Guide for storage and protection of logs and sawn timber

IS 9104 primarily deals with specifications for timber structures. The Introduction section outlines the scope, definitions, and general guidelines but does not provide direct formulas or tables.

Key Points from IS 9104 Introduction:

• Covers materials, workmanship, and structural design principles for timber.
• Emphasizes durability, strength, and serviceability of timber members.
• Defines basic terms related to timber properties and structural use.

Important Specifications (general knowledge):

• Design stresses for timber depend on species, grade, and moisture content.
• Allowable bending stress (Fb), shear stress (Fv), and compressive stress (Fc) are key parameters.
• Use modulus of elasticity (E) for deflection calculations.

Typical Formulas (from timber design practice):

• Bending stress:
  [ \sigma_b = \frac{M}{Z} ]
  where ( M ) = bending moment, ( Z ) = section modulus.

• Shear stress:
  [ \tau = \frac{V}{A} ]
  where ( V ) = shear force, ( A ) = shear area.

• Deflection:
  [ \delta = \frac{PL^3}{48EI} ]
  for a simply supported beam with point load ( P ).

For detailed tables and design values, refer to IS 883 and IS 1905 which complement IS 9104.

flowchart TD
    A[Timber Properties] --> B[Strength Parameters]
    B --> C{Design Stresses}
    C --> D[Bending Stress (Fb)]
    C --> E[Shear Stress (Fv)]
    C --> F[Compression Stress (Fc)]
    B --> G[Modulus of Elasticity (E)]
    G --> H[Deflection Calculations]

Summary: IS 9104 Introduction sets the framework; detailed formulas and tables are in related codes like IS 883.

IS 9104: Scope Overview

IS 9104 (1979) primarily deals with the Code of Practice for Structural Use of Timber in India. It sets guidelines for:

• Selection and grading of timber
• Design principles for timber structures
• Specifications for workmanship and durability
• Methods for calculating stresses and load capacities

Key Specifications & Scope Highlights:

• Applies to timber in structural applications (buildings, bridges, etc.)
• Covers seasoning, preservation, and grading of timber
• Includes allowable stresses for various timber species and conditions
• Addresses jointing, connections, and fasteners

Important Formulas (General Structural Timber Design):

• Bending Stress:
  [ \sigma_b = \frac{M}{Z} ] Where:
  ( M ) = Bending moment,
  ( Z ) = Section modulus

• Shear Stress:
  [ \tau = \frac{V}{A} ] Where:
  ( V ) = Shear force,
  ( A ) = Cross-sectional area

Typical Tables (from IS 9104 & related codes):

Note: Refer to IS 883 and IS 1708 for detailed grading and stress values.

flowchart TD
    A[Timber Structural Use] --> B[Selection & Grading]
    A --> C[Design Principles]
    A --> D[Workmanship & Durability]
    C --> E[Stress Calculations]
    E --> F[Bending Stress]
    E --> G[Shear Stress]

For detailed tables and exact values, consult the full IS 9104 document and related IS codes on timber.

IS 9104 provides guidance on storage of logs in depots and saw mill yards to prevent damage like cracking, mould, decay, and insect attack.

Key Points on Storage from IS 9104:

• Storage Periods: Logs in depots have shorter storage periods than saw mill yards, but all logs must be stored scientifically to avoid losses.
• Protection Measures:
  • Prevent surface and end cracking by proper stacking and covering.
  • Avoid biological deterioration (mould, decay, insects) by ensuring good ventilation and dryness.
• Stacking Guidelines:
  • Use supports (stickers) between log layers for air circulation.
  • Elevate logs from ground to prevent moisture absorption.
• Environmental Control:
  • Store in shaded, well-drained areas.
  • Cover stacks with waterproof sheets but allow air passage.

General Recommendations (from engineering practice):

flowchart LR
    A[Logs] --> B[Stacking with Stickers]
    B --> C[Elevation from Ground]
    C --> D[Cover with Waterproof Sheet]
    D --> E[Allow Ventilation]
    E --> F[Prevent Cracking & Decay]

Note: IS 9104 is a guide; always combine with local climate considerations and timber species properties for best results.

IS 9104: Protection of Logs - Key Points & Specifications

1. Storage & Protection Guidelines (Clause 2.1.4)

• Prophylactic Treatment:

  • Debarked logs must be sprayed with preservatives as per IS 401-1967.
  • Repeat spraying every 3 to 6 months based on biological threat level (fungi, termites, insects).

• Storage Conditions:

  • Store logs under shade to reduce exposure to sun and rain.
  • Place logs on preservative-treated timber supports to avoid ground contact and termite attack.

• End Protection:

  • Apply end coating compositions (paint or spray) on log ends to prevent end-cracking.

2. Important Specifications

Summary Diagram

flowchart TD
    A[Debarked Logs] --> B[Prophylactic Treatment (IS 401)]
    B --> C[Storage Under Shade]
    C --> D[Place on Preservative Treated Timber]
    D --> E[Apply End Coating]
    E --> F[Repeat Treatment Every 3-6 Months]

Note: Refer IS 401-1967 for detailed preservative types and application methods.

IS 9104: Inspection and Handling of Logs – Key Points

IS 9104 focuses on proper storage and protection of logs to prevent damage like cracking, mould, decay, and insect attack.

Key Specifications:

• Inspection of Logs:

  • Check for surface and end cracks.
  • Identify signs of mould, decay, or insect infestation.
  • Logs with defects should be segregated and treated or discarded.

• Handling:

  • Use proper lifting equipment to avoid mechanical damage.
  • Avoid dropping or dragging logs on rough surfaces.
  • Handle logs gently to prevent surface bruising.

• Storage Guidelines:

  • Store logs on well-drained, raised platforms to avoid moisture.
  • Stack logs with uniform spacing for air circulation.
  • Cover stacks with waterproof sheets but allow ventilation.
  • Maintain logs away from soil contact to prevent decay.

Typical Storage Stack Dimensions (Recommended):

Protection Measures:

• Apply fungicides/insecticides if infestation is detected.
• Rotate stock regularly to avoid prolonged storage.

flowchart LR
    A[Log Inspection] --> B{Defects?}
    B -- Yes --> C[Treatment or Segregation]
    B -- No --> D[Proper Handling]
    D --> E[Storage on Raised Platform]
    E --> F[Cover & Ventilate]
    F --> G[Periodic Monitoring]

This ensures logs remain in good condition for conversion into quality timber.

Storage After Conversion in Depots/Yards (IS 9104)

IS 9104 emphasizes proper storage of logs and converted timber to prevent damage such as cracking, mould, decay, and insect attack.

Key Specifications:

• Storage Period: Logs in depots have shorter storage periods than saw mill yards but require proper handling regardless.
• Protection Measures:
  • Logs must be stacked scientifically to avoid surface/end cracking.
  • Apply effective preservatives on insect-damaged parts.
  • Segregate unusable timber after treatment.
• Environmental Control: Ensure good ventilation and protection from moisture to minimize biological deterioration.

Practical Guidelines (from IS 9104 & engineering practice):

Rounding Off:

• Follow IS 2-1960 rules for rounding test values during compliance checks.

flowchart LR
    A[Logs Received] --> B[Inspection for Damage]
    B -->|No Damage| C[Stacking with Airflow]
    B -->|Damage Found| D[Apply Preservatives]
    D --> E[Segregate Unusable Timber]
    C --> F[Regular Monitoring]
    F --> G[Dispatch or Further Processing]

This ensures timber quality is maintained during storage after conversion.

Protection Against Cracks/Splits During Air Seasoning (IS 9104)

Key Specifications (Clause 6.1):

• Species prone to cracking (e.g., sal, laurel, irul) require special treatment during air seasoning.
• Use hygroscopic-cum-antishrink chemicals such as:
  • Polyethylene glycol (PEG-1000) – most effective
  • Urea
  • Common salt
• Treatment method: Spray or soak timber in 50% PEG-1000 aqueous solution with 1-2% sodium pentachlorophenate (for insect/fungi protection).
• Temperature: 45-50°C (can go up to 60°C for better diffusion).
• Treatment duration depends on species refractoriness and cross-section thickness.
• After treatment, close pack timbers briefly, then air-dry under shade/shed per IS 1141-1973.

Important Notes:

• End-coating before stacking reduces end-splits.
• Air seasoning sheds must suit climate, species, and timber thickness.
• Prophylactic treatment before stacking is essential in damp climates.

Summary Table: Protection Method

flowchart TD
    A[Green Timber] --> B[Treatment with PEG-1000 Solution]
    B --> C[Close Packing]
    C --> D[Air Seasoning in Shed/Shade]
    D --> E[Reduced Cracks & Splits]

This ensures minimal cracking/splitting during air seasoning, especially for refractory species.