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Gum, Sydney Blue

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Sydney blue gum is a large hardwood species growing to a height of 60 metres or more. It occurs natively in forests along the coast of New South Wales and southern Queensland. Sydney Blue Gum is also extensively grown as a plantation species in South Africa and South America, where rapid growth yields timber of much lower density than Australian material.

Sydney Blue Gum is an important general construction timber, particularly in New South Wales. It is widely used for flooring, cladding, fencing, paneling and boat building. Other common applications include landscaping (as garden sleepers), furniture and joinery.

The heartwood of the species ranges in colour from dark pink to a reddish brown. Sapwood is distinctly paler. The grain of Sydney blue gum timber is typically straight, with occasional interlocking of grain. Texture is moderately coarse and gum veins are common.

Sydney blue gum is a moderately durable timber with a life expectancy for in-ground applications of between eight and 15 years. Untreated sapwood is susceptible to Lyctid borer attack.

Sydney blue gum timber is easy to dry relative to most other eucalypts. It is also easy to work, dress and fix. It responds well to most finishes and takes a good polish, making it popular for decorative applications where moderate durability is required.

 

Appearance

The heartwood of Sydney blue gum ranges in colour from dark pink to reddish brown. The paler sapwood is readily distinguishable. Grain is typically straight with occasional interlocking. Texture is moderately coarse and gum veins are common.

 

Common Applications

Sydney blue gum timber is an important general construction timber, particularly in New South Wales. It is widely used for flooring, cladding, fencing, panelling and boat building. Other common applications include landscaping (as garden sleepers), furniture and joinery.

 

Common Form

Sawn

Workability

Sydney blue gum is easy to work, dress and fix. It responds well to most finishes and takes a good polish, making it popular for decorative applications where moderate durability is required.

Origin of Timber

NSW

Readily Available

NSW

Availability - Further Information

Sydney blue gum timber is readily available in New South Wales.

Shrinkage

Very Low Low Medium High Very High

Tangential :

9.50%

Radial:

5.40%

Unit Movement Tangential:

0.34%

Unit Movement Radial:

0.24%

Strength Group

Very High

High

Reasonably High

Medium High

Medium

Reasonably Low

Low

Very Low

Unseasoned:

S1

S2

S3

S4

S5

S6

S7

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:

F17

F14

F11

F8

F7

Seasoned:

F27

F22

F17

F14

F11

Density per Standard

Seasoned:

840kg/m3

Unseasoned:

1110kg/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:

76

Modulus of Rupture - Seasoned:

122

Modulus of Elasticity - Unseasoned:

12

Modulus of Elasticity - Seasoned:

15

Maximum Crushing Strength - Unseasoned:

41

Maximum Crushing Strength - Seasoned:

66

Impact - Unseasoned:

17

Impact - Seasoned:

18

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

5.8

Hardness - Seasoned:

8.1

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:

Susceptible

Lyctid Borer Susceptibility - Other:

Termite Resistance:

Not Resistant

Fire Properties

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

Critical Radiance Flux - Higher:

>2.2 and <4.5

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

Fencing

The inherent appeal and strength of timber makes it the obvious choice for fencing. Timber fencing not only provides a natural look in keeping with the outdoor environment but it also enables the construction of a long lasting, durable property boundary. Fences come in many forms including the traditional paling, picket, post and railing styles. Most rely on a structural frame of posts embedded into the ground and two or more rails spanning between the posts. The ultimate selection of a suitable fence type or style is determined by application and aesthetics. A fence can serve a variety of purposes, including the provision of security, privacy and safety in addition to defining property boundaries. Specification for durability is important, especially for posts, given their exposure to high moisture in the ground.

This section provides an overview to best practice methods in specifying, installing and finishing a timber fence.

Retaining Walls (Landscaping)

The natural appeal, strength and versatility of timber makes it an ideal choice for retaining wall landscaping applications.

Retaining wall systems include cantilevered round or sawn timber, mass wall and crib wall construction. Walls up to one metre in height follow a basic design and can usually be constructed using standard proprietary wall systems. An engineer will be required to plan and design walls greater than one metre, including the footings and drainage.

Drainage of retaining walls is a critical factor in influencing the long term stability of the wall and should thus form a significant part of the design and planning process. 

Regular care and maintenance of retaining walls is essential in ensuring the long-term stability and safety of the structure.

Stairs, Interior

Interior staircase work is considered a specialised area of carpentry and joinery as its construction requires high levels of workmanship, detail and accuracy. Many interior stairs are built from quality joinery timber, cut and seasoned especially for staircases. Interior stairs differ considerably in design, from simple straight flights, commonly used in domestic work, to more elaborate stairs, constructed purposely as stand out features in public and commercial buildings.

The construction procedure described here applies to most general type stairs of either conventional or contemporary construction.

Cladding, External

No other cladding material can offer the design freedom, ease of handling, range and natural beauty of timber. Timber cladding can create a building to suit almost any environment, taste or style.

Timber cladding has an inbuilt flexibility that provides natural advantages on sites subject to high winds, extreme climate, highly reactive soils, subsidence or earth tremors. And unlike masonry and other rigid materials, the natural resilience and high strength to weight ratio of timber enables it to withstand far greater stresses and movement.

Modern finishes give a long lasting and attractive appearance to timber cladding and can be used to change the colour and style of the building, making it a versatile material that will keep pace with changing tastes and fashions.

 

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.

Timber flooring is a timeless product, offering a warmth and natural beauty largely unmatched by other flooring options. This article provides an overview of the installation of solid timber strip flooring over bearers and joists, timber based sheet flooring products and concrete slabs. Timber flooring is typically supplied as either solid timber or laminated wood products, made from layers of bonded timber. It fits together with a tongue and groove joint and once in place, is sanded and finished. There is a wide variety of species to select flooring from and the right species for a given application will be dependent on numerous factors. Information relating to species selection, environmental assessment, finish selection and recommended maintenance routines are all provided in this section.

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