Selecting the right timber decking

selecting-the-right-deckingOne question that gets frequently asked by customers is "how do I select the right timber decking?" Good question. Firstly, congratulations on making the decision to build a timber deck. From someone who has recently done it themself, you won't regret it. Timber decking is a 100% natural and sustainable material, aesthetically pleasing, and if the right species is chosen, extremely long lasting. So here are some guidelines that the team at Outlast have developed to assist you in making the right decision in selecting a species.

Hardwoods decking vs Softwood decking. OK, so we're a little biased, but at Outlast we feel that Australian sourced Hardwoods are the way to go. Australian hardwood timbers are beautiful to look at, so they make a superb choice for decking timber. All of our decking timber is of high natural durability meaning there is no need for preservative treatments such as those for treated pine. Also Outlast supplied decking is sourced from properly managed forests or plantations in Victoria, NSW and QLD. This has the added advantage of supporting Australian Jobs now and well into the future.

Sure, you could go down the route of an imported hardwood species that you can find at one of the "Big Box" hardware chains. All of which are readily available, naturally durable and also look good. But they don't support Australian Forestry jobs. In addition, most of these imported timbers come from tropical rainforests with delicate ecosystems. This means that logged areas can take around 100-200 years to recover, and illegal clear fell logging has been rife. Australian hardwoods by contrast take 20-30 years to reach maturity and are managed utilising world best practices. Thus making Australian Forestry sustainable in the true sense of the word.

What colour decking timber do you want? The colour is important, especially if you wish to maintain the "As New" appearance. Unless of course the desired effect is for the timber to grey from weathering. Light coloured timbers will brighten up darker more shaded areas such as alfresco or southern aspects, while dark timbers will contrast nicely with light coloured bricks or render, but again, it does come down to personal taste and preferences. Outlast can provide you with a great selection of light to mid toned timbers such as Silvertop Ash, Cypress Pine, Yellow Stringybark and Southern Mahogany, and just as impressive a range of mid to dark toned timbers like Ironbark, Spotted Gum and Forrest Reds.

So what about Hardness and strength? If you're looking at installing a deck that is in a commercial/public environment or in a much used domestic setting, then this is where Australian Hardwoods shine. Ironbark and Spotted Gum decking in particular, have high strength and are relatively very hard. So it's more difficult to mark and scuff soft timbers like treated pine.

Do you live in an area with termites, or have a location which is wet and damp, so are worried about decay. Again, this is one of the strengths of most Australian hardwood decking products. They are species chosen for such uses as they have a proven record of being mostly termite resistant and naturally durable against wood rot.

Do you live in a high or extreme risk bushfire zone? A timber deck in these areas must be built with this in mind. There are only 7 species suitable for use in BAL 25 areas in accordance with AS 3959, and Outlast carries three of these species in hardwood decking, Ironbark, Spotted Gum and Silvertop Ash.

Please contact Outlast Timber on 03 9587 0366 to discuss all your decking requirements.

The Outlast Timber Quick Selection Guide for your Australian Hardwood Decking requirements.

Timber Species Colour Hardness Termite Resistant Natural Durability* Meets BAL 25 rating
Yellow Stringybark Light to mid brown tones Hard Yes High
(Class 2 AG)
Silvertop Ash Blond to light honey brown and pink tones Hard No High
(Class 2 AG)
Southern Mahogany Light to mid pink tones Hard Yes High
(Class 2 AG)
Cypress Pine Mid orange-yellow colour Moderate-Hard Yes High
(Class 2 AG)
Spotted Gum Mid tans to dark brown Very Hard Yes Very High
(Class 1 AG)
Ironbark Mid pink-red tones Very Hard Yes Very High
(Class 1 AG)
Forrest Red** (mixed species) Mid to dark red colour Hard No High
(Class 2 AG)

* As per AS 5604. Probable Above Ground (AG) life expectancies are: Class 1 AG - 40+ years and 25-40 years for Class 2 AG.

** Comprises a mix of species such as Sydney Bluegum, Forest Redgum and other mid to dark red coloured timbers.

Bush Fire Rated Timber for Bush fire prone Areas

Bushfire Illustration

With the increase in frequency of bush fires and expansion of homes and other buildings into rural Australia, fire protection has never been more important. In many parts of Australia the construction of new buildings and additions to existing buildings will be assessed as being in a bushfire area along with their level of risk, and given a Bal rating (bush fire attack level).

The Victorian Government has released an online tool ( to allow landowners to search their address and determine whether or not their property is in a designated bushfire prone area, with the majority of Victoria falling into this area. If your property does fall into a bushfire prone area, a minimum construction standard applies to all new buildings built on that land, which states they are required to build to a minimum Bushfire Attack Level (BAL) of 12.5. However you still may need to build to a higher BAL rating depending on certain attributes of your property. You can get a rough estimate on the BAL rating of your property by using this online calculator (

There are 6 recognized levels of ratings; from BAL (low), BAL 12.5, BAL 19, BAL 29, and Bal 40 to BAL FZ (highest). The relevant Australian standard AS3959 provides the requirements built in these varied bushfire risk areas.

For some applications, AS 3959 restricts the use of timber in any area greater than Bal 12.5 unless it is one of the following 7 recognized and approved bush fire resistant timbers:

  1. Blackbutt
  2. Merbau
  3. Red ironbark
  4. River Redgum
  5. Silvertop Ash
  6. Spotted Gum
  7. Turpentine

Outlast timber Supplies every one of these timbers with the exception of Merbau (as it is a rain forest timber from ecologically sensitive South East Asia) and can supply them in cladding, decking, posts or structural timber.