Timber Durability Classes

The timber durability rating relates to the natural ability of timber to resist decay and insect pests (including termites) in different environments. This rating is one of the key performance factors used to assess the suitability of timber species for different applications.

Knowing the different types of timber ratings will help you select the right timber for your project.

Natural Durability Class	In-ground life expectancy	Examples	Above-ground life expectancy	Examples
Class 1 – Highly Durable	Greater than 25 years	Treated Pine	Greater than 40 years	Treated Pine
Class 2 - Durable	15 to 25 years	White Cypress	15 to 40 years	Western Red Cedar
Class 3 – Moderately Durable	5 to 15 years	Western Red Cedar	7 to 15 years	Victorian Silvertop Ash
Class 4 – Non-Durable	0 to 5 years	Oregon – Douglas Fir	0 to 7 years	Oregon – Douglas Fir