Blackbutt | Eucalyptus pilularis

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

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.

 

 

Properties

Shrinkage

Very Low Low Medium High Very High
Tangential:          
7.3
Radial: 4 - 5
Unit Movement: 0.37 %

Strength Group

Very High High Reasonably High Medium High Medium Reasonably Low Low Very Low
Unseasoned:S1S2S3S4S5S6S7
Seasoned:SD1SD2SD3SD4SD5SD6SD7SD8

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

Unseasoned: 1100 kg/m3
Seasoned: 900 kg/m3

Joint Group

Very High High Reasonably High Medium Low Very Low
Unseasoned:J1J2J3J4J5J6
Seasoned:JD1JD2JD3JD4JD5JD6

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: 100
Modulus of Rupture - Seasoned: 144
Modulus of Elasticity - Unseasoned: 17
Modulus of Elasticity - Seasoned: 19
Maximum Crushing Strength - Unseasoned: 48
Maximum Crushing Strength - Seasoned: 77
Impact - Unseasoned: 21
Impact - Seasoned: 22
Toughness - Unseasoned: Medium - 15 - 25 Nm
Toughness - Seasoned: Medium - 15 - 25 Nm
Hardness - Unseasoned: 7.3
Hardness - Seasoned: 9.1

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
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 kW/m2
Critical Radiance Flux - Higher: >2.2 and <4.5 kW/m2
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, 19 and 29 – All AS3959 required applications

Description

Botanical Name: Eucalyptus pilularis
Preferred Common Name: Blackbutt
Other Names: Coastal Blackbutt, Pink Blackbutt
Species Type: Hardwood

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.

Common Form

Sawn

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, QLD

Readily Available

NSW, QLD

Availability - Further Information

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.

Applications

  • 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.

  • Exterior Rails and Balustrades

    This guide 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.

  • Exterior Stairs

    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.

  • External Cladding

    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.

  • Flooring

    Whether for structural or finished flooring applications, timber offers durability, versatility and adaptability. The warmth, strength and natural beauty of timber flooring has proved enduringly popular in a wide variety of interior settings.

  • Interior Rails and Balustrades

    With its natural beauty and inherent strength, timber is a popular material choice in internal balustrade construction. 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.

  • Interior Stairs

    Timber should be the material of choice for designers seeking internal staircases of strength, beauty and durability. The construction procedure described here applies to most general type stairs of either conventional or contemporary construction.

  • Pergolas

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

  • Timber Joinery Products

    Timber joinery products offer a classic, unique and stylish touch to any interior design.

  • Timber 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.

  • Timber 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. This application guide provides a comprehensive overview of the process of using timber in the specification, fabrication and erection of portal frame structures.

Case Studies

  • Abigroup House, Brisbane

    Abigroup House, Brisbane Cox Rayner Architects have created an interior that presents Abigroup as a forward-thinking building company, and timber is a highly visible contribution to this effect.

    Applications: Doors, Flooring, Interior Rails and Balustrades, Interior Stairs, Internal Paneling,

  • Eastern Precinct, University of Melbourne, Parkville

    The durability and warmth of timber supports the University of Melbourne’s model, providing a new learning landscape at the Eastern Precinct Student Centre.

    Applications: Decking, Doors, External Cladding, Flooring, Internal Paneling, Windows,

  • Narrabeen House

    Narrabeen House – an innovative use of timber and timber products creates a private paradise in the suburbs.

    Applications: Doors, External Cladding, Fencing, Framing, Interior Stairs, Internal Paneling, Structural Timber Poles, Windows,

  • National Portrait Gallery, Canberra

    Jarrah, Spotted Gum, Blackbutt and Victorian Ash play an essential role in the National Portrait Gallery’s expression of Australian identity.

    Applications: Architectural Roof Trusses, External Cladding, Flooring, Framing, Interior Stairs, Internal Paneling, Windows,

  • The Dickson Apartments, Little Bay

    An innovative coastal refurbishment where the use of timber contributed to an environmentally sustainable development while respecting the site's heritage significance.

    Applications: Doors, Exterior Rails and Balustrades, Exterior Stairs, External Cladding, Fencing, Framing, Interior Rails and Balustrades, Interior Stairs, Internal Paneling, Retaining Walls (Landscaping), Timber Portal Frames, Windows,

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