At a Glance
Sydney backyards range from compact inner-west courtyards to generous Northern Beaches blocks, and decking costs reflect that variety. Most homeowners pay $3,500–$18,000 per job depending on deck size, timber choice, and how much site preparation is involved. Material choice alone can swing the budget significantly — treated pine boards start at $43–$50/m2, while spotted gum sits at $90–$120/m2 before labour and subframe.
What's Included in the Price
- Site preparation and old deck removal (if replacing)
- Subframe construction: concrete piers ($200–$400 each) or screw piles ($150–$300 each), bearers, joists
- Deck board installation, including any step-downs or stairs
- Compliance with AS 1684 Residential Timber-Framed Construction
- Balustrade if the deck is over 1 metre above ground level (must meet NCC requirements: 1,000mm minimum height, no gaps over 125mm, 0.6kN point load rating)
- Initial oil or stain coat
Materials make up roughly 40–50% of the total cost. The rest covers labour, site logistics, and any engineering or council fees.
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 $3,500. A large spotted gum deck with glass balustrade on a steep Mosman block requiring a DA pushes toward $18,000.
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
Red flags: 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.