Which decking timber is best for the Gold Coast?

There is no single best decking timber, but for a Gold Coast deck, spotted gum and blackbutt tick the most boxes. Both are rated to last more than 40 years above ground, both resist termites, and both are on Australia's bushfire-resisting timber list.

Merbau costs a little less than spotted gum but can stain what is under it. Treated pine is the cheapest. Composite boards cost the most, though a finished composite deck prices close to merbau. Below is how each one handles the sun, salt air and termites, and what the main ones cost. Prices checked on 4 October 2026.

How do the main decking timbers compare?

Every hardwood here is rated Class 1 above ground, which means a life of more than 40 years under the Australian standard (AS 5604). The real differences are price, hardness, bushfire rating and how they behave once they are down.

Board widths differ, so prices are best compared per square metre. A 2026 Brisbane cost guide (Sparky) puts boards alone at about $90-$120 per m2 for spotted gum, $73-$80 for merbau and $43-$50 for treated pine, and ModWood composite at $122-$151 per m2.

Built and installed, What's The Damage's 2026 Gold Coast estimates are $175-$345 per m2 for treated pine, $295-$540 for merbau, $275-$540 for composite and $345-$590 for spotted gum.

Spotted gum or blackbutt: which is better for a deck?

Both make a great deck. The differences are small:

• Hardness. Spotted gum is harder and heavier. The Queensland Government's timber data gives it about 1010 kg per m3, against 930 for blackbutt. So it dents a little less.
• Borers. Blackbutt's sapwood is not attacked by lyctid borers. Untreated spotted gum sapwood can be.
• In the ground. Both are Class 2 in the ground (15-25 years), so neither should be used for posts sitting in soil without treatment.

So choose on the colour you like and what the timber yard has in stock.

Merbau or spotted gum: which is better?

For most Gold Coast decks, spotted gum is the better pick, because it is harder and lasts longer in contact with the ground. Merbau's main plus is a slightly lower price. Both are Class 1 above ground, resist termites and are on the bushfire-resisting list. The Queensland Government rates spotted gum "very hard", the top of its six-step scale, and merbau one step lower at "hard". The catch with merbau is tannin bleed.

When merbau gets wet, it leaches natural tannins that stain. WoodSolutions warns that hardwood tannins "may leave an unsightly stain that can be difficult to remove from brickwork, concrete or any paving underneath the deck that is not sealed". One timber supplier says it is worst in the first few weeks after installation but can come back with heavy rain. To limit it, use seasoned boards and seal every surface, including freshly cut ends.

Merbau is only Class 3 in the ground (5-15 years), against Class 2 (15-25 years) for spotted gum, so keep it well clear of the soil.

What about ironbark and tallowwood?

These are the toughest of the lot. Both are Class 1 above and in the ground, and both are rated "very hard", the top of the Queensland Government's six-step scale. Grey ironbark is the densest timber here, at about 1105 kg per m3.

The trade-off is bushfire rating. Grey ironbark and tallowwood are only rated to BAL-19, so if your block is in a higher bushfire zone, choose red ironbark, spotted gum or blackbutt instead.

Is treated pine OK for a deck on the Gold Coast?

Yes, if it is the right grade. According to the Queensland Government's QTimber guide, H3 treatment "offers protection in situations above-ground, exposed to the weather or periodic wetting", and guards against "decay fungi and insects, including termites".

It is the cheapest option by a long way, and it is common for the frame under a hardwood deck. It is softer than hardwood, so it dents more easily. Older CCA-treated timber has not been allowed for new decking boards since 2005, so pine decking sold today uses other treatments.

Is composite decking better near the beach?

Composite boards cost more up front. Sparky puts ModWood at $122-$151 per m2. Built and installed, What's The Damage's 2026 Gold Coast estimate is $275-$540 per m2, about the same band as merbau.

Bushfire ratings depend on the brand and board. ModWood's Flame Shield range is certified up to BAL-40. Trex Transcend is rated BAL-19 for grooved boards and BAL-29 for square-edged ones. We could not find an Australian BAL rating for Millboard.

Composite makers sell it as low maintenance. Check each brand's warranty and care guide before you buy, because they differ. You can see a grey composite pool deck we built in our recent work.

What screws and brackets should I use near the beach?

Near the surf, use 316 stainless steel. Salt air eats ordinary galvanised fixings.

The QBCC treats land within 1 km of a surf coast as a sea spray zone, and 1 to 10 km as a coastal zone. Its guidance on joist hangers and connectors says standard galvanised brackets are only fit for dry indoor spots. Outside, or touching treated timber, they need something tougher, such as stainless steel.

The Australian Stainless Steel Development Association goes further. It says grade 316 "should be selected as a minimum within five kilometres of the surf". That covers most of the Gold Coast strip. Fixings within a metre of a pool edge should be stainless too.

How do I stop rot and termites getting into a deck?

Air flow, the right timber in the right spot, and a yearly look underneath.

• Keep air moving. Decks less than 400 mm off the ground need extra care with ventilation and drainage, and room to get under for termite checks (Timber Queensland).
• Match the timber to its height. Framing more than 150 mm above the ground should be a termite-resistant Class 1 hardwood or H3 treated pine. Lower than that, it needs in-ground Class 1 timber or H5 treated softwood.
• Leave gaps. Hardwood boards up to 90 mm wide need gaps of at least 3 mm. Softwood needs 5 mm.
• Leave it open. The QBCC says framing under decks should not be sheeted in, so it can be inspected.

The Queensland Government suggests you inspect your deck at least once a year.

How often does a timber deck need oiling?

It depends on the product and the sun, with sources ranging from once a year to every few years, so follow the instructions on your oil. Our deck restoration guide compares the makers' advice and what a sand and oil costs on the Gold Coast. If you are planning a new deck, our deck building page shows what we build.

Where does this information come from?

Checked on 4 October 2026: Queensland Government timber properties data and QTimber guide, WoodSolutions, Timber Queensland technical data sheets, the QBCC, NATSPEC (on the APVMA's 2005 CCA rules), the Australian Stainless Steel Development Association, ModWood, Trex and Millboard product pages, Sparky (2026) and What's The Damage (2026).

See our decks and patios work, or check what your job will cost.