Tallowwood

Tallowwood is an extremely hard, durable and versatile Australian native hardwood species. Its timber products are suitable for a wide range of applications.

Botanical Name

Eucalyptus microcorys

Common Form
Sawn
Species Type

Tallowwood is a moderate to large tree occurring in wet sclerophyll forests of coastal regions from the Hunter River district of New South Wales to Maryborough and Fraser Island, Queensland.

The heartwood of this species ranges in colour from pale to dark yellow-brown, with occasional tinges of olive green. Sapwood is a whitish colour. The texture of tallowwood timber is moderately coarse, generally with interlocked grain. Unusually for a eucalypt species, tallowwood is free of gum veins. Figure is lacking but the timber possesses a distinctive lustre and ‘greasy’ appearance.

Tallowwood timber products exhibit exceptional durability in both in-ground and aboveground applications, where life expectancy is greater than 25 and 40 years, respectively. Although tallowwood is highly resistant to decay and will withstand damp and wet conditions quite well, its sapwood is susceptible to lyctid borer (powder post beetle) attack. Untreated timber of this species is equivalent to ‘fire retardant treated timber’ when tested in accordance with AS/NZS 3837.

Historically, tallowwood has been used for bearings, mallet heads, mauls, wheel spokes, and tool handles. Current engineering applications include wharf and bridge construction (as sawn and round timber), railway sleepers, cross-arms, poles, piles and mining timbers. Construction uses range from unseasoned framing to dressed timber cladding, internal and external flooring, linings and joinery. Tallowwood is also used in fencing, landscaping and the construction of retaining walls. Decorative uses include outdoor furniture, turnery and joinery. Other applications include boat building, the construction of coaches, carriages and agricultural machinery, and structural plywood.

 

Shrinkage

Very Low Low Medium High Very High

Tangential :

6.10%

Radial :

3.70%

Unit Movement Tangential:

0.37%

Unit Movement Radial:

0.28%

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:

F34

F27

F22

F17

F14

Density per Standard

Seasoned:

990kg/m3

Unseasoned:

1200kg/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:

87

Modulus of Rupture - Seasoned:

137

Modulus of Elasticity - Unseasoned:

14

Modulus of Elasticity - Seasoned:

18

Maximum Crushing Strength - Unseasoned:

48

Maximum Crushing Strength - Seasoned:

76

Impact - Unseasoned:

20

Impact - Seasoned:

18

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

7.1

Hardness - Seasoned:

8.6

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 11 12 13 14 15 16 17 18 19 20

EFH Ignitibility:

0 1 2 3 4 5 6 7 8 9 10

EFH Spread-of-Flame Index:

EFH Smoke-Developed Index:

Critical Radiance Flux - Lower:

>2.2 and <4.5

Critical Radiance Flux - Higher:

≥4.5

Smoke Development Rate:

<750
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 and 19 – All AS3959 required applications
Appearance

Tallowwood heartwood ranges from pale to dark yellow-brown, in contrast to its typically whitish sapwood. The texture of the timber is moderately coarse, generally with an interlocked grain relatively free of gum veins. Figure is lacking, but tallowwood has a distinctive lustre and greasy appearance.

Common Applications

Historically, tallowwood has been used for bearings, mallet heads, mauls, wheel spokes, and tool handles. Current engineering applications include wharf and bridge construction (as sawn and round timber), railway sleepers, cross-arms, poles, piles and mining timbers. Construction uses range from unseasoned framing to dressed timber cladding, internal and external flooring, linings and joinery. Tallowwood is also used in fencing, landscaping, and the construction of retaining walls. Decorative uses include outdoor furniture, turnery and joinery. Other applications include boat building, the construction of coaches, carriages and agricultural machinery, and structural plywood.

Workability

Tallowwood is very hard (rated 1 on a 6-class scale) in relation to indentation, yet is relatively easy to work with hand tools due to the timber’s natural greasiness – hence the species’ common name. It machines and turns well, readily accepts paint, stain and polish, and is amenable to the use of standard fittings and fastenings. Pre-drilling is recommended for nailing and screwing. Numerous extractives render tallowwood difficult to bond satisfactorily, although success has been reported with the use of polyurethane glues.

Origin of timber
NSW
Readily Available
NSW
A common species in New South Wales and southern 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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Joinery

Timber joinery offers a classic, stylish touch to any interior or exterior space.
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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.
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Fencing

When it comes to fencing, timber is a natural choice. A material that is durable, strong and reliable it compliments almost every outdoor landscape and environment. Clear specification, detailed installation and appropriate maintenance will ensure a timber fence provides a natural and lasting property boundary and back drop for years to come.
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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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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.
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Pergolas

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