Composite or timber decking: which should you choose?

In shortFitted, treated softwood costs £60 to £130 per m², composite £100 to £220 and hardwood £110 to £250, so timber is cheaper on the day. Composite needs no oiling or staining, does not rot or splinter, and Trex and Millboard warrant their boards for 25 years, so over 20 years it usually costs about the same as a softwood deck that is kept in good order. Timber wins on first cost, easy repairs and looks in a traditional garden; composite wins on upkeep and lifespan.

The choice between composite and timber is mostly a choice about the next twenty years, not the next twenty days. Timber is cheaper to buy, kinder on the eye in some gardens and simple to repair. Composite costs more on the day and then asks very little of you. Neither is right for everyone, and the sales pages on both sides overstate their case.

This guide compares the two as they are sold and fitted in the UK in autumn 2026, with prices from published UK price guides and the warranty terms the main board makers publish. Where a figure is our estimate, it says so.

The comparison at a glance

Cost now

Supplied and fitted, treated softwood runs £60 to £130 per m², composite £100 to £220 and hardwood £110 to £250. On a 15 m² ground-level deck that is £900 to £2,000 in softwood against £1,500 to £3,300 in composite. The gap is real, but it narrows on raised decks, because the frame, posts, steps and balustrade cost the same whatever the boards, and those lines dominate a raised build. The cost guide has the tables and a worked example.

Within composite, the range is wide: budget hollow boards sit near the bottom and capped solid boards from premium brands at the top.

Cost over 20 years

Softwood is not finished when the fitters leave. Kept properly, it wants a clean each spring and an oil or stain every one to two years. Done yourself, that is perhaps £60 to £120 in products a time, by our own estimate, plus a weekend. Paid for, a contractor’s clean and treat is a few hundred pounds a visit; a dozen visits over 20 years at around £250 each is roughly £3,000, more than the price gap between the two decks at 15 m². Skip the upkeep and the deck greys, splinters and, if the joists were the wrong treatment class, rots from the bottom, so the saving goes on a replacement around year 12.

Composite asks for a wash twice a year and nothing else. These sums are our estimates, but their shape is not in doubt: a maintained softwood deck costs about as much as composite over 20 years, and a neglected one does not last that long.

Hardwood sits apart. Balau, ipe and cumaru are dense timbers commonly given 25 to 50 years, and they can be left to silver, so their long-run cost is low if you accept grey.

Looks

A new softwood deck looks like new wood, and in six months it looks like weathered wood, which is either the point or the problem. Stains bring colour back; nothing keeps it without work. Hardwood has the richest colour and the same fate without oil.

Composite has moved on from the plastic planks of fifteen years ago. Capped boards from the better brands carry an embossed grain and varied colour that pass at a glance, and Millboard, a resin and mineral board moulded from real timber rather than a wood-plastic composite, is hard to tell from oak at a distance. Cheap uncapped boards still look like what they are, and they lighten noticeably in their first months outdoors. Pick a colour from a weathered sample.

Lifespan

UK guides generally give a well-built, pressure-treated softwood deck 15 to 25 years, assuming it is cleaned and treated. The failures come earlier and almost always from below: joists treated to Use Class 3, meant for timber above ground, sitting on wet soil where Use Class 4 was needed. Treatment makers typically guarantee UC4 timber for around 15 years against rot and insect attack, not against weathering or splitting, and every cut end must be brushed with preservative or the guarantee is void. Capped composite is given 25 to 30 years or more; uncapped less, because the exposed wood fibre takes up water and stains.

Slip

Wet grooved softwood with a film of algae is one of the most slippery surfaces in a British garden. The grooves are a traditional pattern, not an anti-slip feature; they hold water and algae, and TDCA guidance is that a smooth face sheds water better. UK slip resistance is measured with the pendulum test, and a wet value of 36 or more counts as low slip potential. Composite makers publish their results, and most capped boards test well when clean. Clean is the operative word for both. Our note on whether composite decking is slippery covers the figures and the anti-slip inserts made for timber.

Heat

In direct summer sun, dark composite gets a good deal hotter than a timber board of the same shade, hot enough to be unpleasant barefoot, and the brands say so in their own FAQs. Lighter colours, reflective pigments and shade reduce it. A south-facing deck and barefoot children is a point for timber or pale composite.

Warranties

Trex gives a 25-year limited residential warranty on its capped boards in the UK, with cover against fading and staining alongside the structural cover. Millboard gives a 25-year limited structural residential warranty. Other brands publish their own terms, and the periods vary by range, so read the document for the exact board you are quoted, not the headline on the website. Timber has only the treatment guarantee, which covers decay and not appearance.

Every composite warranty has conditions: the board must be fitted to the maker’s guide, at its joist centres and with its expansion gaps, and some exclude pressure washing above a stated pressure. A fitter who ignores the guide can void a 25-year warranty on day one, a reason to care about how you choose the installer. Our notes cover joist spacing, cleaning composite and painting it.

Repairability

Timber is the easier material to live with when something goes wrong. A split board is unscrewed and replaced, a scratch is sanded, a tired deck is sanded and re-oiled. Composite boards can be swapped too, but a board bought five years later will not match a weathered deck, and hidden clips are slower to lift than face screws. Keep a few spare boards from the original batch.

Environment

Certified softwood is renewable, though the preservative limits its end of life; hardwood should only be bought with FSC or PEFC certification; composite is mostly recycled polyethylene and wood flour but hard to recycle again. None of the three is an obviously green choice. The greenest deck is one built properly that lasts.

When each wins

Timber wins when the budget is tight, when the deck is low and simple, when the garden is traditional, and when you will do the upkeep or like the silvered look. Hardwood wins when you want timber and will pay for something that lasts. Composite wins when the deck is raised and the boards are a small part of the bill, when nobody will oil it, when it is a rental or holiday home, and when you want year ten to look like year one. The honest tie-breaker: will you oil it every other spring? If not, buy composite.

When you are ready for quotes, the town pages list installers whose websites we check: all towns.