Composite decking in the UK

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What is composite decking made of?

Composite decking boards mix plastic with wood fibre, rice husk or mineral filler, pressed or extruded into long planks. The wood version is called wood plastic composite, or WPC. Americans call the same thing composite lumber, which is why the phrase turns up in search results, but in a UK merchant you’ll see composite decking boards.

Two details change how a board behaves. Capped boards have a thin protective shell around the core, uncapped boards don’t. EnviroBuild says uncapped boards cost less, suit covered or sheltered spots, and take on more moisture outdoors, so they need more upkeep. The second detail is whether the board is hollow or solid. Hollow boards are lighter and cheaper, solid boards are denser. EnviroBuild puts a 150 mm hollow board at roughly 2.5 to 3.5 kg per metre and a solid one at 4.5 to 6 kg. Our hollow versus solid guide goes into the trade-offs.

Some boards aren’t wood-plastic at all. Millboard’s boards are a polyurethane resin and mineral composite with no wood content.

Is composite decking worth it?

If you want to stop staining and oiling, yes, and the money works out over the years rather than in the first month. Composite costs more to buy than treated softwood. In return you don’t oil it, it doesn’t splinter, and the better lines carry long warranties.

Here’s what owners who’ve filmed their decks keep saying:

• The first year needs almost no cleaning. One UK DIYer’s grey boards hadn’t faded or needed washing after twelve months, though her composite looked dirty with black and green mould by year two.
• Composite marks. She scratch-tested samples before ordering, and the board she chose marked least, but a heavy seat dragged across it still left a light scratch.
• It gets warm. See the heat question below.
• Spills such as wine or ketchup are best wiped up quickly, because left to sit they can stain.

The honest downsides are price, scratches, heat in full sun and a colour that settles in the first year. Composite Prime says its pigments stabilise over the first 6 to 12 months and boards may fade a little before they weather naturally.

What does composite decking cost in the UK?

Board-only prices run from about £37 to £92 per m², depending on the build. EnviroBuild’s 2026 figures are £37 to £55 for uncapped hollow, £55 to £75 for capped hollow and £70 to £92 for capped solid. Installed prices are higher: MyJobQuote’s table, updated in October 2026, runs from £65 to £110 per m² installed.

Treat the table as a guide, not a quote, and note that neither source says whether VAT is included. Our price page converts dated seller prices for named boards into a per m² figure so you can compare like with like, and the calculator adds the frame and fixings.

Does composite decking get hot?

Yes, in direct sun, and dark boards more than light ones. One UK owner says that on a day of about 26 degrees her boards were too hot to sit on directly, so she lays an outdoor rug. A US retailer that tested boards with “cool” pigments in real sun saw no difference against ordinary boards of the same colour. Colour was the thing that mattered, and even pale boards were too hot for bare feet in strong heat.

Practical advice from that: pick a lighter colour for a south-facing spot, and ignore claims about how much cooler a board is.

Is composite decking slippery?

It can be, and the figure to ask for is the wet pendulum test value. HSE counts 36 or more as low slip potential. New boards can also be slippery for a few weeks because of the manufacturing release agent, which Millboard says weathers off in 6 to 8 weeks. Our non-slip guide lists the published numbers.

How low maintenance is it really?

Sweep it, wash it twice a year and clear the gaps between boards. Wickes recommends a full clean about twice a year and says composite doesn’t need a specialist cleaner. The care rules differ by maker, so use ours for the details: how to clean composite decking.

What sizes do composite decking boards come in?

In the boards we’ve verified, widths run from 134 to 200 mm, thicknesses from 21 to 32 mm, and lengths are 3.6 m, 3.65 m, 4 m, 4.8 m or 4.87 m. Eva-Last’s Apex is 140 by 24 by 4,800 mm. Millboard’s Enhanced Grain is 176 by 32 by 3,600 mm. The boards comparison has each product and its source, and the sizes guide shows which length wastes least on your deck.

What does a composite deck need underneath?

A frame at the joist spacing your board maker allows, with every board end supported, a gap to walls and a slight fall so water runs away. The numbers differ by maker, which is why a generic rule is no use:

Boards laid at 45 degrees need closer joists: Millboard says 300 mm for residential use. Read the guide for the exact board you buy, and follow the frame guide for the layout. For a quick board and joist count, use the composite decking calculator.

How long does composite decking last?

The warranty is the only number a maker will stand behind. Eva-Last gives 30 years on Apex and 25 on Infinity, Millboard 25 years residential on the lines we’ve checked, and Envirobuild 25 years on Frontier but 15 on Explorer. Composite Prime’s commercial warranty runs 5 or 10 years depending on the line. uk.trex.com says 25 to 50 years across its range without a per-line breakdown. Read what each one covers: fading and staining are often excluded or limited. See our lifespan guide.