: Good
Customer Service: Average
Product Range: Poor

Other Notable Suppliers

SUPPLIER
COST
DELIVERY TIME
WEBSITE
BUILDING SUPPLIES ONLINEFrom £64.26 per sq/metreBetween 5-7 days
BUY NOW
HOMEBASEFrom £104.65 per sq/metreOver 7+ days
BUY NOW
JEWSONTrade OnlyBetween 1-3 days
BUY NOW

All pricing & information was correct at the time of writing. We regularly review our content to ensure it is still up-to-date. Customer service information has been gathered from Trust Pilot review scores & information. If any information in this article has changed or looks incorrect, please contact us for amendment. Thanks!

Section 3: Installation

Installation of this type of decking generally costs a similar amount to that of wooden structures. However it’s very important that the person installing your decking (if this is not you) follows the manufacturer’s guidelines, which often differ from one another.

Most manufacturers will supply custom fasteners and parts – including balustrades, mouldings & railings. These will be fashioned in the custom colour & style of your chosen boards.

There are some things you should always consider with the installation of WPC decking –

  • It is less stable & weaker than wood, which means:
    – Because the boards rapidly shrink & expand with varying moisture & temperature, it’s important to leave the correct spacing between boards to compensate for this. Most manufacturers will provide specific guidelines on how much space to leave between boards. You will also need to leave enough gapping between the decking structure & any abutting wall. When you get to the last few boards, you may need to cut the last piece lengthwise to help it fit sufficiently. Place the cut edge towards the abutting wall.
    – The weakness of the boards means that these decks generally need more supporting joists than wooden structures. You will need to account for this in the framing.
  • This type of decking is also known for its tendency to expand & contract because of its moisture content. As a result, drainage & airflow are key considerations during the installation of your decking. The area underneath the deck should be sloped or fitted with a drainage system allowing any water to drain away.
  • It’s generally recommended to use reverse thread screws (sometimes known as ‘composite decking screws’) when screwing your deck boards. This helps to prevent mushrooming – where screws pull the materials out of the core during installation. If mushrooming does still occur, tap this with a hammer so that the excess material covers the screw head.

Top Tip: to calculate how many fasteners you’re likely to need for your structure, follow our simple calculation: number of joists x number of decking boards = number of fasteners.

If you’re using hollow composite boards, these will leave open ends which aren’t aesthetically pleasing. They will also collect dirt & other organic materials from your garden. Most manufacturers supply starter strips or caps to close off the ends. These hide the fact that the boards are hollow.

Important: most WPC manufacturers will offer lifespan warranties or guarantees on their products. However you must follow their installation guidelines to the exact specifications – or you risk voiding this warranty.

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Section 4: Maintenance

Wood-plastic structures are incredibly popular because they are known to be one of the easiest materials to maintain. Aside from an annual scrubbing with deck cleaner & water, there really is very little maintenance required.

Because of its durability & resistant nature, there is also no need to treat WPC decking with any sort of preservative.

FAQ: What if my wood-plastic decking has faded? Can I paint or stain my composite deck?
Generally, most manufacturers will recommend against painting or staining their boards. They will usually claim the colour of their decking is permanent, though many will admit that it is likely to fade under intense UV exposure. And while it is possible to spruce up an old composite, it’s not always recommended. It will mean having to sand off the outside capping, which will open up the surface of your decking to the elements.

However if it’s gotten to the stage where this has become necessary, it’s recommended to take the following steps –

  1. First scrub the surface of your deck with a wire brush & decking cleaning fluid. You should never paint or stain surfaces which contain mold or mildew.
  2. Sand the surface of your deck with a very fine sandpaper. Aim to sand with the grain rather than against it. You should completely remove any capstock which has been used to seal your deck.
  3. If you’re looking to paint your deck, you should prime it with an exterior latex stain-blocking primer which can be used on composite decking. You don’t need to do this if you’re looking to stain your decking.
  4. Finish the process by applying a high quality decking paint or staining product.

If you do undertake this process & remove the capping from the top of your boards, you will likely need to sand & re-seal your deck every 3-5 years following to keep up its appearance.

Should you apply a latex coating when sealing your deck, be careful not to use an oil-based product in any future applications. Mixing the two products may risk your structure developing cracks & splits which can risk the lifespan of your decking.

For new structures, you should wait at least 8 weeks before undertaking the process; allowing the boards to acclimatise to their new surroundings.

Cleaning: keep your boards looking like new

You should try and clean your WPC deck at least once a year.

Because of its wood & plastic composition, this type of material is particularly susceptible to mildew. The wood flour acts as a food source for mildew to feed on. If your boards are capped this usually isn’t too much of a problem. However for uncapped boards, it’s recommended that those in high temperature, high moisture environments use mildewcide or mildew-resistant treatment on their boards to keep them clean. Keeping your surface dry & clean is the most effective way to combat the growth of mildew. Bleach will kill mildew spores but it will also kill plants, vegetation & wildlife in your garden & is not recommended.

A power washer can used when cleaning your deck, ideally alongside a specialised decking cleaning product. Decking preservatives which contain Zinc are recommended as they naturally combat the growth of mold & mildew. Our experts recommend that you should allow a maximum water pressure of no more than 1500 psi, being careful to spray with the grain (usually along the length of the boards) rather than against it. Hold your power washer at roughly a 35° angle. This will help to prevent any damage to your deck. Use a fan tip nozzle if possible.

Cleaning guidelines –

  1. When using decking cleaner, pre-wet your boards with water for maximum results.
  2. Always fully remove any decking cleaner from your surface. This will be much easier if you have a pressure washer or garden hose.
  3. Follow the cleaning product guidelines at all times.

For those in colder environments, you may climates where ice & snow form on your boards. It is fine to use rock salt or Calcium Chloride to combat this, but bear in mind these will leave a white residue which will need cleaning from your boards.

FAQ: How do I remove any scratches from my composite boards?
Scratches, nicks & cuts can usually be removed from this material very easily by using a wire brush. You should try work with the grain, brushing along the length of the boards. After 2 months of weathering any scratches should have mostly disappeared.

For deeper scratches you may need to consider using a soldering iron. This will help to melt the material & even out any scratches. It’s recommended that you practice on a spare cut-off of composite to understand what impact this is likely to have on your deck in advance. Soldering irons with a rounded tip usually work best as they help to blend the scratches.

Section 5: Environmental Impact

This type of decking is highly durable, which means decks last much longer before they need to be replaced. WPC decks are estimated to last anywhere up to 30 years – and many manufacturers offer lifespan guarantees. There is an environmental benefit in this; as wooden decking structures sometimes need to be replaced after just 10 years.

The composition of this type of decking (a mix of wood & plastic) also has its benefits over soft/hard wood structures –

  • Wood: because the wood used is simply ground into a flour, manufacturers don’t need to be picky with their wood. The wood used in composites often comes from off-cuts, mill waste & old pallets. Virgin wood which would be useful for other purposes is never used & as such, manufacturers don’t need to cut down any trees for their decking.
  • Plastic: much of the plastic used in this decking comes from recycled plastics such as shopping bags & old plastic bottles.

The only downside is that because it is a mix of wood & plastic, most materials can’t be recycled like plastic decking. Neither is it compostable. This means that once your decking is removed in the future it is bound for the landfill. It also means any unused materials are headed the same way. By planning your size requirements accurately you can save yourself some money; while helping to minimise the amount of materials which end up on the scrapheap.