If you are planning to renovate your outdoor space and have wondered “what is composite decking?”, this guide will give you everything you need to know. From the materials it is made of, how it differs from traditional timber, its advantages and disadvantages, to how to choose the right type and how long it lasts in UK conditions. By the end, you’ll be well-equipped to decide if composite decking is right for your garden or outdoor space.
What exactly is composite decking?
Composite decking is a modern alternative to traditional wood or timber decking. It is made from a blend of wood fibres (often recycled hardwood or softwood) and plastic materials, mixed with additives, bonding agents and colour pigments. Some composite boards are capped, meaning they have an extra protective polymer layer over the surface to give enhanced resistance against weathering, fading, staining, mildew or mould.
In more technical terms, composite decking falls under the category of wood-plastic composites (WPCs). The term refers to materials that combine lignocellulosic elements (wood fibre, wood flour, or wood residues) with thermoplastics such as polyethylene, polypropylene or similar polymers. Some boards may also include other fillers or reinforcements.
How composite decking is made
The manufacturing process of composite decking usually involves several stages. First, the wood fibres and recycled plastic (sometimes waste plastic from other industries) are cleaned, processed, and mixed. Then they are extruded or moulded into boards, often under heat and pressure. In some products a co-extrusion step adds a polymer “cap” or shell around or over parts of the board for extra protection. Pigments, UV stabilisers, anti-fungal or anti-mould additives may also be included.
Types of composite decking
Not all composite decking is the same. Key types include:
- Capped composite decking: Boards which have a protective outer layer. This improves resistance to moisture, staining, UV fading and wear.
- Uncapped (or traditional) composite decking: Standard boards without that extra outer shell; often cheaper but somewhat more vulnerable.
- Solid vs hollow boards: Some composite boards are solid (more mass, generally heavier), others are hollow or have internal voids/honeycomb structure to save weight, cost or materials. Hollow boards might need more care in certain installations (e.g. with loads, span, support).
What composite decking isn’t
It helps to be clear what composite decking does not do, or cannot do as well as timber in certain respects. Composite boards do not give exactly the same texture, feel or smell as natural wood: for many people the look is close, but wood remains unique.
Also, while composite decking is low-maintenance, it is not totally maintenance-free: you will still need to clean it, remove debris, perhaps treat slips and mould in damp climates. And there are limits: colour fading can happen (especially for darker shades), boards can expand or contract slightly with temperature changes, and cheaper composites are more vulnerable to damage.
Advantages of composite decking
Composite decking has grown enormously in popularity in the UK, and for good reason. Its main benefits include:
Long lifespan. Composite decking can last 25 years or more when properly installed and maintained. Warranties for many capped composite boards often stretch to two decades or more.
Low maintenance. Unlike timber, composite boards do not require yearly staining, sealing, or painting. Cleaning every few months with mild detergent or warm soapy water and a soft brush is usually sufficient.
Resistance to rot, warping, splitting, mould and insect damage. The combination of wood fibre and plastic, plus added protective layers in many products, means composite decking survives UK weather far better than many untreated or even treated woods.
Better slip resistance. Because composite decking tends to absorb less water, and often has specially designed grooved, textured or capped surfaces, it is safer underfoot in wet weather.
Greater design flexibility. You will find boards in a wide range of colours, finishes, grain patterns, and even reversible boards (one side one finish, the reverse another). This allows creative designs, borders (picture frames), and matching with your home or garden features.
Environmental benefits. Many boards are made using recycled wood fibres, recycled plastics, or both; some are also certified by sustainability organisations (for example FSC for the wood content). Using recycled plastic and wood diverts waste from landfill and reduces pressure on forestry.
How long composite decking lasts in UK climates
In the UK, with its mix of wet weather, frost, cold winters and bright sun in summer, deck materials face multiple stresses. Composite decking, especially high-quality and capped varieties, has proven very resilient to these conditions. Many reputable UK manufacturers and suppliers offer warranties of 20-25 years or more.
For example, reports suggest a well-maintained composite deck can last upwards of 25 years. Proper installation on a good subframe, correct spacing to allow for expansion, and regular cleaning are key factors influencing lifespan.
Composite decking vs timber decking
To understand when composite might be better (or not), it helps to compare it with more traditional timber decking:
Timber decks (softwood or hardwood) have a more natural feel, may be cheaper initially, and are deeply familiar in garden design. However, they require more upkeep: treatments, staining, sealing, sanding, occasional repairs.
Wood is prone to splitting, rotting, warping, mould, insect attack etc. If left untreated or poorly maintained, a timber deck may degrade significantly over 10-20 years depending on the wood species and exposure. Composite decking aims to reduce or avoid many of those issues.
One trade-off is the texture and authentic wood character: some people prefer how timber weathers (silvering, grain changes etc.), whereas composite tends to show fewer imperfections but also fewer signs of natural ageing. Also, if a timber board gets damaged, replacing or refinishing may be simpler (for some types of wood) than composite boards.
How to choose the right composite decking
If, after reading this, you are leaning towards composite decking, here are factors you should consider when selecting your boards:
- Capped or uncapped — a capped board will offer more protection but cost more.
- Colour and finish — darker colours look dramatic but may fade more; lighter or medium tones may show less heat, less fading. Look at grain patterns, reversible boards.
- Board profile and design — solid vs hollow; grooved vs smooth; slip resistance; hidden fasteners or visible fixings.
- Warranty and certifications — what is the warranty period for structural stability, colour fade, stain resistance? Does the wood component have FSC or similar certification?
- Subframe and installation — composite decking still relies on a good foundation. Proper joist spacing, correct fasteners, space for expansion, drainage etc. are essential.
- Cost vs long-term value — consider not just the purchase and installation but how much maintenance you’re likely to save over 10-20 years.
Maintenance tips for composite decking
To ensure composite boards reach their maximum lifespan and retain good appearance:
Wash regularly with soft brush or cloth and warm soapy water. Avoid harsh chemicals or very strong detergents unless recommended by the manufacturer.
Remove leaves, debris or anything that might trap moisture or lead to mould or algae growth. Clean between gaps so drainage is not blocked.
Inspect periodically for any loose fixings, signs of damage, mould or mildew, and clean or repair promptly.
Avoid pushing heavy objects without pads or protection; composite can get scratched, though better quality boards resist this well.
Follow manufacturer instructions for pressure washing (if allowed); too close nozzles or too high pressure can damage boards.
Frequently asked questions
Is composite decking waterproof?
Composite boards are not completely waterproof in the sense that water will never affect them, but they absorb much less water than traditional timber, especially when boards are capped and properly installed. Because moisture absorption is low, risks like rotting, mould and warping are greatly reduced.
Is composite decking slippery when wet?
High-quality composite decking will often have textured or grooved surfaces, anti-slip features, or may be designed so that the grooves, ridges or the profile help reduce slipperiness. Lower water absorption means less pooling, less mould/slime growth, which also helps safety. But any decking material can be slippery if not maintained or cleaned.
Can I install composite decking on any structure?
Composite decking still needs a solid support system: a well-constructed subframe, correct joist spacing, good drainage, and fixings suited for composite boards. The weight of boards (especially solid composite) must be taken into account. In damp or exposed sites, you’ll want a structure that doesn’t trap moisture.
Is composite decking right for you?
Composite decking is an excellent option for many homeowners who want a durable, low-maintenance, attractive deck that will stand up to British weather. While the upfront cost is higher than some timber alternatives, the long-term savings in upkeep, plus the extended lifespan, often make composite a better investment in many situations.
If you value appearance, reliability, safety and want fewer chores over the years, composite decking will likely serve you well. If, however, you love natural timber aesthetics, don’t mind maintenance, and want lower initial outlay, timber remains a valid choice.
At Decking Superstore, we offer a wide selection of composite decking boards and accessories, with expert advice to help you choose the right product for your garden. Feel free to contact us if you’d like help picking the right type, assessment of costs, samples or installing tips.
Get in touch today to explore the possibilities.
Call us on: 0208 187 1467
