Woollybutt

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Woollybutt is a hardwood timber species natively occurring in coastal regions of southern New South Wales. The true wood of this species is a medium to dark red in colour, with distinctively paler sapwood. Texture is medium to fine. Grain is typically straight but occasionally interlocked. Woollybutt timber surfaces often exhibit a waxy sheen when dressed.

Because of its extreme durability (class 1 on a 6-class scale), woollybutt finds a wide variety of applications in engineering and general building construction. Commonly used for posts, utility poles, sleepers, wood blocks, stumps, printing blocks and fence posts, woollybutt is also suitable for a variety of marine applications, including bridge and wharf construction, boatbuilding and decking. Being durable in contact with the ground and resistant to heavy traffic – woollybutt is a very hard timber – it is also used for paving blocks.

Care is needed in drying woollybutt in order to minimise surface checking and splitting. A slight collapse of the timber is known to occur during seasoning.

In accordance with AS 5604, the heartwood of this species has been deemed termite-resistant for inside, above ground applications. If untreated, woollybutt sapwood is susceptible to lyctid (powder post beetle) borer attack.

 

Appearance

Woollybutt heartwood is a medium to dark red in colour, sapwood being distinctively paler. Grain texture is medium to fine, typically straight but occasionally interlocked. Dressed timber surfaces often have a waxy sheen.

Common Applications

Woollybutt is commonly used for posts, poles, sleepers, wood blocks, in bridge and wharf construction, as stumps, printing blocks and fence posts. It is also suitable for building framework.

 

Common Form

Sawn

Workability

Care is needed in drying woollybutt in order to minimise surface checking and splitting. A slight collapse of the timber is known to occur during seasoning.

Origin of Timber

NSW

Readily Available

NSW

Availability - Further Information

Woollybutt is relatively common along the southern coast of New South Wales.

Availability - Further Information

Native Forest

Shrinkage

Very Low Low Medium High Very High

Tangential :

10.70%

Radial:

5.70%

Unit Movement Tangential:

0.37%

Unit Movement Radial:

0.27%

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:

1070kg/m3

Unseasoned:

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:

87

Modulus of Rupture - Seasoned:

128

Modulus of Elasticity - Unseasoned:

13

Modulus of Elasticity - Seasoned:

16

Maximum Crushing Strength - Unseasoned:

48

Maximum Crushing Strength - Seasoned:

77

Impact - Unseasoned:

17

Impact - Seasoned:

13

Toughness - Unseasoned:

Toughness - Seasoned:

Hardness - Unseasoned:

8.8

Hardness - Seasoned:

11.2

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:

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

Portal Frames

Timber portal frames are one of the most favoured structural applications for commercial and industrial buildings whose functions necessitate long spans and open interiors. As a material choice, timber offers designers simplicity, speed and economy in fabrication and erection.

Timber portal frames offer a strong, sound and superior structure. Structural action is achieved through rigid connections between column and rafter at the knees, and between the individual rafter members at the ridge. These rigid joints are generally constructed using nailed plywood gussets and on occasion, with steel gussets.

From material selection to finishing, this application guide provides a comprehensive overview of the process of using timber in the specification, fabrication and erection of portal frame structures.

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.

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.

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