Composite WPC decking has transformed the garden decking market in the UK. It looks like wood, feels like wood, but lasts far longer and requires a fraction of the maintenance. If you're planning a decking project and considering composite boards, this guide covers everything you need to know — from understanding the difference between WPC and timber, to calculating how many boards you need and planning your installation.
Composite Decking vs Timber
Why more UK homeowners are making the switch
Traditional timber decking has been the go-to choice for UK gardens for decades. But composite WPC decking has been growing rapidly in popularity, and for good reason. The key advantages of composite over timber are longevity, maintenance, and safety.
Timber decking requires annual treatment — sanding, staining, or painting — to maintain its appearance and prevent rot. Without regular treatment, timber decking will grey, crack, and eventually rot. Composite decking requires no annual treatment — just a wash with soap and water once or twice a year.
Timber decking can also become slippery when wet, and can develop splinters over time — a particular concern for families with young children. Composite decking is splinter-free and, with a grooved surface, provides better grip when wet.
The main advantage of timber is cost — timber decking boards are generally cheaper per board than composite. But when you factor in the cost of annual treatment and the shorter lifespan of timber, composite decking is often the better long-term investment.
- Composite: no annual treatment, splinter-free, 25+ year lifespan
- Timber: lower upfront cost, but requires annual treatment and has shorter lifespan
- Composite is safer for families — no splinters, better grip when wet
- Long-term, composite is often the more cost-effective choice
Grooved vs Woodgrain Finish
Understanding the two main composite decking profiles
Our composite decking boards are available in two profiles: grooved and woodgrain. The choice between the two affects both the appearance of the finished deck and the installation method.
Grooved boards have a series of channels running along the length of the board. These channels are designed to accept our hidden side-joining clips, which fix the boards to the sub-frame without any visible screws. The result is a clean, fastener-free surface that looks sleek and contemporary.
Woodgrain boards have a more textured, natural wood appearance. They are fixed to the sub-frame with visible screws, which are then covered with matching colour plugs. The woodgrain finish is more traditional in appearance and is popular with homeowners who want a deck that looks as close to natural timber as possible.
- Grooved: hidden fixing system, clean contemporary look, no visible screws
- Woodgrain: visible screw fixing, more natural timber appearance
- Both profiles are 100% waterproof and UV-stabilised
- Both profiles are available in anthracite grey, charcoal black, and natural brown
Calculating How Many Boards You Need
A simple step-by-step calculation
To calculate how many composite decking boards you need, start by measuring the area of your deck in square metres. Multiply the length by the width to get the total area.
Our composite decking boards measure 3600mm long x 140mm wide. Each board covers 0.504 square metres. Divide your total deck area by 0.504 to get the number of boards required. Add 10% for cutting waste.
For example, a deck measuring 4m x 3m = 12 square metres. 12 ÷ 0.504 = 23.8 boards. Rounded up and with 10% contingency, you'd need 27 boards.
You'll also need structural WPC joists for the sub-frame, colour-matched trim boards for the edges, and side-joining clips (for grooved boards). Our team will help you calculate the correct quantities for all accessories when you submit your order request.
- Measure deck area: length x width = square metres
- Each board covers 0.504 square metres
- Boards needed: deck area ÷ 0.504 (round up, add 10%)
- Example: 12sqm ÷ 0.504 = 23.8 → 27 boards (with 10% contingency)
Planning Your Sub-Frame
A solid sub-frame is the foundation of a great deck
A properly constructed sub-frame is essential for a long-lasting, level composite deck. We recommend using our structural WPC joists for the sub-frame — they're rot-resistant, weatherproof, and designed specifically for use with composite decking.
Joists should be spaced at 400mm centres for grooved boards and 500mm centres for woodgrain boards. The sub-frame should be level and stable, with adequate drainage beneath the boards to prevent water pooling.
For decks at ground level, we recommend laying the joists on concrete pads or adjustable pedestals to keep them off the ground and allow for drainage. For raised decks, the joists should be supported by a structural timber or steel frame.
Colours and Finishes
Choosing the right colour for your garden
We stock composite decking in three colours: anthracite dark grey, charcoal black, and natural brown. All three colours are available in both grooved and woodgrain finishes.
Anthracite dark grey is our most popular colour — it's a sophisticated, contemporary choice that works well with modern garden designs and complements most exterior colour schemes. Charcoal black is a bolder choice that makes a strong visual statement. Natural brown is the most traditional option, closest in appearance to natural timber.
All our composite decking boards are UV-stabilised to resist fading and discolouration. Over time, all composite decking will lighten slightly in colour as it weathers — this is normal and expected. The UV stabilisation ensures that the colour change is gradual and even.
- Anthracite dark grey: most popular, contemporary, versatile
- Charcoal black: bold, modern, makes a strong statement
- Natural brown: traditional, closest to natural timber look
- All colours UV-stabilised to resist fading
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