How is timber durability classified in this code?

It is based on 'graveyard tests' (field tests) of heartwood. High durability is >120 months, Moderate is 60-120 months, and Low is <60 months.

What do Classes A, B, and C mean for timber seasoning?

They refer to refractoriness to air seasoning. Class A is highly refractory (prone to cracking/splitting), Class B is moderately refractory, and Class C is non-refractory (easy and fast to dry).

What geographical zones are defined for timber distribution?

The code divides India into six zones: North, East, Central, South, West, and Andamans.

IS 399

: 1966

Classification of Commercial Timbers and Their Zonal Distribution

CurrentSpecializedGuidelinesMaterials Science · Timber and Wood

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This standard categorizes Indian commercial timbers based on their geographical availability across six zones. It provides essential data on species-specific properties like durability, seasoning refractoriness, and treatability, helping engineers and architects select the right wood for construction and manufacturing.

Provides a classification system for various commercial timbers based on their properties and geographical distribution in India.

Quick Reference Values

Number of geographical zones6

High durability timber lifespan (graveyard test)> 120 months

Moderate durability timber lifespan60 to 120 months

Low durability timber lifespan< 60 months

Practical Notes

Always specify both the standard trade name and botanical name in BOQs to prevent the procurement of inferior substitute woods.

Timbers classified as low durability must not be used in exposed structural applications without proper chemical preservative treatment as per IS 401.

When selecting timber, consider its seasoning class; Class A timbers require slow, careful seasoning to avoid severe cracking and splitting.