Timber Species and Material Comparison
Not all decking timber is equal, and understanding the price tiers saves you from overpaying or underspecifying.
Composite decking. Manufactured boards (wood fibre + plastic) that require no oiling. Australian brand ModWood runs $122–$151/m2 for boards. US brand Trex sits at $215–$265/m2 but carries a 25-year warranty. Ekodeck (using NewTechWood boards) is available at Bunnings. Composite eliminates the annual oiling commitment but can reach surface temperatures 16°C higher than hardwood in direct sun — lighter colours are recommended for sun-exposed north or west-facing decks.
The footing system sits under every deck and can meaningfully affect the total cost, especially on reactive soils or sloping sites.
Screw piles ($150–$300 per pile installed). Steel shafts with helical plates, mechanically driven into the ground. Same-day installation, minimal site disturbance, and removable if needed. Better suited to reactive clay soils (common in parts of Adelaide, Melbourne, and Brisbane) because they anchor below the reactive zone. Must comply with
AS 2159 Piling — Design and Installation. Increasingly popular for residential decks.
Concrete piers ($200–$400 per footing fully installed). The traditional approach — holes are dug, formwork set, and concrete poured. Requires 3–7 days cure time before the build can continue. Standard for most residential decks on stable soils.
Steel posts on concrete pads (cost varies with post height and load requirements). A hybrid approach — steel posts bolted to shallow concrete pads. Used where ground conditions suit and the deck height is modest. The most engineered option, suited to elevated or high-load situations.
Balustrade Options and Cost
Any deck over 1 metre above finished ground level requires a balustrade under the NCC. Heights over 4 metres also need anti-climb provisions (no horizontal elements between 150mm and 760mm). Balustrade costs are per lineal metre, installed:
All balustrades must meet AS 1170 loading requirements: 0.6kN point load and 0.4kN/m distributed load at the handrail, with no gaps allowing a 125mm sphere to pass through.
What Affects the Cost
Deck area (m2). The single biggest multiplier. A 15m2 entertaining platform is a different job to a 50m2 wraparound. Installed costs (all-in) typically range from $250–$700/m2 depending on species and complexity.
Timber species vs composite. Treated pine boards at $43–$50/m2 versus jarrah at $150–$250/m2 is a 3–5x material cost difference before labour. Composite eliminates maintenance but adds upfront cost.
Height off the ground. Ground-level decks need minimal subframe. Elevated decks need taller stumps, bracing, and often a balustrade ($200–$700/lm depending on type). Anything over 1 metre typically requires council approval.
Footing type. Concrete piers ($200–$400 each) versus screw piles ($150–$300 each). Screw piles save time but may cost more per unit on straightforward sites.
Deck shape and layout. A simple rectangular platform costs less per square metre than an L-shaped or multi-level design with step-downs and transitions.
Site access. If timber has to be carried through the house because there is no side gate, expect extra labour charges.
Soil conditions. Reactive clay (common in parts of Adelaide, Melbourne, and Brisbane) may require engineered footings to
AS 2870 Residential Slabs and Footings. Soil classes range from A (non-reactive) through H1/H2 (highly reactive) to E (extremely reactive — over 75mm ground movement).
Council requirements. Development Applications or Complying Development Certificates add $500–$2,000+ in fees and 3–8 weeks of lead time.
Finishing. A quality decking oil costs $26–$45/L depending on brand. Popular products include Cabot's Aquadeck (~$26/L, 8–10 m2/L coverage),
Intergrain UltraDeck (~$31/L, 10–14 m2/L), and Sikkens Cetol Deck Ultra (~$45/L, 8–10 m2/L). Annual oiling runs roughly $2.50–$4/m2 in materials for a DIY job, or $30–$80/m2 if you hire a professional deck maintenance service.
A small treated pine deck on a flat suburban block with good side access sits toward $3,600. A large hardwood deck with glass balustrade, engineered footings, and council approval on a sloping site pushes toward $21,200.
If you are building a pergola alongside or over the deck, allow $3,000–$20,400 per job separately and coordinate both trades. For timber decks that need more than annual oiling, professional deck and fence painting costs $500–$3,200 per job, with preparation and coating matched to the timber’s condition.
City and Regional Price Comparison
Sydney sets the baseline for decking pricing. Melbourne and Brisbane track close to Sydney rates, though Brisbane's outdoor living culture means strong demand and consistent carpenter availability. Smaller trade pools and materials logistics influence Perth and Adelaide quotes; see the Pricing by City table for ranges. Within any city, the price swing comes down to your specific property.
A new-build estate home in a growth corridor (think Oran Park in Sydney, Tarneit in Melbourne, or Springfield in Brisbane) has flat ground, easy access, and standard soil conditions. That is a predictable job. An older suburb with a steep backyard, narrow side passage, and a deck that needs to step down 2 metres creates a more complex build. Inner-city properties in heritage overlay zones may face design restrictions that add both time and cost to the approval process. Coastal properties in bushfire zones require specific timber treatments or non-combustible materials under AS 3959 Construction of Buildings in Bushfire-Prone Areas, further affecting the budget.
Hiring a Licensed Carpenter or Builder
Every state requires licensed builders for decking work above certain value thresholds — $5,000 in NSW, $3,300 in QLD, $16,000 for domestic building insurance in VIC, and $20,000 in WA and SA. Verify your builder's licence through the relevant state authority before signing a contract.
Look for a builder who specifies timber species, treatment grade, and footing type in their quote — not just "hardwood deck." A good quote should itemise the subframe (bearers, joists, footings), deck boards, fixings, balustrade (if required), and council fees separately so you can compare like-for-like.
The WoodSolutions website, run by Forest & Wood Products Australia, publishes span tables, design guides, and timber species data sheets that can help you evaluate what a builder is proposing.
How We Calculate
Estimates are based on surveyed trade rates for licensed carpenters and builders across Australian capital cities, adjusted for regional labour markets and typical material costs. All prices include GST. Figures cover standard residential decking construction. Commercial builds, pool surrounds, and rooftop decks may fall outside these ranges.