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IS 7308 : 1999Non-coniferous logs

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UNECE Recommended Standard for the Grading of Non-Coniferous (Hardwood) Logs · EN 1309-2 · EN 1316-1
CurrentSpecializedSpecificationMaterials Science · Timber and Timber Stores
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OverviewValues7InternationalTablesFAQ4Related

IS 7308:1999 is the Indian Standard (BIS) for non-coniferous logs. This standard lays down the requirements for grading non-coniferous (hardwood) logs intended for conversion into sawn timber, veneers, and other wood-based products. It classifies logs based on girth and grades them (Grade I, II, III) based on permissible defects like knots, splits, decay, and straightness.

Non-coniferous logs

Overview

Status
Current
Usage level
Specialized
Domain
Materials Science — Timber and Timber Stores
Type
Specification
International equivalents
UNECE Recommended Standard for the Grading of Non-Coniferous (Hardwood) Logs · UNECE (United Nations Economic Commission for Europe), Geneva, SwitzerlandEN 1309-2:2006 · CEN (European Committee for Standardization), EuropeEN 1316-1:1997 · CEN (European Committee for Standardization), EuropeEN 1310:1997 · CEN (European Committee for Standardization), Europe
Typically used with
IS 399IS 707
Also on InfraLens for IS 7308
7Key values4Tables4FAQs
Practical Notes
! The Quarter-Girth formula (V = (G/4)^2 * L) is the standard method for volume calculation and forms the basis for commercial transactions.
! Always measure girth over the bark at the mid-point of the log. Disputes often arise from incorrect measurement practices.
! Refer to IS 707 for precise definitions of defects (e.g., 'sound knot' vs 'dead knot') as their permissibility varies significantly between grades.
Frequently referenced clauses
Cl. 3ClassificationCl. 4Measurement of LogsCl. 5Requirements for Grade I LogsCl. 6Requirements for Grade II LogsCl. 7Requirements for Grade III Logs
Pulled from IS 7308:1999. Browse the full clause & table index below in Tables & Referenced Sections.
timberhardwoodnon-coniferous logs

International Equivalents

Similar International Standards
UNECE Recommended Standard for the Grading of Non-Coniferous (Hardwood) LogsUNECE (United Nations Economic Commission for Europe), Geneva, Switzerland
HighCurrent
UNECE Recommended Standard for the Grading of Non-Coniferous (Hardwood) Logs
Provides a framework for qualitative classification (grading) of non-coniferous logs based on defects and dimensions.
EN 1309-2:2006CEN (European Committee for Standardization), Europe
HighCurrent
Round and sawn timber - Method of measurement of dimensions - Part 2: Round timber - Requirements for measurement and volume calculation rules
Directly addresses the measurement of log dimensions and volume calculation, a core component of IS 7308.
EN 1316-1:1997CEN (European Committee for Standardization), Europe
MediumCurrent
Hardwood round timber - Qualitative classification - Part 1: Oak and beech
Specifies grading rules for non-coniferous logs, but is limited to specific European species (Oak and Beech).
EN 1310:1997CEN (European Committee for Standardization), Europe
MediumCurrent
Round and sawn timber - Method of measurement of features
Details the standardized methods for measuring defects (features) like knots and slope of grain, which are graded in IS 7308.
Key Differences
≠IS 7308 specifies measuring the mid-girth (circumference) for volume calculation, whereas European standards like EN 1309-2 mandate the measurement of mid-diameter under bark.
≠The Indian standard traditionally uses the quarter-girth (Hoppus) formula for volume calculation, which provides an allowance for squaring the log. International standards like EN 1309-2 use more precise geometric formulae like Huber's formula, which calculate the true cylindrical volume.
≠The grading system in IS 7308 is generalized into Grade I, II, and III for a wide variety of Indian species. The UNECE and EN standards provide more granular A, B, C, D classes, often with detailed sub-grades and specific quantitative limits tailored to end-uses like veneer or high-quality sawn timber.
≠IS 7308 provides classifications based on large groups of species (e.g., teak, sal). EN 1316-1, as an example of the European approach, provides extremely detailed grading rules for specific species like Oak and Beech, which is not common in the broader IS code.
Key Similarities
≈All standards share the primary goal of sorting logs into quality classes based on visual assessment of defects to determine their commercial value and suitability for processing.
≈The types of defects that influence grade are universally recognized across all standards, including knots (sound, unsound), decay, splits, checks, curvature, and insect damage.
≈All standards employ a hierarchical grading system (e.g., Grade I/II/III or Class A/B/C) where the highest grade signifies logs with the minimum number and severity of defects.
≈The fundamental principle of measuring log length as the shortest distance between the two ends and a cross-sectional dimension (girth or diameter) at or near the mid-point is common to both IS 7308 and its international counterparts.
Parameter Comparison
ParameterIS ValueInternationalSource
Primary Measurement for VolumeMid-girth (circumference) in cm.Mid-diameter under bark in cm or mm.EN 1309-2:2006
Volume Calculation FormulaQuarter-girth formula: (Girth/4)^2 x Length.Huber's formula: (π/4 x mid-diameter^2) x Length.EN 1309-2:2006
Primary Grade DesignationsGrade I, Grade II, Grade III.Quality Class A, B, C, D.UNECE Recommended Standard
Measurement of Log LengthShortest distance between the two ends.Shortest distance between the two cross-sections, measured parallel to the log axis.UNECE Recommended Standard
Measurement of KnotsThe mean of the maximum and minimum diameters of the knot.The smallest diameter of the visible part of the knot on the log surface.EN 1310:1997
Measurement of Curvature (Sweep)Maximum deviation from straight line, expressed in cm per metre of length.Maximum deviation from straight line, expressed as cm/m or as a percentage of the mid-diameter.UNECE Recommended Standard
⚠ Verify details from original standards before use

Key Values7

Quick Reference Values
Minimum log length for grading1.5 m
Minimum girth for Class A logs150 cm and over
Minimum girth for Class B logs120 cm to below 150 cm
Minimum girth for Class C logs90 cm to below 120 cm
Girth measurement locationMid-point of the log over bark
Permissible end splits (Grade I)Total length not to exceed 1/2 of girth
Permissible number of sound knots (Grade I)Not to exceed 4 per 4 m length
Key Formulas
V = (G/4)^2 * L — Quarter Girth Formula for calculating log volume, where G is mid-girth and L is length.

Tables & Referenced Sections

Key Tables
Table 1 - Classification of Logs According to Girth
Table 2 - Permissible Defects for Grade I Logs
Table 3 - Permissible Defects for Grade II Logs
Table 4 - Permissible Defects for Grade III Logs
Key Clauses
Clause 3 - Classification
Clause 4 - Measurement of Logs
Clause 5 - Requirements for Grade I Logs
Clause 6 - Requirements for Grade II Logs
Clause 7 - Requirements for Grade III Logs

Related Resources on InfraLens

Cross-Referenced Codes
IS 399:1966Classification of Commercial Timbers and Thei...
→
IS 707:2011Timber Technology And Utilization of Wood, Ba...
→

Frequently Asked Questions4

How are logs classified by size in this standard?+
Logs are classified into four classes based on mid-girth: Class A (≥150 cm), Class B (120-150 cm), Class C (90-120 cm), and Class D (60-90 cm) as per Table 1.
What are the main grades for non-coniferous logs?+
The logs are graded as Grade I, Grade II, and Grade III, with Grade I being the highest quality with the least number of defects (Clause 3.2).
How is the volume of a log calculated?+
Volume (in cubic meters) is calculated using the quarter-girth formula: V = (G/4)^2 * L, where G is the girth at mid-length in meters and L is the length in meters (Clause 4.3).
What is a major defect for rejecting a log from Grade I?+
A log with any signs of heart rot (decay in the center) is not permitted in Grade I (Table 2).

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