Merbau Decking: Benefits and Limitations
What Is Merbau?
Merbau is a tropical hardwood known for its strength, durability and rich reddish-brown colour. It is commonly used for decking, flooring, outdoor furniture, boardwalks and other exterior projects.
The timber is mainly sourced from Southeast Asia and parts of the Pacific. It is also called Kwila or Ipil in some markets.
Freshly cut Merbau usually appears yellowish-brown or orange-brown. It gradually darkens into a deeper brown or reddish-brown colour. Its grain may be straight, interlocked or slightly wavy, giving each board a distinctive appearance.
How Durable Is Merbau Decking?
Merbau heartwood is naturally resistant to decay and termite attack.
Under the Australian natural durability classification system, Merbau is rated:
- Class 1 for above-ground use: Expected service life of more than 40 years
- Class 3 for in-ground use: Expected service life of approximately 5 to 15 years
These figures explain why Merbau performs better as raised decking than in direct contact with soil.
However, the classification is a general guide, not a warranty. Actual service life depends on timber quality, drainage, ventilation, climate, installation and maintenance. The pale sapwood is also less durable than the darker heartwood.
Benefits of Merbau Decking
Strong and Wear-Resistant
Merbau is hard and dense. It can withstand frequent foot traffic and the movement of outdoor furniture.
It can be used for:
- Residential terraces
- Hotels and resorts
- Restaurants
- Pool surrounds
- Commercial walkways
- Boardwalks
A strong decking board still needs a correctly designed supporting structure. Merbau cannot compensate for weak joists, poor drainage or incorrect installation.
Attractive Appearance
Merbau’s warm brown and reddish-brown tones suit both traditional and modern buildings.
Colour variation between boards is normal. Some pieces may initially appear lighter or more orange than others. Exposure to light usually darkens the timber and helps the colours blend over time.
Good Stability
Properly dried Merbau generally remains stable and experiences relatively low movement.
However, all timber expands and contracts as moisture conditions change. Installers must provide suitable spacing between boards and adequate ventilation beneath the deck.
Available in Different Profiles
Merbau can be manufactured as smooth, grooved, reeded, reversible or rounded-edge decking. Custom profiles may also be possible.
Grooves do not automatically make a deck less slippery. Dirt, water and algae can collect inside upward-facing grooves if the surface is not cleaned properly.
Limitations of Merbau Decking
Coloured Extractive Bleeding
Merbau contains water-soluble natural extractives. Rain can carry these substances out of the wood, producing red or brown runoff.
The runoff may stain:
- Concrete
- Pale stone
- Tiles
- Pool coping
- Rendered walls
- Painted surfaces
Pre-washing or weathering the boards can reduce bleeding, but it may not stop immediately. Good drainage and protection of surrounding surfaces are especially important around swimming pools.
More Difficult to Install
Merbau is harder to cut and fasten than softer timber. Its natural deposits can also build up on cutting equipment.
Installers should use sharp tools and pre-drill screw holes. Driving screws directly into the boards may cause splitting, particularly near the ends.
Reaction With Iron
Merbau can develop dark marks when it comes into contact with iron and moisture.
Use suitable corrosion-resistant fasteners and remove metal filings before the deck becomes wet. Poolside and coastal projects may require a specific grade of stainless steel.
Natural Colour Variation
Merbau is a natural material, so individual boards will not look identical. A small sample cannot represent every colour and grain pattern in a full order.
Buyers should agree on acceptable grading and sapwood limits before production.
The Colour Changes Without Maintenance
Uncoated Merbau gradually weathers to a silver-grey colour. This colour change does not necessarily mean that the timber is decaying.
A suitable pigmented decking finish can help preserve the original brown colour. Maintenance frequency depends on sunlight, rainfall, foot traffic and the chosen coating.
Is Merbau Suitable for Pool Decking?
Merbau can be suitable for pool surrounds because it is durable, strong and attractive.
Its coloured runoff may stain pale coping and tiles, so the boards need appropriate preparation and drainage. Regular cleaning is also necessary because algae and dirt can make any decking surface slippery.
Conclusion
Merbau combines high durability, strength, stability and a distinctive reddish-brown appearance. Its Class 1 above-ground durability rating makes it a strong option for properly constructed exterior decks.
Buyers must also consider extractive bleeding, colour variation and more demanding installation. Correct specifications, good drainage and proper fastening are essential for reliable performance.
Backed by over 40 years of timber expertise and trusted by more than 280 corporate customers across 30 countries, Sitra Global supplies Merbau decking in export quantities. Contact us today!