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IS 1362:1968 is the Indian Standard (BIS) for structural timber - dimensions. This standard specifies the preferred dimensions, cross-sections, lengths, and allowable tolerances for sawn timber used in structural applications such as beams, columns, and trusses.
Specifies standard dimensions for various structural timber elements used in building and construction.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Dimensions specified are for sawn timber; appropriate allowances must be made by the designer if the timber is to be planed or dressed.
! Engineers should verify the local commercial availability of specific standard sizes and lengths prior to finalizing the design to minimize wastage and cost.
! Tolerances assume the timber is at an equilibrium moisture content; green timber may experience shrinkage.
BS EN 1313-1:2010BSI (British Standards Institution), UK / CEN (European Committee for Standardization), Europe
HighCurrent
Round and sawn timber - Permitted deviations and preferred sizes - Part 1: Sawn softwood
Specifies preferred sizes and permitted dimensional deviations for sawn softwood timber.
DOC PS 20-20US Department of Commerce, USA
HighCurrent
American Softwood Lumber Standard
Establishes standard nominal and minimum-dressed dimensions for various softwood lumber classifications.
AS/NZS 1748.1:2011Standards Australia / Standards New Zealand
MediumCurrent
Timber - Sawn - Commercially produced in Australia - Part 1: General requirements
Covers requirements for dimensions, tolerances, and moisture content for commercially sawn timber.
ISO 19934:2018ISO (International Organization for Standardization)
HighCurrent
Timber structures — Sawn timber — Dimensions, species and grades
Provides guidance on dimensions for sawn timber used in structural applications, intended for international trade.
Key Differences
≠IS 1362 provides a single set of asymmetric tolerances (+3/-1 mm), whereas modern standards like EN 1313-1 define multiple tolerance classes (e.g., T1, T2) allowing for different levels of precision.
≠IS 1362 specifies dimensions at a reference moisture content of 12%. In contrast, DOC PS 20 explicitly provides different minimum dimensions for 'green' (>19% MC) and 'dry' (≤19% MC) lumber to account for shrinkage.
≠The dimensional system in IS 1362 is a simple list of metric sizes. The US system (DOC PS 20) is based on nominal sizes (e.g., '2x4') which correspond to smaller actual dressed dimensions (1.5"x3.5"), a concept not present in the IS code.
≠IS 1362:1968 is a standalone dimensional standard. Modern equivalents are typically part of an integrated system where dimensions (EN 1313-1) are directly linked to strength grading standards (e.g., EN 14081).
Key Similarities
≈All standards share the primary goal of standardizing the cross-sectional dimensions (thickness and width) of sawn timber for structural use.
≈Both IS 1362 and its international counterparts provide tables of preferred or standard sizes to promote interchangeability and manufacturing efficiency.
≈All standards acknowledge manufacturing variability by specifying permissible deviations (tolerances) on the target dimensions.
≈The scope of all compared standards is primarily focused on timber with rectangular or square cross-sections, as this is the most common form for structural members like beams, joists, and posts.
Parameter Comparison
Parameter
IS Value
International
Source
Reference Moisture Content (MC) for Dimensions
12% MC
Separate dimensions for 'Dry' (≤19% MC) and 'Green' (>19% MC)
DOC PS 20-20
Standard Thickness (example)
50 mm, 75 mm, 100 mm
38 mm (from nominal 2"), 89 mm (from nominal 4"), 140 mm (from nominal 6")
DOC PS 20-20
Standard Width (example)
100 mm, 150 mm, 200 mm
89 mm (from nominal 4"), 140 mm (from nominal 6"), 184 mm (from nominal 8")
DOC PS 20-20
Thickness Tolerance (for dimensions < 100mm)
+3 mm, -1 mm
±1 mm (for Tolerance Class 1)
BS EN 1313-1:2010
Width Tolerance (for dimensions > 100mm)
+6 mm, -2 mm
±1.5 mm (for Tolerance Class 1)
BS EN 1313-1:2010
System of Preferred Sizes
Prescriptive list (25, 40, 50, 65...)
Based on Renard series R20/R40 (e.g., 22, 25, 32, 40, 50...)
BS EN 1313-1:2010
⚠ Verify details from original standards before use
Key Values4
Quick Reference Values
Tolerance on dimensions less than 100 mm+3 mm, -2 mm
Tolerance on dimensions 100 mm and above+6 mm, -3 mm
Tolerance on length+50 mm, -0 mm
Standard length increments0.5 m
Tables & Referenced Sections
Key Tables
Table 1 - Standard Cross-Sectional Dimensions of Structural Timber