Imagine stepping into your garden and enjoying a lovely outdoor living space. Perhaps you will barbecue or take a kip in the hammock. With a deck, you open up so many possibilities for fresh air and sunshine. Homeowners often list their deck as their favourite home improvement.

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 price:

• Size of the deck
• Type of timber
• 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 council

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

• According to HiPages.com.au, decking costs between $200 – $1,000 per square metre, depending on your deck’s type of timber and specifications.

• Hiretrades.com.au estimates the cost between $200 to $560 per square metre, depending on the structure’s size and the types of decking materials used.

• Serviceseeking.com.au states the price of building a standard-sized deck per square metre averages $187.50/m2.  

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

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

Size and Shape of Your Deck

The size and shape of your deck also impact the cost. If you want a unique shape, such as rounded edges or building around existing fixtures in the garden, the cost will be more than a standard regularly-shaped deck. If you want to add inlays or other decorative elements, this will also drive up the costs.

Building on a raised or sloped elevation can add considerable costs to your deck. Consider that a raised deck will also need to be fenced and have stairs leading to the garden. You may also need to add balustrades or roofing. You should also consider lighting while your deck is under construction.

If your garden requires special grading or has accessibility challenges, you may need to hire a builder with specialist equipment or scaffolding.

How Much Does It Cost to Build a Deck by Size?

As you might expect,  Serviceseeking.com.au estimates that for every square metre in additional space, you should expect to see 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?

 

 

 

 

 

 

 

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 based on the maintenance of the material.

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.

How much does it cost to build a timber deck?

As noted earlier, the cost of decking 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 in your personal time in 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.

How much does it cost to build a composite deck?

Composite materials may be an expensive option at the time of construction but require virtually no maintenance. Additionally, composite boards often come with manufacturer’s warranties 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/m2 or more, depending on the brand. Popular brands include Trex, ModWood and FutureWood.

How does cost factor into the waterproofing of 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 25m deck. If you don’t want to DIY and hire professional tradesmen to reseal your deck, expect additional costs for labour. 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 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.

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.