How Long Does Decking Last? Composite, Softwood and Hardwood Compared
Updated: 2 days ago
Good-quality composite decking typically lasts 25 years or more, and most reputable boards carry a manufacturer's warranty of 20-25 years. Treated softwood decking usually lasts 10-15 years with regular maintenance, and hardwood 25 years or more. In practice, how long any deck lasts depends as much on the frame underneath, the ventilation and the upkeep as on the boards.
How long does composite decking last?
Composite boards don't rot, splinter or need staining, so the boards themselves are very long-lived. Capped composite (boards with a protective outer shell) resists staining and fading better than the older uncapped boards, and it's what we recommend.
The limiting factor on a composite deck is usually the subframe. Most composite decks sit on treated timber joists, and if those joists are undersized, too far apart or sitting in wet ground, they can fail well before the boards do. An aluminium subframe or a well-built, well-ventilated timber frame lets the boards reach their full life.
How long does wooden decking last?
Treated softwood (pressure-treated pine or spruce): typically 10-15 years, sometimes more with good maintenance and a dry, ventilated site; less in shade or on damp ground.
Hardwood (such as balau, ipe or iroko): typically 25 years or more, because the timber is naturally dense and durable.
Softwood lasts longest when the boards are cleaned and treated every year or two, the frame is kept off the soil, and water can drain freely off and under the deck.
What shortens a deck's life?
Most decks we're asked to replace early have failed for the same handful of reasons:
Frame in contact with soil. Timber sitting on or in the ground stays wet and rots, even when treated.
No ventilation. A low deck with no airflow underneath stays damp and grows algae and fungus.
Joists too far apart. Boards flex, fixings loosen and boards crack.
Cut ends left untreated. Treated timber is only fully protected on the outside; every cut end needs an end-grain preserver.
Shade and leaf litter. Decks under trees stay damp and collect debris between the boards.
Poor fixings. Mild steel screws rust and stain; stainless or coated deck screws last.
Our guide on how to build decking covers the frame details that avoid most of these.
How to clean decking
Clean a deck at least once a year, ideally in spring, and a second time in autumn if it's shaded.
Timber decking
Sweep off leaves and debris and clear the gaps between boards.
Scrub with a stiff brush and a proprietary deck cleaner, following the product's instructions.
Rinse with a hose. A pressure washer can be used with care on a low setting and a wide fan nozzle, but held too close it tears up the grain and leaves the surface furry.
Once dry, re-oil or stain if the colour or water resistance has faded.
Composite decking
Sweep and clear the gaps.
Wash with warm soapy water and a soft or medium brush, working along the grain.
Rinse well. Check the manufacturer's guidance before using a pressure washer or any strong cleaner, as some void warranties.
Avoid steel wool or wire brushes on either material; they scratch composite and leave metal particles that rust on timber.
How to make a deck last longer
A few habits add years to any deck:
Keep the gaps clear. Leaves and soil packed between boards hold water against the edges.
Deal with shade. Cutting back overhanging branches lets the deck dry out between showers.
Keep planters off the boards. Pots standing directly on a deck leave damp patches; use feet or stands.
Treat timber on schedule. Re-oil or stain softwood every year or two, before it greys and starts to crack.
Check the fixings. Tighten or replace lifted screws before they snag and let water into the board.
Look underneath. A quick check of the joists every year or two catches rot before it spreads.
Does the climate make a difference?
It does. In the UK, the biggest enemy of a deck is prolonged damp rather than heat or cold. A deck that gets sun and airflow dries out between showers and lasts far longer than one in permanent shade. Freeze-thaw cycles also open up cracks in timber that has been allowed to dry out and split, which is another reason to keep softwood treated.
When should you replace decking?
Replace individual boards when they're soft, split or badly warped. Consider replacing the whole deck when the frame is soft when you push a screwdriver into it, when joists have rotted at the ends, or when more boards are failing than sound. A spongy feel underfoot almost always means a frame problem.
If the frame is still sound, it's sometimes possible to replace old timber boards with composite, provided the joist spacing suits the composite manufacturer's requirements, which is usually closer than for softwood.
Does a raised deck last as long?
A raised deck is easier to ventilate, which helps, but it puts more load on the posts and fixings, and those need inspecting. Raised decks also bring planning into play: a deck more than 30cm above the ground normally needs planning permission, which we cover in our post on decking planning permission.
We build and replace decking in Kettering and the surrounding area, in timber and composite, and we're always happy to look at an existing deck and tell you whether it needs repair or replacement. If you're weighing a deck against paving, our patios team can price both. Get in touch to arrange a visit.
Comments