Grey Gum (Eucalyptus propinqua)

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

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 an extremely durable timber, 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
This is the measure of the percentage reduction in dimension from the unseasoned to 12% moisture content condition.
Tangential This is the measure of the percentage reduction
7.0
Radial
4-5

STRENGTH GROUPS

  Very High High Reasonably High Medium High Medium Reasonably Low Low Very Low
Uneasoned
S1
S2
S3
S4
S5
S6
S7
Seasoned
SD1
SD2
S3
SD4
SD5
SD6
SD7
SD8

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
F22
F22
F17
F14
F11
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.

Unseasoned 1240kg/m3
Seasoned 1060kg/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
Seasoned
JD1
JD2
JD3
JD4
JD5
JD6

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
Shade
 
 

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 – 25 Nm
Toughness – Seasoned
Medium – 15 – 25 Nm
Hardness – Unseasoned
10
Hardness – Seasoned
14

DURABILITY

  Low Moderate Reasonably High High
 
(0-5 years)
(5-15 years)
(15-25 years)
(> 25 years)
In Ground  
 
(0-7 years)
(7-15 years)
(15-40 years)
(>40 years)
Above Ground    
  (0-20 years, usually <5) (21-40 years) (41-64 years) (>65 years)
Marine Borer Resistance    
 
Lyctid Borer Susceptibility
Not Susceptible
Termite Resistance
Resistant

FIRE PROPERTIES

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
EFH Ignitability
                     
             
                                       
EFH Spread of Flame Index
1
2
3
4
5
6
7
8
9
10
             
           
                                       
EFH Smoke Developed Index
1
2
3
4
5
6
7
8
9
10
   
           
                                       
Critical Radiance Flux – Lower
>2.2 and <4.5kWm 2
Critical Radiance Flux – Higher
>4.5kWm 2
Smoke Development Rating
<750
Fire Properties Group Number
1 – Non Combustible
2 – reasonably non combustible
3 – slightly combustible
4 – combustible
                   
         
                                       
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, 19 and 29 – All AS3959 required applications
                                         

Botanical Name:

Eucalyptus propinqua

Common Name:

Grey Gum

AKA:

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

Type:

Hardwood

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 superior-quality butcher’s blocks suitable for use in both commercial and domestic environments.

Common Form

Sawn

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.

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.

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.

Fencing

When it comes to fencing, timber is your natural choice. A material that is durable, strong and reliable it compliments almost every outdoor landscape and environment. Clear specification, detailed installation and appropriate maintenance will see any timber fence provide a natural and lasting property boundary and back drop 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.

Framing

Since people began building simple shelters, wooden framing has played an important role in shaping structures of many kinds. One of the most popular types of wooden framing is known as lightweight timber construction.

Internal Panelling

Timber paneling creates interiors as warm as they are stylish. Commonly utilising an MDF or plywood substrate, internal timber paneling is natural and versatile and comes as either solid natural timber panels or as sheets of engineered wood products

Pergolas

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

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 Posts

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 Joinery Products

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

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.