Composite Decking vs Timber Decking Cost in Australia 2026

Every decking conversation in Australia ends up at the same fork in the road: spend less now on timber, or spend more now on composite and stop oiling it every second summer. The brochures are no help, because composite suppliers price boards and carpenters price finished decks — so you end up comparing a $140/m² number against a $500/m² number and getting nowhere.

Composite decking vs timber decking cost in 2026 comes down to about a 9% premium over merbau and a 93% premium over treated pine on an installed, per-square-metre basis. That's the real spread once you're comparing supplied-and-laid against supplied-and-laid rather than board price against finished deck. The maintenance saving is real too — it's just smaller than the sales pitch, and it takes about 15 years to catch merbau rather than the five to seven years you'll see quoted.

This guide separates board supply from installed cost, gives whole-deck totals for a 24 m² backyard deck and a 40 m² elevated one, prices the maintenance on both sides using real Australian rates, and works out the actual break-even year. If you'd rather skip to a number for your own deck, Leadkit's free decking quote calculator will give you a ballpark in under a minute.

Last updated: October 2026

Quick answer

Composite decking costs $350–$550 per square metre installed in Australia in 2026; timber decking costs $200–$280/m² for treated pine and $280–$420/m² for hardwoods like merbau and spotted gum. On Leadkit's own decking rate card, composite carries a 1.93× multiplier against treated pine and merbau carries 1.77× — so composite is roughly 9% more per square metre than merbau, and roughly double the cost of pine. Over a 15-year hold, composite and merbau land within about $20 of each other on a 24 m² deck once maintenance is counted.

This is a price indication only. Your tradie will confirm the final price after assessing the job.

Key takeaways

• Composite decking costs $350–$550/m² installed in Australia in 2026, against $200–$280/m² for treated pine and $280–$420/m² for hardwood — so composite is about double the price of pine and roughly 9% dearer than merbau.
• Composite board supply alone is $100–$170/m²; timber board supply runs $60–$180/m² depending on species. Boards are only about a third of a finished deck's cost.
• On Leadkit's decking rate card, a treated pine deck is priced at $250–$380/m² all-in, with multipliers of 1.47× for blackbutt, 1.60× for spotted gum, 1.77× for merbau and 1.93× for composite.
• A standard 4 m × 6 m (24 m²) ground-level deck comes to about $7,900 inc. GST in treated pine, $14,000 in merbau and $15,300 in composite on those default rates.
• The composite premium over merbau on that same 24 m² deck is about $1,270 inc. GST — and the maintenance saving recovers it in roughly 15 years, not the five to seven commonly quoted.
• Against treated pine the composite premium is about $7,370 on 24 m², which no maintenance saving ever recovers.
• Composite decking maintenance cost is a wash, not a seal: about $125 inc. GST for a professional clean on a 24 m² deck, against about $300 for a clean-and-oil on timber — roughly $86 a year in difference.
• Height is the most expensive thing you can do to a deck: mid-height adds 25% and elevated (over 1 m) adds 55% to the deck build on Leadkit's rate card, before any balustrade.
• Balustrade at $300 per linear metre and stairs at $350 per step make up about a fifth of a mid-height 24 m² deck — they're the two lines homeowners leave out of their own budget most often.
• Decking carries a $3,500 default minimum job fee on Leadkit, one of only six calculators at or above that level in a 202-calculator library where the median minimum is $800.

This is a price indication only. Your tradie will confirm the final price after assessing the job.

Table of contents

• How much does composite decking vs timber decking cost per square metre?
• What does a whole deck cost to build?
• How does the merbau decking cost comparison stack up?
• What does composite decking maintenance cost?
• When does composite decking actually become cheaper than timber?
• Why does composite cost more to install, not just to buy?
• What's in a decking quote and what gets added later?
• Which material suits Australian conditions?
• What approvals and licences does a deck need?
• FAQ
• How do you get a decking quote fast?

How much does composite decking vs timber decking cost per square metre?

Composite decking costs $350–$550 per square metre supplied and installed in Australia in 2026. Timber decking costs $200–$280/m² in treated pine and $280–$420/m² in hardwood — merbau, spotted gum, blackbutt or ironbark. Those are finished-deck rates: boards, substructure, fixings, labour and GST.

Board supply figures are market observation from Australian decking suppliers and retailers, not Leadkit data. This is a price indication only. Your tradie will confirm the final price after assessing the job.

Notice what the first column does to the argument. Composite boards are often cheaper to buy than merbau boards — it's the installation, not the material, that pushes composite to the top of the table. More on why below.

Leadkit's decking rate card — the first-party numbers

Leadkit's decking calculator is configured by Australian decking businesses using their own rates, and the platform defaults give a clean like-for-like comparison because every species is priced as a multiple of the same treated pine base.

Methodology and disclosure: these multipliers and the $300/m² base rate are the shipped defaults in Leadkit's own decking quote calculator — this is Leadkit's product, not neutral third-party survey data. The calculator's base rate is adjustable between $150 and $500/m², with a stated Australian working band of $250–$380/m² for treated pine, and GST is added on top of the subtotal at 10%. Apply the multipliers across that band and composite lands at $482–$733/m² ex. GST, which sits above the broader market range in the first table — a reminder that configured tradie rates skew toward full custom builds rather than kit decks. Our separate decking cost per square metre guide breaks the base rate down into substructure, boards and labour.

This is a price indication only. Your tradie will confirm the final price after assessing the job.

What does a whole deck cost to build?

A standard 4 m × 6 m (24 m²) ground-level deck costs roughly $7,900 inc. GST in treated pine, $14,000 in merbau and $15,300 in composite in 2026. Per-square-metre rates are useful for comparing materials; they're useless for budgeting, because height, balustrade and stairs can add more than the boards do.

All figures inc. GST, generated from the default rates in Leadkit's decking quote calculator. This is a price indication only. Your tradie will confirm the final price after assessing the job.

Three defaults are doing the heavy lifting in that second and third row: balustrade at $300 per linear metre, stairs at $350 per step (that's the stringer, tread and fixings for one step), and a roof or pergola allowance of $5,500.

Here's the part people miss when they budget a deck themselves. On the mid-height 24 m² composite build above, the balustrade and stairs come to $4,400 of a $21,770 subtotal — about a fifth of the job, and the two lines most often left out of a homeowner's own spreadsheet entirely.

Height is the other quiet multiplier. Leadkit's calculator applies a 25% premium for a mid-height deck (300 mm to 1 m above ground) and 55% for an elevated deck (over 1 m), because elevated builds need deeper footings, more posts and extra bracing. That premium applies to the deck build itself, so it scales with your material choice — the dearer the board, the dearer the height.

Want a figure for your actual deck? Enter your length, width, material and height in the decking quote calculator and you'll have a breakdown in under a minute. It's an indication only — your carpenter confirms the final price on site.

How does the merbau decking cost comparison stack up?

Merbau is the closest timber to composite on price, sitting about 9% below it per square metre — $584/m² against $637/m² inc. GST on Leadkit's default rates. That makes merbau versus composite the only genuinely close call in decking. Every other timber is a long way cheaper.

This is a price indication only. Your tradie will confirm the final price after assessing the job.

Merbau earns its place at the top of the timber table honestly. It's a dense imported hardwood with a durability class 2 rating under AS 5604 — the standard that grades timber by how long it survives above ground and in ground — which means 25 to 40 years of service with reasonable care. It's dimensionally stable, it takes a fixing without splitting, and the deep red-brown colour is what most Australians picture when they picture a deck.

Two merbau realities to price in. It bleeds tannin for the first few months, which stains light-coloured concrete and render underneath it, so budget for a tannin-blocking wash or accept the marks. And merbau's sustainability credentials depend entirely on the chain of custody — ask for certification rather than assuming it.

Spotted gum and blackbutt are the Australian-grown alternatives at 21% and 31% below composite respectively, and both are class 1 or 2 for durability. If you want hardwood and you want to keep $2,500–$3,500 in your pocket against composite on a 24 m² deck, that's where it is.

What does composite decking maintenance cost?

Composite decking maintenance cost is about $125 inc. GST for a professional clean on a 24 m² deck, against about $300 for a clean-and-oil on the same deck in timber — a difference of roughly $86 a year on a two-yearly cycle. Composite still needs washing; it just doesn't need coating.

Those numbers come from Leadkit's pressure-washing rate card, which prices a patio or deck wash at $4/m², a heavier moss and lichen clean at a 20% premium, and sealing at $6.50/m², all ex. GST with a $150 minimum job fee.

Figures inc. GST, from the default rates in Leadkit's pressure-washing quote calculator. This is a price indication only. Your tradie will confirm the final price after assessing the job.

DIY changes the maths but not the direction. A 4 L tin of decking oil from Bunnings covers roughly 20–25 m² a coat and runs $70–$100, so two coats on a 24 m² deck is $140–$200 in materials plus most of a weekend. Call it $4–$8/m² in product, which is market observation rather than Leadkit data.

This is where the composite sales pitch overreaches. You'll see annual timber maintenance quoted at $300–$800 a year for a typical deck, and 20-year savings of $4,000 to $16,000. Price the same work at what Australian cleaning and decking businesses actually charge on our platform and a two-yearly oil on a 24 m² deck is $149 a year, not $500. The saving is genuine; it's about a sixth of the figure that gets advertised.

Timber also has one maintenance cost composite doesn't: re-coating is the thing that keeps the lifespan you paid for. Skip the oil on merbau for five years and you get surface checking, greying and board cupping. Skip the wash on composite and you get a dirty deck.

Pricing the upkeep rather than the build? The pressure washing quote calculator prices a deck wash and seal by area — results are an indication only, and the operator confirms the price on site.

When does composite decking actually become cheaper than timber?

Composite breaks even against merbau at about year 15 on a 24 m² deck, and never breaks even against treated pine. That's the payback at an $86-a-year maintenance difference against the upfront premiums in the table above.

Run it as a 15-year total cost of ownership and the merbau comparison is a dead heat:

Build figures from Leadkit's decking calculator defaults, maintenance from its pressure-washing defaults, both at a two-yearly service cycle. This is a price indication only. Your tradie will confirm the final price after assessing the job.

Twenty dollars apart over 15 years. On those numbers, choosing composite over merbau is a lifestyle decision, not a financial one — you're buying out of the oiling weekend, not saving money.

One honest caveat on the bottom of the table. Treated pine looks unbeatable at $10,157 over 15 years, and it is — right up to the point where a 15-to-20-year-old pine deck needs replacing and a hardwood or composite deck of the same age has 10 to 30 years left in it. Factor a second build into a 30-year horizon and pine stops winning.

Why does composite cost more to install, not just to buy?

Composite boards are often cheaper to buy than merbau, but cost 9% more installed, because composite substructures are built tighter and composite boards are fixed differently. Three technical requirements account for most of the gap.

Closer joist centres. Most composite systems specify joists at 400 mm centres where a hardwood deck runs happily at 450 mm, and diagonal or picture-frame layouts tighten that further to around 300 mm. More joists means more timber, more joist hangers and more labour in the substructure — the bearers and joists under the boards — before a single composite board goes down.

Hidden clip-fix systems. Composite is almost always fixed with concealed clips that sit in a groove in the board edge, rather than top-fixed with stainless screws. The finish is cleaner, but clip-fix is slower per square metre and the clips themselves add to the materials bill.

Expansion gaps. Composite moves more with temperature than hardwood does, so butt joints need deliberate gaps — typically 5–6 mm — and board runs need planning around the manufacturer's expansion allowance. Get it wrong and the boards buckle in a Brisbane February.

Add the cut waste. Composite is sold in fixed lengths and you can't rip a board down and re-use the offcut the way you can with timber, so on an awkward-shaped deck the waste factor runs higher.

That's the whole explanation for why the two tables at the top of this guide disagree: on material alone composite is competitive, and on installed cost it isn't.

What's in a decking quote and what gets added later?

A decking quote should cover footings, substructure, boards, fixings, labour and GST — and should separately price balustrade, stairs, a roof, and demolition of an old deck. Those four are the usual source of the gap between the quote you accepted and the invoice you received.

Here's what each adds on Leadkit's default rates:

• Balustrade — $300 per linear metre installed. The platform's adjustable band is $200–$450/LM for timber and glass. Mandatory, not optional, once the deck is more than 1 m above the ground beneath it.
• Stairs — $350 per step. Covers the stringer, tread and fixings for one step at roughly a 170 mm rise. Four steps is $1,400; a flight off an elevated deck can be ten.
• Roof or pergola — $5,500 allowance. A basic roofed structure over the deck, with an adjustable band of $3,000–$8,000. If a roof is the main event rather than an add-on, price it properly with the pergola quote calculator instead.
• Demolition and removal of an existing deck. Rarely in the headline number. Ask for it as a line item, and ask who's paying for the skip.

Two more worth asking about directly: engineering certification, which most states require once a deck goes over 1 m, and footing type — whether you're getting concrete pad footings, stirrup-mounted posts or screw piles, because reactive clay soils in Melbourne and Adelaide can turn footings into the most expensive part of the substructure.

A note on how decking is priced as a trade: Leadkit's decking calculator ships with a $3,500 default minimum job fee — the smallest job a decking business will mobilise for. Across the 202 calculators in the library, 53 carry a minimum job fee at all and the median is $800. Decking is one of only six at or above $3,500. If you're after a 6 m² landing off a back door, expect the minimum to bite well before the per-metre rate does.

Which material suits Australian conditions?

Composite wins on pool surrounds, termite exposure and low-maintenance coastal sites; timber wins on cost, bushfire compliance above BAL-29, and surface temperature in full sun. The right answer is site-specific more than it is budget-specific.

Treated pine is graded by hazard class under AS 1604: H3 is rated for above-ground outdoor use and is what your boards and joists will be, while H4 is rated for in-ground contact and is what your posts need to be. Getting H3 posts in the ground is one of the more common ways a cheap deck becomes a short deck.

Hardwoods are graded by natural durability class under AS 5604 instead of being treated — merbau, spotted gum, blackbutt and ironbark all sit in class 1 or 2 above ground, which is why they last without chemical treatment.

Composite is immune to termites and rot, doesn't splinter, and holds its colour in UV far better than an un-oiled timber deck. Capped composite — where a polymer shell is bonded over the core — resists staining and fading better than uncapped board, and carries the longer warranties. Brands you'll see quoted in Australia include Trex, Modwood and Ekodeck; warranties commonly run 10 to 25 years, so read what the warranty actually covers before you treat it as a lifespan.

Three site conditions that override everything else:

• Bushfire-prone land. AS 3959 restricts what can be used for a deck close to the building, and above BAL-29 the options narrow to bushfire-resisting timbers or non-combustible materials. Not every composite board is tested to those levels — ask for the manufacturer's BAL certification before you commit.
• Full afternoon sun. Dark composite gets noticeably hotter underfoot than timber. If the deck faces west in Perth or Adelaide, choose a lighter board or plan the shade.
• Pool and coastal exposure. Chlorinated splash-out and salt air are hard on timber coatings. This is composite's strongest practical case, and it's a durability argument rather than a cost one.

For colour and coating, the oils Australian carpenters most often specify are Cutek and Intergrain, and most will have a view on which one suits your species — ask them, because re-coatability is part of what you're buying with timber.

What approvals and licences does a deck need?

Most Australian decks need either a building permit or confirmation that they qualify as exempt development, and anything beyond a very small job needs a licensed tradesperson. The thresholds are state-based, so check yours rather than the national average.

Under the National Construction Code, published by the Australian Building Codes Board, a deck more than 1 m above the surface beneath it needs a barrier at least 1 m high, with no opening a 125 mm sphere can pass through. That's the rule that turns a $14,000 deck into a $22,000 deck, and it's not negotiable at inspection.

On licensing, NSW Fair Trading requires a licence for residential building work valued over $5,000 including GST, with home building compensation cover kicking in above $20,000. Queensland's QBCC threshold is lower at $3,300, and Victoria requires a registered building practitioner and a major domestic building contract for work over $10,000. Every one of those thresholds sits below the cost of a typical hardwood or composite deck.

Approval is separate from licensing. In NSW, a low-level deck can fall under exempt development if it stays within the area and height limits in the Codes SEPP — generally no more than 1 m above ground — but councils interpret setbacks, heritage overlays and strata consent differently. Ring your council before you order boards, not after.

Timber framing under the deck is built to AS 1684, the residential timber-framed construction standard, which sets out span tables for bearers and joists. If a quote can't tell you its joist span and centres, that's a reasonable thing to query. The Housing Industry Association and Master Builders Australia both publish guidance on contracts and progress payments worth reading before you sign, and the Australian Bureau of Statistics Producer Price Indexes are the place to track what's actually happening to timber and building material input costs rather than relying on what a supplier tells you about price rises.

FAQ

Q: Is composite decking cheaper than timber in the long run?

A: Only against merbau, and only after about 15 years. On a 24 m² deck, composite costs about $1,270 more to build than merbau and saves about $86 a year in maintenance, so the payback lands around year 15 — at which point the 15-year total cost of ownership is $16,236 for composite and $16,256 for merbau. Against treated pine the composite premium is about $7,370 and the maintenance saving would take roughly 86 years to recover, so it never pays back on cost alone. The commonly quoted five-to-seven-year break-even assumes $300–$800 a year in timber maintenance, which is several times what Australian operators actually charge for a deck wash and oil. This is a price indication only.

Q: What is composite decking price per square metre in Australia?

A: Composite decking costs $350–$550 per square metre supplied and installed in Australia in 2026, and $100–$170/m² for the boards alone. On Leadkit's decking calculator defaults it prices at $579/m² ex. GST or $637/m² inc. GST, reflecting full custom builds by configured decking businesses rather than kit decks. The installed figure includes footings, substructure, hidden clip fixings, labour and GST, and excludes balustrade, stairs and any roof. A 24 m² ground-level composite deck lands around $15,300 inc. GST. Your site, access and deck height move that number more than the brand of board does. This is a price indication only. Your tradie will confirm the final price after assessing the job.

Q: How much does a 20 m² deck cost in Australia?

A: A 20 m² ground-level deck costs roughly $6,600 inc. GST in treated pine, $10,560 in spotted gum, $11,680 in merbau and $12,740 in composite on Leadkit's default rates. Add a balustrade at $300 per linear metre and stairs at $350 per step if the deck sits above 1 m, which can add $4,000 or more. Keep in mind that decking carries a high minimum job fee — $3,500 is the platform default — so small decks don't scale down proportionally. Below about 12 m², the minimum fee rather than the area is what sets your price. This is a price indication only.

Q: Why is composite decking more expensive to install than timber?

A: Three reasons. Most composite systems specify joists at 400 mm centres against 450 mm for hardwood, so the substructure needs more timber and more labour before any board goes down. Composite is fixed with concealed clips rather than top-fixed screws, which is slower per square metre and adds a materials line. And composite expands more with temperature, so butt joints need 5–6 mm gaps and the board layout has to be planned around the manufacturer's expansion allowance. Add higher cut waste — you can't rip and re-use a composite offcut the way you can with timber — and you get a 9% installed premium over merbau despite composite boards often costing less to buy.

Q: Does composite decking need any maintenance at all?

A: Yes — it needs washing, it just doesn't need coating. Budget about $127 inc. GST for a professional wash of a 24 m² composite deck every year or two, against about $300 for the same deck in timber where an oil or seal coat is also needed. Composite still collects pollen, mould and barbecue grease, and capped board resists staining better than uncapped. What you're buying out of is the sanding and re-oiling cycle, not cleaning. Ask your deck cleaner to price the wash and the coat as separate lines so you can see exactly what the composite saving is on your own deck. This is a price indication only.

Q: How often do you need to oil a merbau deck?

A: Every one to two years in most Australian climates, and annually on a deck in full sun or near the coast. The job is a wash, a dry-out, then one or two coats of a penetrating oil — Cutek and Intergrain are the products carpenters most commonly specify. At platform rates that's about $300 inc. GST per service professionally, or $140–$200 in product if you do it yourself over a weekend. Skipping it for several years doesn't just dull the colour: you get surface checking, greying and board cupping, which is how a 30-year deck becomes a 15-year deck.

Q: Which is better for a pool surround, composite or timber?

A: Composite, in most cases. Chlorinated splash-out and salt air are hard on timber coatings, so a pool-side timber deck needs re-oiling more often than the same deck elsewhere in the yard — and that's exactly the cost composite removes. Composite also doesn't splinter underfoot, which matters more around a pool than anywhere else. The trade-off is surface temperature: dark composite gets hot in direct sun, so choose a lighter board for a north or west-facing pool deck. Pool fencing is a separate compliance job with its own rules and its own cost. This is a price indication only.

Q: Do I need council approval for a deck in Australia?

A: Usually yes, unless it qualifies as exempt development. In NSW a low-level deck — generally no more than 1 m above the ground and within the area limits in the Codes SEPP — can be built without development consent, but setbacks, heritage overlays and strata consent all change the answer. Anything over 1 m needs a barrier under the National Construction Code and typically engineering certification. Licensing is separate: NSW requires a licensed tradesperson over $5,000, Queensland over $3,300 and Victoria a registered practitioner over $10,000 — all below the cost of a typical deck. Ring your council before you order materials.

Q: What's the cheapest way to build a deck?

A: Treated pine, ground level, square, and close to the house. Those four decisions do almost all the work: pine is 93% cheaper per square metre than composite on platform rates, staying under 300 mm avoids the 25% mid-height premium and the balustrade requirement entirely, a rectangle has no cut waste, and proximity keeps access easy for materials. A 24 m² ground-level pine deck at about $7,920 inc. GST is less than the balustrade and stairs alone on an elevated build. Just use H4-rated posts in the ground — H3 is above-ground only, and in-ground H3 is the most common corner-cut that shortens a cheap deck's life.

Q: Does a deck add value to an Australian home?

A: A well-built deck is consistently one of the better-regarded outdoor additions in Australian housing, largely because it extends usable living space at a far lower cost per square metre than an internal extension. What matters for resale is that it looks like part of the house rather than bolted on, that it's compliant — unapproved structures come up in conveyancing and can cost you at settlement — and that it's in good condition, which is where the maintenance argument becomes a value argument. Keep your approval paperwork and engineering certificates together; you'll want them at sale.

Q: Can I use composite decking in a bushfire-prone area?

A: Sometimes, but check before you buy. AS 3959 restricts what can be used for a deck within a certain distance of the building, and from BAL-29 upward the compliant options narrow to bushfire-resisting timbers or non-combustible materials. Some composite products are tested to specific BAL levels and some aren't, so ask the manufacturer for the certification rather than assuming the board qualifies. If your site is BAL-40 or Flame Zone, talk to your certifier before you make a material decision — it's the one scenario where the cost comparison in this guide may be irrelevant.

Q: Should I get more than one decking quote?

A: Yes — three is the usual advice, and insist they're quoted on the same scope. Decking quotes vary wildly because different carpenters include different things: one prices demolition and the skip, another doesn't; one quotes pad footings, another screw piles. Ask every quote to separate substructure, boards, balustrade, stairs and any roof, and to state its joist centres. Using a per-square-metre rate from this guide as a sense-check will tell you fast whether an outlier is cheap because it's efficient or cheap because something's missing. For related carpentry pricing, the carpentry cost guide covers hourly and day rates.

How do you get a decking quote fast?

Composite decking vs timber decking cost in Australia 2026 comes to this: composite is $350–$550/m² installed, hardwood $280–$420/m², and treated pine $200–$280/m². Composite is roughly 9% dearer than merbau and about double the price of pine, and the maintenance saving recovers the merbau premium in around 15 years rather than the five to seven you'll see advertised. Against pine, it never does.

So the decision is cleaner than the brochures make it. If you want hardwood and you'll oil it, buy merbau or spotted gum and keep the difference. If you'd rather never oil a deck again and you're staying put for 15 years, composite costs you nothing extra over merbau on a 15-year view. If the budget is the constraint, build a low pine deck properly and spend the savings on shade.

The fastest next step: use the free decking calculators to enter your deck's length, width, material and height — you'll get a full breakdown with balustrade, stairs and GST in under a minute, built on real Australian rates. Results are an indication only; your carpenter confirms the final price after seeing the site.

Run a decking or landscaping business? Embed a free Leadkit calculator on your own site in 60 seconds, set your own rates, and every homeowner who prices a deck becomes a lead with their contact details and job details attached.

All prices in this guide are indicative and include GST unless marked ex. GST. Leadkit-sourced figures are generated from the default rates in Leadkit's own decking and pressure-washing quote calculators — this is our product, not third-party survey data, and individual businesses configure their own rates. Actual costs depend on your site, access, soil conditions, material selection and your tradie's rates. This is a price indication only. Your tradie will confirm the final price after assessing the job.