Grey Gum (Eucalyptus punctata) is an Australian native hardwood that has quietly earned a reputation among Sydney builders for its balance of strength, durability, and striking colour. If you are weighing timber options for a new deck and you are tired of seeing the same handful of species mentioned, Grey Gum deserves a closer look. In this guide from 5 Star Decking, we walk through what to expect, where it suits Sydney conditions, and whether it is the right timber for your project.
Why Grey Gum is a sensible choice for Sydney decks
Grey Gum is a Class 2 durability hardwood, which puts it in the same tier as Blackbutt and just below Class 1 species like Spotted Gum and Ironbark. For above-ground use such as decking boards, Class 2 is more than sufficient to handle Sydney humid summers, coastal salt air, and the temperature swings we get between November and March.
The timber Janka hardness sits around 9, meaning it resists denting from foot traffic, outdoor furniture, and pet claws better than softwoods. For families and busy backyards in Sydney inner west, northern beaches, and eastern suburbs, that hardness matters more than you might think on a new deck.
Appearance: what Grey Gum actually looks like
Grey Gum heartwood ranges from warm reddish-brown to pinkish tones, with a tight, interlocked grain that takes oil finishes well. When freshly installed, you will see a bright, almost coppery hue. Over the first season, expect the colour to settle and deepen. Regular oiling keeps that rich tone indefinitely; letting it weather gives you a soft, silvery-grey surface that pairs beautifully with harbourside and beachside homes.
Compared to Merbau (which leans orange-brown and can show yellow streaks) or Spotted Gum (which has wider colour variation and prominent gum veining), Grey Gum gives a cleaner, more consistent appearance. If you prefer uniform colour over a feature-rich, varied board, Grey Gum is the better pick.
Durability in Sydney climate
In above-ground applications, properly maintained Grey Gum decking boards typically last 25 years or more. The species handles humidity, sun exposure, and salt air well, conditions Sydney homes experience in spades, especially along the coast from Bondi to Cronulla and around the Northern Beaches.
One important caveat: Class 2 refers to above-ground durability. Do not use Grey Gum for ground-contact or structural posts. If your deck subframe is timber rather than steel, use a Class 1 species (like Spotted Gum or Ironbark) for joists and bearers, or H3.1-treated pine for subfloor framing. Contact us for honest advice on the right structural pairing for your deck.
Maintenance: oiling and tannin bleed
Grey Gum accepts oil finishes well, which makes it a practical option for homeowners who want to maintain their own deck.
Plan to oil a new Grey Gum deck within 4 to 6 weeks of installation, after the initial tannin bleed has eased (more on that below), then every 12 to 18 months depending on sun exposure. West-facing decks in Sydney summer sun typically need oiling annually; shaded south-facing decks can stretch to 18 months.
Choose a quality pigmented decking oil with a UV inhibitor. Lightly tinted finishes last longer than fully transparent ones for our climate. Avoid water-based acrylic stains unless the manufacturer specifically rates them for interlocked-grain eucalypts, and always test a new finish on an offcut first.
Tannin bleed: Grey Gum is moderately tannin-heavy. After installation, expect brown-tinged water runoff during the first few rainfalls. This is normal and not a defect. The bleed eases over 4 to 6 weeks. To reduce staining on concrete, pavers, or render, time the installation so the deck gets rained on before adjoining surfaces are finished, or hose the boards down daily for the first week. Wait until tannins have stopped leaching before oiling; oiling too early traps tannins in the grain and causes blotching.
If marks appear on nearby surfaces, oxalic acid or a proprietary deck cleaner will remove them. Do not use chlorine bleach, it can lighten timber and damage surrounding surfaces.
Sizes, profiles, and pricing
Grey Gum decking is most commonly stocked in 86×19 mm and 130×19 mm standard profiles. Wider boards (130 mm) give a more contemporary look with fewer visible joints. Narrower boards suit traditional homes and smaller decks where you want a busier pattern. Matching step treads in 140×40 mm are sometimes available, call timber yards ahead of time, as supply varies.
As of 2026, budget roughly $120 to $160 per square metre for Grey Gum decking boards at Sydney timber yards, delivered. A full installed deck costs more; our 2026 deck pricing guide walks through a realistic breakdown including subframe, fixings, and labour.
Is Grey Gum right for your project?
Best suited to:
- Homeowners who want a durable, attractive hardwood that is less common than Merbau
- Coastal and near-coastal homes where Class 2 durability is sufficient
- Decks that will receive regular oiling
- Contemporary or traditional homes that suit a warm reddish-brown timber
Less suited to:
- Tight-budget projects (Grey Gum sits above the price of treated pine and Merbau)
- Anyone wanting a cool-toned or grey-scale deck finish (Grey Gum runs warm)
- Very low-clearance decks needing in-ground durability (use a Class 1 species for structural members)
- Set-and-forget expectations; like any hardwood, Grey Gum needs periodic oiling
How 5 Star Decking can help
5 Star Decking is a licensed NSW deck builder (Licence 395250C) based in Sydney. We have built and maintained hardwood decks across Sydney inner west, eastern suburbs, and Northern Beaches for over 15 years. If you are considering Grey Gum or want to compare it against Spotted Gum, Merbau, Ironbark, or composite alternatives, we will give you an honest recommendation, an onsite inspection, and a detailed quote.
Call us on 0433 334 415, or reach out through our contact page to arrange a consultation.
This article is for general information only and does not constitute building advice. Timber availability, pricing, and building regulations change. For current pricing, site-specific advice, or council approval questions, contact a licensed builder. 5 Star Decking holds NSW Contractor Licence 395250C.
