Blackbutt

Blackbutt is a large Australian hardwood that is commonly used for structural and exterior applications. It is also used to produce plywood.

Other Names

Coastal Blackbutt, Pink Blackbutt

Botanical Name

Eucalyptus pilularis

Common Form
Sawn
Species Type
Hardwood
  • Overview

    • The common name blackbutt came about due to the tree's appearance after bushfire, whereby the buttress - or butt - was significantly darkened. It is also known as coastal blackbutt to distinguish it from the tableland species, New England blackbutt.

    Due to its quick growth and versatility, blackbutt makes a good plantation timber. It is a commonly available commercial hardwood species in New South Wales and southern Queensland, often used for building framework.

    The heartwood ranges from golden yellow to pale brown, although occasionally a slight pinkish colour may be present. The sapwood, which is not always easy to distinguish, is much paler in appearance and is resistant to attack by lyctid borer. Blackbutt has an even texture and generally straight grain making it appealing for interior use applications.

    Blackbutt can be stained, painted or polished but there can be issues with painting because of its tendency to surface check. The high extractives of mature wood can cause problems with some adhesives, but this is much less of an issue with young regrowth wood. These extractives can also cause staining on painted surfaces exposed to the weather. Blackbutt machines well but is only fair for steam bending.

    Blackbutt provides good fire resistance and is one of seven hardwood timber species that was found to be suitable by the Building Commission in Victoria for home construction in bushfire areas (provided it has a thickness greater than 18mm).

    A strong, durable hardwood, blackbutt can be used for a range of structural, exterior and interior applications including framework, decking, flooring and poles.

     

     

    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.
    7.30%

    Radial : Radial shrinkage is perpendicular to the growth rings. It is shrinkage in the direction towards the centre of the tree. Measurement is % value
    4.30%

    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.
    0.37%

    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:

    F27

    F17

    F14

    F11

    F8

    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:

    900kg/m3

    Unseasoned:

    1100kg/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.
    87

    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.
    144

    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.
    19

    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.
    48

    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.
    77

    Impact - Unseasoned: Provides the Izod value, which is the energy taken in joules (J) to fracture the timber.
    21

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

    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.
    6.5

    Hardness - Seasoned: Refers to the Janka hardness test and is a measure of timber’s resistance to indentation.
    8.9

    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.

    Not Susceptible

    Lyctid Borer Susceptibility - Other:

    Termite Resistance: Indicates whether a species is resistant (R) or not resistant (NR) to termites.

    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: A measure of the tendency of a material to ignite measured on a scale of 0 – 20. An index of 0 indicates that the material did not ignite during the 20 minutes that the test takes. An index of 20 indicates that the material ignited in the first minute.
    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, 19 and 29 – All AS3959 required applications
    Appearance

    Blackbutt has an even texture. The grain can be interlocked but it is generally straight, making it appealing for interior use applications such as flooring and joinery. The heartwood ranges from golden yellow to pale brown, although occasionally a slight pinkish colour may be present. The sapwood, which is not always easy to distinguish, is much paler in appearance. Small gum veins may also be visible.

    Common Applications

    Blackbutt is a versatile timber and is used for structural, exterior and interior applications. In New South Wales and southern Queensland it is very popular for timber framing but is also used for cladding, internal and external flooring, decking, joinery, landscaping and furniture. Blackbutt is also used in the manufacture of plywood.

    Workability

    Care needs to be taken when drying as blackbutt is prone to surface checking on the tangential surface. Blackbutt should not be re-conditioned as this will widen any surface checks. Blackbutt can be stained, painted or polished but there can be issues with painting because of its tendency to surface check. The high extractives of mature wood can cause problems with some adhesives, but this is much less of an issue with young regrowth wood. These extractives can also cause staining on painted surfaces after exposure to the weather. Blackbutt machines well but is only fair for steam bending.

    Origin of timber
    NSW
    Readily Available
    NSW
    Blackbutt grows in the coastal regions of New South Wales and Queensland and can be found from Bega in New South Wales up to Maryborough in Queensland. It is generally readily available in these areas. Suppliers can provide information on availability in other parts of Australia.
    a kitchen with wooden cabinets and a countertop

    Joinery

    Timber joinery offers a classic, stylish touch to any interior or exterior space.
    a deck with a pool and a deck with a couch and a bench

    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.
    a close-up of a wood sculpture

    Mouldings

    Mouldings are extremely versatile and durable, enhancing the aesthetics of any interior and functioning as the icing on the cake for designs with a focus on beauty and splendour.
    a wooden stairs with railings

    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.
    a staircase with a hole in the ground

    Rails and Balustrades, Interior

    With its natural beauty and inherent strength, timber is a popular material choice for internal balustrades. Commonly built from treated softwoods and durable hardwoods, interior balustrades and handrails are typically finished with a clear lacquer to generate the most natural result.
    a staircase in a building

    Stairs, Interior

    Timber is the material of choice for designers seeking internal staircases of strength, beauty and durability.
    a patio with a deck and chairs

    Pergolas

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

    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.
    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.

    Are you looking for a supplier?

    Start Your Search

    Social Media Feeds