External Timber Options

Shown below are our preferred timbers for external applications. These have been selected not only because of their natural durability, but also because they are commercially available and provide a range of colours and grain patterns and level of feature to accommodate most applications. Most timbers designated for external applications can also be used internally.

Top Left to Right- Cumaru, Qld Spotted Gum, Silvertop Ash, Gympie Messmate, Coastal Blackbutt

Middle – Left to Right Southern Mahogany, Pacific Jarrah, Ironbark, Darwin Stringybark, Clarisia

CUMARUDipteryx Odorata– (also known as Southern Spotted, Tonka, Brazilian Teak) An attractive mid brown colour this extremely durable timber is ideal for decking and cladding. The timber is classified as non leeching meaning tannin bleed is almost non existent- perfect in decking or cladding applications where adjacent or over hanging paving and painted surfaces. Readily available in set lengths it is ideal for vertical cladding and makes a stunning facade due to its characteristic grain.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Cumaru cladding showing the beautiful grain pattern and typical gold- mid brown tones
Back sawn Cumaru with a natural coating showing the typical grain pattern
Impressive architectural cladding profiles accentuate the grain on Cumaru cladding

PACIFIC JARRAH Manilkara Bidentata – Pacific Jarrah is a dense hardwood with pale sapwood and dark red brown heartwood with medium lustre and a fine texture. It is a very strong, durable timber ideal for external applications. It is a highly attractive timber with and is exceptionally strong and heavy and can be polished to a high lustre.   Highly resistant to termites and biological attack.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Pacific Jarrah is exceptional as a hard wearing flooring due to its high Janka rating
Pacific Jarrah has deep reddish brown to mid brown tones and high lustre if polished
Class 1 durability makes it an exceptional timber for external applications

PACIFIC CROWS ASH / GOLDEN ASH Apuleia leiocarpa – (Also known as Garapa) is a light yellow when cut changing to honey-brown and its interlocked grain has a fine texture. It is a very durable timber that resists rot & decay. The timber is lustrous and does not bleed and has excellent weathering characteristics, fading to silver grey and it is highly resistant to checking and grain lift.

It has a high silica content and is scratch resistant.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Golden Ash makes an excellent deck with its fine grain and excellent weathering
When cut the timber is golden yellow but oxidises quickly to honey brown
The golden colours will fade to a light silvery grey if left exposed to UV

DARWIN STRINGYBARK Eucalyptus tetrodonta. Darwin Stringybark is an exceptionally durable and dense timber ideal for external applications. Typically colour ranges from pinkish brown to deep russet brown with a wide sapwood which is lighter in colour. It is one of the Northern Territories few commercial timbers and is harvested and milled primarily by indigenous groups providing local jobs and livelihoods.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Darwing Stringybark is an extremely hard, durable timber ideal for decking
Darwin Stringybark has a reddish brown hue similar to ironbarks
Darwin Stringybark is ideal for external furniture and constructions such as pergolas

SPOTTED GUM Eucalyptus maculata, Eucalyptus citriodora, Eucalyptus henryi Qld Spotted gum is one of Australia’s premium native hardwoods with a striking appearance and a high degree of natural durability and strength, making it an ideal timber for a variety of structural, exterior and interior applications. Architects and designers throughout the world value spotted gum timbers for their back-sawn grain structure, attractive markings and vibrant colour palette. NSW Spotted Gum is lighter in colour than its northern cousin and typically has less colour variation – being similar to Cumaru (also called Southern Spotted) in tones.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Spotted Gum can have significant variation in colour which may be further accentuated by the pale sapwood
Typical colouring for Qld Spotted Gum, but expect colour variation – NSW spotted Gum tends to be lighter in colour
Special grading can reduce colour variation but this adds to the cost. If colour variation is not desired maybe look at other species

GYMPIE MESSMATE Eucalyptus cloeziana Gympie messmate features yellow-brown heartwood that is strong, hard and extremely durable. Its sapwood is noticeably paler in colour, ranging from white to grey-white. The grain is generally uniform, unfigured, with a fine to medium texture that can sometimes be shallowly interlocked. It is highly resistant to rot and can withstand wet conditions. It does suffer from some tannin bleed as green timber but less so when dried and sealed.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring, wharves

Gympie Messmate is an excellent flooring choice if a lighter colour is required
The Golden Tones and attractive grain make Gympie Messmate a popular choice
Gympie Messmates durability and hardness make it an excellent alternative to Blackbutt

WHITE MAHOGANY Eucalyptus acmenoides (Yellow Stringybark Qld) – White mahogany timbers are available in a narrow range of colours with the heartwood ranging from light brown to yellow brown in colour and has a similar appearance to tallowwood. The sapwood is usually creamy brown, clearly lighter in colour than the heartwood and generally less than 20mm wide. A mostly uniform and medium textured wood, white mahogany can sometimes have an interlocked grain. It can also feature distinctive markings caused by moth grub holes and occasional gum veining. It has a slightly greasy feel, although not as greasy as the similarly coloured tallowwood or spotted gum.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Unfinished White Mahogany showing the lovely grain pattern
Typical variation in White Mahogany – expect some feature and insect marks
White Mahogany features well in furniture where an interesting grain is required

COASTAL BLACKBUTT Eucalyptus pilularis Not to be confused with New England Blackbutt which is less durable and typically has more feature from insects and gum, of WA Blackbutt which is typically darker in colour, Coastal Blackbutt colour runs from creams to light pinkish browns. Typically it has a moderate amount of feature including pin holes, insect trails and gum vein. Although durable it has a tendency to check quite readily in external applications and should be protected with coatings to preserve its appearance. Internally it makes a beautiful flooring or even paneling. And don’t discount the New England Blackbutt if you are seeking a variation in colour and feature. Other options to look at might be White Mahogany or even better- Gympie Messmate

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Typical New England Blackbutt flooring with tonings tending straw to light browns
Typical Coastal Blackbutt flooring showing the creams to pinkish tones
WA Blackbutt has a tendency towards darker browns

CLARISIAClarisia Racemosa – is bright yellow when first cut but quickly oxidises to beautiful golden tones similar to teak. It is a moderately priced timber making it an excellent option for residential cladding or decking projects on a budget where an alternative to Merbau is sought. It is durable & resistant to checking with virtually no leaching of tannins. Typically the timber is clean and free of knots and gum vein. Currently only available in decking sizes but can be teamed with Pacific Crows Ash if larger sections are required.

Suitable for: Decking, cladding, flooring

Clarisia is bright yellow when first cut quickly oxidising to the colour of teak.
Its prominent grain and golden brown tones, Clarisia makes an attractive cladding or deck
Clarisia is a very cost effective option where a lighter coloured timber is required

SILVERTOP ASH E.Sierberi Silvertop Ash colour runs from silvery white to light brown similar in tones to Tasmanian Oak and Victorian Ash. Although durable it has a tendency to surface checking and grain lift making it more suitable to cladding than decking unless well maintained. Characteristically it has a med-high amount of feature including insect trails, gum vein and pin holes and is often only available in ‘run of mill’ grade – a mixture of grades from high feature to select. It is a class 2 durability timber and is widely used in cladding and decking as it is typically is less expensive than other higher quality timbers. Its main characteristic is its abundance of feature.

Suitable for: Decking, cladding, flooring

Expect significant amounts of gum vein and insect marks in Silvertop Ash
Silvertop Ash makes a very nice cladding where you are seeking a more rustic aesthetic
Silvertop stains well has interesting feature.

IRONBARK Eucalyptus paniculata, Eucalyptus sideroxylon Both Grey Ironbark & Red Ironbark grow in the same locations and as such many mills prefer to supply it as mixed Ironbark which is more cost effective and results in a colour range from pale grey through brown to russet colours. However the species can be graded into Grey or Red Ironbark giving a more constrained colour variation. Both species are extremely hard and durable with a fine grain. Like most Australian natives these timbers contain some feature such as insect holes but these are not as readily visible due to the colour of the timber. Ironbark of either species is an excellent choice for flooring, decking and cladding being hard wearing with a fine grain.

Suitable for: Structural applications – Pergola’s, decking, cladding, flooring

Red Ironbark makes exceptional flooring -it is extremely hard wearing and polishes well
Ironbark is a premium Australian timber with colour ranging from grey to reddish brown.
Timber is often supplied as a mix of Red & Grey Ironbark which shows some variation

Timber is a natural product and images shown are representative of the species. Colours and grain patterns will vary from board to board and samples are indicative only

If you don’t see what you like, please contact us. We suggest you take the time to view the contours lining boards and cladding profiles pages in conjunction with this page to select the profile for your timber. Also – don’t forget to check out our coatings page to ensure your timber cladding is well protected.

Some additional considerations when selecting your timber.

Timber is a beautiful natural product and often people fall in love with the look of a certain species, but its good advice to consider the suitability of a timber for your application to make sure it will meet your service expectations as well then seek out a timber which has the colour and feature you want.

Different timber species have differing characteristics that enable you to match them to the application they are best suited to. In general the qualities that define the applications are:

Natural durability: This defines the timbers ability to resist biological attack from rot, mould and fungi and is defined by class 1-4 with 1 being the most durable and 4 least durable. Typically you should only select class 1 or 2 timbers for external use and if in the subtropical areas we recommend class 1 only.

Class 3 or 4 timbers are more suited to internal applications. Some variables that may extend timber life or reduce maintenance is the degree of direct exposure to the elements the timber will experience in the external applications – UV & water are the enemies of timber but if it is used in protected spaces such as under cover or partially concealed – this can dramatically extend the timbers life and reduce maintenance

Other considerations are then defined by the application – such as:

Flooring & decking – the harder the timber the more resistant to damage it is – generally timbers with a Janka rating greater than 10 are considered better wearing and more suited for flooring but softer timbers such as Oak and Victorian Ash are popular as well – but be aware these softer timbers are also more susceptible to damage from furniture, high heels and dropped objects. Any timber with a Janka rating less than 6 is best avoided in flooring applications although it may be perfect for other applications such as walls and furniture.

Cladding & lining boards – generally timber does not need to be as hard for cladding as it does for decking as its not subject to as much physical contact – but if the area is prone to storms consider things like potential hail damage or if there is a lot of bird life, soft timbers like cedar may be prone to attack.

Maintenance – Timber used internally usually requires little maintenance but always check if it will be exposed to UV through windows and doors – in this case use a coating that has good UV rating.

External timbers will require more consideration to minimise maintenance. Even class 1 timbers will age and each species will react differently if not maintained. Some timbers are more prone to surface checking, splintering or grain lift than others which may make them less suitable for decking areas where bare feet are more likely to come in direct contact with the timber.


This refers to the timbers natural resistance to rot and decay when not maintained and is measured on a scale of 1-4 (Above Ground Use).

1- Highly Durable – > 40 years

2 – Reasonably Durable – 15-40 years

3 – Moderately Durable – 7-15 years

4 – Low Durability – 0-7 years

It is more important when relating to external timbers. ITT only recommend class 1 or 2 timbers for external use where exposed to weather

Fire Resistance

Where the building has a Bushfire Attack Level overlay you need to select external timbers that have the appropriate BAL rating. The BAL overlays specify what timber is required to meet the bushfire threat.

Most of our exrtterna hardwoods are rated BAL29 which is the highest rating timber can achieve.

Please refer to your local authorities to determine the requirements

Internally all timbers are classified as Group 3 fire rating under the National Construction Code. Group 1 can be achieved by applying coatings such as Fireshield


There are many beautiful species of timber that have limited availability. Although we can source these on occasion for specific projects we have chosen to only list timbers that are reasonably priced and are commercially available.

If you have specific requirements please contact us.


All timbers we recommend are legally logged in accordance with the source locations environmental standards

Check the timber fact sheets for the level of certification on that specific timber. As a guide – most Australian natives are certified under the PEFC scheme, whilst most exotic timbers will be certified under the FSC scheme.