Mahogany, White

White mahogany is a premium Australian hardwood used for structural, interior and exterior applications.

Other Names

Yellow Stringybark (Qld), White Stringybark, Narrow-leaved White Mahogany, Eucalyptus Umbra, Eucalyptus tenuipes

Botanical Name

Eucalyptus acmenoides

Common Form
Sawn
Species Type

White mahogany is one of Australia's premium native hardwoods with a high degree of natural durability and strength, making it an ideal timber for a variety of structural, exterior and interior applications.

White mahogany is the common name for four species that grow along the east coast of Australia, from mid-New South Wales to northern Queensland, with isolated pockets north of the Queensland tablelands. Sawn timbers from these species are readily available across Australia.

They have straight, slender trunks with rough, fibrous bark that is shed in strips, giving the trees their characteristic stringy appearance and resulting in the common local names of yellow or white stringybark.

The species varies in appearance but not in durability class or other properties. The heartwood is light brown to yellow brown in colour. The sapwood is usually creamy brown and is uniformly lighter than the heartwood. White mahogany wood has a slightly greasy feel, a characteristic that aids machining and boring.

It is termite resistant and the sapwood can be easily treated with preservatives. The heartwood is too dense to accept readily available commercial preservation processes.

The wood is used as a sawn timber in engineering applications such as wharf and bridge construction, railway sleepers, cross-arms and mining timbers. It is suitable for a range of building applications, such as posts and poles, framing, flooring, lining, decking and cladding. White mahogany is also used in the manufacture of veneer and plywood. Other applications include boatbuilding, coach and carriage building, and agricultural machinery.

Shrinkage

Very Low Low Medium High Very High

Tangential :

5.40%

Radial :

2.80%

Unit Movement Tangential:

Unit Movement Radial:

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

S8

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:

950kg/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:

101

Modulus of Rupture - Seasoned:

130

Modulus of Elasticity - Unseasoned:

16

Modulus of Elasticity - Seasoned:

17

Maximum Crushing Strength - Unseasoned:

49

Maximum Crushing Strength - Seasoned:

76

Impact - Unseasoned:

17

Impact - Seasoned:

14

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

8.9

Hardness - Seasoned:

10

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:

Not 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:

Group Number - Other:

3 if used on MDF or particleboard ≥12mm; veneer thickness 0.6-0.85mm

Average Specific Extinction Area:

<250

Bushfire Resistance:

BAL 12.5 and 19 – All AS3959 required applications
Appearance

White mahogany timbers are available in a narrow range of colours. The heartwood is light brown to yellow brown in colour and has a similar appearance to tallowwood. The sapwood is usually creamy brown, clearly lighter in colour than the heartwood and generally less than 20mm wide.

A mostly uniform and medium textured wood, white mahogany can sometimes have an interlocked grain. It can also feature distinctive markings caused by moth grub holes and occasional gum veining. It has a slightly greasy feel, although not as greasy as the similarly coloured tallowwood or spotted gum.

Common Applications

White mahogany is often used for above ground framing and decking in both protected and unprotected contexts. It can also be used for heavy construction work, from sawn and round timber in wharf and bridge construction to railway sleepers, cross arms, poles, piles. and as mining timbers. It is employed in general house framing, as cladding, linings, joinery, fencing, landscaping and in retaining walls. The species is also suitable for use in structural plywood, boat building (keel and framing components, planking), coach, vehicle and carriage building and agricultural machinery. It is often used in internal and external flooring as its hardness means it does not easily dent, and is also frequently used in outdoor furniture due to its durability.

Workability

White mahogany machines well due to its natural greasiness, and there is no difficulty using it with standard fittings and fastenings. Due to its hardness, the timber is not easily worked with hand tools. As with other high-density species, machining and surface preparation should be done immediately before gluing. Easily painted, stained, and polished, the sapwood readily accepts preservatives but the density of the hardwood makes it resistant to current commercial preservative compounds.

Origin of timber
NSW
Readily Available
NSW
White mahogany is an important commercial species in NSW and Queensland.
Source of timber
Native Forest
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Portal Frames

For buildings that require large spans and column free interiors, timber portal frames provide one of the most aesthetically pleasing solutions. Utilising modern engineering technology, portal frame design transforms timber into a highly effective, efficient and economical structural product.
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Retaining Walls (Landscaping)

When it comes to retaining wall, landscape design and construction, timber is the natural choice. A material that is durable, sturdy and reliable, it has natural aesthetics that help it blend seamlessly with the outdoors. Careful consideration during the specification and design process will facilitate the creation of a long lasting, durable and beautiful timber retaining wall that will complement its surrounding landscape for years to come.
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Cladding, External

The natural appeal, versatility and strength of timber makes it the superior choice for external cladding. Through specification, planning, design and finishing processes, timber cladding not only creates a building of superior strength, acoustic and thermal performance but also creates a place of beauty, style and natural appeal.
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Shear walls

Lateral loads such as wind or earthquake on framed timber buildings - either post and beam or stud and joist - need to be resisted and shear walls and diaphragms offer an effective and economical solution.
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Structural Timber Poles

Timber poles are utilised in structural construction to provide support for gravity loads and resistance against lateral forces. Not only serving a structural function, timber poles provide many aesthetic benefits, with their use in construction often complementing architectural designs aimed at harmonisation with the natural environment.
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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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