From Ironbark to Radiata Pine, timber can be a significant part of many buildings and is a material loved by many. To ensure you get the most out of this beautiful product, consider three metrics; hazard, durability and appearance grade. To ensure the longevity of your build (and that you don't spend too much or too little money) establish timber’s purpose in the design.

First, a note on sustainability. Timber is great; it is salvageable, reusable, recyclable and renewable. Therefore the most sustainable path is to use reclaimed timber. Unfortunately, it isn’t always easy to source and build with reclaimed timber, so if not recycled, look for timber from well-managed sources and avoid timber from old-growth forests. 

1- Hazard level (see: http://www.tpaa.com.au/faq/) is straightforward enough rated from H1-H6. H1, the lowest rating timber, should be used inside, undercover, protected from the weather, and well ventilated. H6 is the most extreme rating, which can be used in a marine environment. 

2 - Durability relates to the useful life expectancy of the timber to resist pests (fungi, borers and termites) and its environment (hazard level). In contrast to the Hazard Level (H1-H6), durability ratings range from high to low. Class 1 is highest (generally hardwood) with a +15yr life expectancy. Class 4 is lowest, it may not last five years (depending on where you use it).

3- Appearance grading is broken into three grades; Select, Standard and Merchant. Select grade is best for furniture (often divided again into sub-grades A to D). Standard grade is suitable for most decks and cladding. Merchant grades are generally rough, containing knots and varying greatly in looks.

The other rating you’ll see when purchasing timber is the stress grading (an 'F' or 'MGP'). While the building engineer specifies this, it’s useful to know what the ratings mean; the strength of the timber to bear a force without failure. Failure (in this case) is when the timber bends too much. The F-number stands for the amount of force (MPa) the timber can withstand, F4 (low) to F34 (high). It’s also commonly rated with MGP (Machine-graded pine), which can be converted to an F rating but let’s leave that discussion for another day when we have some ice-coffees, spiced danishes, and a warm spot to sit in the sun.

By matching timber’s use to its hazard, durability and appearance grades, you’ll ensure that you’re spending the right amount and building something stunning that will last.