Ironbark vs Spotted Gum Decking: Which Should You Choose?

Two QLD Class 1 hardwoods, two different decks

Ironbark and Spotted Gum are the two headline species in our Australian hardwood range. Both carry supplier-documented Class 1 above-ground durability with a 40+ year indicative service expectation, and both are displayed as QLD Class 1 Hardwood on our product pages. Durability will not separate them, so the choice comes down to colour, hardness, availability and how the timber behaves on the tools.

Side by side

Indicative service ranges are classifications under AS 5604, not product warranties. Actual performance depends on species, installation, exposure, drainage, maintenance and site conditions. Note that our supplier's flyers carry conflicting Janka and BAL figures for Spotted Gum, so we do not publish those values rather than pick a number.

Choose Ironbark if

• Maximum hardness and mass matter. Grey Ironbark's supplier-documented Janka 16 and 1106 to 1170 kg/m3 density make it one of the densest decking hardwoods on the market, suited to high-traffic decks and heavy outdoor structures.
• You want deep, rich colour. Chocolate browns and deep reds with grey undertones, weathering to a deep grey-brown.
• Lead time is flexible. Ironbark is more often supplied to order than held as broad shelf stock, so allow for longer lead times, and expect pre-drilling as standard fixing practice.

Choose Spotted Gum if

• You want the classic figured look. Pale gold to warm brown boards with the darker gum-vein flecking the species is named for; a favourite for exterior architectural work.
• Availability and timing matter. As one of the most widely available Australian-grown decking hardwoods, Spotted Gum typically means shorter lead times, and both random-length supply and published set-length packs exist for this species.
• You want a slightly easier board to work. Still a dense Class 1 hardwood, but without Grey Ironbark's extreme hardness on tooling.

What they share

Both species are termite resistant per supplier documentation, both are sold per linear metre in random lengths with preferred lengths by quote, and both are available in the same four profiles including the 135 x 35 thick board with a 140 x 35 option. Whichever you choose, the deck will need the same care: correct ventilation and clearances at install, sealed cut ends, and cleaning plus re-oiling on a regular cycle. Neither species removes maintenance.

Get numbers for both

Linear metre prices are shown on both product ranges, so the practical way to decide is to compare real numbers. Measure your deck, convert to linear metres with the timber calculator, then price both species in your profile and add your metres to the cart, or request a quote for pack quantities and trade volumes. Browse the boards at Ironbark decking and Spotted Gum decking, or see how they sit against the rest of the range in the full hardwood comparison.

Reviewed by the Sydney Timber Supply team. Last updated 25 August 2026.