Gum, Mountain

Mountain gum is a hardwood tree reaching heights of up to 50 metres in favourable conditions. It occurs naturally in Queensland, New South Wales, Victoria and Tasmania.

The heartwood of this species is pale pink or pinkish brown in colour; sapwood is visually indistinct. The texture of this straight-grained timber ranges from fine (latewood) to relatively coarse (earlywood). Growth rings are prominent because of the darker latewood.

Due to its moderate hardness and durability, applications of mountain gum timber include general building construction, joinery, flooring and the fabrication of tool handles. Heartwood lacks natural termite-resistance, and untreated sapwood is susceptible to lyctid borer (powder post beetle) attack.

Mountain gum timber products have limited commercial availability.

 

Appearance

The heartwood of mountain gum, not readily distinguishable from the sapwood, is pale pink or pinkish brown in colour. The texture of this straight-grained timber ranges from fine (latewood) to relatively coarse (earlywood). Growth rings are prominent because of the darker latewood.

Common Applications

Mountain gum timber is suitable for joinery, flooring and general construction applications.

Workability

Mountain gum is reasonably easy to work, however gum vein can interfere with its finish, so selection and quality control are factors to consider in uses which bear on the workability level required.

Readily Available

NSW

Availability - Further Information

Mountain gum timber products are of limited commercial availability, but if available can be found in most states across Australia

Shrinkage

Very Low Low Medium High Very High

Tangential :

11.50%

Radial:

5.40%

Unit Movement Tangential:

0.35%

Unit Movement Radial:

0.22%

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:

F14

F11

F8

F7

F5

Seasoned:

F17

F14

F11

F8

F7

Density per Standard

Seasoned:

690kg/m3

Unseasoned:

1150kg/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:

64

Modulus of Rupture - Seasoned:

117

Modulus of Elasticity - Unseasoned:

9.5

Modulus of Elasticity - Seasoned:

13

Maximum Crushing Strength - Unseasoned:

30

Maximum Crushing Strength - Seasoned:

57

Impact - Unseasoned:

16

Impact - Seasoned:

8

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

5.2

Hardness - Seasoned:

5.7

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

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 – Door and window joinery only

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