Decking Timber

The best timber for decking depends on your specific needs, but Australian hardwoods consistently outperform other options. Spotted Gum, with a Janka hardness rating of 11.0 kN, offers excellent durability and is classified as a Class 1 hardwood with an expected lifespan of over 40 years.

Blackbutt is increasingly popular for decking across Australia, featuring strong fire resistance and is one of seven timber species suitable for bushfire-prone areas.

Ironbark stands among the world's hardest hardwoods with a Janka rating of 14.0 kN—approximately two and a half times harder than Spotted Gum—with an above-ground lifespan exceeding 40 years.

Jarrah timber is naturally resistant to weather, rot, termites and marine borers, making it highly durable for outdoor applications.

For most residential projects, Spotted Gum and Blackbutt offer the best balance of workability, durability, and value. Choose Ironbark or Jarrah when maximum longevity is essential.

All four species are sustainably sourced from managed Australian forests.

Australian timber decking must comply with the National Construction Code (NCC) and relevant Australian Standards to ensure safety, durability, and structural integrity.

National Construction Code (NCC): Sets minimum requirements for deck construction, including structural design to withstand dead loads (deck weight), live loads (people and furniture), and environmental loads (wind and weather). All materials must meet NCC durability standards.

Balustrade Requirements: Decks more than 1 metre above ground level require compliant balustrades at least 1 metre high. Balustrades on decks over 4 metres must be non-climbable with no horizontal elements between 150mm and 760mm that could serve as footholds.

Structural Standards - AS 1684: Specifies bearer and joist sizing, spacing, span limitations, and fixings for timber-framed construction. Ensures your deck safely supports expected loads without structural failure.

Termite Management: The NCC requires termite protection, especially in Brisbane and Queensland. Use naturally termite-resistant Class 1 hardwoods (Blackbutt, Spotted Gum, Ironbark, Jarrah) that don't need chemical treatment, and maintain adequate clearance for termite inspection.

Bushfire Requirements - AS 3959: Properties in bushfire-prone areas must use compliant decking materials. Blackbutt, Spotted Gum, Ironbark, and Jarrah all meet BAL-29 requirements, with Ironbark achieving BAL-40 for extreme bushfire zones.

Australian hardwoods represent the premium choice for decking timber:

Blackbutt – This hardwood showcases warm honey tones, features a Class 1 durability rating, and offers natural resistance to termites and decay. It regenerates easily, making it readily available and a sustainable plantation timber.

Spotted Gum – This dense hardwood displays stunning colour variations from pale grey to dark brown, has a Class 1 or 2 durability rating, and performs exceptionally well in coastal environments.

Ironbark – With a Janka rating of 14.0 kN, Ironbark offers Class 1 durability with an above-ground lifespan exceeding 40 years and an in-ground life over 25 years. It excels in high-traffic commercial applications.

Jarrah – This Western Australian hardwood is classified as a bushfire-resisting timber according to AS 3959-2009 and is extensively fire-tested for bushfire-prone construction. All four are Class 1 durability hardwoods, ensuring decades of performance. Choose based on your aesthetic preference, budget, and environmental conditions.

H3 treatment is suitable for timber kept off the ground and exposed to weather conditions, commonly used for decking, fascia, and pergola posts above ground. H4 treatment is ideal for timber in ground contact or continually damp conditions, designed to minimise termite attack and resist decay.

For decking boards: H3 is the standard choice. H3-treated pine timber is recommended for deck construction as it resists moisture and is suitable for above-ground use. For structural posts: H4 is the minimum recommended treatment level for outdoor posts installed in-ground.

For Australian hardwoods (Blackbutt, Jarrah, Ironbark, Spotted Gum): Chemical treatment is unnecessary. Class 1 or 2 hardwoods are recommended for timber decking as these possess natural durability and termite resistance. These premium hardwoods have inherent biological resistance that exceeds the performance of H3- and H4-treated wood.

Use H3 for treated pine decking boards, H4 for in-ground supports, or choose premium Australian hardwoods that require no chemical treatment.