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).

IS 7308

: 1999

Non-coniferous logs

CurrentSpecializedSpecificationMaterials Science · Timber and Timber Stores

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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

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.

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.