Ironbark, Grey | Eucalyptus paniculata

Grey ironbark is a premium native Australian hardwood with a wide range of applications from industrial construction to house framing, flooring and sporting goods.

Other Names: White Ironbark, Eucalyptus drepanophylla, Eucalyptus siderophloia, Eucalyptus decepta

Overview

Grey ironbark is a premium native hardwood that has been well regarded as a high quality timber in Australia throughout human history. Indigenous Australians use it to make spear throwers and boil its bark for treating sores.

It is a particularly hard, strong and durable timber, with a broad range of applications, due to its resistance to lyctid borers and termites.

The grey ironbark is a medium sized tree of 30 to 50m with a stem diameter of 1.5m. The bark is hard, coarse, with deep furrows and ridges, ranging from dark brown to black in colour and grows even on the small branches.

E. drepanophylla is found from northern New South Wales to Bundaberg, Queensland. It is also found in scattered patches as far north as the Atherton Tableland. E. paniculata is found in New South Wales only from Bega to Coffs Harbour.

A very heavy timber, at 1120 kilograms per cubic metre, grey ironbark is dense and can be difficult to work. Dressed surfaces take on a steely sheen.

The timber's appearance ranges from reddish to dark brown heartwood. The sapwood is lighter in colour and is 20mm thick on average. Grain is usually tight and straight and no distinctive figure is encountered.

Both sawn and round grey ironbark timber have a wide range of applications. Engineering uses include railway sleepers, construction, poles and cross-arms, and bridge construction. Unseasoned timber is used in house framing, while dressed timber can be employed for both internal and external use. It has also been used in boat, coach, vehicle and carriage building and to create sporting goods.  

Properties

Shrinkage

Very Low Low Medium High Very High
Tangential:          
7.5
Radial: 4 - 5
Unit Movement: 0.39 %

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: F22 F22 F17 F14 F11
Seasoned: F34 F34 F27 F22 F17

Density per Standard

Unseasoned: 1210 kg/m3
Seasoned: 1100 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: 120
Modulus of Rupture - Seasoned: 181
Modulus of Elasticity - Unseasoned: 20
Modulus of Elasticity - Seasoned: 24
Maximum Crushing Strength - Unseasoned: 60
Maximum Crushing Strength - Seasoned: 95
Impact - Unseasoned: 24
Impact - Seasoned: 27
Toughness - Unseasoned: High - 25 Nm and above
Toughness - Seasoned: High - 25 Nm and above
Hardness - Unseasoned: 11
Hardness - Seasoned: 14

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: ≥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 and 19 – All AS3959 required applications

Description

Botanical Name: Eucalyptus paniculata
Preferred Common Name: Ironbark, Grey
Other Names: White Ironbark, Eucalyptus drepanophylla, Eucalyptus siderophloia, Eucalyptus decepta
Species Type: Hardwood

Appearance

Grey ironbark sapwood is almost white, making it highly distinct from the heartwood, that ranges from light grey or light chocolate with occasional darker reds and browns. The texture is moderately coarse and even, and the grain usually straight, and only occasionally interlocked. Grey Ironbark may have regional variations in colour, with some having black narrow to broad streaks running through the timber.

Common Applications

Due to its class 1 strength and durability ratings, grey ironbark is commonly used in engineering applications as a sawn and round timber. It can be specified for wharf and bridge construction, railway sleepers, cross arms, poles, piles and mining timbers.

The unseasoned timber is excellent for general house framing, while seasoned and dressed grey ironbark timber is used for cladding, internal and external flooring, linings and joinery. It is also ideal for fencing, landscaping and retaining walls.

The timber's versatility extends to boat building (keel and framing components, planking), including reputed use in the hulls of early ice-breaker ships. Coach, vehicle and carriage building, agricultural machinery, mallet heads, mauls and bearings, sporting goods (croquet mallets, parallel bars) and bowling ninepins have all been made from grey ironbark.

Common Form

Sawn

Workability

Grey ironbark has been employed for decorative purposes such as in outdoor furniture, turning and joinery, although its density makes it hard to work in applications requiring fine detail.

It is slow drying and should be handled carefully to avoid surface checking.

Origin of Timber

NSW, QLD

Readily Available

NSW, QLD

Availability - Further Information

Grey Ironbark is common to coastal regions of NSW and in southern Queensland. E paniculata is the most common commercial species of Ironbark timber. It is not generally available in a range of sizes, but can be supplied to order. Large sizes in particular are commonly ordered for structural uses, so it is more readily available in this form

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.

  • 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.

  • 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 boasts 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 eye catching timber retaining wall that will complement its surrounding landscape for years to come.

  • 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.

  • 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

  • Cranbourne Botanic Gardens Visitor Centre

    The new Visitor Centre in the Australian Garden of the Royal Botanic Gardens, Cranbourne becomes a model of sustainable design the public can apply at home.

    Applications: Decking, Doors, External Cladding, Framing, Windows,

  • Lewis St House, Thornbury

    A stunning residential renovation and addition that uses timber and timber products throughout with a commitment to sustainable design.

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

  • Mingara One Fitness Centre

    A breathtaking addition to the Mingara Recreation Club campus on the NSW central coast, covering 2000sqm of commercial gymnasium over two levels.

    Applications: Doors, External Cladding, Flooring, Interior Stairs, Internal Paneling,

  • Peninsula Hot Springs

    At the Peninsula Hot Springs Gregory Burgess Architects use timber to create environments that enhance the spirit.

    Applications: Decking, External Cladding, Flooring, Framing, Interior Stairs, Structural Timber Poles,

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