The standard outlines specifications for Himalayan coniferous sawn timber in the forms of baulks and scantlings. It establishes grading rules based on allowable and forbidden defects, dimensional tolerances, measurement methods, and marking protocols to guarantee timber quality for building and structural uses. This code is vital for suppliers, engineers, and builders handling these timber species.
Overview
The standard outlines specifications for Himalayan coniferous sawn timber in the forms of baulks and scantlings. It establishes grading rules based on allowable and forbidden defects, dimensional tolerances, measurement methods, and marking protocols to guarantee timber quality for building and structural uses. This code is vital for suppliers, engineers, and builders handling these timber species.
Audience
Contents
Structure
Overview of the standard’s scope covering coniferous sawn timber types—baulks and scantlings—found predominantly in the Himalayan region. Specification of species as per Clause 4.1, with definitions aligned to IS 707:1976 terminology. Instructions for rounding numerical test results in accordance with IS 2:1960 to maintain appropriate significant figures.
Details of related standards incorporated within the code, including IS 2:1960 for rounding rules, IS 707:1976 for timber terminology, IS 401:1982 for timber preservation, IS 1141:1973 for seasoning practices, and IS 3364 (Part 2):1976 for defect measurement. These ensure consistency in timber classification, treatment, and quality assurance.
Definitions used throughout the standard are based on IS 707:1976. Timber is categorized into Special Grade, Grade 1, and Grade 2, dependent on allowable defects as specified in Clause 7. Trade names and botanical names of species are provided along with their symbols for easy identification.
Lists the coniferous species covered, such as Chir, Cypress, Deodar, Fir, Kail, Khasi pine, Red fir, and Spruce, including their abbreviations. Specifies that timber lots must contain a single species except for fir and spruce, which may be mixed. Prescribes marking requirements for traceability including supplier details, year, species, grade, and dimensions.
Instructions to measure width and thickness at the narrowest point of the timber with an accuracy of ±10 mm. Emphasizes species uniformity per lot except for allowed mixing. Numerical values must be rounded in accordance with IS 2:1960.
Describes volume computation as length × width × thickness (in meters) rounded to three decimal places per IS 2:1960. Explains the three-tier grading system based on permissible defects. Lists trade names, botanical names, and symbols. Summarizes defect limits for each grade.
Enumerates defects not allowed in any grade such as spiral grain, warp, decay, and live insect infestation. Additional restrictions for Special Grade including absence of center heart, wane, cup shakes, borer holes, sapstain, and knots. Defines permissible defect limits for each grade in detail.
Advises prophylactic preservation of timber following IS 401:1982, including pressure and non-pressure methods to protect against fungi, insects, and termites. Specifies minimum retention levels of preservatives based on timber use. Quality control and defect evaluation are performed according to IS 3364 (Part 2):1976.
Requires coating the ends of baulks and scantlings to prevent cracks and splits, extending a minimum of 25 mm beyond the longest visible split, using materials compliant with IS 1141:1973. Coating should be applied immediately after inspection. References related preservation and defect measurement standards.
Specifies that each timber piece must be clearly and permanently marked with the supplier’s identifier, year of supply, species abbreviation, grade, and size. The standard mark may also be applied for quality assurance. Defect control and marking facilitate traceability and quality monitoring.
Frequently Asked
This standard includes Himalayan coniferous timber species such as Chir (Pinus roxburghii), Cypress (Cupressus torulosa), Deodar (Cedrus deodara), Fir (Abies species excluding Abies densa), Kail (Pinus wallichiana), Khasi pine (Pinus insularis), Red fir (Abies densa), and Spruce (Picea smithiana). These species are categorized into Special Grade, Grade 1, and Grade 2 based on their permissible defect limits, ensuring consistent quality for construction uses.
Coniferous sawn timber is classified into Special Grade, Grade 1, and Grade 2 according to the extent of permissible defects. All grades prohibit spiral or twisted grain, warp, decay, and live insect damage. Special Grade demands the highest quality with no knots, wane, cup shakes, sapstain, or borer holes permitted. Grade 1 allows limited knots and center heart with no cup shakes, while Grade 2 permits more defects but still excludes structural faults like spiral grain and decay.
Permissible defects vary by grade: Special Grade timber allows minimal live knots up to 25 mm without grouping and restricts dead knots to small sizes and low frequency. Surface checks in Special Grade must not exceed 5 mm depth, whereas Grade 1 permits checks up to 15 mm, and Grade 2 up to 25 mm. Wane is not allowed in Special Grade but accepted up to certain widths and proportions in Grades 1 and 2. Borer holes and center heart are prohibited in higher grades but allowed within limits in lower grades.
Timber must be air-seasoned so that its moisture content does not exceed 20% within a 15 mm depth from the surface, excluding 300 mm from each end. This ensures the timber is adequately dried to minimize shrinkage, warping, and potential decay, enhancing durability and performance in structural applications.
Timber dimensions—width and thickness—must be measured at their narrowest points with ±10 mm accuracy. Each piece should be permanently and clearly marked with the supplier’s name or trademark, year of supply, species abbreviation, grade, and size. End coating must be applied immediately after inspection extending 25 mm beyond the longest split using materials per IS 1141:1973 to prevent cracking. Defect evaluation and measurement follow IS 3364 (Part 2):1976.
Ask AI about any clause, requirement, or provision in IS 190. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required