Natural durability of timbers under Indian environmental conditions – An overview

• Timber is a biological material susceptible to deterioration.
• Some timbers naturally have inheritance capacity to resist deterioration.
• Durability is attributed by the physical and chemical properties of wood.
• Condition in which wood timber is put use also contribute towards the degree of deterioration.
• Knowledge of durability of wood is important for the rational and judicial utilization of timber.

Over the millennia, mankind has recognized the inherent resistance of certain wood species against attack by fungi, insects and marine borers. Despite our advances in wood protection technology, people still rely on naturally durable timbers for construction of various structures. Of late, this property of several wood species, known for their high durability, has become unreliable due to changes in silvicultural and pre-harvesting practices, which reportedly interfere with their durability performance. This warrants a periodic assessment and rating of natural durability properties to select the right species for various end uses. Moreover, the drastic decline in the availability of naturally durable timber species towards the end of 20th century has resulted in the import/export of timber world-wide. The inherent durability of these species under different climatic conditions is unknown but must be determined to utilize them effectively. Studies on natural resistance of wood to biological damage are therefore of prime importance. Before initiating durability studies, background information on different factors that impart durability to a timber is vital. This paper aims to compile secondary data on such aspects and to provide a necessary check-list of durability ratings of Indian and exotic timbers that have been tested under Indian environmental conditions. Probable factors responsible for imparting a built-in resistance to wood against bio-deterioration have also been discussed.