Decking Cost Australia 2026: Timber vs Composite Price Guide

A well-designed deck can transform your outdoor living space, adding value to your Adelaide home while creating the perfect area for entertaining during those long, warm South Australian summers. But before you start planning, understanding decking costs is essential for setting a realistic budget.

Whether you are considering natural timber or low-maintenance composite materials, this guide breaks down every cost factor so you can make an informed decision and get matched with qualified deck builders in Adelaide.

Average Decking Costs in Australia (2026)

Decking costs vary significantly depending on the material, size, and complexity of the project. Here is what you can expect to pay in 2026:

Treated pine decking: $200 to $350 per square metre (installed)
Hardwood timber decking (Merbau, Spotted Gum): $350 to $650 per square metre
Composite decking: $400 to $700 per square metre
Premium composite (capped): $550 to $850 per square metre
Aluminium decking: $600 to $1,000 per square metre

These prices include supply, subframe, and professional installation. For a standard 20-square-metre deck, you are looking at a total cost of $4,000 to $14,000 depending on your material choice. Use the landscaping cost calculator to estimate your specific project.

Timber Decking: Costs, Pros, and Cons

Timber remains the most popular decking choice across Adelaide, prized for its natural beauty and warmth underfoot. However, not all timber is created equal.

Treated Pine

Treated pine is the most budget-friendly option, making it ideal for those watching costs. It is readily available and easy to work with, though it requires regular staining and sealing, particularly important in Adelaide's harsh UV environment. Expect to re-stain every 12 to 18 months to maintain its appearance.

Hardwood Timber

Australian hardwoods like Spotted Gum, Blackbutt, and Merbau offer superior durability and stunning grain patterns. These timbers naturally resist termites and decay, making them well-suited to South Australia's conditions. While more expensive upfront, hardwoods can last 25 to 40 years with proper maintenance.

Key considerations for timber decking in Adelaide:

Hot summers mean timber can become uncomfortable underfoot. Lighter-coloured species stay cooler
Low humidity can cause boards to shrink and cup if not properly seasoned
Regular oiling is essential to prevent greying and cracking from UV exposure
Bushfire zones in the Adelaide Hills may require BAL-rated timber or non-combustible alternatives

Composite Decking: Costs, Pros, and Cons

Composite decking has grown enormously in popularity, and for good reason. Made from a blend of recycled wood fibres and plastic polymers, composite decking offers the look of timber with dramatically reduced maintenance. Professional decking installers report that composite now accounts for nearly 40 per cent of all new deck builds in Adelaide.

Types of Composite Decking

Uncapped composite: The more affordable option ($400 to $550 per square metre), but can fade and stain over time
Capped composite: Features a protective polymer shell that resists fading, staining, and scratching ($550 to $850 per square metre)
Co-extruded composite: Premium boards with multi-layer construction for maximum performance ($700 to $1,000 per square metre)

Advantages in Adelaide's Climate

Composite decking is particularly well-suited to Adelaide's Mediterranean climate. It will not crack or split in dry summers, does not require annual oiling, and resists mould growth during the wetter winter months. Many products also come with 25-year warranties, providing long-term peace of mind.

The main drawback is heat retention. Darker composite boards can become very hot in direct summer sun. Opt for lighter colours and ensure adequate ventilation beneath the deck to minimise heat buildup.

What Affects Decking Installation Costs?

Beyond material selection, several factors influence the total cost of your decking project:

Deck size and shape: Larger decks benefit from economies of scale, but complex shapes with curves or multiple levels increase labour costs
Height and access: Elevated decks require more substantial subframes and may need engineering certification
Site preparation: Sloping Adelaide Hills blocks may need excavation or retaining work before decking can begin
Balustrades and stairs: Add $150 to $400 per lineal metre for timber balustrades, or $300 to $600 for glass
Built-in features: Bench seating, planter boxes, and integrated lighting add $500 to $3,000 or more
Council permits: Decks over 500mm high generally require a building permit in SA, adding $300 to $1,000 in fees

Timber vs Composite: Which Should You Choose?

The best choice depends on your priorities. Here is a quick comparison to help you decide:

Choose timber if: You love the natural look, do not mind regular maintenance, want a cooler surface in summer, and have a tighter upfront budget (treated pine)
Choose composite if: You want minimal maintenance, plan to stay in the home long-term, prefer consistent colour over decades, and do not mind a slightly higher upfront investment

Over a 20-year period, composite often works out cheaper when you factor in the cost of oils, stains, sanding, and re-coating that timber demands. A 20-square-metre hardwood deck might cost $2,000 to $3,000 in maintenance products alone over two decades. For a broader view, see how much landscaping costs overall.

Understanding Decking Subframe Costs

One cost that often surprises Adelaide homeowners is the subframe, which typically accounts for 30 to 40 per cent of the total decking budget. The subframe is the structural skeleton that supports your deck boards, and in Adelaide's conditions, it needs to be built to last.

For ground-level decks, the subframe usually consists of concrete pad footings, bearer beams, and joists. Treated pine subframes are the most affordable option at $50 to $80 per square metre, while hardwood or steel subframes cost $80 to $150 per square metre. On sloping Adelaide Hills blocks, the subframe can become the most expensive component, requiring steel posts, concrete footings up to 600mm deep, and potentially engineered bracing to handle the site's gradient.

Steel subframes have gained popularity in recent years due to their consistent dimensions, resistance to warping and twisting, and compatibility with both timber and composite deck boards. They are particularly well-suited to Adelaide's reactive clay soils, as steel does not absorb moisture and expand like timber can during wet winters.

Council Requirements and Building Permits in Adelaide

Before starting your deck project, it is essential to understand the regulatory requirements in South Australia. Decks over 500mm above ground level generally require a building permit from your local council, which involves submitting plans and paying application fees of $300 to $1,000.

If your property is in a heritage zone, character area, or bushfire-prone zone in the Adelaide Hills, additional requirements and approvals may apply. Properties with a Bushfire Attack Level (BAL) rating may need to use non-combustible materials for the subframe and select specific deck board materials that meet the required rating.

Setback requirements also apply. In most Adelaide council areas, decks must maintain minimum distances from property boundaries, and overlooking provisions may require screening if the deck is elevated above neighbouring properties. A qualified deck builder familiar with local regulations can handle the approval process on your behalf, saving you time and ensuring compliance.

Seasonal Considerations for Deck Building in Adelaide

The time of year you build can affect both cost and quality. Autumn and winter are generally the quieter months for deck builders in Adelaide, which can mean shorter lead times and potentially better pricing. Building during cooler months also allows the deck to cure and settle before the heavy use that comes with summer entertaining.

If using timber, cooler weather during construction means boards are at their most expanded state (absorbing winter moisture), so gaps left during installation will be minimal when the timber shrinks in summer. Conversely, if building in summer, experienced builders will leave slightly larger gaps to accommodate expansion in winter. This level of detail is one reason professional installation is so important for a long-lasting result.

Get Matched with Adelaide's Best Deck Builders

A quality deck is an investment that should last decades. Whether you choose timber or composite, professional installation ensures proper drainage, structural integrity, and a finish you will be proud of. Connect with qualified decking professionals in Adelaide to get detailed quotes tailored to your property and budget.