converted timber (coniferous): Part 1 Light furniture

IS 5247 Part 1: Scope and Key Specifications

1. Scope (Clause 3.1)

• Applies to coniferous sawn timber baulks and scantlings.
• Timber species allowed are listed with Standard Trade Names, Botanical Names, and Abbreviated Symbols:

2. Rounding and Tolerances

• Values must be rounded per IS 2-1960 rules.
• Number of significant digits in results must match those in the standard.

3. References

• Definitions per IS 707-1976 apply.
• No explicit dimensional tables in this clause; refer to other parts or IS 707 for sizes.

Summary Diagram (Timber Species and Symbols)

graph TD
    CHR[Chir: Pinus roxburghii]
    CYP[Cypress: Cupressus torulosa]
    DEO[Deodar: Cedrus deodara]
    FIR[Fir: Abies spp.]
    KAL[Kail: Pinus wallichiana]
    KPI[Khasi Pine: Pinus kesiya]
    SPR[Spruce: Picea smithiana]
    CHR -->|Symbol| CHR
    CYP -->|Symbol| CYP
    DEO -->|Symbol| DEO
    FIR -->|Symbol| FIR
    KAL -->|Symbol| KAL
    KPI -->|Symbol| KPI
    SPR -->|Symbol| SPR

For detailed dimensions and mechanical properties, consult IS 707 and subsequent parts of IS 5247.

IS 5247 Part 1: Key Definitions & Specifications

1. Definitions (Clause 2.0)

• Definitions follow IS 707-1976 (Timber Terminology) plus additional terms in IS 5247.
• Timber species are identified by Standard Trade Names and Botanical Names.

2. Timber Species (Clause 3.1, Table 3)

3. Dimensions & Tolerances (Clause 7.3)

• Permissible defects are detailed in Table 1 of IS 5247.
• Defect measurement per IS 3364 (Part II)-1976.
• Rounding off results follows IS 2-1960: retain the same significant figures as specified.

Summary Diagram: Timber Selection & Quality Control

flowchart TD
    A[Start: Timber Selection] --> B{Species?}
    B -->|Chir| C[Use CHR]
    B -->|Cypress| D[Use CYP]
    B -->|Deodar| E[Use DEO]
    B -->|Fir| F[Use FIR]
    B -->|Kail| G[Use KAL]
    B -->|Khasi Pine| H[Use KPI]
    B -->|Spruce| I[Use SPR]
    C --> J[Check Defects per Table 1]
    D --> J
    E --> J
    F --> J
    G --> J
    H --> J
    I --> J
    J --> K[Measure defects per IS 3364]
    K --> L[Round off

IS 5247 Part 1 - Species of Timber: Key Specifications

1. Species of Timber (Clause 3.1)

2. Defect Limits (Summary from Table 1)

• Knots:
  • Live knots up to 10 mm (Grade 1) & 25 mm (Grade 2) diameter permissible.
  • Dead knots up to 6 mm (Grade 1) & 10 mm (Grade 2) permissible.
  • Larger knots allowed but limited in frequency (e.g., one per 60 cm or 1 m length).
• Sap Stain: Permissible unless specified otherwise.
• Grain deviation: Max 1 in 15 (Grade 1), 1 in 12 (Grade 2).
• Surface cracks: Depth limits vary with thickness (e.g., 1 mm for ≤50 mm thickness in Grade 1).
• Twist: Permissible up to 4 mm per 30 cm length (Grade 2).
• Centre heart: Allowed only in pieces >500 cm² cross-section and sound.

3. Dimensional Tolerances

• Warp (bow, crook, cup) limited to:
  • 2.0 mm per 30 cm length (bow)
  • 3 mm per 30 cm width (crook)
  • 4 mm per 30 cm width (cup)

Summary Diagram: Timber Defects and Limits

graph TD
    A[Timber Species] -->

IS 5247 Part 1 - Dimensions and Tolerances Summary

1. Species (Clause 3.1)

• Timber species allowed include:
  • Chir (CHR) - Pinus roxburghii
  • Cypress (CYP) - Cupressus torulosa
  • Deodar (DEO) - Cedrus deodara
  • Fir (FIR) - Abies spp.
  • Kail (KAL) - Pinus wallichiana
  • Khasi Pine (KPI) - Pinus kesiya
  • Spruce (SPR) - Picea smithiana

2. Dimensions and Tolerances (Clause 4.2)

• These tolerances apply irrespective of nominal size.

3. Defects (Clause 7.3)

• Permissible defects as per Table 1 (not provided here).
• Measurement of defects follows IS 3364 (Part II)-1976.

Notes:

• Thickness tolerance is only positive (+8 mm), meaning thickness can be larger but not smaller than nominal.
• Width tolerance is symmetric (±2 mm).
• Rounding rules follow IS standards for numerical values.

flowchart LR
    A[Nominal Size] --> B{Apply Tolerances}
    B -->|Width| C[± 2 mm]
    B -->|Thickness| D[+ 8 mm only]
    C & D --> E[Final Size Range]

This ensures dimensional control for coniferous sawn timber used in structural applications.

IS 5247 Part 1: Grading and Requirements Summary

1. Grading & Defects (Clause 5.1)

• Two grades of planks and scantling based on permissible and prohibited defects.
• Refer to Clause 5.2 and 7 for detailed defect specifications.

2. Species of Timber (Clause 3.1)

3. Width Tolerance (Clause 4.2.1)

• Minus tolerance in width not allowed in >25% of supply.
• For width range (e.g., 150 mm to 250 mm), no minus tolerance on minimum width or plus tolerance on maximum width permitted.

Practical Notes:

• Ensure timber grading strictly follows defect limits for intended use (light furniture).
• Use species abbreviations for documentation and specification clarity.
• Maintain dimensional tolerances to ensure quality and fit.

flowchart LR
    A[Timber Supply] --> B{Width Tolerance Check}
    B -->|Minus tolerance ≤25%| C[Accept Supply]
    B -->|Minus tolerance >25%| D[Reject Supply]
    C --> E{Grade Check}
    E -->|Permissible Defects| F[Grade 1 or 2]
    E -->|Prohibited Defects| D

For detailed defect tables and grading criteria, refer to Clauses 5.2 and 7 of IS 5247 Part 1.

IS 5247 Part 1 - Measurement & Volume Calculation of Timber Planks and Scantlings

Measurement Specifications (Clause 6.2)

• Length (m): Measured in metres; fractions rounded down to nearest 0.01 m
• Width (cm): Measured at narrowest point; rounded down to nearest 1 cm
• Thickness (cm): Measured at narrowest point; rounded down to nearest 0.5 cm
• Volume (m³): Calculated using accepted sizes, accurate to 3 decimal places

Tolerances (Clause 4.2)

Note: No tolerance added in volume calculation; use accepted sizes only.

Volume Calculation Formula

[ \text{Volume} = \text{Length (m)} \times \text{Width (m)} \times \text{Thickness (m)} ]

• Convert width and thickness from cm to m before calculation.

Summary Table for Measurement Rounding

flowchart TD
    A[Measure Length] --> B[Round down to 0.01 m]
    A --> C[Measure Width at narrowest point]
    C --> D[Round down to 1 cm]
    A --> E[Measure Thickness at narrowest point]
    E --> F[Round down to 0.5 cm]
    B & D & F --> G[Calculate Volume = L × W × T]
    G --> H[Round volume to 3 decimal places]

This ensures consistent, standardized measurement and volume calculation for timber as per IS 5247 (Part 1).

IS 5247 Part 1: Permissible Defects Summary

Key Points from Clause 7.3 & Table 1:

• Defects in timber are permissible only to the extent specified in Table 1.
• Defects must be measured as per IS 3364 (Part II) - 1976.
• Defects are considered collectively, not individually (Clause 7.2).

Measurement Specifications (Clause 6.2):

• Length: Measured in meters, rounded down to nearest 0.01 m.
• Width: Measured at narrowest point, rounded down to nearest 1 cm.
• Thickness: Measured at narrowest point, rounded down to nearest 0.5 cm.
• Volume: Calculated to three decimal places based on accepted sizes.

Typical Permissible Defects (from Table 1, IS 5247 Part 1):

Additional:

• Prophylactic treatment of timber as per IS 401-1982 (Clause 10.1).

Practical Use:

Volume (m³) = Length (m) × Width (m) × Thickness (m)

• Measure dimensions carefully as per Clause 6.2.
• Check defects collectively against Table 1 limits.
• Reject timber exceeding permissible defect limits.

flowchart TD
    A[Timber Sample] --> B[Measure Dimensions]
    B --> C{Check Defects}
    C -->|Within Limits| D[Accept Timber]
    C -->|Exceeds Limits| E[Reject Timber]

References:

• IS 5247 Part 1: Clause 6.2, 7.2, 7.3, Table 1
• IS 3364 (Part II) - 1976 for defect measurement
• IS 401-1982 for treatment

IS 5247 Part 1: Marking and Certification Key Points

• Marking Requirements (Clause 8.1):
  Each timber piece must be branded legibly and indelibly with:

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

• Certification Mark (Clause 8.1.1):

  • Timber may carry the ISI Certification Mark indicating compliance with the standard.
  • ISI Mark assures production under strict inspection, testing, and quality control supervised by ISI.
  • Licensing conditions for ISI Mark use are governed by the Indian Standards Institution (Certification Marks) Act.

• Rounding Off Numerical Values:

  • Follow IS 2-1960 for rounding test results.
  • Retain the same number of significant figures as specified in the standard.

Summary Table for Marking

ISI Certification Mark Flow

flowchart LR
    A[Timber Production] --> B[Inspection & Testing]
    B --> C{Complies with IS 5247?}
    C -->|Yes| D[ISI Certification Mark Granted]
    C -->|No| E[No Certification]
    D --> F[Continuous ISI Surveillance]

This ensures timber traceability and quality assurance as per IS 5247 Part 1.

IS 5247 Part 1: End Coating to Prevent Cracking

Key Points from Clause 9.1:

• End coating must cover the timber ends at least 25 mm beyond the longest split length.
• Coating materials should conform to IS: 1141-1973 (commonly bituminous or similar protective coatings).
• Apply coating immediately after inspection to prevent moisture ingress and cracking.

Practical Specification:

Additional Notes:

• End coating minimizes moisture loss, reducing end splitting.
• Ensure coating is uniform and continuous.
• For prophylactic treatment, refer to IS: 401-1982 (Clause 10.1).

Formula for Coating Length:

[ L_c = L_s + 25 \text{ mm} ]

Where:

• (L_c) = Length of coated end
• (L_s) = Length of longest split

flowchart LR
    A[Timber Inspection] --> B[Measure Longest Split (L_s)]
    B --> C[Calculate Coating Length (L_c = L_s + 25 mm)]
    C --> D[Apply End Coating (IS:1141-1973)]
    D --> E[Prevents Moisture Loss & Cracking]

This ensures durability and minimizes defects as per IS 5247 Part 1.

IS 5247 Part 1 - Prophylactic Treatment Key Points

1. Prophylactic Treatment (Clause 10.1):

   • All timbers may be treated as per IS: 401-1982.
   • Treatment type and application depend on purchaser-supplier agreement.

2. End Coating to Prevent Cracking (Clause 9.1):

   • Ends of planks/scantlings must be coated up to at least 25 mm beyond the longest split length.
   • Use materials specified in IS: 1141-1973.
   • Apply coating immediately after timber inspection.

3. Species Covered (Clause 3.1, Table 3):

4. Measurement & Rounding (Clause 4):
   • Final test values rounded per IS: 2-1960 to match precision of specified values.

Summary Diagram: Prophylactic Treatment Process

flowchart TD
    A[Timber Inspection] --> B{Is treatment agreed?}
    B -- Yes --> C[Apply Prophylactic Treatment as per IS:401-1982]
    B -- No --> D[No treatment applied]
    C --> E[End Coating Application]
    E --> F[Coat ends ≥ (Longest split + 25 mm) per IS:1141-1973]
    F --> G[Ready for use/storage]
    D --> G

Note: Refer to IS:401-1982 and IS:1141-1973 for detailed chemical treatment types and coating materials.