Merbau decking is a dense tropical hardwood commonly used for outdoor decks, stairs, screens and other exterior structures. It is valued for its strength, natural durability, rich reddish-brown colour, and natural resistance to decay and insect damage. These qualities have made Merbau one of the most recognised hardwood decking materials in Australia.

But does that mean it is the right choice for every project?

Not necessarily. 

Merbau offers many advantages, but it also has characteristics that homeowners should understand before making a decision. Tannin bleeding, regular maintenance, and responsible sourcing are all important considerations. This is where many people get caught out. They focus on the timber’s appearance without understanding how it performs over time.

This guide explains what Merbau decking is, why it is widely used, where it works best, and what maintenance it needs to keep performing well.

What Is Merbau Timber?

Merbau is a tropical hardwood that comes primarily from trees belonging to the Intsia species. It grows naturally in parts of Southeast Asia and the Pacific region.

The timber is known for its dense grain, high strength, and natural durability. Freshly milled Merbau typically has a rich orange-brown or reddish-brown colour that gradually deepens with age. Without protective coatings, prolonged exposure to sunlight and rain causes the surface to weather into a silver-grey finish.

Because of its durability, Merbau timber is commonly used for:

• Outdoor decking
• External stairs
• Screening and privacy panels
• Pergolas
• Boardwalks
• Exterior landscaping projects

Its natural resistance to moisture, insects, and decay has made it a popular choice for outdoor construction for many years.

Why Is Merbau Decking So Popular?

Merbau decking has earned its reputation because it performs well in demanding outdoor conditions. Strength matters, but durability often matters more. A deck is exposed to sun, rain, changing temperatures and heavy foot traffic every year.

Merbau handles these conditions well when installed and maintained correctly.

Some of the key reasons homeowners and builders continue to choose Merbau decking include:

Natural Durability

Merbau contains natural oils that help resist fungal decay and insect attack. This contributes to its long service life in outdoor environments.

It is important to understand one point. Natural resistance does not mean maintenance-free. Dirt, moisture and weather still affect the surface over time.

High Strength

As a dense hardwood, Merbau is capable of handling regular foot traffic and everyday outdoor use. This makes it suitable for residential decks, entertaining areas and many commercial applications where a durable timber surface is required.

Attractive Appearance

One of Merbau’s biggest selling points is its colour.

Its warm reddish-brown tones create a classic hardwood appearance that suits both modern and traditional homes. Many people choose Merbau simply because they prefer the look of natural timber.

Over time, this appearance changes unless the boards are regularly maintained with suitable finishes.

Good Stability

Merbau generally performs well under changing weather conditions when installed correctly with appropriate ventilation, drainage and fixing methods.

Installation still matters. Even high-quality hardwood cannot compensate for poor construction practices.

Where Is Merbau Decking Commonly Used?

Although it is best known for decking, Merbau hardwood is used across a wide range of outdoor applications.

Common uses of the timber include:

• Residential decks
• Outdoor entertaining areas
• Pool surrounds
• External staircases
• Garden walkways
• Pergolas
• Privacy screens
• Commercial outdoor spaces

The suitability of any timber product depends on the intended application, local building requirements and project specifications. This point matters more than people realise. Material selection should always comply with relevant Australian standards and regulatory requirements.

What Sizes Are Available for Merbau Decking?

Merbau decking is supplied in several board sizes to suit different projects and design preferences.

A common Merbau decking size is 140 x 19 mm. 

Board lengths can vary depending on supplier availability and manufacturing batches.

The right board size depends on factors such as deck design, structural requirements, span calculations and visual preference. In practice, selecting board dimensions should always form part of the overall deck design rather than being treated as a cosmetic decision.

Does Merbau Decking Need Maintenance?

Yes. Every natural timber deck requires ongoing maintenance, including Merbau.

Many homeowners assume hardwood means maintenance-free. It doesn’t.

Regular care helps preserve appearance, minimise weathering and extend the life of the deck.

Typical Merbau decking maintenance includes:

• Sweeping away leaves and debris
• Washing dirt and mould from the surface
• Cleaning spills promptly
• Inspecting fixings periodically
• Reapplying decking oil or protective finishes when required

Maintenance frequency depends on exposure to sunlight, rainfall and general wear.

A neglected deck usually shows its age much sooner than a well-maintained one.

Why Does Merbau Decking Bleed?

One characteristic unique to Merbau is tannin bleed.

Merbau contains naturally occurring tannins that can leach from the timber when newly installed boards become wet. Rainwater may carry these tannins onto nearby paving, walls or concrete surfaces, leaving brown stains.

This is often misunderstood.

Tannin bleed is a natural property of the timber rather than a manufacturing defect.

Many installers recommend allowing new Merbau decking to weather naturally for a period before applying decking oil. Cleaning away excess tannins during this preparation stage helps reduce staining.

The exact preparation period depends on the board condition and the coating product being used. Always follow the decking oil manufacturer’s recommendations before applying finishes.

How Long Does Merbau Decking Last?

Merbau has an excellent reputation for longevity.

When installed correctly and maintained appropriately, Merbau decking can last for several decades under normal residential conditions.

The actual lifespan depends on factors including:

• Installation quality
• Drainage
• Ventilation
• Exposure to weather
• Maintenance routine
• Surface protection

Poor installation shortens the life of almost any decking material. Good maintenance extends it significantly.

Does Merbau Change Colour Over Time?

Yes.

Fresh Merbau typically displays rich reddish-brown tones that many homeowners find appealing.

Without protective coatings, ultraviolet exposure and rain gradually weather the timber to a silver-grey appearance. Some people prefer this natural weathered look, while others choose to maintain the original colour using decking oils.

Neither approach is right or wrong. It simply depends on the appearance the homeowner wants to maintain.

Is Merbau Suitable Around Swimming Pools?

Merbau is commonly used around swimming pools because of its strength and outdoor durability.

However, good performance depends on much more than timber selection alone.

Proper drainage, ventilation, fixing systems, slip resistance considerations and ongoing maintenance all contribute to the long-term performance of pool decking. Pool deck construction should always comply with relevant Australian regulations and project-specific design requirements.

Is Merbau Sustainably Sourced?

This question has become increasingly important.

Merbau is harvested from tropical forests, so sustainability depends on where and how the timber has been sourced.

Responsible suppliers work with manufacturers that source timber through recognised sustainable forestry practices wherever possible.

When purchasing Merbau decking timber, it is worth asking about responsible sourcing and any available certification. Many buyers focus entirely on price. In practice, responsible sourcing deserves equal attention.

Is Merbau Decking Right for Your Project?

Merbau remains one of Australia’s most widely recognised hardwood decking materials because it combines durability, strength and natural beauty.

It performs well outdoors, develops character over time and can provide decades of service with proper maintenance.

That said, every project is different.

The most suitable decking material depends on design requirements, intended use, structural considerations, maintenance expectations and compliance with relevant Australian regulations. Choosing a decking product should always take the complete project into account rather than focusing on appearance alone.

If you’re planning a decking project in Melbourne, Titan Trade Centre supplies quality Merbau decking and other decking materials along with wall cladding, accessories and building products to support residential and commercial projects. The right material starts with the right advice, and selecting products that meet your project’s requirements is always the best place to begin.

FAQs

Is Merbau good for decking?

Yes. Merbau is widely used for decking because it is strong, durable and naturally resistant to decay and insect attack.

Is Merbau decking hardwood or softwood?

Merbau is a tropical hardwood known for its density and durability.

Does Merbau decking need to be sealed?

Merbau can weather naturally, but many homeowners apply a suitable decking oil to help preserve its colour and protect the surface.

Why does Merbau decking bleed?

Merbau contains natural tannins that can wash out when new boards are exposed to rain or moisture. This is a natural characteristic of the timber.

How long should Merbau weather before oiling?

The preparation period depends on the condition of the boards and the coating product being used. Always follow the decking oil manufacturer’s instructions.

Does Merbau decking turn grey?

Yes. If left uncoated, Merbau gradually weathers to a silver-grey colour due to sun and rain exposure.

Is Merbau decking termite-resistant?

Merbau has natural resistance to termites, but it should not be considered completely termite-proof.

Is Merbau suitable for pool decking?

Yes. It is commonly used around pools when appropriate drainage, ventilation, fixings and maintenance practices are followed.

Is Merbau decking sustainable?

That depends on where the timber was sourced. Choosing responsibly sourced or certified products helps support sustainable forestry practices.

Can Merbau decking be painted?

It can be coated, but decking oils and exterior timber finishes are generally preferred. Proper preparation is important before applying any finish.