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

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

Tangential :

2.50%

Radial :

1.20%

Unit Movement Tangential:

0.30%

Unit Movement Radial:

0.19%

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

Seasoned:

SD1

SD2

SD3

SD4

SD5

SD6

SD7

SD8

Stress Grade

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:

860kg/m3

Unseasoned:

1150kg/m3

Joint Group

Very High

High

Reasonably High

Medium

Low

Very Low

Unseasoned:

J1

J2

J3

J4

J5

J6

Seasoned:

JD1

JD2

JD3

JD4

JD5

JD6

Colour

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

Mechanical Properties

Modulus of Rupture - Unseasoned:

118

Modulus of Rupture - Seasoned:

147

Modulus of Elasticity - Unseasoned:

15

Modulus of Elasticity - Seasoned:

18

Maximum Crushing Strength - Unseasoned:

59

Maximum Crushing Strength - Seasoned:

82

Impact - Unseasoned:

18

Impact - Seasoned:

7.7-14

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

7.6

Hardness - Seasoned:

8.5

Durability

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

In-Ground:

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

Above ground:

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

Marine Borer Resistance:

Lyctid Borer Susceptibility:

Susceptible

Lyctid Borer Susceptibility - Other:

Termite Resistance:

Resistant

Fire Properties

0 1 2 3 4 5 6 7 8 9 10

EFH Spread-of-Flame Index:

EFH Smoke-Developed Index:

1 - non-combustible 2 - reasonably non-combustible 3 - slightly combustible 4 - combustible

Fire Properties Group
Number:

Average Specific Extinction Area:

<250

Bushfire Resistance:

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
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