Coniferous Sawn Timber (Baulks and Scantlings)

IS 190: Scope Summary

• Scope: Covers Indian standard specifications for Coniferous Sawn Timber (Baulks and Scantlings).
• Timber Species: As per Clause 4.1, specific coniferous species are covered (refer to IS 190 full text for exact species list).
• Definitions: Use definitions from IS 707:1976 for timber terminology.
• Rounding Off: Final test or analysis values must be rounded per IS 2:1960, maintaining the same number of significant figures as the standard’s specified values.

Key Points:

Rounding Off Rule (IS 2:1960):

• Round off numerical values to the same significant figures as specified.
• Example: If specified value = 12.3, result = 12.4 (rounded to 3 significant figures).

flowchart LR
    A[Timber Species] --> B[Coniferous Species as per IS 190]
    C[Definitions] --> D[IS 707:1976]
    E[Rounding Off] --> F[IS 2:1960 Rules]
    B & D & F --> G[Compliance with IS 190]

For detailed species and grading, refer to full IS 190 document.

IS 190 References Overview

IS 190 relies on several key standards and rules for compliance, rounding, and terminology:

• Rounding Off (IS 2:1960)
  Numerical results must be rounded off following IS 2 rules, retaining the same number of significant digits as specified values.

• Definitions (IS 707:1976)
  All timber-related terms follow definitions provided in IS 707 (Glossary of timber technology).

• Related Standards for Timber

  • IS 401:1982 — Preservation of timber
  • IS 1141:1973 — Seasoning of timber
  • IS 3364 (Part 2):1976 — Measurement and evaluation of defects in converted timber

These references ensure uniformity in timber terminology, testing, and treatment procedures essential for structural design and quality control.

graph LR
A[IS 190] --> B[IS 2:1960 Rounding Rules]
A --> C[IS 707:1976 Glossary]
A --> D[IS 401:1982 Timber Preservation]
A --> E[IS 1141:1973 Timber Seasoning]
A --> F[IS 3364(Part 2):1976 Defects Evaluation]

Summary: Use IS 2 for rounding, IS 707 for terms, and IS 401/1141/3364 for timber treatment and quality standards.

IS 190: Definitions & Key Specifications

• Definitions: As per Clause 3.1, all definitions follow IS 707:1976 (Glossary of terms for timber technology).

• Rounding Off: Final test/analysis values must be rounded per IS 2:1960 rules, retaining the same significant figures as specified.

• Timber Grades (Clause 6.1):
  Coniferous sawn timber is classified into:

  • Special Grade
  • Grade 1
  • Grade 2
    Based on permissible defects (detailed in Clause 7).

• Trade Names & Botanical Names:

• Related Standards (Clause 2.1):
  • IS 401:1982 – Timber preservation
  • IS 707:1976 – Timber glossary
  • IS 1141:1973 – Timber seasoning
  • IS 3364 (Part 2):1976 – Defect measurement

This framework ensures uniform terminology, grading, and quality control for coniferous timber under IS 190.

IS 190: Species and Supply Conditions for Timber

1. Species Covered (Clause 4.1 & Table 6.1)

• Timber in one lot must be of one species, except fir and spruce which may be mixed (Clause 4.2).

2. Grades of Coniferous Sawn Timber (Clause 6.1)

• Special Grade
• Grade 1
• Grade 2

Grades depend on permissible defects (see Clause 7).

3. Marking (Clause 10.1)

Each timber piece must be marked with:

• Supplier's name or trademark
• Year of supply
• Species abbreviation
• Grade
• Size/dimensions

Summary Table of Species and Symbols

| Species       | Symbol |
|---------------|--------|
| Pinus roxburghii | CHR  |
| Cupressus torulosa | CYP  |
| Cedrus deodara  | DEO   |
| Abies spp. (excl. A. densa) | FIR |
| Pinus wallichiana | KAL  |
| Pinus insularis | KPI   |
| Abies densa    | RFI   |
| Picea simthiana | SPR   |

This ensures uniformity in supply and traceability for quality control.

IS 190: Dimensions and Measurements Key Points

• Width & Thickness Measurement (Clause 5.2.2):

  • Measure at the narrowest place of the timber.
  • Accuracy: correct to 10 mm.

• Timber Species (Clause 4.2):

  • Timber in one lot must be of one species.
  • Exception: Fir and Spruce can be mixed.

• Rounding Off (Clause 5):

  • Follow IS 2:1960 for rounding numerical values.
  • Retain the same number of significant figures as specified.

Summary Table for Dimensions:

Notes:

• Always measure width and thickness at the narrowest point to ensure compliance.
• Ensure timber species uniformity per lot except for fir and spruce.
• Round off values carefully following IS 2:1960 rules.

flowchart TD
    A[Timber Lot] --> B{Species Uniform?}
    B -- Yes --> C[Proceed]
    B -- No --> D{Fir or Spruce?}
    D -- Yes --> C
    D -- No --> E[Reject Lot]

    C --> F[Measure Width & Thickness]
    F --> G[At Narrowest Point ±10 mm]
    G --> H[Round Off per IS 2:1960]

This ensures standardized and accurate timber dimension measurements as per IS 190.

IS 190 - Requirements and Grading of Coniferous Sawn Timber

1. Volume Calculation (Clause 5.2.3)

• Volume (m³) = Length × Width × Thickness (in meters)
• Round off to 3 decimal places as per IS 2:1960.

2. Grading (Clause 6.1)

• Timber is graded into:
  • Special Grade
  • Grade 1
  • Grade 2
• Grading depends on permissible defects (see Clause 7).

3. Trade Names & Symbols

4. Key Permissible Defects by Grade (Summary from Table 1)

IS 190: Prohibited and Permissible Defects in Coniferous Sawn Timber

1. Prohibited Defects (Clause 7.1)

• All grades: No spiral/twisted grain, warp, decay, or live insect attack.
• Special Grade: Additionally free from centre heart, wane, cup shakes, borer holes (dead infestation), sapstain, and knots.
• Grade 1: Free from cup shakes.

2. Permissible Defects (Clause 7.2 & Table 1)

Prophylactic Treatment of Timber as per IS 190 & IS 401:1982

• Reference Standard:
  IS 401 : 1982 — Code of Practice for Preservation of Timber (3rd Revision) governs prophylactic treatment.

• Applicability:
  Clause 8.1 of IS 190 states all timbers may be given prophylactic treatment as per IS 401, subject to purchaser-supplier agreement.

• Purpose:
  To protect timber against biological deterioration (fungi, insects, termites).

• Common Treatments (per IS 401):

  • Pressure treatment with preservatives like Copper Chrome Arsenate (CCA), creosote, or water-borne preservatives.
  • Non-pressure methods: brushing, spraying, dipping.

• Key Parameters:

  • Retention of preservative: Specified in kg/m³ depending on timber use.
  • Penetration depth: Minimum penetration into sapwood (usually several mm).

• Measurement & Quality:

  • Defects and quality are checked per IS 3364 (Part 2): 1976.
  • Rounding off test values per IS 2:1960.

Summary Table: Typical Preservative Retention (IS 401)

flowchart TD
    A[Timber] --> B{Treatment Required?}
    B -- Yes --> C[Select Preservative]
    C --> D{Method}
    D -- Pressure --> E[Pressure Treatment]
    D -- Non-Pressure --> F[Brushing/Dipping/Spraying]
    E & F --> G[Check Retention & Penetration]
    G --> H[Quality Check per IS 3364]
    H --> I[Approval for Use]
    B -- No --> I

Note: Always confirm treatment details in contract documents per IS 401.

IS 190: End Coating and Protection of Timber - Key Points

• Clause 9.1 (End Coating):

  • Ends of baulks and scantlings must be coated to prevent cracking/splitting.
  • Coating length = longest split length + 25 mm minimum.
  • Use materials per IS 1141:1973 (seasoning code) for coating.
  • Apply coating immediately after timber inspection.

• Clause 8.1 (Prophylactic Treatment):

  • Timbers may be treated as per IS 401:1982 (preservation code), subject to buyer-supplier agreement.

• Defects & Measurement:

  • Permissible defects per Table 1 (IS 190) based on timber grade.
  • Defects measured as per IS 3364 (Part 2):1976.

Summary Table for End Coating Length

Reference Standards for Protection & Defects

flowchart LR
    A[Timber Inspection] --> B[Measure Longest Split]
    B --> C[Calculate Coating Length = Split + 25mm]
    C --> D[Apply End Coating (IS 1141:1973 Material)]
    D --> E[Prophylactic Treatment (Optional, IS 401:1982)]

In brief: Always coat timber ends beyond the longest split by 25 mm using IS 1141-approved materials immediately after inspection to minimize cracking and splitting. Use prophylactic treatment as agreed.

IS 190 - Marking of Timber: Key Specifications & Tables

Marking Requirements (Clause 10.1):
Each timber piece shall be legibly and indelibly marked at a convenient place with:

• Supplier's name, initials, or trademark
• Year of supply
• Abbreviation of species
• Grade of timber
• Size (dimensions)

Standard Mark (Clause 10.1.1):
Timber pieces may also bear the Standard Mark for quality assurance.

Permissible Defects for Different Grades of Coniferous Sawn Timber (Table 1, Clause 7.1)

Rounding Off (Clause None):

Values must be rounded per IS 2:1960, retaining the same significant digits as specified.

Summary Diagram: Marking & Defect Control

flowchart TD