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IS 1326:1992 is the Indian Standard (BIS) for non-coniferous sawn timber (baulks and scantlings). This standard specifies requirements for non-coniferous (hardwood) sawn timber converted into baulks and scantlings for structural and general purposes. It covers dimensions, tolerances, grading based on defects, and permissible species.
Non-coniferous sawn timber (Baulks and scantlings)
EN 1313-2:2010CEN (European Committee for Standardization), Europe
HighCurrent
Round and sawn timber - Permitted deviations and preferred sizes - Part 2: Sawn hardwood
Specifies permitted deviations and preferred sizes for sawn hardwood, directly aligning with the dimensional scope of IS 1326.
ISO 738:2003ISO (International Organization for Standardization), International
HighCurrent
Sawn timber — Sizes — Permissible deviations and shrinkage
Provides a global framework for permissible deviations in sawn timber sizes, covering both hardwoods and softwoods.
MS 758:2001Department of Standards Malaysia, Malaysia
MediumCurrent
Sawn Timber of Hardwood - Specification
Covers grading, sizing, and defects for Malaysian hardwoods, a major source of non-coniferous timber.
NHLA Rules for the Measurement and Inspection of Hardwood and CypressNHLA (National Hardwood Lumber Association), USA
LowCurrent
Rules for the Measurement and Inspection of Hardwood and Cypress
Serves as the de-facto North American standard for grading hardwood lumber, but focuses on yield of clear cuttings, not dimensional scantlings.
Key Differences
≠IS 1326 specifies fixed dimensional tolerances (e.g., +3 mm, -2 mm for thickness), whereas standards like ISO 738:2003 provide tolerances that vary based on the nominal dimension of the timber.
≠The grading system in IS 1326 is a simple two-tier system (Grade I, Grade II). This contrasts with the more complex, multi-grade appearance classes in EN 975-1 or the yield-based system (FAS, Common, etc.) of the NHLA rules.
≠IS 1326 does not mandate a moisture content at the time of supply, only that it be recorded if measured. European and ISO standards often link dimensional tolerances to a reference moisture content (typically 20%).
≠IS 1326 uses specific terminology like 'Baulks' (>225 cm² area) and 'Scantlings' (25-225 cm² area). While the terms are used internationally, the precise definition by cross-sectional area is unique to the Indian standard.
Key Similarities
≈All standards address and set limits for a common set of defects, including knots, splits, checks, slope of grain, wane, and various forms of warp (bow, spring, twist).
≈The fundamental principle of providing a positive tolerance (oversize) on thickness and width to allow for shrinkage and subsequent planing/processing is common across IS 1326 and its international counterparts.
≈The basic methodology for measuring timber dimensions (width, thickness, length) and quantifying defects (e.g., knot size, length of a split) is broadly consistent.
≈The scope of all compared standards is primarily focused on visually graded, unseasoned or partially seasoned sawn timber intended for general construction or further remanufacturing.
Parameter Comparison
Parameter
IS Value
International
Source
Tolerance on Thickness/Width (for dimensions < 100mm)
+3 mm, -2 mm
±1 mm (at 20% MC)
ISO 738:2003
Tolerance on Thickness/Width (for dimensions > 100mm)
+3 mm, -2 mm
+3 mm, -1 mm (at 20% MC)
ISO 738:2003
Tolerance on Length
+25 mm, -0 mm
No specified negative tolerance, positive tolerance subject to agreement
EN 1313-2:2010
Moisture Content (MC) Reference for Tolerances
Not specified; tolerances apply at time of inspection.
Tolerances apply at a reference MC of 20%.
ISO 738:2003
Definition of 'Scantling'
Cross-sectional area between 25 cm² and 225 cm².
General term for timber of smaller cross-section, not precisely defined by area.
General Usage
Slope of Grain Limit (Highest Grade)
1 in 15 (Grade I)
Varies by grade and species; not always a primary metric in appearance grading.
EN 975-1:2009
End Splits Limit (Highest Grade)
Not to exceed 50 mm in length
Shall not exceed the nominal width of the piece
MS 758:2001 (Prime Grade)
⚠ Verify details from original standards before use
Key Values3
Quick Reference Values
tolerance on width and thickness up to 100mm± 2 mm
tolerance on width and thickness above 100mm± 3 mm
tolerance on length+ 50 mm, - 0 mm
Tables & Referenced Sections
Key Tables
Table 1 - Standard Sizes of Baulks and Scantlings
Table 2 - Permissible Defects for Different Grades
Baulks are sawn timber pieces of larger cross-sections, while scantlings refer to sawn timber pieces with specific smaller structural dimensions outlined in the standard.
How are the grades of timber classified in this code?+
Grades are classified based on the presence, size, and frequency of permissible defects such as knots, shakes, and wanes.
Is preservative treatment covered in this IS code?+
No, preservation guidelines are generally covered in separate codes like IS 401; this code focuses primarily on dimensions, species, and grading of sawn timber.