Composite decking: the questions people ask most, answered

These are the questions Australians search for most about composite decking, going by keyword search data for October 2026, each with a short answer and a link to the full guide. If your question isn't here, the composite decking hub is the place to start.

What is composite decking?

Composite decking is a deck board made from reclaimed timber fibre mixed with plastic. It doesn't rot, and it needs a wash rather than oil. It isn't the same thing as PVC decking, which is all plastic. The plain-English version is in what is composite decking.

What is composite decking made of?

Wood fibre blended with plastic, plus additives such as UV stabilisers and bonding agents. One maker's uncapped board is about half reclaimed timber and the rest mostly recycled polyethylene³. Capped boards add a shell of plain polymer over that core. One maker says the mix of timber and plastic largely decides how much the board expands in the heat. I've covered the shell and what it changes in capped vs uncapped composite decking.

How do you install composite decking?

Build the frame to the joist centres in the maker's guide first. The boards then go down from the outer edge or from the house, whichever the guide says. Each board is clipped or screwed at the joists with the gap the guide specifies. Where two board ends meet, one guide wants the joist doubled under the join, and every board needs room to move at a wall. The maker's install guide is the document that matters, because the warranty depends on following it⁷. The sequence and the common mistakes are in how to install composite decking.

How hard is it to install composite decking?

The boards are the easier part. One maker's hidden clip spaces the boards for you, and the boards cut with a hardwood blade. The frame is where I'd take the most care, because the joist centres come from the board's guide and the warranty depends on following it. If you can build a level frame at those centres, I'd say you can lay a composite deck.

How much does composite decking cost?

It depends on the range, the board size and your state, and I keep prices out of guides because they go out of date. The prices page shows current board prices by state with the date each was checked. The cost per square metre calculator works out what the boards cost for your deck size. The frame and labour are extra.

Is composite decking expensive?

Usually, yes, up front. A Whirlpool member weighing composite against merbau in December 2025 found it "literally more expensive per plank"¹¹, and a Trex owner on ProductReview said they "specifically spent more" to avoid maintenance and fading¹⁰. What you get back is time. Owners in that Whirlpool thread describe oiling a timber deck again every six to twelve months, while one composite maker asks for a general clean at least once a year¹. Why so many Australians are switching covers both sides.

How much does it cost to install composite decking?

It depends on the frame, the height and how easy the site is to get to, so the only firm figure is a builder's price for your job. The cost per square metre calculator shows what the boards cost in your state, and the deck designer lists the frame you'd need under them.

Is composite decking worth it?

For a deck in the weather that you'll own for a decade or more, I'd usually say yes. For a covered deck you'll sell with the house in three years, the extra outlay is harder to justify. Is composite decking worth it? walks through how I'd decide. The reasons that aren't about money are in why so many Australians are switching.

Does composite decking get hot?

Yes, and a dark board in afternoon sun can be too hot for bare feet. A Trex owner in New South Wales wrote on ProductReview two years ago that with any sun on it the deck "burns the feet"¹⁰. Makers say darker colours absorb more heat, and one says two of its darker colours can get quite hot underfoot, especially when new. A light grey board will run cooler than a charcoal one in the same sun, so I'd put colour ahead of brand. Does composite decking get hot covers what you can do about it.

How do you clean composite decking?

Warm water, dishwashing liquid and a soft brush, then a rinse with the hose. One maker asks for that at least once a year. I'd also do it straight after any spill, because the stain warranties only cover spills you've cleaned within the time allowed⁸. The full routine, including mould on shaded decks, is in how to clean composite decking.

How do you wash a composite deck?

With a hose and a soft brush. Pressure washers are a risk. One maker's manual says a high-pressure washer "could cause irreparable damage" and tells you not to use one at all¹, and another says not to use high pressure cleaners on its boards⁴. A third allows a pressure washer with a fan tip held at least 203 mm from the boards, up to a set pressure limit⁹. If you use one where it's allowed, keep it on the gentlest setting and keep it moving.

Can you paint composite decking?

Some uncapped boards can take a coating once they've weathered. ModWood says its uncapped range will accept some decking oils when fully weathered, and can be stained with a composite sealer⁴. I'd expect to keep coating it from then on. Capped boards are a different story. The capped makers advise against any coating¹, and the fade warranties cited here are void once one goes on⁸. The better fixes for a faded deck are in can you paint composite decking.

Can composite decking be installed over concrete?

Yes, on a low frame, never straight onto the slab. One maker says its boards must not be laid directly on a solid surface such as concrete, and asks for at least 40 mm of clearance where drainage is good¹. Another wants 50 mm over concrete⁵. Getting the height right at the door is the part I'd plan first. Composite decking over concrete runs through the options.

Can you put composite decking over a wood frame?

Over a new frame built to the board's guide, yes. Over the old frame from a timber deck, I'd check it hard before you decide. Measure the joist centres against the new board's guide, look for rot at the post bases, and run a straight edge across the joists. One Whirlpool member laid new boards over an old frame at 450 mm centres where the maker recommended 400, checked with the maker first, and still found "a bit of bounce"¹². Composite decking on an existing deck frame explains what to check.

How far apart are decking joists for composite?

It depends on the board, and the maker's guide gives a maximum. One solid board allows 450 mm centres on a house deck⁵, and one hollow-core board is listed at 400 mm for residential use and 350 mm for commercial². Another maker asks for 400 mm on a house deck and 300 mm for steps and commercial decks⁶, with closer centres again for boards laid at 45 degrees. The reasons and the traps are in joist spacing for composite decking.

Do you have to screw composite decking into every joist?

Yes, the board is fixed at every joist it crosses. One maker's guide says to double-fix on each joist⁵, and another says two screws per board wherever it crosses a joist⁶. Clip systems hold the board at the joists too, and one adds one locking clip near the middle of each board so it can't shift out of line¹. Hidden clips vs face screws explains both systems.

How do you fasten composite decking?

With hidden clips in grooved-edge boards, or with screws through the face. Some makers sell colour-matched screws for that. One maker says face-fixing the whole deck voids its warranty, and keeps face screws to the fascia and to spots where they can't be avoided¹. The fixing has to suit the frame material, and the warranties cited here exclude fasteners the maker hasn't supplied or approved⁷.

How do you frame deck stairs for composite?

With stringers at closer centres than the deck itself. One maker's solid board drops from 450 mm on a house deck to 400 mm on stairs and landings, which are designed for a heavier load¹. The same maker wants the boards fully supported at stair treads. Riser boards, a nosing and the right balustrade height all need planning before the first cut. Composite decking stairs sets out the framing.

What is the best composite decking in Australia?

The right board depends on your sun, shade, budget and frame, so I don't rank one above the rest. I'd start with which ranges are capped and which carry a fade warranty, and the brand pages set that out range by range, with each range's published warranty terms and the document they came from.

Is PVC decking better than composite?

It's a different product rather than a better one. A PVC board is all plastic, while composite mixes plastic with wood fibre. Which suits you depends on heat, weight, fire rating and budget, and PVC vs composite decking compares them point by point.

How long does composite decking last and what does the warranty cover?

The capped ranges I checked carry between 10 and 50 years for a house deck, with 25 the most common⁸. Owners report decks that still look good at ten years and more. On Whirlpool in December 2025, one poster said a composite deck built about ten years earlier "still looks exactly the same"¹¹. The warranty covers defects in the board itself, such as rot or termite damage⁷. It excludes scratches and installation errors. Most terms step down after about year ten, and labour is almost never included⁷. Lifespan and what warranties really cover goes through the fine print. Read fading and scratches for what happens to the surface.