A deck in Australia is usually priced per square metre, and as a rough guide you are looking at about $200 to $550 plus per square metre installed, depending mostly on the decking material. Treated pine sits at the cheap end, hardwood in the middle, and composite at the top. A typical deck lands somewhere around $5,000 to $15,000 plus once it is built.
That is the short version. The longer version is that the headline rate hides a lot, because a deck is really two jobs stacked together: the frame underneath that nobody sees, and the boards on top that everybody admires. Two decks of the same size and boards can cost very different amounts once you factor in height, site access and what the structure has to do. So treat the numbers below as a starting point, not the invoice.
Why decks are priced per square metre
A deck is a flat thing you walk on, so the floor area in square metres is the natural unit, and it maps reasonably well to the cost of the boards and the labour to lay them. Quote a builder a rough size and they can give you a ballpark in their sleep.
The catch is that the per square metre rate quietly assumes a fairly standard, ground-level deck on a friendly site. The moment your deck climbs into the air, wraps around a corner or sits over a steep, hard-to-reach block, that assumption breaks and the rate climbs with it. Which is the whole reason a real quote beats a calculator.
A ground-level deck is a floor. An elevated deck is a small building, and it is priced like one.
Cost by decking material
Here is the rough lay of the land for the common decking choices in Australia. These are supplied and installed ranges per square metre, last checked June 2026, and they are deliberately wide because that is the honest picture. Prices vary by material, height and site, so use them to compare options, not to budget to the dollar.
| Decking material | Typical cost (installed, per m²) | Notes |
|---|---|---|
| Treated pine | $200 to $350 | Cheapest option, needs regular staining or oiling, good budget choice |
| Hardwood (merbau, spotted gum) | $320 to $450 | Premium look, durable, needs oiling to keep its colour |
| Composite decking | $350 to $550+ | Dearest up front, low maintenance, no oiling, splinters or fading |
A couple of honest caveats. Treated pine is cheap to lay but thirsty for maintenance, asking for a stain or oil every year or two to look its best. Hardwood like merbau or spotted gum looks genuinely premium and lasts, but it silvers off to grey if you let it, so it wants oiling too. Composite costs the most on day one and the top of that range is open-ended, since the better capped boards sit higher, but you trade that for years of barely lifting a finger. There is no single right answer, only the one that suits how much weekend maintenance you can stomach.
What actually drives the cost
The decking material is only one lever. Four others move the number just as hard, sometimes harder.
Height
Height is the big one. A ground-level deck can almost float on simple footings. Lift it up to chase a sloping block or meet a first-floor door, and you suddenly need bigger posts, beefier bearers and proper engineering to hold it all steady. Past a certain height the law also requires a balustrade, which is more material, more labour and a safety standard to meet. The jump from a low platform to an elevated deck is not a gentle slope on the invoice, it is a step up.
The substructure
Under every nice set of boards sits a frame of posts, bearers and joists, and that frame is a chunk of the cost you never actually see. On a flat, accessible block it is straightforward. On a slope, or where footings have to go deep into poor soil, the structure does more work and costs more accordingly. It is also not the place to cut corners, since everything above it depends on it.
A roof, pergola or balustrade over or around it
The deck itself is rarely the end of the wish list. Add a roof or a pergola for shade and you are adding a second structure on top of the first, with its own posts, framing and sometimes its own approval. Balustrades, screening and built-in seating all add up too. A bare deck and a fully kitted outdoor room are very different numbers, even on the same footprint.
Site access
If the build is on a flat block with a wide side gate, materials and tools roll straight in. Up the back of a steep, narrow or fenced-in yard, everything gets carried by hand and the labour bill grows. Access is invisible on a plan and very visible on a quote, which is one more reason the only honest price comes from someone standing in your yard. The cleanest way to compare is to get decking quotes from local carpenters and see how the numbers stack up against your site.
Approvals and the rules
Here is the part people would rather skip. A low, freestanding deck close to the ground can often be built without council sign-off, but the moment a deck climbs above a certain height, or attaches to the house, it usually needs approval and has to meet the Building Code.
The rules that bite most often are about height and safety. Once a deck surface sits high enough above the ground, a balustrade becomes mandatory, and the Code sets minimum heights for it so nobody takes an unplanned shortcut to the garden. The exact trigger heights vary by state and situation, so the safe move is to check with your local council or building certifier before anyone picks up a drill. Getting this wrong is expensive twice over: once to build it, and again to fix or remove it if it does not comply.
Building a deck rarely happens in isolation, either. If you are reshaping a sloping yard to fit it, you may be weighing it up alongside a retaining wall or wider landscaping work, and it pays to price the whole outdoor project together rather than in dribs and drabs.
How to keep the number sensible
A few habits keep a deck budget honest. Decide early how much maintenance you are realistically willing to do, because that single choice between pine, hardwood and composite swings the price more than almost anything else. Keep the shape simple, since every corner, level change and curve adds cutting and labour. Sort the approval question up front so you are not redesigning halfway through. And get more than one quote, because a deck is exactly the kind of job where prices spread widely and the cheapest bid is sometimes cheap for a reason. If you are not sure how to separate a good builder from a cheap one, our guide on how to find a good tradie covers what to ask and what to check.
The bottom line
Budget somewhere around $200 to $550 plus per square metre installed for a deck in Australia, last checked June 2026, with treated pine cheapest, hardwood in the middle and composite at the top. Expect a typical deck to land in the $5,000 to $15,000 plus range once it is finished. But remember the rate assumes a simple, low deck on an easy site, and that height, the structure underneath, any roof or balustrade and site access can all push it well past the guide. The figures here are for planning, not paying. Only a written quote from a builder who has actually seen your block is real, so get a couple, compare what is in them, and build from there.