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Jarrah

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Jarrah is a unique Australian hardwood renowned for its versatility. Its durability and strength make it an ideal timber for a range of structural and design applications, with timbers that display colours ranging from deep red to blonde.

Jarrah trees grow on the iron and aluminium rich plains of south-western corner of Western Australia, from the ranges east of Perth down to Albany. They are slow growing, their roots often reaching to great depths in search of nutrients and water. Their long, straight trunks, can grow up to 40 metres tall and 2 metres in diameter, creating beautifully coloured and grained timbers. The bark is rough with a fibrous texture, and covers the entire trunk and smallest branches. The trees do not germinate from seed, but from lignatubers, large underground swellings that store energy and nutrients, allowing young trees to regenerate after bushfires.

Jarrah timbers reflect the hues of the Western Australian landscape. The heartwood varies in colour from rich reds to browns, while sapwood ranges from a pale yellow to orange. The texture of the timber is moderately coarse and even-textured grain, although some interlocked, wavy grain may feature, creating interesting fiddle-back figure. This makes it an appealing architectural and design material.

Jarrah's natural properties include a high resistance to weather, rot, termites and even marine borers, making it valuable for a range of outdoors uses. Its density also makes it fire resistant. It can be used in wharf and bridge construction, railway sleepers, cross arms, poles and piles. Construction applications include general house framing, flooring, linings, joinery and fencing. Jarrah's decorative qualities make it prized for use in furniture, turnery, joinery and parquetry.

Jarrah makes a versatile and aesthetically pleasing decking board based on its natural durability and bushfire resistance properties (BAL 12.5 and 10 per all AS3959 applications; BAL 29 when used in conjunction with non-combustible wall cladding and enclosed subfloor. A copy of the EWFA Certificate of assessment can be downloaded here.

Appearance

Jarrah is renowned for its rich red colours that deepen over time. The heartwood ranges from deep browns to burgundy hues. Jarrah sapwood exhibits shades from pale yellow to pink-orange. The timber displays a moderately coarse and even textured grain. The occasional incidence of wavy and interlocking grain produces some samples with a sought after fiddle-back figure.

Common Applications

Jarrah has a history of use in engineering applications such as wharf and bridge construction, railway sleepers, cross-arms, piles, and for road bases. Its structural applications include posts and poles, framing, flooring, lining, decking and cladding.

A highly versatile timber, jarrah can also be used for woodturning, making it useful in the manufacture of high quality indoor furniture and weather resistant outdoor furniture that stands the test of time. The wood is also prized by luthiers for creating guitar and banjo necks.

Common Form

Sawn

Workability

Jarrah is easiest to work when it is green. Once seasoned, it is relatively easy to work, despite its density, if tools are maintained in sharp condition. Jarrah timber can be machined and turned easily. When using it in a planer, the blade must be set to 15 degrees to give the best surface quality. It can be glued and satisfactorily steam bent, but care must be taken when using nails, due to the density. Jarrah timbers readily accept paint, stain and polish.

 

Origin of Timber

WA

Readily Available

WA

Availability - Further Information

Jarrah can only be sourced from old growth and native forest regrowth in Western Australia, where it is more commonly available. Many of these forests are now reserved and little to no jarrah is currently grown in commercial plantations. This limits supply and Australia grows few other readily available species with jarrah's distinctive colour and character. While some recycled material is available, this is also a restricted resource as it relies on the demolition of existing buildings.

Availability - Further Information

Native Forest

Shrinkage

Very Low Low Medium High Very High

Tangential :

7.40%

Radial:

4.80%

Unit Movement Tangential:

0.30%

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:

F14

F11

F8

F7

F5

Seasoned:

F22

F17

F14

F11

F8

Density per Standard

Seasoned:

820kg/m3

Unseasoned:

1100kg/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:

68

Modulus of Rupture - Seasoned:

112

Modulus of Elasticity - Unseasoned:

10

Modulus of Elasticity - Seasoned:

13

Maximum Crushing Strength - Unseasoned:

36

Maximum Crushing Strength - Seasoned:

61

Impact - Unseasoned:

13

Impact - Seasoned:

10

Toughness - Unseasoned:

Low - up to 15 Nm

Toughness - Seasoned:

Low - up to 15 Nm

Hardness - Unseasoned:

5.7

Hardness - Seasoned:

8.5

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

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

EFH Ignitibility:

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:

≥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, BAL 29 - Decking (in conjunction with non-combustible wall cladding and enclosed subfloor). A link to the Certificate of Assessment is under the Overview tab.

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.

 

Panelling, Interior

Internal panelling, also known as appearance boards and linings, is not just a practical means of covering one or more walls and ceilings in a building, its inclusion in a room's interior design can generate looks that are both dramatic and stylish. Internal paneling comes as either solid natural timber paneling or as sheets of engineered wood products that provide a durable and hardwearing surface for areas subject to high impact. As they typically function as appearance products they generally have no structural requirements. This guide describes the variety of panelling products available and outlines the straightforward process of installing them.

Decking

Download the WoodSolutions Technical Design Guide on Domestic Timber Decking here.

Timber decks are a practical and attractive addition to any outdoor landscape. Natural timber decks blend seamlessly with their surrounding environment and will serve as popular entertaining areas all year long.

As an external structure, carrying large loads of traffic, timber decking has high structural performance requirements. In addition decks are usually raised clear off the ground and fully exposed to the weather meaning an effective deck must be able to cope with wear and tear from repeated use and in addition discharge rainwater efficiently. Roundin the corners (easing the arris) of the decking will help run off water while spacing for ventilation between the decking boards will prevent water ponding on the deck surface. 

Timber decking is available in both seasoned and unseasoned wood, in a wide range of species, sizes and grades. The natural appeal and strength of timber makes it a practical choice for outdoor decking. This guide provides an overview of best practice methods for specifying, installing and finishing a timber deck.

Mouldings

Timber mouldings add style, class and an elegant touch to any interior, offering a depth of beauty and warmth in a way only wood can. From period times to those more contemporary, timber mouldings have graced the most stylish and chic of interiors, decorating furniture, doors and windows. Decorative mouldings such as architraves, skirtings, cornices and ceiling roses remain an ever popular choice for designers seeking a finished result of beauty, style and quality. Like all timber products, mouldings are extremely versatile and durable, enhancing the aesthetics of any interior and functioning as the perfect finishing touch for designs with a focus on beauty and splendour.

Mouldings can be created from any commercially available species of timber and the moisture resistant wood product, MDF, is also a popular choice. When it comes to style and design, the sky is the limit with many suppliers offering custom matching to existing mouldings, as well as efficient supply of those that are individually designed. Installation is a breeze, with the majority of mouldings easily attached with a reputable wood adhesive. Finishes can be tailored by design requirements and the preferences of the end user, with mouldings commonly being both stained and/or painted.

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, Exterior

All exterior stairs serve a functional purpose, but the choice of timber in the application will turn a functional building element into an aesthetically pleasing feature. And while the construction of stairs is demanding, the investment of time will be returned, with a well constructed timber staircase typically lasting decades.

Exterior stairs are usually built from treated softwood and durable hardwoods and typically finished with paint. The construction procedure described here applies to most general type stairs of either conventional or contemporary construction.

When it comes to stairs there is a multitude of variations available for application depending on the structural requirements of the building. This guide discusses the most commonly specified stair types.

Rails and Balustrades, Interior

The versatility, beauty and strength of timber makes it the ideal material choice for interior handrails and balustrades. Treated softwood and durable hardwoods are the most popular timber choices and these can be turned to create a range of unique styles and designs to suit a variety of tastes and decors.

When used internally balustrades and handrails are typically finished with a clear lacquer to showcase the natural beauty of the timber and with appropriate care and attention will last a lifetime. Find here general information on member sizes, connections and suitable materials, as well as important considerations, for the specification and construction of interior handrails and balustrades.

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.

Pergolas

Timber pergolas offer an attractive and economical way to create functional living and entertainment areas in the outdoors.  Pergolas designed with care can maximise both winter sunshine and summer shade, ensuring outdoor living is enjoyed all year round. With its natural look, durability and versatility there are few other materials that can match the advantages of timber in pergola construction.

Pergolas are typically constructed via a straightforward post and beam process, which can be attached to an existing building or form a free standing structure. A protective finishing coat will preserve the life of the pergola and a variety of paints and stains are available on the market to facilitate this.

 

Rails and Balustrades, Exterior

The versatility, strength and natural beauty of timber makes it the ideal material choice for external handrails and balustrades. Usually built from treated softwood and durable hardwoods these timbers can be turned to create a range of styles and designs, resulting in balusters that are unique as they are individual. Painting, staining and oil based finishes broadly cover the wide range of finishing options available and with the appropriate care and attention a timber balustrade can last a lifetime.

This guide provides general information on member sizes, connections and suitable materials to enable the construction of a long lasting, attractive and durable timber handrail or balustrade.

Windows

Timber windows are usually supplied as joinery items with a primer or base coat, as factory glazed components requiring site finishing or as fully glazed and finished windows.

Demand is ever increasing for high performance windows that promote efficient energy use in buildings. Careful window selection and placement is rightly viewed as a means of reducing demand for artificial light and climate control. Timber is an ideal material when considering these aspects as it is a material that is light, strong, natural and renewable. It can be moulded to any shape, so will meet the thermal, acoustic and design requirements of even the most unusual window.

This guide discusses the common elements involved in specifying, constructing and installing timber windows

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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