Merbau and spotted gum are two of the most popular decking timbers in Melbourne, and for good reason. Both are durable, beautiful, and well suited to our climate. But they have distinct personalities, and the right choice depends on the look you are after and how you plan to use your outdoor space.
Colour and grain character
Merbau starts life as a rich reddish-brown with golden highlights through the grain. Over time, if left unoiled, it will silver off to a soft grey. With regular oiling, it maintains that warm, deep tone that most people associate with a classic Australian deck.
Spotted gum is lighter and more varied. It ranges from pale browns and creams through to deeper chocolate tones, often with a distinctive wavy or interlocked grain pattern. The natural variation means every board is slightly different, which gives spotted gum decks a more dynamic, textured appearance.
Lucas's personal favourite is actually ironbark, but for clients choosing between these two, the decision usually comes down to whether you prefer the consistent warmth of merbau or the varied character of spotted gum.
Hardness and durability
Both timbers are classified as durable hardwoods suitable for outdoor use, but they are not identical. Spotted gum has a Janka hardness rating of around 11 kN, making it one of the hardest decking timbers commercially available. It resists dents, scratches, and wear exceptionally well.
Merbau sits at around 8.5 kN on the Janka scale. Still very hard, still very durable, but slightly softer than spotted gum. In practical terms, both will handle foot traffic, furniture, and outdoor living without issue. The difference is more noticeable in high-traffic commercial applications than in residential use.
Both timbers are naturally resistant to termites and decay when used above ground. For in-ground or ground-contact applications, separate treatment considerations apply.
Tannin bleed and maintenance
Merbau is known for its tannin bleed, particularly in the first few months after installation. When it rains, the natural tannins in the timber leach out as a reddish-brown residue that can stain surrounding concrete, pavers, and paths. This is temporary and settles down over time, especially with proper oiling. If your deck is adjacent to light-coloured paving, this is worth factoring in.
Spotted gum has far less tannin bleed, which makes it a better choice for installations near pools, light-coloured render, or white pavers.
Both timbers need regular oiling to maintain their colour and protect the grain. The frequency is similar: once or twice a year, depending on exposure and foot traffic.
Want to see both timbers side by side? We bring samples to every site visit.
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Merbau is an imported timber, primarily sourced from Southeast Asia. It has been the go-to decking timber in Melbourne for decades, and supply is generally consistent. Pricing can fluctuate with import costs and availability.
Spotted gum is an Australian native timber. It is domestically sourced, which can make supply more stable and pricing more predictable. However, the higher hardness of spotted gum means it takes longer to work with. Pre-drilling is essential, and the timber can be more demanding on tools and blades. This can add slightly to labour costs.
On a per-square-metre basis, the two are often comparable. Spotted gum may cost slightly more for materials, but the difference is usually not dramatic.
Our take
Both are excellent decking timbers. If you want a warm, consistent colour with a proven track record in Melbourne, merbau is a safe and beautiful choice. If you prefer a lighter, more varied look with maximum hardness and minimal tannin issues, spotted gum is the way to go.
We are happy to bring samples to your site visit so you can see both timbers in person and compare them against your house colours, your garden, and the surrounding landscape. That is the best way to make a decision you will be happy with for years to come.