Improving durability to enhance the value of plantation, regrowth and regenerated Eucalyptus

Posted 20 June 2020

Timber durability is generally rated by its resistance to fungal decay and insect attack and is a key factor for market acceptance of new building products. Researchers at the University of Tasmania are investigating various aspects of the durability of plantation, regenerated and regrowth eucalyptus species.

Exciting research is underway at the University of Tasmania’s Centre for Sustainable Architecture with Wood (CSAW) that aims to shorten the timeframes for establishing the durability of plantation, regenerated and regrowth Eucalyptus timber products.

The research is largely funded by the National Institute for Forest Products Innovation as well as timber industry and research partners including the National Centre for Timber Durability and Design Life.

There is an excellent opportunity to enhance the value of plantation, regenerated and regrowth Eucalyptus timbers by using them to manufacture high quality and bespoke products for the built environment, instead of chipping them for much lower returns in the pulp and paper market.

However, many Eucalyptus species have low natural durability and need to be treated with chemical preservatives or otherwise modified before they can be safely used in the built environment. In addition, plantation, regenerated and regrowth timbers are typically harvested at younger ages than the old growth timbers on which durability rating systems are based, and we have limited understanding of the durability characteristics of these much younger timbers.

Benchmarking natural and treated durability is a crucial first step for achieving broad market acceptance of new products made from plantation timbers. Durability assessment generally takes a long time because the best way to assess durability is to put a piece of timber in or close to the ground and collect data, sometimes over several decades, as it decays.

These types of tests are generally known as ‘graveyard’ and ‘ground proximity’ tests and one has recently been installed at field trial site in Tasmania, with a sister site in tropical Queensland.

Whilst baseline natural durability data is being collected, research led by chief investigator Dr Kyra Wood, will continue into establishing shorter duration (commercially viable) durability assessment techniques suitable for use with collapse-prone hardwoods used in Australian conditions for external cladding, decking and composite products such as glulam.