Classification Based on Durability:
Durability tests are conducted by the forest research establishment. They cover test specimen of size 600 × 50 × 50 mm in the ground to half their length and monitor their conditions frequently over various years. Then timbers are classified as followed:
High durability: If average life is more than ten years then it is in High durable. Moderate durability: Average life between 5 to 10 years then it is average durable. Low durability: Average life less than 5 years then it is low durable.