In shortUsually not, and on capped boards no: the polymer shell does not hold paint, and the makers' warranties generally exclude painted or coated boards. Older uncapped composite can take a suitable exterior paint once it has weathered, but it is a job you repeat and a sign the board is near the end of its good years. If the colour is the problem, cleaning or replacement is the better route.
People ask this for two reasons. Either an older composite deck has faded and looks tired, or the colour chosen ten years ago no longer suits the garden. With timber the answer is easy: sand, stain or paint. Composite is a different material and the honest answer is mostly no.
Whether it can be painted at all depends on which kind of composite you have, so start there.
Capped or uncapped?
Early composite boards were a plain blend of wood flour and polyethylene, the same mix all the way through. These are now called uncapped. Wood fibre sits at the surface, which is why they stain, fade and grow mould more than the newer boards, and also why paint can get some grip on them.
Capped boards, which make up most of what is sold today, have that same core wrapped in a bonded polymer shell on three or four sides. Trex Transcend and Enhance, Composite Prime’s HD Deck ranges, Ecodek Signature, Cladco Signature and NeoTimber Advanced are all capped. The shell is dense and smooth, which is what keeps stains out and colour in. It also keeps paint out.
Millboard is neither. It is a resin and mineral board with an elastomer surface, and it should not be painted or coated at all.
If you are unsure which you have, look at a cut end or lift a board: a capped board shows a thin skin of a different colour around the core.
Painting a capped board
Do not. There are three reasons.
Paint does not bond to the shell. It may look fine for a season and then peel in sheets, and once it has, the patchy result is worse than the fade you set out to cure.
It ends the warranty. Trex and Millboard publish 25-year residential warranties on their boards, and warranties of this kind exclude boards that have been painted, stained, sealed or otherwise coated. Other brands’ documents are written the same way. A deck with a warranty is worth more than a deck with a coat of paint.
There is no need. A capped board that looks dull almost always just needs a wash. Pollen, grime and a film of algae make a board look faded when the colour underneath is intact. Follow the method in the note on how to clean composite decking before deciding anything is wrong with the colour.
Painting an uncapped board
It can be done, with some care, and it can give an old deck a few more presentable years. The conditions:
- The board must have weathered for a season or more, so the surface has opened up and any factory sheen has gone.
- Clean it thoroughly and let it dry for at least two dry days.
- Use a paint or solid stain made for exterior composite or plastic, following the maker’s instructions on primer. Ordinary fence paint and decking oil are made for timber; oil in particular will not soak into composite and sits on top as a sticky film.
- Expect to recoat. Paint on a plastic surface wears at the walking lines, and foot traffic will show through in a year or two.
Check the board’s warranty first. Many uncapped boards sold in the UK carry ten years or so, and if yours is still in that period, painting it will almost certainly end the cover.
The plain opinion is that paint on an uncapped deck is a holding measure. If the boards are sound but the colour has gone, that is one thing. If they are also cupping, cracking or soft at the ends, paint is money spent on a deck that wants replacing, and a sound frame can often take new boards; see the note on decking joist spacing for what to check before re-boarding.
Why composite fades in the first place
All composite weathers in its first weeks outside. Uncapped boards lighten noticeably in roughly their first two to three months, as the wood fibre at the surface is bleached by sun and rain. Makers describe this as the board settling to its final colour, and good merchants show samples both new and weathered so you can see what you will end up with. After that the change slows right down, though an uncapped board will keep fading gently for years.
Capped boards fade far less. The pigment sits in the shell, protected from moisture, and the main brands warrant it against fading and staining for the life of the residential warranty, in Trex’s and Millboard’s case 25 years. The exact wording of what counts as fading is in each brand’s document and is worth reading before you buy.
Fading is not the same as dirt. The commonest cause of a “faded” deck is a surface that has not been washed in two years.
Alternatives to painting
- Wash it properly first. This fixes most complaints.
- For a persistent colour change on an uncapped board, a composite deck brightener or cleaner may restore some depth.
- Replace the boards and keep the frame, if the joists are sound and the centres suit the new board.
- Choose a capped board next time, in a colour you have seen weathered, not just in the showroom.
Deciding between a fresh composite board and timber, which can be painted and stained freely, is the subject of the guide to composite or timber decking. The decking cost guide gives the price of re-boarding against a new deck.
When you are ready for quotes, the town pages list installers whose websites we check: all towns.