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IS 190 : 1991Coniferous Sawn Timber (Baulks and Scantlings)

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EN 1313-1 · PS 20 · ISO 738
CurrentSpecializedSpecificationMaterials Science · Timber and Timber Stores
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OverviewValues4InternationalTablesFAQ3Related

IS 190:1991 is the Indian Standard (BIS) for coniferous sawn timber (baulks and scantlings). This standard lays down the specifications, standard dimensions, grading rules, and permissible defects for coniferous sawn timber in the form of baulks and scantlings used for general building construction.

Coniferous Sawn Timber (Baulks and Scantlings)

Overview

Status
Current
Usage level
Specialized
Domain
Materials Science — Timber and Timber Stores
Type
Specification
International equivalents
EN 1313-1:2022 · CEN (European Committee for Standardization), EuropePS 20-20 · U.S. Department of Commerce / American Lumber Standard Committee, Inc. (ALSC), USAISO 738:2009 · ISO (International Organization for Standardization), InternationalBS 4978:2007+A2:2017 · BSI (British Standards Institution), UK
Typically used with
IS 287IS 707IS 1150IS 3364
Also on InfraLens for IS 190
4Key values2Tables3FAQs
Practical Notes
! Coniferous timber (like Pine, Fir, and Deodar) generally has better strength-to-weight ratios for structural framing but requires careful grading for knots and shakes.
! Always specify the required moisture content based on the climatic zone (IS 287) where the timber will be permanently installed to prevent warping and shrinkage.
! Grading is purely visual. Structural engineers should align the visual grade (Select, I, II) with permissible stresses given in IS 883 for design.
Frequently referenced clauses
Cl. 4Species of TimberCl. 5Dimensions and TolerancesCl. 6Grading and Permissible DefectsCl. 7Moisture Content
Pulled from IS 190:1991. Browse the full clause & table index below in Tables & Referenced Sections.
timberconiferous woodbaulksscantlingswood

International Equivalents

Similar International Standards
EN 1313-1:2022CEN (European Committee for Standardization), Europe
HighCurrent
Round and sawn timber — Permitted deviations and preferred sizes — Part 1: Softwood sawn timber
Covers dimensional tolerances and preferred sizes for coniferous sawn timber, directly aligning with a key part of IS 190.
PS 20-20U.S. Department of Commerce / American Lumber Standard Committee, Inc. (ALSC), USA
MediumCurrent
American Softwood Lumber Standard
Establishes standard sizes, grading provisions, and inspection for North American softwood lumber, but with different sizing and grading systems.
ISO 738:2009ISO (International Organization for Standardization), International
HighCurrent
Coniferous and broadleaved sawn timber — Sizes — Permitted deviations and preferred sizes
Specifies permitted deviations and preferred sizes for sawn timber, covering the core dimensional aspects of IS 190.
BS 4978:2007+A2:2017BSI (British Standards Institution), UK
MediumCurrent
Visual strength grading of softwood - Specification
Focuses specifically on the visual grading of softwood for strength, which corresponds to the defect-based grading in IS 190, but uses a different methodology (strength classes).
Key Differences
≠IS 190 uses a simple visual grading system (Grade I, Grade II) based on permissible defects. European standards (e.g., EN 14081-1) use strength classes (C16, C24, etc.) determined visually or by machine, while US standards (PS 20) use complex grade names tied to end-use categories (e.g., 'Select Structural', 'No. 2').
≠IS 190 specifies timber sizes and tolerances in actual millimeters. The US system (PS 20) is based on 'nominal' sizes (e.g., 2x4) which are larger than the actual, 'dressed' dimensions, and links moisture content to final size.
≠The Indian standard lists species common to the Indian subcontinent, such as Deodar, Kail, and Chir. International standards focus on species prevalent in their respective regions, such as Spruce/Pine/Fir in Europe (EN) and Douglas-fir/Southern Yellow Pine in North America (PS 20).
≠IS 190 uses specific terminology like 'Baulks' (>50 cm² cross-section) and 'Scantlings' (25-50 cm²). International terminology differs, with the US using terms like 'Dimension Lumber' and 'Timbers' based on nominal thickness and width.
Key Similarities
≈All standards share the fundamental purpose of providing a standardized framework for sawn coniferous timber to ensure quality, predictable performance, and interchangeability in construction.
≈All standards fundamentally rely on controlling natural wood defects such as knots, slope of grain, splits, and wane. While the limits differ, the principle of limiting them to ensure structural integrity and appearance is a common foundation.
≈All standards recognize moisture content as a critical parameter influencing dimensional stability, strength, and durability. They all specify maximum allowable moisture levels for different conditions (e.g., dry, green, service class).
≈The principles for measuring dimensions (thickness, width) and defects (e.g., knot size as a proportion of the face width) are broadly consistent across the standards to ensure repeatable assessments.
Parameter Comparison
ParameterIS ValueInternationalSource
Primary Grading MethodVisual assessment of defects into Grade I and Grade II.Assignment to strength classes (e.g., C18, C24) via visual or machine grading.EN 14081-1
Standard Moisture Content20% maximum for general use.19% maximum for lumber stamped 'S-DRY' or 'KD'.PS 20-20
Dimensional Tolerance (Width > 100mm)±5 mmFor Tolerance Class 1 (TC1): -1 mm to +3 mm (on target size).EN 1313-1:2022
Slope of Grain (Highest Grade)Not steeper than 1 in 15 (Grade I).Not steeper than 1 in 10 for SS (Special Structural) Grade.BS 4978:2007+A2:2017
Knot Size Limit (Highest Grade)Max diameter 1/4 of the face width.Defined by Knot Area Ratio (KAR); e.g., for C24 strength class, marginal KAR is ≤ 1/3.EN 1912 / EN 14081-1
Size Terminology (Large Section)Baulk: Cross-sectional area > 50 cm².Timber: Least nominal dimension is 5 inches (approx. 127mm) or more.PS 20-20
⚠ Verify details from original standards before use

Key Values4

Quick Reference Values
standard lengths1 to 6 meters (typically in increments of 0.25m or 0.5m)
dimensional tolerance width thickness+3 mm, -0 mm for sections up to 100 mm
moisture content referenceDetermined as per IS 287 depending on climatic zones
grading categoriesSelect Grade, Grade I, and Grade II

Tables & Referenced Sections

Key Tables
Table 1 - Standard Sizes of Baulks and Scantlings
Table 2 - Permissible Defects for Different Grades
Key Clauses
Clause 4 - Species of Timber
Clause 5 - Dimensions and Tolerances
Clause 6 - Grading and Permissible Defects
Clause 7 - Moisture Content

Related Resources on InfraLens

Cross-Referenced Codes
IS 287:2022Code of Practice for Design of Timber Structu...
→
IS 707:2011Timber Technology And Utilization of Wood, Ba...
→
IS 1150:2000Trade names and abbreviated symbols for timbe...
→
IS 3364:2000Methods of measurement and evaluation of defe...
→

Frequently Asked Questions3

What is the difference between baulks and scantlings?+
Baulks are roughly squared timber logs of larger dimensions (often exceeding 100mmx100mm), while scantlings are sawn timber pieces with smaller, specific cross-sectional sizes.
How is the timber graded according to this code?+
It is graded visually into Select Grade, Grade I, and Grade II based on the frequency and size of permissible defects like knots, shakes, splits, and wanes.
What is the permissible moisture content for sawn coniferous timber?+
The code does not fix a single value; it directs engineers to IS 287, which specifies moisture content limits based on the geographic and climatic zone of the end-use location.

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