Gum, Southern Blue

Southern blue gum is a widely forested Australian hardwood species. Its timber products are readily available and suitable for flooring, furniture and a range of general construction applications.

Other Names

Eurabbie, Tasmanian Blue Gum, Maiden's Gum, Gippsland Blue Gum

Botanical Name

Eucalyptus globulus

Common Form
Sawn
Species Type
Hardwood
  • Overview

    • Native to the coastal sclerophyll forests of eastern Tasmania, southern blue gum is the world's most widely planted eucalypt species. It is the preferred tree species in plantations throughout Australia. Originally forested for wood chips, pulp and paper fibre, some of the larger plantation trees have been used to produce both timber furniture and flooring material.

    The colour of southern blue gum timber ranges from pale straw to brown, often with blue, green or grey tinges. Regrowth material can exhibit shades of pink. Sapwood is somewhat paler than the heartwood, but not always clearly demarcated. Growth rings are prominent on end sections. Grain is often interlocked with a medium and relatively even texture. Timber produced from plantations often exhibits areas of pinhole.

    Southern blue gum is a moderately durable timber. It is not termite-resistant and untreated sapwood is susceptible to Lyctid borer attack.

    Although very hard, the timber is relatively easy to work, fix and dress.

    Due to its density, seasoning requires care in order to minimise checking of tangential surfaces. Southern blue gum blunts cutting edges but good results can be achieved with careful working and the use of correct machinery. The timber can be worked to a smooth and resilient surface that readily accepts most standard finishes. Southern blue gum can be difficult to drill, but holes are usually very clean and to size. Seasoned material can be difficult to nail and utmost care is required when gluing. Southern blue gum is suitable for steam bending if carefully selected for straightness of grain.

    Suggested applications of southern blue gum include flooring, joinery, furniture and general construction. The hardness and brightness of this timber makes it an ideal flooring material for indoor sports centres and other venues. Other applications include wagon building, framing, boat building, handles, piles, posts, sleepers, paving blocks, spokes, wheel rims and shafts.

    Shrinkage

    Very Low Low Medium High Very High
    Check mark Check mark

    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.
    14.40%

    Radial : Radial shrinkage is perpendicular to the growth rings. It is shrinkage in the direction towards the centre of the tree. Measurement is % value
    6.90%

    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.
    0.39%

    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.
    0.26%

    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
    Check mark

    Seasoned:

    SD1

    SD2

    SD3

    SD4

    SD5

    SD6

    SD7

    SD8
    Check mark

    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:

    F34

    F27

    F22

    F17

    F14

    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:

    970kg/m3

    Unseasoned:

    1140kg/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
    Check mark

    Seasoned:

    JD1

    JD2

    JD3

    JD4

    JD5

    JD6
    Check mark

    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
       
    Check mark

    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.
    84

    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.
    146

    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.
    20

    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.
    43

    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.
    83

    Impact - Unseasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.
    20

    Impact - Seasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.
    27

    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.
    High - 25 Nm and above

    Hardness - Unseasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    7.3

    Hardness - Seasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    12

    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.

    Not Resistant

    Fire Properties

    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.

    ≥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

    Southern blue gum ranges in colour from pale straw to brown, often with blue, green or grey tones. Regrowth material can exhibit shades of pink, while timber produced from plantation will often carry areas of pinhole. The sapwood is paler than the heartwood, but not always clearly demarcated. Grain is often interlocked, with a medium and relatively even texture. Growth rings are prominent on end sections.

    Common Applications

    Common applications of southern blue gum include flooring, joinery, furniture and general construction. The hardness and brightness of this timber makes it an ideal flooring material for indoor sports centres and other venues. Other applications include wagon building, framing, boatbuilding, handles, piles, posts, sleepers, paving blocks, spokes, felloes and shafts.

    Workability

    Although very hard, the timber is easy to work, fix and dress. Considerable collapse can occur if not carefully seasoned. Southern blue gum is suitable for steam bending if carefully selected for straightness of grain.

    Origin of timber
    VIC
    Readily Available
    NSW
    Southern blue gum products are commercially available throughout southeast Australia.
    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 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.

    Are you looking for a supplier?

    Start Your Search

    Social Media Feeds