Composite vs timber decking: the 25-year comparison
Over 25 years a composite deck usually costs less in total than softwood despite costing more to build, because softwood needs oiling every year or two and board replacement along the way. Timber still wins on a tight budget, on decks you expect to alter, and where you want a warm, natural surface underfoot.
How the arithmetic works out
Composite costs roughly £900 to £1,100 more to build on a 20m² deck. Softwood then spends that difference back on oil, a weekend of your time each year, and a set of replacement boards somewhere around year 15 to 18. Cross-over usually arrives between years 10 and 14. Below that horizon, timber is the cheaper deck. Above it, composite is, and it also arrives at year 20 still looking like a deck rather than a chore you have been losing to.
The caveat that undoes the whole table: both figures assume the same subframe. Building composite on a cut-price frame simply means the expensive boards get lifted in year eight so someone can replace the joists underneath. Whichever surface you choose, the money below the boards is the money that decides the lifespan.
Maintenance, stated honestly
Composite is low maintenance. It is not maintenance free, and it is not slip-proof. Two washes a year with deck cleaner keeps a capped board looking near new. Skip that in a shaded garden and algae builds a film that is genuinely slick by November. Timber needs the same washing plus oil every one to two years, and if you skip the oil the timber silvers and looks tired without actually rotting, since the pressure treatment does the protecting.
Slip and shade: the Teesside test
A large share of Teesside back gardens face north or sit behind a tall close-boarded fence, so they see little direct sun and dry slowly. Algae, not the board material, is what makes decking slippery, and it grows on anything that stays damp. In those gardens the choices that matter are drainage below the boards, a ventilated perimeter, cutting back anything that overhangs, brushed or grooved surfaces, and anti-slip strips on steps. A south-facing Yarm garden that dries out by mid-morning has an easier time of it with either material.
Fade, heat and how they age
Capped composite lightens slightly in its first season and then holds steady. Uncapped budget composite keeps drifting and stains where water sits, which is why the capped or uncapped question matters more than the brand name. Dark composite also runs hot underfoot in full sun, noticeably hotter than timber, which matters with young children or dogs. Timber greys steadily unless oiled, and many people genuinely prefer the weathered look, which is a legitimate reason to choose it.
When timber is the right answer
- Budget now matters more than budget later, for instance a deck for a house you intend to sell within a few years.
- You expect to change it: timber cuts, extends and adapts easily, and matches existing structures.
- Character: on a period property or a cottage garden in Guisborough or Great Ayton, hardwood or a well-oiled softwood deck sits better than a moulded board.
- Hardwood as the long game: balau at £150 to £220 per square metre installed can run 30 years and beats both on longevity, if you will keep oiling it.
Prices for both routes are on the composite and timber pages, and the full breakdown is in the Teesside cost guide.
| Item | Softwood | Composite |
|---|---|---|
| Build cost | £1,700–£2,400 | £2,600–£3,500 |
| Annual upkeep | £30–£60 oil, 2–3 hrs | £10–£20 cleaner, 1–2 hrs |
| Oiling over 25 years | £450–£900 | n/a |
| Board replacement | 1 full replacement likely | unlikely |
| Realistic surface life | 15–20 years | 25 years plus |
| 25-year total | £3,900–£5,700 | £3,000–£4,100 |