When Sydney homeowners picture a hardwood deck, they usually think of Merbau, Spotted Gum or Blackbutt. Tallowwood rarely makes the shortlist — and that’s a missed opportunity. It’s one of Australia’s toughest building timbers, grown locally in NSW and southern Queensland, and it’s been quietly holding up Sydney wharves, bridges and railway sleepers for over a century.
So does it actually make sense for your backyard deck? Here’s what you need to know before you decide.
What Tallowwood Actually Is
Tallowwood (Eucalyptus microcorys) is an Australian native hardwood that grows in the wet sclerophyll forests of the NSW coast, from the Hunter River district up through to Maryborough and Fraser Island in Queensland. It’s a common NSW species, which means it’s locally grown rather than imported like Merbau.
Its heartwood ranges from pale yellow-brown to a darker tan, sometimes with a faint olive tinge. The sapwood is paler and should be treated or removed, since it’s susceptible to lyctid borer attack. The texture is moderately coarse, with grain that typically interlocks.
The standout feature is the absence of gum veins — unusual for an Australian eucalypt. That gives a tallowwood deck a clean, even face with a distinctive natural lustre and “greasy” sheen. If you’ve ever wished for something calmer than a heavily streaked Spotted Gum board, Tallowwood is the answer.
Durability: Class 1 Across the Board
Tallowwood sits in Durability Class 1 — the highest rating in AS 5604 — for both in-ground and above-ground applications. In practical terms:
- Above-ground life expectancy: more than 40 years
- In-ground life expectancy: more than 25 years
- Termite resistance: resistant
- Marine borer resistance: resistant (rare, and useful near coastal salt spray)
For context, Merbau runs at roughly Class 2 in-ground, and Spotted Gum only reaches Class 2 below the soil line. Tallowwood’s shared Class 1 rating in both exposures is exactly why it was historically used for railway sleepers and bridge beams — environments where timber sits in damp, termite-prone ground for decades.
Density is around 990 kg/m³ seasoned with a hardness of 8.6 kN. That’s firmly in hardwood-decking territory and resists indentation well underfoot.
Bushfire Rating
Untreated Tallowwood performs equivalently to fire-retardant-treated timber when tested under AS/NZS 3837, with bushfire ratings of BAL-12.5 and BAL-19. That makes it suitable for many suburban bushfire-prone blocks in Sydney’s north, the Sutherland Shire and the Hills District.
If your property sits in a higher-risk BAL-29 or BAL-40 zone, you’ll need to talk to us first — Tallowwood alone won’t satisfy those thresholds, although it can still be used within a compliant sub-floor design. Our decking team can help you work out what your council requires.
How Tallowwood Compares
- vs Merbau: Merbau is cheaper and more widely stocked, but imported, has heavy tannin bleed that stains paving for months, and sits at Class 2 in-ground. Tallowwood is locally grown, lower in tannin, and lasts longer in contact with soil.
- vs Spotted Gum: Both are Class 1 above ground. Spotted Gum is famously figured with prominent gum veins; Tallowwood has a cleaner, less streaked face with a similar price bracket.
- vs Blackbutt: Blackbutt is paler and looks great painted, but is more prone to surface checking. Tallowwood is denser and resists wear better underfoot.
- vs Ironbark: Both are Class 1 (see our Ironbark deep-dive). Ironbark is darker and harder to work; Tallowwood machines more cleanly and suits mid-tone, even-grain finishes.
Maintenance
Like all oiled hardwood decks, Tallowwood will silver to a soft grey within 6–12 months if left unoiled. To keep the warm honey-brown colour, plan to oil every 12–18 months with a quality penetrating deck oil. Thanks to its lack of gum veins and natural oil content, Tallowwood tends to take oil more evenly than Spotted Gum or Blackbutt — a real plus for DIY touch-ups between professional applications.
For a full seasonal care schedule, see our spring deck maintenance guide.
Cost Ballpark
As a locally grown Class 1 hardwood, Tallowwood typically sits around the price of Spotted Gum, slightly above Merbau and below rarer imports like Iroko or Cumaru. Installed prices across Sydney for an average 20–30 m² ground-level tallowwood deck generally start around $350–$500 per m² depending on site access, sub-floor complexity, balustrade choice and permits. For a full breakdown of what drives deck pricing in 2026, see our practical Sydney deck cost guide.
Should You Pick Tallowwood?
Tallowwood is a great fit if you want a locally grown Australian hardwood, a clean even grain without heavy gum veins, Class 1 durability for a 40-plus-year deck, marine borer resistance near the coast, or a bushfire-rated timber without going composite. It’s less ideal if price is the only priority (Merbau is cheaper) or if you specifically want the streaked figure of Spotted Gum. But for a deck that will sit out there for decades and keep looking natural and unfussy, Tallowwood is one of the best-kept secrets in the Sydney hardwood market.
Talk to a Sydney Deck Builder
At 5 Star Decking, we’ve built decks across Sydney with Merbau, Spotted Gum, Blackbutt, Ironbark, composite and — increasingly — Tallowwood. We’ll help you weigh up timber choices honestly, give you a real installed price for your block, and make sure the design meets your council’s bushfire and planning rules.
Call us on 0433 334 415 or get in touch through our contact page for a free quote. We’re a licensed NSW builder — Licence No. 395250C — and we cover Sydney’s Inner West, Eastern Suburbs, Northern Beaches, Hills District, North Shore and Sutherland Shire.
