How Much Does a Deck Cost in Australia?
Building a deck is one of the best value home improvements in Australia — it adds usable outdoor living space, can be done in a few days by a licensed carpenter, and is cheaper per square metre than an enclosed room extension. Expect to pay $200–$600/m² all-in depending on materials, height, complexity and your location.
For a standard 20m² treated pine low deck, you're looking at roughly $4,000–$6,000 installed. A premium hardwood deck of the same size could run $8,000–$14,000. Composite decking sits in the middle — typically $350–$500/m² — with the upside of very low ongoing maintenance.
Decking Materials Compared
Treated Pine ($150–$250/m² installed)
The entry-level choice for Australian decking. H3 treated pine (for above-ground outdoor use) is widely available, easy to work with and significantly cheaper than hardwood. It requires regular oiling or staining every 2–3 years to maintain appearance and prevent checking (surface cracking). Structurally it's fine for most residential applications. H4 or H5 treatment is required for in-ground posts.
Merbau Hardwood ($250–$380/m² installed)
Merbau is Australia's most popular decking hardwood — imported from South-East Asia (primarily PNG and Indonesia). It's dense, naturally oils-rich, and reddish-brown in colour. It's more durable than pine and requires oiling less frequently (every 3–4 years). However, sustainability concerns mean some builders and councils are moving away from Merbau toward Australian species.
Australian Hardwoods — Spotted Gum, Ironbark ($280–$420/m²)
Spotted Gum and Ironbark are premium Australian hardwoods with exceptional hardness and durability. Both are sourced locally, making them the most sustainable choice. Spotted Gum in particular has a beautiful natural finish. They're among the hardest timbers in the world and last 30–50 years with basic maintenance. More expensive than Merbau but increasingly competitive as supply chains improve.
Composite Decking ($300–$500/m² installed)
Composite boards are made from a blend of recycled timber fibre and plastic. They look like timber from a distance, feel solid underfoot, and require virtually no maintenance — no oiling, no staining, just an annual wash down. Most composite products carry a 25+ year warranty. The main drawback is cost and the fact that they look slightly artificial up close. Popular brands in Australia include Trex, Ekodeck and ModWood.
Aluminium Decking ($400–$600/m² installed)
Aluminium decking is the most durable option — it won't rot, crack or fade, is non-combustible (important in bushfire zones), and requires almost zero maintenance. Used widely in commercial and marine applications. The main negatives are high cost and a somewhat industrial aesthetic. For Bushfire Attack Level (BAL) rated properties, aluminium may be required.
Worked Example 1: Standard Pine Deck
A 4m × 5m (20m²) low treated pine deck in Melbourne:
- Decking boards (90mm × 19mm pine): ~$600
- Frame (bearers and joists): ~$500
- Footings (4 post holes + concrete): ~$400
- Fixings, bolts, joist tape: ~$200
- Labour (1.5 days, carpenter + labourer): ~$1,800
- Total: approximately $3,500 → $175/m²
Worked Example 2: Elevated Merbau Deck with Balustrade
A 5m × 4m elevated deck (1m above ground) in Sydney requiring a balustrade:
- Merbau decking boards: ~$1,400
- Frame and posts: ~$900
- Concrete footings: ~$600
- Stainless wire balustrade (18m perimeter): ~$2,700
- Labour (3 days): ~$3,000
- Total: approximately $8,600 → $430/m²
Do I Need a Building Permit for a Deck?
In most Australian states, a deck requires a building permit if it is more than 1m above ground level, covers more than 10m², or is attached to the house structure. In Victoria, decks under 10m² and under 1m high are often exempt. NSW uses the Complying Development pathway for many standard decks. Always check with your local council — the permit process is typically straightforward for residential decks and ensures the structure is safe and compliant.
Deck Maintenance: What to Budget For
Timber decks require ongoing maintenance. Budgeting a rough maintenance cost per year helps you make a true cost-of-ownership comparison across materials:
- Treated pine: $100–$200/year (oiling + occasional board replacement)
- Merbau/hardwood: $80–$150/year
- Composite: under $30/year
- Aluminium: near zero
Over 25 years, the maintenance cost for timber can rival the initial cost difference versus composite. Many homeowners who've upgraded to composite say they'd never go back.
5 FAQs About Decking in Australia
Treated pine, well-maintained: 15–25 years. Hardwood (Merbau, Spotted Gum): 25–40+ years. Composite: 25–30 years (board warranty). Aluminium: 50+ years effectively. Australian conditions are tough on timber — UV, heat and moisture cycles cause checking and greying. Proper oiling is the single most important maintenance task.
Under the NCC (National Construction Code), balustrades are required for any deck more than 1m above the ground (or above the surface below). The minimum height is 1,000mm for residential decks. Balusters must be spaced no more than 125mm apart. Toughened glass, stainless wire and timber are all compliant options.
Yes — this is a popular approach. A deck built on top of an existing slab uses a sleeper frame system (low bearers laid directly on the concrete) rather than raised footings. It's cheaper than building from scratch, removes the excavation cost, and is structurally straightforward. The slab needs to be in reasonable condition and free of major cracking.
Not officially, but sustainability concerns are real. Merbau from PNG and Indonesia has been linked to illegal logging. Certifications like FSC (Forest Stewardship Council) help identify responsibly sourced timber. Many Australian builders now prefer locally grown Spotted Gum or Blackbutt, which are equally beautiful and fully traceable. If sustainability matters to you, ask your supplier for FSC-certified timber.
Generally yes — outdoor entertaining areas are highly valued by Australian buyers, particularly in QLD, NSW and VIC. A well-built deck in good condition can return 70–100% of its cost in added property value, according to various realestate.com.au surveys. The return depends heavily on the quality of the build, how it integrates with the home, and local market conditions. A deck that's too large, obstructs natural light, or doesn't suit the house style may not add value.