Blog: November 2025

Decking Done Right: Composite Vs Timber In NSW And What It Really Costs

If you are building a deck on the NSW Central Coast or Sydney’s coastal suburbs, you are choosing between two proven options, composite boards or Australian hardwood. Both can look stunning by the ocean, both will handle backyard entertaining, and both come with different costs over the life of the deck. This guide breaks down realistic per square metre pricing, install factors that shift the quote, lifespan and maintenance in salty, sunny conditions, and the real feel underfoot when it is wet and hot. You will also see straight answers on mould, fading, what can ruin composite boards, council approval basics, and ballpark prices for popular deck sizes.

What drives the price of a deck in NSW?

How much to build a deck in NSW depends on more than the boards. Your site access, height off ground, subframe material, footings, stairs, handrails, lighting, pergola integration, and compliance can move the total up or down.

Typical ranges we see for full supply and install:

• Treated pine subframe with hardwood decking: from $350 to $600 per m2

• H3 or H4 treated pine subframe with composite decking: from $450 to $750 per m2

• Steel subframe with composite or hardwood: add $100 to $200 per m2

• Elevated decks over 1 m high, complex shapes, or steep sites: allow 15 to 30 percent more for footings, bracing, and access

These are indicative only. We always confirm final costs after a site visit, engineering, and your selected finishes.

Composite decking cost per m2 and what you should pay

How much does a composite deck cost per m2? For coastal NSW, quality capped composites typically land between $150 and $250 per m2 for materials alone, depending on brand, board profile, colour, and clip system. Installed on a treated pine frame, how much should I pay for composite decking as a complete build often sits between $450 and $750 per m2 as noted above. Wide boards, picture framing, fascia details, and stainless fixings can push the top end. Budget composites can be cheaper upfront, but you often sacrifice colourfastness, heat management, and warranty.

What a 12x12 or 20x20 composite deck might cost

Let us turn the figures into real spaces. Many homeowners ask, how much would a 12x12 composite deck cost? Using a simple 3.6 m by 3.6 m footprint, that is about 13 m2. At $500 to $700 per m2 installed, you are looking at roughly $6,500 to $9,000, assuming ground level, straightforward access, and a single stair.

How much would a 20x20 composite deck cost? A 6 m by 6 m footprint is about 36 m2. At the same $500 to $700 per m2, the guide sits around $18,000 to $25,000. Add more if you want a pergola roof, integrated lighting, glass balustrade, or a steel subframe for a coastal high exposure site.

Composite vs Australian hardwood in coastal conditions

Lifespan: What is the lifespan of a composite deck? Quality capped composite typically offers 25 to 30 years of structural life with a fade and stain warranty that runs 20 years or more. Premium Australian hardwood, such as Spotted Gum or Blackbutt, can also last 25 years plus with proper oiling and maintenance, especially on a well detailed subframe.

Maintenance: Composite needs periodic washing to remove salt, pollen, and debris. Hardwood needs regular oiling or staining to maintain colour and to slow checking. By the ocean, expect to oil hardwood every 6 to 12 months depending on exposure.

Slip resistance when wet: Is composite decking slippery when wet? Most capped composites meet or exceed a P3 to P4 slip rating with grain textures that maintain grip. Always check the board’s published slip rating and choose a grippier finish around pools or shaded, damp areas. Hardwood can also achieve strong slip ratings with the right profile, but oil build up, algae, and mould will reduce traction if maintenance lapses.

Heat and comfort: Darker colours get hotter in full sun, whether composite or timber. Composites can feel warmer due to density, while light colours and ventilated subframes reduce heat. A pergola or shade sail helps significantly.

Aesthetics: Timber gives a natural, evolving patina. Composite offers colour stability and clean modern lines. If you love the movement and grain of Australian hardwood, timber may win your heart. If you want consistent colour year after year, composite is hard to beat.

Does composite decking increase home value

A well built, well designed deck increases usable living space, which buyers value. Composite brings lower maintenance and a modern look that appeals to busy households. The uplift depends on your home and suburb, but we see outdoor living improvements pay back strongly when integrated with a pergola, garden lighting, and a cohesive landscape plan.

Common concerns, mould, fading, and what ruins composite decking

Mould and algae: These do not feed on composite itself, but they can grow on dust, pollen, and organic matter sitting on the surface. Routine rinsing and an occasional soft scrub with a composite safe cleaner prevents buildup. Good airflow under the deck is essential.

Fading: Uncapped composites can fade. Capped composites carry fade warranties and hold colour well. Expect slight lightening in the first months as the board settles, then stability. What ruins composite decking: Harsh solvents, abrasive scouring, hot metal fire pits placed directly on boards, dragging furniture with sharp feet, and blocked drainage that traps moisture can damage the surface. Use pads under furniture, clean gently, and allow airflow. Around the coast, stainless fasteners and properly flashed interfaces prevent corrosion stains.

How to save money on composite decking without cutting corners

Choose standard colours and board widths that are readily available to avoid special order costs and waste. Keep the footprint simple. Straight runs, minimal angles, and thoughtful set out reduce offcuts. Build once with the right subframe. H3 or H4 treated pine, correct joist spacing per the board spec, stainless screws, and proper flashing save you from rework. Integrate the pergola or privacy screens in the same project so footings and posts are coordinated, not duplicated. Stage lighting and extras. Run conduits now and add fixtures later.

Council approval basics in NSW

Do I need council approval for a deck in NSW? Some decks fall under exempt development if they meet strict rules on height, size, setbacks, and location. Many suburban and coastal decks will be complying development or require a development application if elevated or attached to a dwelling. Bushfire zones, flood or coastal overlays, and heritage controls can change the pathway. We help you check controls, coordinate engineering, and submit the right documents so your project proceeds cleanly.

What is better than composite decking

There is no single winner. For a coastal family that wants predictable colour, minimal upkeep, and a sleek modern finish, composite is often the better choice. For lovers of warm, natural grain with the willingness to oil and maintain, Australian hardwood remains exceptional. The best option is the one that suits your lifestyle, orientation, microclimate, and broader landscape design.

Working with a specialist deck and pergola team

At Key Landscaping, we design and build decks that suit coastal living, from low platforms that flow from the living room to elevated entertaining spaces with integrated pergolas, privacy screens, and pool surrounds. If you are researching options for composite decking central coast and want a straight, well coordinated build, talk to our team. We are an experienced deck builder central coast with end to end capability, from design and approvals to final detailing and handover.

Summary and next steps

Composite installed on a treated pine subframe generally sits around $450 to $750 per m2, with hardwood from $350 to $600 per m2, plus extras for height, steel, and detailing. A 12x12 composite deck of roughly 13 m2 often lands near $6,500 to $9,000; a 20x20 of about 36 m2 often sits around $18,000 to $25,000, subject to site and selections. Composite provides strong slip ratings, consistent colour, and low maintenance; hardwood delivers natural beauty with higher upkeep.

Lifespan for both can exceed two decades when built and maintained correctly.

Plan for shade, airflow, and good drainage, and avoid harsh chemicals to protect composite surfaces.

If you want a costed concept and practical advice for your site, get in touch.

We can integrate your deck with a pergola, lighting, and planting for a cohesive outdoor space that feels effortless to use and easy to maintain. Start your project with a local, detail focused team and enjoy your deck for years to come. For broader outdoor upgrades, our team also delivers landscape construction central coast with the same craftsmanship and

support.