Merbau

Merbau is a popular hardwood from South East Asia used in a wide range of applications; from construction to indoor and outdoor furniture.

Other Names

Kwila, Ipil, Vesi, Johnstone River Teak or Scrub Mahogany

Botanical Name

Insia Bijuga

Common Form
Sawn
Species Type
Hardwood
  • Overview

    • Merbau is a popular hardwood derived largely from areas in South East Asia, Papua New Guinea, the Pacific islands, and northern Queensland. With its high degree of natural durability and strength it is used externally in engineering, construction and marine applications. 

    Merbau also features in backyards as outdoor furniture, and internally in a range of joinery, flooring and other uses.

    Merbau is harvested from tropical forests and, in some cases, may be sourced from forests legally converted to other land uses or where there are inadequate controls. Certified merbau is available in Australia, so it is suggested you check with your supplier. Certification and chain of custody systems, including DNA tracking, will provide assurance that the wood is from legal and/or well managed forests.

    In its natural setting in North Queensland, Malaysia, Fiji, Vietnam, the Philippines, Madagascar, Papua New Guinea, Thailand, Solomon Islands, New Caledonia, Vanuatu and Samoa, the merbau species can grow up to 40 metres in height, with a 0.6 metre trunk diameter. The bushy tree, with distinctive local names, will often form a spreading canopy.

    The attractive yellow-orange brown hue of freshly cut heartwood deepens or reddens with ageing. This contrasts markedly with the merbau sapwood, which is white, pale yellow or buff coloured. If left untreated, the sapwood is susceptible to lyctid borer attack. Beyond that, merbau is quite resistant to termites and seasons well with kiln or air-drying, exhibiting only a low degrade and very little shrinkage or movement. The grain of merbau can vary but it is usually interlocked or wavy, with a coarse but even texture, often prized for its attractiveness on backsawn material.

    It will finish well with paint, stain, and polish although gum bleed is a possibility.  

    Merbau is a versatile wood product. It is utilised for larger-scale projects and general construction, along with common use for outdoor settings and barbeque trolleys, and for joinery, flooring and fitting purposes. As it turns well and responds to hand tools it can be applied to more specialised work, such as cabinet making, musical instruments, boat building, carving and tool handles.

    Shrinkage

    Very Low Low Medium High Very High
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    Tangential : Provides a simplified rating for tangential shrinkage. This is the measure of the percentage reduction in dimension from the unseasoned to 12% moisture content condition.
    2.50%

    Radial : Radial shrinkage is perpendicular to the growth rings. It is shrinkage in the direction towards the centre of the tree. Measurement is % value
    1.20%

    Unit Movement Tangential: This is the percentage of dimensional change for each 1% moisture content change between about 3% moisture content and the fibre saturation point for the particular species.
    0.30%

    Unit Movement Radial: This is the percentage of dimensional change for each 1% moisture content change between about 3% moisture content and the fibre saturation point for the particular species.
    0.19%

    Strength Group Strength groups are given for unseasoned (S1-S7) and seasoned (SD1-SD8) timber in accordance with AS 2878. S1 and SD1 yield the highest strength and stiffness whereas S7 and SD8 yield the lowest.

    Very High

    High

    Reasonably High

    Medium High

    Medium

    Reasonably Low

    Low

    Very Low

    Unseasoned:

    S1

    S2

    S3

    S4

    S5

    S6

    S7

    S8
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    Seasoned:

    SD1

    SD2

    SD3

    SD4

    SD5

    SD6

    SD7

    SD8
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    Stress Grade A stress grade is defined in AS 1720 as the classification of timber for structural purposes by means of either visual or machine grading. The stress grade indicates the basic working stresses and stiffnesses to be used for structural design purposes. Measured in MPa.

    Structural
    No. 1    		 Structural
    No. 2    		 Structural
    No. 3    		 Structural
    No. 4    		 Structural
    No. 5

    Unseasoned:

    F27

    F17

    F14

    F11

    F8

    Seasoned:

    F27

    F22

    F17

    F14

    F11

    Density per Standard Seasoned density is based on moisture content of 12%. Unseasoned density is an approximation as it depends on the moisture content at the time of measurement. Measured kg/m3.

    Seasoned:

    860kg/m3

    Unseasoned:

    1150kg/m3

    Joint Group The joint group is a classification of the strength of a species in joint design. The values are from 1 (very high strength) to 6 (very low strength).

    Very High

    High

    Reasonably High

    Medium

    Low

    Very Low

    Unseasoned:

    J1

    J2

    J3

    J4

    J5

    J6
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    Seasoned:

    JD1

    JD2

    JD3

    JD4

    JD5

    JD6
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    Colour The colour of seasoned heartwood can vary between species and often within a species. The information provided should be used as a general guide only. In most cases, the colour of sapwood is either a lighter shade of the heartwood or a white/cream colour.

      White, yellow, pale straw to light brown Pink to pink brown Light to dark red Brown, chocolate, mottled or streaky
       
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    Mechanical Properties

    Modulus of Rupture - Unseasoned: This property is a measure of maximum stress which timber can momentarily sustain when loaded slowly and continuously as a beam. Measured in MPa.
    118

    Modulus of Rupture - Seasoned: This property is a measure of maximum stress which timber can momentarily sustain when loaded slowly and continuously as a beam. Measured in MPa.
    147

    Modulus of Elasticity - Unseasoned: This property is of importance in determining the deflection of a beam under load — the greater the stiffness, the less the deflection. Measured in GPa.
    15

    Modulus of Elasticity - Seasoned: This property is of importance in determining the deflection of a beam under load — the greater the stiffness, the less the deflection. Measured in GPa.
    18

    Maximum Crushing Strength - Unseasoned:

    Also referred to as compression strength. This property measures the ability of the timber to withstand loads applied on the end grain. Measured in MPa.
    59

    Maximum Crushing Strength - Seasoned: Also referred to as compression strength. This property measures the ability of the timber to withstand loads applied on the end grain. Measured in MPa.
    82

    Impact - Unseasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.
    18

    Impact - Seasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.
    7.7-14

    Toughness - Unseasoned: This is a measure of timber’s ability to resist shocks and blows, and is synonymous with impact strength. It is measured in Nm.
    Medium - 15 - 24 Nm

    Toughness - Seasoned: This is a measure of timber’s ability to resist shocks and blows, and is synonymous with impact strength. It is measured in Nm.
    Medium - 15 - 24 Nm

    Hardness - Unseasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    7.6

    Hardness - Seasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    8.5

    Durability

    Low Moderate Reasonably High High
    (0 - 5 yrs) (5 - 15 yrs) (15 - 25 yrs) (more than 25 yrs)

    In-Ground: Durability is defined as the inherent resistance of a timber species to decay, or to insect or marine borer attack. All references to durability refer to the heartwood only. A scale of low to high (durability class 4 = low; 1 = high) has been adapted for above and in-ground durability.

    		 Check mark
    (0 - 7 yrs) (7 - 15 yrs) (15 - 40 yrs) (More than 40 yrs)

    Above ground: Durability is defined as the inherent resistance of a timber species to decay, or to insect or marine borer attack. All references to durability refer to the heartwood only. A scale of low to high (durability class 4 = low; 1 = high) has been adapted for above and in-ground durability.

    		 Check mark
    (0 - 20 yrs, usually < 5) (21 - 40 yrs) (41 - 64 yrs) (More than 60 yrs)

    Marine Borer Resistance: Indicates whether a species is resistant (R) or not resistant (NR) to marine borer attack.

    		 Check mark

    Lyctid Borer Susceptibility: Indicates whether a species is susceptible (S) or not susceptible (NS) to lyctid borer attack.

    Susceptible

    Lyctid Borer Susceptibility - Other:

    Termite Resistance: Indicates whether a species is resistant (R) or not resistant (NR) to termites.

    Resistant

    Fire Properties

    0 1 2 3 4 5 6 7 8 9 10

    EFH Spread-of-Flame Index: This is a material's propensity to burn rapidly and spread flames based on a scale of 0 to 10 where 0 means that the materials will not cause flames to reach the ceiling and 10 indicates that the material could be expected to cause flames to reach the ceiling of a room within 10 seconds of ignition.

    EFH Smoke-Developed Index:This is a measure of the concentration (measured by optical density) of smoke a material emits as it burns. It is based on an arbitrary scale of 0 to 10. The higher the index, the greater the hazard from smoke is likely to be.
    1 - non-combustible 2 - reasonably non-combustible 3 - slightly combustible 4 - combustible

    Fire Properties Group
    Number:

    Average Specific Extinction Area: This value is determined by the volume of smoke measured over the mass loss of the tested sample per test carried out in accordance with ‘Cone Calorimeter Test’ AS/NZS 3837. It is measured in units of m2/kg.
    <250

    Bushfire Resistance: Naturally bushfire-resisting timbers are those with inherent bushfire-resisting properties. Some species have been tested and a number are in the process of being tested and are measured by Bushfire Attack level (BAL). BAL -12.5: Ember attack, BAL – 19: Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 12.5 and 19 kWm3, BAL – 29: Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 19 and 29 kWm3.
    BAL 12.5, 19 and 29 – All AS3959 required applications
    Appearance

    In its natural setting the merbau species can grow up to 40 metres in height, with a trunk of 0.6 metres in diameter. The bushy tree will often form a spreading canopy. Once cut, the heartwood will initially appear as yellowish-brown or orange-brown before deepening to a pale to dark reddish brown. This contrasts with the merbau sapwood, which appears white, pale yellow or buff. The wood grain is variable but usually interlocked or wavy, which produces a ribbon figure on the radial surface. The timber has a coarse but even texture. It has a characteristic oily odour when cut.

    Common Applications

    Merbau spans a variety of uses in the fields of engineering, construction, marine and furnishings, both for the indoors and outside. It has been utilised for infrastructure projects including cross arms, bridge building, piles, sleepers, posts, wharves and mining timbers. In the construction context merbau is used in framing, decking, treads and other general needs. Many boats, particularly the decks, are made of merbau, as are a variety of vats, musical instruments and tool handles. As a furniture material merbau is prominent in outdoor settings and barbeque trolleys, as well as being valued for turning, paneling, joinery, shop fitting, cabinet making, parquet flooring, carving, veneer, counter and bench tops.

    Workability

    Merbau takes well to paint, stain and polish, however the finish can sometimes be affected by gum bleed-through or oily patches. Its vessels also contain a yellow substance that stains textiles and concrete. It turns well and is relatively easy to work with hand tools, though it can be variable when it comes to machining. It will generally cut cleanly but there may be some blunting or gumming effect on the cutting edges. Merbau tends to split unless pre-bored, but holds fastenings well.

    Origin of timber
    QLD
    Readily Available
    NSW
    Merbau grows naturally in South East Asia, the Philippines, Solomon Islands, Fiji and Papua New Guinea and is imported to Australia from these countries.
    Merbau grows in Australia in a specific region by the Johnstone River and in the Daintree area of Far North Queensland. It is often referred to as Johnstone River teak or scrub mahogany.
    Source of timber
    Native Forest
    a kitchen with wooden cabinets and a countertop

    Joinery

    Timber joinery offers a classic, stylish touch to any interior or exterior space.
    a deck with a pool and a deck with a couch and a bench

    Decking

    Timber decking creates spaces that are functional, practical and aesthetically pleasing. With the right design and care a timber deck will make a valuable addition to any home or business, creating an outdoor living space that will be enjoyed for years to come.
    a wooden stairs with railings

    Stairs, Exterior

    For outdoor applications, timber is one of the leading material choices. Timber use in external staircase applications creates structures of strength and durability, sheathed in a natural beauty that blends seamlessly with the outdoor environment.
    a staircase with a hole in the ground

    Rails and Balustrades, Interior

    With its natural beauty and inherent strength, timber is a popular material choice for internal balustrades. Commonly built from treated softwoods and durable hardwoods, interior balustrades and handrails are typically finished with a clear lacquer to generate the most natural result.
    a staircase in a building

    Stairs, Interior

    Timber is the material of choice for designers seeking internal staircases of strength, beauty and durability.
    a patio with a deck and chairs

    Pergolas

    A timber pergola is a practical, functional and attractive way to extend living and entertainment spaces into the outdoors.
    a house with a pool in the back

    Rails and Balustrades, Exterior

    This provides general information on member sizes, connections and suitable materials for construction of handrails and balustrades in external applications. Commonly built from treated softwood and durable hardwoods, they can be finished with a wide variety of paints or stains, creating balustrades that with the right care and attention, will comfortably withstand the elements for decades to come.
    a glass building with a wood deck

    Windows

    With natural aesthetic appeal, versatility and sound structural performance, timber provides excellent window joinery design options. Whether stained to bring out natural tones, or painted to compliment particular décors, timber windows can be tailored to suit a huge variety of styles and can be installed into any type of building.
    a room with benches and paintings on the wall

    Flooring

    The warmth, strength and natural beauty of timber flooring is enduringly popular in a wide variety of domestic, commercial and industrial applications.

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