Composite Decking vs Timber: Which Is Better in Melbourne?

Side by side

Composite Decking vs Timber, Side by Side

Composite decking vs timber comes down to four things: price, upkeep, heat and looks. Timber wins on the build price, the feel underfoot and how easily it repairs. Composite wins on upkeep and on looking the same in year ten as it did in year one. Bushfire ratings and stains depend on which timber and which board you compare.

If one row decides it for you, it's usually the second or the third. Anyone who's oiled a deck before already knows exactly how they feel about doing it again.

Cost over time

Which Costs Less Over 20 Years, Composite or Timber?

Timber costs less to build and composite costs less to keep. On a 25 m2 deck at typical Melbourne rates, merbau comes to about $11,000 and composite about $14,500. Paying someone to clean and re-oil the timber costs about $800 a coat, so composite pulls level somewhere between year five and year seven.

Two things change that answer. Oil the deck yourself and the timber column shrinks to the price of the oil, so you're paying in Saturdays instead. And the composite column only holds for a good board: entry-level uncapped composite is rated for 15 to 20 years, against 25 or more for capped boards.

The frame under both

Both boards sit on the same kind of frame: footings, bearers and joists. Composite usually wants its joists closer together, three to four hundred millimetres apart against four hundred and fifty for timber, so its frame takes more joists. A steel frame is the other option, and The Quote Yard notes it resists termites but costs more. For the full price breakdown, see our guide to decking costs in Melbourne.

Heat

Does Composite Decking Get Hotter Than Timber?

Yes, in full sun composite decking usually runs hotter than timber, and dark colours run hottest. How much hotter depends on who's holding the thermometer. One composite maker's own test found two degrees in it, a homeowner with an infrared heat gun found eight to ten, and a national cost guide says 15 to 20.

The last row is the one we'd pay attention to. It wasn't a heatwave. It was a mild Melbourne day in November, and the couple had been told there wasn't much difference.

Bunnings' own staff answer in that thread agrees that darker composite colours absorb more heat, and that airflow under the boards helps them cool. So if your deck faces north with no roof, look at the lightest board on offer, or stand on a sample at two in the afternoon. Your feet will tell you more than the brochure will.

Upkeep

How Much Maintenance Does Each One Need?

Timber needs oiling every 12 to 18 months in Melbourne to keep its colour. Composite needs a wash. Leave timber unoiled and it turns silver-grey, which some people love and everyone else calls weathered. You can always sand timber back and start again.

Oiling day comes round every year or so, and it always lands on the weekend you'd planned something better. That's the real cost of timber, and only you know what your weekends are worth.

Composite still changes. A composite maker's rep on Bunnings' own guide says the boards lose a little colour in the first months. One south east Melbourne owner with a north-facing composite deck reported on OzBargain after three years: "Has faded a touch, but I factored that into my selection".

Most composite can't be sanded back, either. Whatever it looks like in year twelve is the look, so choose the colour for the deck you'll have then.

Merbau

Is Merbau Decking Still a Good Choice in Melbourne?

Merbau decking is still a good choice in Melbourne. It's dense, it resists termites, and Wood Solutions rates it for bushfire areas up to BAL-29. The two catches are tannin and sourcing. New merbau bleeds red tannin for weeks, and it's imported, so where it was logged is worth asking about.

The red stain on your paving

Merbau's tannin washes out with the rain and onto whatever sits below or beside the deck. A Bunnings team member puts the bleed at six to twelve weeks depending on rainfall, and suggests covering the area underneath with builder's plastic until it stops.

If your new deck sits on pale paving or against fresh render, it's better to plan for that now than to find out after the first storm. Spotted gum is the timber we'd look at instead, because Wood Solutions describes it as less prone to bleed-through of tannins than other species.

Where the timber comes from

Merbau grows across South East Asia, Papua New Guinea and the Pacific. Investigators from EIA and Telapak documented large-scale merbau smuggling out of Papua in 2010, and since 3 March 2025, Australian importers must assess the risk of illegally logged timber before it arrives. It's fair to ask where your boards were logged, and a straight answer is a good sign.

Which timber

Which Decking Timber Suits Melbourne Best?

The best decking timber in Melbourne for most yards is a hardwood: merbau, spotted gum or blackbutt. All three resist termites and are rated for bushfire areas up to BAL-29. Treated pine is the cheapest decking wood in Melbourne, but it lasts about 8 to 12 years here against 25 to 40 for a well-kept hardwood.

Building on a bushfire-prone block

If your block has a bushfire attack level, or BAL, the deck has to meet it. Merbau, spotted gum and blackbutt are all listed for BAL-12.5, 19 and 29. Composite boards vary product by product, so ask for the board's own test result before you pick it. Above BAL-29 the rules tighten again, and that's a conversation for your building surveyor.

Whatever the board, plan on a permit. Boroondara Council puts it simply: "You always need a Building Permit to build a deck."

Around a pool

Is Composite or Timber Better Around a Pool?

Around a pool, composite usually wins on upkeep. Melbourne landscaping firm Whyte Gardens notes composite is generally more resistant to chlorine than most timbers. Heat is its weak spot, because pool decks are the ones people cross barefoot in January. A light board, or shade over it, matters more here than anywhere.

Timber can work too, with eyes open. Whyte Gardens puts the problem plainly: "When decking is used for the pool coping, a common complaint is the pool water removes the seal from the timber easily and so needs re-coating."

So a timber pool deck means oiling more often than the rest of the yard. If you're planning a pool deck as part of a bigger build, our pool landscaping in Melbourne covers the paving, fencing and planting around it in the same job.

Environment

Which Is Better for the Environment?

Neither wins outright, and each side's case comes from the people selling it. Composite makers point to recycled content: one maker's rep on Bunnings' guide says its boards are over 90 percent reclaimed timber, bamboo and recycled plastic. Timber suppliers point to the end of the deck's life: Mortlock says composite can be more difficult to recycle than timber.

A Bunnings Workshop member who has built decks in just about every material raised one more point, about cutting composite on site: "instead of generating sawdust it creates what is effectively something that will become micro-plastic waste." Responsibly sourced timber, for its part, is renewable and stores carbon for as long as the deck stands.

If the environment is the deciding factor for you, a certified Australian hardwood is the simplest answer to defend. If it's one factor among several, heat and upkeep will probably decide it first.

From the field

How We Help You Choose on Site

We build in both, so I'd rather ask you five questions than hand you a favourite. Your answers usually pick the board before we've finished walking the yard.

1. Which way does it face, and is there a roof? North-facing and open means heat matters most, so we'd look at timber or a light composite.
2. What sits right next to it? Pale paving, render or a pool beside new merbau means tannin, so spotted gum or composite moves up the list.
3. Who's on it barefoot? Kids and dogs in January change the answer faster than anything else here.
4. Will you oil it? Be honest. Nobody's checking, but the deck will know by year two.
5. Does the block have a BAL? Then the board has to carry the rating, whichever one it is.

Then we check the levels, the drainage and how the frame meets the house, because the frame is the same job whichever boards go on top. If you'd like that conversation on your own block, book a free, measured quote.

Questions

Composite and Timber Decking Questions