A new deck is one of the most common building projects for homeowners in Sydney and regional NSW. It is also one of the hardest to get a straight answer on when it comes to cost. Prices vary widely depending on the size, materials, height off the ground, and site conditions, and most online guides give ranges so broad they are not useful.
This guide breaks down real deck building costs in NSW for 2026, organised by material, size, and deck type. We also cover the additional costs that sit outside the build itself, like council approval, balustrades, and stairs, so you can budget accurately before talking to a builder.
Decking Costs by Material (Per Square Metre, Installed)
The material you choose for the deck boards is the single biggest factor in the per-square-metre price. Here are the current installed rates in the Sydney and Macarthur region, which include supply of materials, subframe construction, and labour.
Treated pine: $180 to $280 per square metre. Treated pine is the most affordable option. It is structurally rated and suitable for outdoor use, but it is softer than hardwood, more prone to splintering over time, and requires staining or painting every one to two years to maintain its appearance.
Merbau (Kwila): $300 to $450 per square metre. Merbau is the most popular imported hardwood for decking in Australia. It has a rich reddish-brown colour, good durability, and reasonable pricing compared to domestic hardwoods. The main drawback is tannin leaching: Merbau releases a dark reddish-brown tannin when it gets wet, which can stain adjacent concrete, pavers, and walls for the first 12 to 18 months.
Spotted Gum: $380 to $520 per square metre. Spotted Gum is an Australian native hardwood with excellent durability (Class 1 above ground) and a distinctive grain pattern with colour variation from light brown to chocolate. It is harder and more durable than Merbau and does not leach tannin to the same degree.
Blackbutt: $370 to $500 per square metre. Another Australian native hardwood with high durability (Class 1 above ground). Blackbutt has a lighter, more uniform colour than Spotted Gum, ranging from golden to pale brown. It machines well and is a popular choice for a clean, modern deck look.
Ironbark: $420 to $580 per square metre. Ironbark is one of the hardest and most durable timbers available in Australia. It is extremely dense, highly resistant to termites and rot, and has a deep red-brown colour. The trade-off is that it is difficult to work with because of its density, which increases labour time and tool wear.
Composite decking (capped): $450 to $750 per square metre. Composite boards are made from a mix of wood fibre and polymer. Premium capped products have a protective shell that resists fading, staining, and moisture absorption. The installed cost is higher than timber, but the maintenance cost over the life of the deck is close to zero. See our timber vs. composite comparison for the full lifecycle cost breakdown.
Deck Cost by Size
To give you a practical reference point, here are installed cost ranges for common deck sizes using a mid-range hardwood (Spotted Gum or Blackbutt) with a treated pine subframe.
Small deck (10 to 15 sqm): $4,500 to $8,000. This covers a compact entertaining area off the back door, roughly 3 metres by 4 metres. Suitable for a small table setting and a couple of chairs.
Medium deck (20 to 30 sqm): $9,000 to $16,000. This is the most popular size range. A 5 metre by 5 metre deck gives enough room for a dining table, a lounge area, and space to move between them. Most family decks in the Macarthur region fall in this range.
Large deck (35 to 50 sqm): $16,000 to $27,000. A deck this size wraps around a corner of the house or spans the full width of the rear. It creates a genuine outdoor living room with distinct zones for cooking, dining, and relaxing.
Extra-large or wraparound deck (50 to 80 sqm): $27,000 to $45,000. Multi-level decks, pool surrounds, and wraparound designs fall in this category. The cost increases with complexity, multiple level changes, and the length of balustrade required.
These ranges assume a deck height of 600mm or less above ground level with straightforward site access. Higher decks and difficult access push costs upward.
What Affects the Price Beyond Materials and Size
Several factors can move the final cost significantly above or below the per-square-metre rates listed above.
Deck height is one of the biggest variables. A low-level deck sitting 200 to 400mm off the ground needs minimal subframe and usually no balustrade. A high deck sitting 1,000mm or more above ground requires deeper posts, larger bearers and joists, cross-bracing, and a balustrade that meets the Building Code of Australia. The subframe cost alone can double on a high deck compared to a low one.
Site slope changes everything. A flat block in Gregory Hills or Oran Park is straightforward to build on. A sloping block in Picton, Camden, or the Southern Highlands may need retaining walls, stepped footings, or deeper post holes to create a level deck surface. This can add 15 to 30 percent to the build cost.
Access to the site matters more than people expect. If materials can be delivered directly to the build location by truck or forklift, the labour cost stays low. If boards and bearers need to be carried by hand through the house, down a narrow side passage, or over fences, the labour time increases and the cost follows.
Subframe material is a hidden cost decision. Most decks use a treated pine subframe because it is cost-effective and structurally rated for outdoor use. Some builders use hardwood for the subframe as well, which adds durability (especially in high-moisture areas near pools or under trees) but increases the material cost by 30 to 50 percent.
Fastening system affects both the cost and the finished look. Face-screwing is the standard and cheapest method. Concealed clip systems hide the fasteners between the boards for a cleaner appearance but add $15 to $30 per square metre in materials and labour. Some composite decking systems require proprietary clips, which are included in the composite pricing above.
Additional Costs Outside the Deck Build
The deck itself is only part of the total project cost. Here are the common additional items you need to budget for.
Balustrades: Required by law for any deck more than one metre above the ground. Timber balustrades cost $200 to $350 per linear metre. Stainless steel wire balustrades cost $300 to $500 per linear metre. Glass panel balustrades cost $400 to $700 per linear metre. A 25 square metre deck with balustrade on two sides might need 8 to 10 linear metres, adding $2,000 to $7,000 depending on the style.
Stairs: If your deck is elevated, you need stairs. A basic set of hardwood timber stairs costs $800 to $2,000. Wider or longer stairs with landings cost more.
Council approval: Most decks in NSW that are higher than 600mm above ground level, or attached to the house, require either a Complying Development Certificate (CDC) or a Development Application (DA). A CDC costs $1,500 to $3,000. A DA costs more. See our council approval guide for the full breakdown.
Demolition and removal: If you are replacing an existing deck, budget $500 to $2,000 for demolition and disposal depending on the size and material of the old structure.
Landscaping and site reinstatement: Building a deck often means digging up garden beds, removing existing paving, or cutting back trees. Budget $1,000 to $3,000 for post-build landscaping work.
Lighting: Recessed LED deck lights or step lights add $500 to $2,000 depending on the number of fittings and whether new electrical circuits are needed.
Pool Decking: A Special Case
Pool surrounds have specific requirements that affect the cost. The decking material must be slip-resistant when wet. The subframe needs to handle constant moisture exposure without rotting. Drainage around the deck must direct pool splash water away from the house.
Hardwood species like Spotted Gum and Ironbark are naturally slip-resistant when oiled and are popular choices for pool decking. Composite decking works well around pools because it does not absorb moisture, but you need to choose a product with a textured, slip-resistant surface and be mindful of heat underfoot in full sun.
Pool decking projects in the Macarthur region typically cost $400 to $600 per square metre installed using hardwood, or $500 to $750 per square metre for composite. The higher cost reflects the additional waterproofing, drainage, and finishing requirements.
How to Get an Accurate Deck Quote
The per-square-metre rates in this guide give you a solid starting point for budgeting. But the final cost for your deck depends on your specific block, the height and layout of the deck, the material you choose, and the access conditions on site.
The best way to get an accurate number is to have a deck builder visit your property, take measurements, assess the site, and provide a detailed, itemised quote. Make sure the quote specifies the deck board species, the subframe material, the fastening method, whether balustrades and stairs are included, and whether council approval costs are covered.
Token Building has built hundreds of decks across the Macarthur and Narellan region, from compact entertaining decks to large wraparound pool surrounds. We provide free on-site consultations with clear, no-surprise pricing.
Contact us today to get a quote for your deck project.