What Affects the Cost
Deck size. A 15m2 platform off the back door is a different budget to a 40m2 entertainer wrapping around two sides of the house. Installed costs run $250–$700/m2 all-in depending on species and complexity.
Timber species. Treated pine ($43–$50/m2 boards) keeps the price down. Spotted gum ($90–$120/m2) and merbau ($73–$80/m2) are Sydney's popular hardwoods, lasting 25+ years with annual oiling using products like
Intergrain UltraDeck (~$31/L, covers 10–14 m2/L) or Cabot's Aquadeck (~$26/L). Composite boards from
ModWood ($122–$151/m2) or
Trex ($215–$265/m2) eliminate oiling entirely.
Height and subframe. Ground-level decks on flat blocks are straightforward. Elevated decks on sloping blocks in suburbs like Mosman or Wahroonga need substantial subframes, bracing, and balustrades — timber ($200–$450/lm), wire ($350–$700/lm), or frameless glass ($280–$425/lm).
Council approval. Decks within the
NSW exempt development thresholds (under 25m2, under 1m high, 900mm+ from boundaries, behind the building line) need no approval. Beyond that, a CDC costs $1,500–$5,000 with a 20-day turnaround, while a full DA runs $300–$800 in council fees and takes 40–60+ days.
Deck layout. L-shaped or multi-level designs with step-downs cost more per square metre than a simple rectangular platform.
Site access. Narrow side passages in terraces and semi-detached homes across the inner west mean timber gets carried in by hand, adding labour time.
Bushfire zone materials. Properties rated BAL-19 or above under
AS 3959 must use higher-density hardwoods or non-combustible materials, increasing both material cost and design complexity.
A small treated pine deck on a flat block in Kellyville or Oran Park with good side gate access sits toward $3,600. A large spotted gum deck with glass balustrade on a steep Mosman block requiring a DA pushes toward $21,200.
Sydney-Specific Considerations
Inner west and inner south. Newtown, Marrickville, Balmain, Leichhardt. Blocks are small but property values are high, so homeowners invest in quality decking to make the most of limited outdoor space. Tight rear access is common — materials carried by hand through the house adds labour time. Many of these areas fall under Heritage Conservation Areas, which can restrict deck heights, materials, and even colours. Heritage overlay DAs take longer to process and may require a heritage impact statement. Check with your local council before committing to a design.
North Shore and Northern Beaches. Mosman, Wahroonga, Manly, Dee Why. Larger blocks but often sloping, meaning elevated decks with substantial subframes and bracing. These suburbs tend toward spotted gum or composite builds with frameless glass balustrades ($280–$425/lm) to preserve views. Council DAs are standard for elevated builds. Screw piles ($150–$300 each) are increasingly popular on sloping North Shore blocks because they can be installed same-day with minimal site disturbance, versus 3–7 days cure time for concrete piers.
Western Sydney and growth corridors. Kellyville, Oran Park, Marsden Park. New-build homes on flat blocks with good access. These are the most predictable and cost-effective decking jobs in Sydney. Treated pine is popular for budget builds, with merbau ($73–$80/m2) as the step-up option. Most of these jobs fall within exempt development thresholds, avoiding council fees entirely.
Bushfire zones. Parts of the Hills District, Blue Mountains fringe, and northern suburbs near bushland are designated bushfire-prone areas under AS 3959. Decking in BAL-12.5 zones can use standard hardwood. BAL-19 and BAL-29 require higher-density species like spotted gum, blackbutt, or ironbark, plus screening beneath the structure. BAL-40 prohibits solid timber externally — only non-combustible decking materials and subframes are permitted. BAL-FZ (Flame Zone) requires fully non-combustible construction throughout.
Hiring a Licensed Carpenter in NSW
In NSW, a contractor licence is required for any residential building work valued over $5,000 (including GST). Verify your carpenter or builder's licence through NSW Fair Trading. For jobs over $20,000, the builder must carry Home Building Compensation Fund (HBCF) insurance through icare — this protects you if the builder dies, disappears, or becomes insolvent.
Ask for:
Current NSW contractor licence number (verify it online)
Proof of public liability and HBCF insurance (for jobs over $20,000)
A written fixed-price quote specifying timber species, treatment grade, footing type, and fixings
Confirmation of whether the deck falls within exempt development thresholds or needs a CDC/DA
Worth checking: Cannot provide a licence number, wants full payment upfront before starting, or suggests skipping council approval for an elevated deck.
How We Calculate
Estimates are based on current licensed carpenter and builder rates across the Sydney metropolitan area, adjusted for typical material costs in NSW. All prices include GST. Figures cover standard residential decking construction. Pool surrounds, rooftop decks, and commercial builds may fall outside these ranges.