Gum, Sydney Blue

Sydney blue gum is an Australian native hardwood timber species that is widely used in general construction and for flooring, furniture and joinery.

Other Names

Blue Gum

Botanical Name

Eucalyptus saligna

Common Form
Sawn
Species Type

Sydney blue gum is a large hardwood species growing to a height of 60 metres or more. It occurs natively in forests along the coast of New South Wales and southern Queensland. Sydney Blue Gum is also extensively grown as a plantation species in South Africa and South America, where rapid growth yields timber of much lower density than Australian material.

Sydney Blue Gum is an important general construction timber, particularly in New South Wales. It is widely used for flooring, cladding, fencing, paneling and boat building. Other common applications include landscaping (as garden sleepers), furniture and joinery.

The heartwood of the species ranges in colour from dark pink to a reddish brown. Sapwood is distinctly paler. The grain of Sydney blue gum timber is typically straight, with occasional interlocking of grain. Texture is moderately coarse and gum veins are common. Sydney blue gum is a moderately durable timber with a life expectancy for in-ground applications of between eight and 15 years. Untreated sapwood is susceptible to Lyctid borer attack.

Sydney blue gum timber is easy to dry relative to most other eucalypts. It is also easy to work, dress and fix. It responds well to most finishes and takes a good polish, making it popular for decorative applications where moderate durability is required.  

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.

9.50%

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

5.40%

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.

0.34%

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.

0.24%

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:

F17

F14

F11

F8

F7

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:

840kg/m3

Unseasoned:

1110kg/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.

76

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.

122

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.

12

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.

15

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.

41

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.

66

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

17

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

18

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.

5.8

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

8.1

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.

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(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.

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(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.

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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.

Not 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.

Critical Radiance Flux - Lower: This measures the radiant (heat) energy required to sustain burning. It is used in Australia to regulate floor coverings. The requirements are set out in BCA
Specification C1.10a, providing CRF values for floor coverings based on Class of building, the location within the building (general use or use in fire isolated exits) and whether or not the building is sprinkler protected or not. CRF is measured in kW/m2.

>2.2 and <4.5

Critical Radiance Flux - Higher: This measures the radiant (heat) energy required to sustain burning. It is used in Australia to regulate floor coverings. The requirements are set out in BCA
Specification C1.10a, providing CRF values for floor coverings based on Class of building, the location within the building (general use or use in fire isolated exits) and whether or not the building is sprinkler protected or not. CRF is measured in kW/m2.

>2.2 and <4.5

Smoke Development Rate: This is the speed at which smoke increases as determined by testing flooring materials in accordance with AS ISO 9239.1. The rate is expressed in terms of percent/minutes. For buildings not protected with a sprinkler system, a maximum smoke development rate of 750 percent/minute applies.

<750
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 and 19 – All AS3959 required applications
Appearance

The heartwood of Sydney blue gum ranges in colour from dark pink to reddish brown. The paler sapwood is readily distinguishable. Grain is typically straight with occasional interlocking. Texture is moderately coarse and gum veins are common.  

Common Applications

Sydney blue gum timber is an important general construction timber, particularly in New South Wales. It is widely used for flooring, cladding, fencing, panelling and boat building. Other common applications include landscaping (as garden sleepers), furniture and joinery.  

Workability

Sydney blue gum is easy to work, dress and fix. It responds well to most finishes and takes a good polish, making it popular for decorative applications where moderate durability is required.

Origin of timber
NSW
Readily Available
NSW
Sydney blue gum timber is readily available in New South Wales.
a wood fence with trees in the background

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.
a wooden fenced hillside with plants and a fenced yard

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.
a staircase in a building

Stairs, Interior

Timber is the material of choice for designers seeking internal staircases of strength, beauty and durability.
a close-up of a building

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.
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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