Gum, Grey

Grey gum is an extremely hard and durable native Australian hardwood timber, suitable for a wide range of engineering and construction applications.

Other Names

Grey Iron Gum, Eucalyptus punctata, Large-fruited Grey Gum, Small-fruited Grey Gum, Eucalyptus canaliculata, Eucalyptus major, Brown Grey Gum,

Botanical Name

Eucalyptus propinqua

Common Form
Sawn
Species Type

Grey gum is a medium-sized hardwood tree growing up to 40 metres in height and one metre in stem diameter. Varieties of grey gum occur along the east coast of Australia, from the Hawkesbury River in New South Wales as far north as Maryborough, and inland to the Carnarvon Ranges and Blackdown Tablelands in Queensland.

The heartwood of this species is a red to reddish-brown colour, visually distinct from the paler sapwood. Grain is usually interlocked, with a coarse but even texture. Grey gum is similar in general appearance to the ironbarks, but often marked by characteristic grub holes.

Grey gum timber is extremely durable, with an in-ground life expectancy in excess of 25 years. For aboveground applications, life expectancy exceeds 40 years. Grey gum heartwood is termite-resistant, and untreated sapwood is not susceptible to lyctid borer attack. Grey gum sapwood is readily impregnated with commercially available preservatives.

The timber is very hard, rated 1 on a 6-class scale in relation to both indentation and ease of working with hand tools. It machines well, although care is required in working the timber’s interlocked grain. Grey gum readily accepts paint, stain and polish, and is amenable to the use of standard fastenings and fittings. As with most high-density species, machining and surface preparation should be done immediately prior to the application of adhesives.

Grey gum is widely used in heavy engineering and marine construction, where it is found as poles, piles, railway sleepers, cross-arms and mining timbers. In general construction it is used for building framework, flooring and decking. Grey gum is also extensively used in landscaping and boat building. It is renowned for making superior-quality butcher’s blocks suitable for use in both commercial and domestic environments.

 

Shrinkage

Very Low Low Medium High Very High

Tangential :

7.00%

Radial :

4.50%

Unit Movement Tangential:

Unit Movement Radial:

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

S8

Seasoned:

SD1

SD2

SD3

SD4

SD5

SD6

SD7

SD8

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

F27

F22

F17

F14

Density per Standard

Seasoned:

1050kg/m3

Unseasoned:

1250kg/m3

Joint Group

Very High

High

Reasonably High

Medium

Low

Very Low

Unseasoned:

J1

J2

J3

J4

J5

J6

Seasoned:

JD1

JD2

JD3

JD4

JD5

JD6

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:

110

Modulus of Rupture - Seasoned:

140

Modulus of Elasticity - Unseasoned:

16

Modulus of Elasticity - Seasoned:

18

Maximum Crushing Strength - Unseasoned:

51

Maximum Crushing Strength - Seasoned:

72

Impact - Unseasoned:

19

Impact - Seasoned:

21

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

10

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

Lyctid Borer Susceptibility - Other:

Termite Resistance:

Resistant

Fire Properties

1 - non-combustible 2 - reasonably non-combustible 3 - slightly combustible 4 - combustible

Fire Properties Group
Number:

Group Number - Other:

3 if used on MDF or particleboard ≥12mm; veneer thickness 0.6-0.85mm

Average Specific Extinction Area:

<250

Bushfire Resistance:

BAL 12.5 and 19 – All AS3959 required applications
Appearance

The heartwood of this species is a red to red-brown colour, visually distinct from the paler sapwood. Grain is usually interlocked with a coarse but even texture. Grub holes are an occasional feature in sawn timber products.

 

Common Applications

Grey gum is widely used in heavy engineering and marine construction, where it is found as poles, piles, railway sleepers, cross-arms and mining timbers. In general construction it is used for building framework, flooring and decking.

Grey gum is also extensively used in landscaping and boat building. It is renowned for making quality butcher’s blocks for both commercial and domestic use.

Workability

Because of its density and grain structure, grey gum is difficult to work when dry. It machines satisfactorily, although care is required in working the timber’s interlocked grain. Grey gum readily accepts paint, stain and polish, and is amenable to the use of standard fastenings and fittings. As with most high-density species, machining and surface preparation should be done immediately prior to the application of bonding agents.

Origin of timber
NSW
Readily Available
NSW
Grey Gum timber products are readily available in New South Wales and Queensland.
Source of timber
Native Forest
Image

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.
Image

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.
Image

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.
Image

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