ISO 1031:1974

Overview - ISO 1031:1974 (Coniferous sawn timber - Defects - Terms and definitions)

ISO 1031:1974 establishes international terminology and definitions for defects in coniferous sawn timber (softwoods) that are classified under ISO 1029. It applies to unplaned sawn timber and to timber that has been surfaced to size or planed but without profiling. The standard is a trilingual edition (English / French / Russian) and replaces the earlier ISO Recommendation R 1031. Numerous illustrative figures in the document show defect examples to support consistent interpretation.

Key topics and technical requirements

• Scope and purpose: Provide standardized terms and definitions for defects so that grading, specification and communication are consistent across users and countries.
• Knots: Defined by shape, position, mutual arrangement, degree of intergrowth and condition.
  • Shape by cross‑section ratios: round (max/min ≤ 2), oval (>2 and ≤4), splay/spike (>4).
  • Position: face, edge (rive), arris, and traversing splay (exposed on two arrises).
  • Arrangement: scattered, group/cluster, branched (moustaches).
  • Intergrowth: intergrown (annual rings intergrown ≥ 3/4 of knot perimeter), partially intergrown (between 1/4 and 3/4), dead/non‑adherent (≤ 1/4).
  • Condition: sound (no decay - light or dark resinous), unsound (decay affecting up to 1/3 of knot cross‑section), rotten (decay affecting more than 1/3).
• Shakes and checks: Separation of wood fibres along the grain, with subtypes such as heart shakes, ring shakes, and checks (gerces) described by location and extent.
• Illustrative figures: The standard includes many figures to clarify visual identification and measurement conventions.

Applications - practical value

• Use ISO 1031:1974 to support:
  • Timber grading and quality control in sawmills and timber yards
  • Procurement specifications and contract language for structural timber
  • Inspection, acceptance and rejection criteria for shipments of coniferous sawn timber
  • Training materials for graders and quality inspectors
  • Reference vocabulary for standards writers, engineers and architects specifying timber performance

Who should use this standard

• Sawmill operators and production managers
• Timber graders and quality control inspectors
• Procurement officers and merchants in timber trade
• Structural engineers, architects and building inspectors specifying or evaluating softwood timber
• Standards developers and certification bodies

Related standards

• ISO 1029 - classification referenced by ISO 1031 (used together for grading/classification)
• ISO 1031 replaces the earlier ISO Recommendation R 1031 (1969) and was developed by ISO/TC 55 (Timber)

Keywords: ISO 1031:1974, coniferous sawn timber, defects, knots, shakes and checks, timber grading, ISO 1029.