Spotted Gum vs Merbau Decking: Which to Choose?

We compare two of Australia’s most popular decking materials.

Both are hardwoods meaning they’re a great choice for your deck’s resilience and longevity.

But there are a few important of differences between them so here’s a brief guide on what to look out for when deciding which is right for you.

What is Spotted Gum?

Spotted Gum has proven to be one of the most popular Australian hardwoods, with great durability and appearance.

Grown in plantations across Australia, it is a sustainable option with a wide range of uses. Spotted gum trees are found in abundance along the east coast of Australia from northern Queensland down to Victoria.

Spotted gum trees | Building & Landscaping Materials
Spotted gum trees

It is commonly used for structural applications such as house framing, as well as decking.

Spotted gum is also suitable for:

  • Fencing
  • Decking
  • Landscaping
  • Cladding
  • Flooring
  • Furniture
  • Joinery

The timber comes in a range of colours from pale browns through to dark chocolate hues and is characterized by its distinctive gum vein markings. The grain pattern can be interlocked or straight and the texture ranges from medium to coarse.

Spotted Gum has long been a popular choice for outdoor construction projects due to its durability and versatility.

The tree itself can grow to heights of 60m and, in the wild, can live for up to 500 years.

The trunks of spotted gum trees are straight and cylindrical with the bark typically shedding in ribbons or plates to reveal patches of cream, light brown, grey and chocolate brown. The texture of the heartwood ranges from coarse to medium.

What is Merbau?

Merbau is a popular hardwood from South East Asia used in a range of furniture and construction applications.

Also, known as Kwila, it is popular thanks to its hardness, durability and attractive appearance.

Because of its high density, Merbau is durable and resistant to rot and insect attack – as well as being quite hard wearing. This makes it ideal for outdoor applications like decking, pergolas and other constructions.

Merbau deck | Building & Landscaping Materials

There are also some downsides to Merbau that needs to be considered.

First, Merbau can bleed tannins significantly. This can lead to staining issues over time. Staining can be avoided with adequate preparation and by coating with oil but this needs to be maintained regularly.

The second issue is whether the Merbau is sourced ethically and in a sustainable way. This can be difficult to trace, as all Merbau in Australia is imported.

Merbau grows throughout South East Asia but most of the timber that is imported into Australia comes from Indonesia, Papua New Guinea and Malaysia.

Spotted Gum vs Merbau – Key Similarities


Both of these hardwoods are very strong and are suitable for a range of construction applications.

Here are the relevant strength ratings, according to WoodSolutions:

Spotted GumHighHigh
MerbauHighReasonably High
Source 1, Source 2

They are both very dense (Spotted gum slightly more so) which means they have a high volume of actual wood material in each unit volume of wood. Or in other words, there is very little air inside the wood.


Both species are also considered very durable.

The durability ratings are as follows:

IngroundOutside Above Ground
Spotted Gum21
Source: Timber Queensland Outdoor Timber Technical Datasheet.

And here are the descriptions of the durability ratings:

Durability classAbove-ground life expectancyIn-ground life expectancy
1> 40 years> 25 years
215 to 40 years15 to 25 years
37 to 15 years5 to 15 years
40 to 7 years0 to 5 years
Source: AS 5604-2005 Timber—natural durability ratings (Standards Australia 2005)

Termite Resistant

The Timber Queensland Technical Datasheet lists that the heartwood of both of these species is “Resistant” to termites.

Spotted Gum vs Merbau – Key Differences


Spotted Gum is an Australian timber while Merbau comes from Indonesia.


Merbau is a more red/brown colour that deepens over time, while Spotted gum is more chocolate brown which turns more golden as it ages.

Merbau also has more variance in its appearance.

Merbau deck 1 | Building & Landscaping Materials


Both of these timbers bleed however Merbau much more so. Tannin bleeding, or leaching, occurs when the natural tannins in timber leak out onto surrounding surfaces.


Sourcing environmentally friendly Merbau can be a bit more difficult, and it can sometimes come from non-sustainable sources.


While prices due vary with supply, Spotted Gum is usually more expensive than Merbau.

Photo of author

Steve Kropp

Based in Melbourne, Steve's passion is vegetable gardening, and he’s been writing about it for almost 5 years. He also loves all things DIY and is always looking for a new project. When not working on his own garden projects or blogging, Steve enjoys spending time with his family, cooking meals with produce harvested from his garden, and coaching his son’s footy team.


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