How Much Does It Cost to Build a Timber Deck?

Most homeowners opt for timber or composite deck boards. Timber has a natural appeal, and some hardwoods are very durable. Nonetheless, as a natural material, timber is susceptible to decay and requires regular upkeep to keep its looks. Composite decking, a combination of wood fibre and recycled plastic, is much more resilient to the elements and insects than wooden decks. Composites also require very little maintenance, usually just a wash and rinse twice yearly.

So, what’s holding you back from building your dream deck?

Price? No worries, we’ve got you covered. While different building sources list a variety of deck costs, there is universal agreement that a range of factors will affect the total cost:

• Size of the deck
• Deck design
• Type of deck board
• Accessories, including lumber for bearers and joists, nuts, bolts, posts and fasteners
• Stairs, railing, roofing or a pergola
• Site conditions
• Elevation
• Building permits required from the council
• Landscaping

But you’d like to know some of the hard costs of decking. Fair enough. Here’s the range:

• According to HiPages.com.au, decking costs between $200 to $1,000 per square metre, depending on your deck’s type of timber and specifications.
• Hiretrades estimates the cost between $200 to $560 per square metre, depending on the structure’s size and the types of decking materials used.
• Serviceseeking states the price of building a standard-sized deck per square metre averages $187.50 per square metre.

An essential factor is labour costs, and your postcode matters. Hiretrades provides the following estimate showing that the most expensive installation will be found in New South Wales, while Western Australia is the least costly.

STATE ESTIMATED LABOUR COST PER M2

• New South Wales $200 to $210
• Victoria $190 to $200
• Queensland $185 to $190
• Western Australia $170 to $180

How Much Does It Cost to Build a Deck per Square Metre?

As you might expect, Serviceseeking estimates that for every square metre in additional space, you should expect an increase in cost.

Deck size Average deck pricing range

• 10 square metres $3,600 – $5,500
• 20 square metres $3,800 – $5,300
• 30 square metres $4,000 – $6,800
• 40 square metres $5,000 – $7,000
• 50 square metres $5,300 – $7,200
• More than 50 square metres $5,900 – $11,500+

What Type of Decking Is Available?

• Timber Deck
• Composite Deck

The two main types of decking boards are timber and composite. The material you choose will significantly affect the upfront costs, but you should also consider the long-term costs of materials based on their maintenance requirements.

The most commonly used Australian timber for decking projects include:

• Treated pine – an inexpensive softwood
• Merbau – a popular, durable and affordable hardwood which is also resistant to insects and rot
• Ironbark – an extremely durable heavy hardwood
• Blackbutt – a fire-resistant and termite-resistant Australian native species
• Jarrah – a durable, fire-resistant, expensive timber
• Spotted Gum – a durable and dense timber which is attractive for decking in bushfire-prone zones
• Stringybark – yellow variation is durable enough for outdoor use (white is not such a good choice)

Decks must meet the Building Code of Australia (BCA), which has been revised to make decks more fire-resistant and to address the dangers of bushfires. If you live near the coast, consider installing cyclone-rated decking.

How Much Does It Cost to Build a Timber Deck?

As noted earlier, the cost of a deck depends on the type and quality of wood used. You may pay just $200 per square metre for treated pine decking, $320 or more per square metre for hardwood timber decking, or $350 or more per square metre for composite decking. For the budget-conscious, the decision may appear straightforward.

However, the costs of maintaining treated pine can be high over time—not just financially but also in terms of your personal time spent sealing and staining the timber each year. Sunshine can fade and dry out timber, causing it to warp and split. Water can rot the timber or cause fungal infection to take over. To remedy this, you’ll want to waterproof as much as possible.

What Type of Timber is Best for My Deck?

There is no “average deck,” so it’s impossible to say which timber is best. It depends on your personal taste, the availability of the timber species you want, and the cost. If your budget is modest, pressure-treated pine will reduce the cost of timber decking. Otherwise, look to the high-end hardwoods, which have a tight grain that makes them durable and rot-resistant. Wood from native species, such as Merbau decking, is often less expensive than exotic imports.

How Much Does It Cost to Build a Composite Deck?

Composite materials may be an expensive option at the time of construction, but they require virtually no maintenance. Additionally, composite boards are identical from one to the next, so decking installation goes fast. Composites often come with a manufacturer’s warranty as long as 25 years.

Composite decks, made from a combination of recycled timber fibres and plastic, are durable and waterproof. The average cost for a basic composite deck starts at $100/m2 and goes up to $350/m2or more, depending on the brand. Popular brands include Trex, ModWood and FutureWood. (In the USA, “square foot” is the preferred unit of measure. There are about 10.75 square feet in a square metre.)How Does Cost Factor into Waterproofing Your Deck?

Higher-quality timber has greater staying power; however, any timber deck should be sealed and/or stained annually or biannually. This cost can average about $400 in oil and sealants for a 25m2 deck. If you don’t want to DIY and hire professional tradesmen to reseal your deck, expect additional labour costs. These costs add up year after year, so consider this when deciding between timber and composite decking.

During construction, don’t just focus on the decking boards. Remember the substructure, the joists and the bearers, too.

The good news is that adding joist tape to your construction adds little to the overall costs but can add years of life to your deck. Trex Protect Joist, Bearer & Rim Tape, a high-quality butyl tape:

• Protects the top of the joist, bearers, rim joist, and the ledger board from developing rot and timber decay
• Butyl-based tape helps deck screws hold longer and stronger than acrylic or asphalt-based tape
• Acts as a barrier between timber and galvanized metal, such as joist hangers
• Seals deck fasteners and prevents moisture penetration
• Eliminates splitting from freeze and thaw

To protect an average size deck measuring 3.5m x 7.5m will require approximately five rolls of Trex Protect Joist Tape and one roll of Trex Protect Bearer Tape. For less than a $130 investment, your deck substructure can last as long as the decking it supports. To check exact costs, use our materials estimator.

Is Building or Council Approval Necessary for Deck Building?

In most urban areas, you’ll need some type of approval before you build a deck, especially if it is elevated or large. Rural and remote areas tend to have fewer rules and restrictions, but ask your local authorities before starting any work. What works in Queensland might not be allowed in Victoria.

Usually, you or your decking contractor will need to submit scale drawings of the deck for approval. In some cases, you may also have to survey the land and have an engineer and building certifier sign off on the plans before they can be considered for approval.

Ready to Build?

Remember to check with your local council to see if you need a permit to build your new deck.

When hiring a deck builder, ensure you get the best professional for the job. Take time to ask them:

• Are you licensed and insured?
• How long will the build take?
• Can you take care of the council approval/building permit for me?
• Do you have references? Can I see examples of your work?

Be sure to ask for a written quote. With your knowledge of how much a new deck will cost and the various considerations that increase or decrease the price tag, you’ll be in a great position to know if the builder’s offer is good.