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IS 399 : 1966Classification of Commercial Timbers and Their Zonal Distribution

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EN 13556 · EN 350 · BS EN 1912
CurrentSpecializedGuidelinesMaterials Science · Timber and Wood
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OverviewValues4InternationalTablesFAQ3Related

IS 399:1966 is the Indian Standard (BIS) for classification of commercial timbers and their zonal distribution. 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.

Overview

Status
Current
Usage level
Specialized
Domain
Materials Science — Timber and Wood
Type
Guidelines
International equivalents
EN 13556:2003 · CEN - European Committee for Standardization, EuropeEN 350:2016 · CEN - European Committee for Standardization, EuropeBS EN 1912:2012+A2:2019 · BSI - British Standards Institution, UK / CENASTM D2555-19 · ASTM International, USA
Typically used with
IS 401IS 1141IS 1150
Also on InfraLens for IS 399
4Key values1Tables3FAQs
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.
Frequently referenced clauses
Cl. 4Zones of DistributionCl. 5.1Classification based on DurabilityCl. 5.2Classification based on SeasoningCl. 5.3Treatability Classification
Pulled from IS 399:1966. Browse the full clause & table index below in Tables & Referenced Sections.
timberwoodcommercial timber

International Equivalents

Similar International Standards
EN 13556:2003CEN - European Committee for Standardization, Europe
MediumCurrent
Nomenclature of timbers used in Europe
Provides a definitive list and nomenclature for commercial timbers within a specific continent (Europe), similar to how IS 399 lists Indian timbers.
EN 350:2016CEN - European Committee for Standardization, Europe
HighCurrent
Durability of wood and wood-based products - Testing and classification of the durability to biological agents of wood and wood-based materials
Directly corresponds to the durability and treatability classification sections within IS 399, although with more detailed and modern methodologies.
BS EN 1912:2012+A2:2019BSI - British Standards Institution, UK / CEN
MediumCurrent
Structural timber. Strength classes. Assignment of visual grades and species
Focuses on assigning timber species to strength classes for structural use, which is a modern equivalent to IS 399's strength-based grouping.
ASTM D2555-19ASTM International, USA
LowCurrent
Standard Practice for Establishing Clear Wood Strength Values
Defines the methodology for determining the strength properties of timber, which are the foundational data used for classification in standards like IS 399.
Key Differences
≠IS 399 is geographically prescriptive, mapping timber species to five specific zones within India. International standards are generally country-agnostic or continental (e.g., Europe) and do not provide such sub-national zonal distribution.
≠The classification system in IS 399 is based on broad groups (A, B, C) derived from modulus of elasticity and modulus of rupture. Modern standards (e.g., Eurocode 5 suite) use a more granular system of strength classes (C14, C24, D30, etc.) based on 5th-percentile characteristic values.
≠IS 399 is a relatively static, descriptive standard from 1966. International equivalents are performance-based, subject to frequent updates, and integrate a statistical approach to material properties and reliability.
≠IS 399 combines multiple classifications (strength, durability, treatability, seasonality, zonal distribution) into one document. Modern international practice separates these into distinct, specialized standards (e.g., EN 338 for strength classes, EN 350 for durability).
Key Similarities
≈The fundamental objective is the same: to classify timber species based on their properties to ensure appropriate selection and safe, efficient use in construction and other applications.
≈Both IS 399 and international standards use a combination of physical and mechanical properties, such as strength, stiffness, and durability, as the primary basis for classification.
≈Both systems provide a simplified grouping mechanism (e.g., Groups A/B/C in IS 399; C/D classes in EN standards) to allow designers to specify timber by performance category rather than by individual species.
≈Both rely on the correct botanical identification of timber species as the foundation for classification, providing lists of botanical names alongside common or trade names.
Parameter Comparison
ParameterIS ValueInternationalSource
Primary Strength ClassificationThree groups (A, B, C) based on Modulus of Rupture and Modulus of Elasticity in bending.Strength classes (e.g., C16, C24, D30) based on characteristic values for bending strength, density, and stiffness.EN 338:2016
Natural Durability ClassificationThree classes based on average life in years: Class I (>120 months), Class II (60-120 months), Class III (<60 months).Five durability classes (DC 1 'very durable' to DC 5 'not durable') based on resistance to wood-destroying fungi.EN 350:2016
Wood Preservative TreatabilityFive classes (a to e) describing heartwood from 'easily treatable' to 'very refractory'.Four classes (1 'easily treatable' to 4 'extremely difficult to treat') based on the permeability of the species.EN 350:2016
Geographic ScopeFive zones within India: Northern, Central, Western, Eastern, and Southern.No direct equivalent; lists species commonly found and used across the European continent.EN 13556:2003
Timber NomenclatureLists Trade Name, Botanical Name, and common names in regional Indian languages.Provides a unique 4-letter code, Botanical Name, and standard names in major European languages.EN 13556:2003
Basis of Strength ValuesBased on average strength values from tests on small clear specimens, likely without modern statistical adjustments.Based on 5th-percentile characteristic strength values derived from population testing, adjusted for size, and duration of load.EN 384:2018
⚠ Verify details from original standards before use

Key Values4

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

Tables & Referenced Sections

Key Tables
Table 1 - Classification of Commercial Timbers
Key Clauses
Clause 4 - Zones of Distribution
Clause 5.1 - Classification based on Durability
Clause 5.2 - Classification based on Seasoning
Clause 5.3 - Treatability Classification

Related Resources on InfraLens

Cross-Referenced Codes
IS 401:2001Code of Practice for Preservation of Timber
→
IS 1141:1993Seasoning of timber- Code of practice
→
IS 1150:2000Trade names and abbreviated symbols for timbe...
→

Frequently Asked Questions3

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.

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