Mahogany, Southern

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Southern mahogany is a large, fast-growing species indigenous to coastal south eastern Australia, from Bairnsdale in Victoria to north of Newcastle in NSW. It is closely related to Sydney blue gum and is valued for its rapid growth, tolerance of frost and striking red wood.

An excellent timber tree, it has deep pink to red-brown heartwood with distinctively paler sapwood. The timber is hard, strong and dense with a medium, even texture and interlocking grain. It is durable and lyctid borers rarely attack the sapwood.

Southern mahogany seasons readily. It turns, machines, and glues well but can blunt knives and saws more quickly than other eucalypts. It is prone to severe growth stresses when young and should be quarter sawn to reduce damage. It can be difficult to dry and air-drying in protected stacks can reduce its susceptibility to end splitting and collapse.

The timber is used in cabinetry, furniture, flooring, decking, and veneer applications as well as general construction, poles and firewood. Historically it was used in heavy construction for sleepers and posts. 

 

Appearance

Southern mahogany features deep pink to red-brown heartwood with a distinctively paler sapwood. The timber is hard, strong and dense with a medium, even texture and interlocking grain. 

 

Common Applications

The timber is used in cabinetry, furniture, flooring, decking and veneer applications, as well as general construction, poles and firewood.

 

Common Form

Sawn

Workability

Southern mahogany seasons readily. It turns, machines and glues well but can blunt knives and saws more quickly than other eucalypts. It is prone to severe growth stresses when young and should be quarter sawn to reduce damage. It can be difficult to dry.

 

Origin of Timber

NSW

Readily Available

NSW

Availability - Further Information

Southern mahogany is relatively common on the south coast of NSW.

Availability - Further Information

Native Forest

Shrinkage

Very Low Low Medium High Very High

Tangential :

9.80%

Radial:

5.10%

Unit Movement Tangential:

0.37%

Unit Movement Radial:

0.28%

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:

F27

F17

F14

F11

F8

Seasoned:

F27

F22

F17

F14

F11

Density per Standard

Seasoned:

920kg/m3

Unseasoned:

1200kg/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:

84

Modulus of Rupture - Seasoned:

130

Modulus of Elasticity - Unseasoned:

15

Modulus of Elasticity - Seasoned:

18

Maximum Crushing Strength - Unseasoned:

46

Maximum Crushing Strength - Seasoned:

77

Impact - Unseasoned:

18

Impact - Seasoned:

18

Toughness - Unseasoned:

Medium - 15 - 24 Nm

Toughness - Seasoned:

Medium - 15 - 24 Nm

Hardness - Unseasoned:

7.0

Hardness - Seasoned:

9.0

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

Joinery

Timber joinery products offer a classic, unique and stylish touch to any interior or exterior design. The products are produced for a variety of internal applications including door and window frames, cabinetry, skirtings, mouldings and architraves. When looking to the outdoors, joinery products range from decorative eaves and posts to eye-catching railings.

Many timber species are suitable for joinery products and care should be taken in selecting the perfect timber for the particular product and its intended finish. Rare and exotic species such as Teak and Rosewood can generate pieces of outstanding beauty but material cost and availability are also important considerations.

Commercially available species like Tasmanian oak, Australian cypress, spotted gum and the like, often make the more practical choice, with the added benefit that they can be easily matched with other timber products within the building, like flooring.

Solid timber for joinery products is generally supplied as ‘clear finish grade' but ‘paint grade' options are available and these are usually comprised of a composite material like MDF or glulam.

A large number of specialist suppliers and producers offer the consumer extensive choice of profiles for all of the most common and popular joinery products. Choice is in many cases, limited only by imagination.

Cabinetry is often associated with joinery and most typically includes, cupboards, benches and other similar ‘built in' furniture. Like joinery, cabinetry is generally specified as either paint or clear finish grade and naturally for clear finish grade timbers, appearance and surface finish are critical in achieving a successful application.

 

Structural Timber Poles

Timber pole construction is typically utilised to provide support for gravity loads and resistance against lateral forces. The natural appeal of timber ensures that its role is not purely structural however, with timber poles complimenting architectural designs aimed at harmonisation with the natural environment. The small number of footings required in pole frame construction also ensures minimal disturbances to the site.

With a double bearer system, poles can be spaced further apart than is usual, creating a more spacious building interior, that allows greater interior design flexibility. While poles are usually placed in a grid like system this is not compulsory and the flexibility of the application means the system can cope with a wide variety of designs, enabling designers to take full advantage of beautiful outlooks.

This article provides a comprehensive overview of the process involved in specifying, designing and constructing a solid timber pole construction.

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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