Indian timbers for furniture and cabinets- Classification

IS 13622: Scope & Key Specifications Summary

Scope (Clause 3.1):

• Applies to timber species as defined in IS 707:1976 and additional species listed in this standard.

Group III Timbers (Clause 4.1.4 & Annex D):

• Criteria:
  • Strength coefficient ≥ 50
  • Weight relative to teak (100)
  • Grain, texture, finish suitable for polishing and appearance
• Examples of Group III species:

(Complete list in Annex D of IS 13622)

General Requirements (Clause 5.2.5):

• Maximum allowable bow and spring: 1 mm per metre length

Notes:

• The standard mark ensures compliance with BIS quality and testing.
• Detailed species properties and treatment requirements are in the annexes.
• For design, use strength coefficients and species-specific data from IS 707 & IS 13622.

flowchart TD
    A[IS 13622 Scope] --> B[Timber Species per IS 707]
    A --> C[Group III Timbers]
    C --> D[Strength Coefficient ≥ 50]
    C --> E[Weight relative to Teak]
    C --> F[Grain & Finish Quality]
    C --> G[Annex D Species List]
    A --> H[General Requirements]
    H --> I[Max Bow & Spring: 1 mm/m]

For detailed design, refer to IS 707 for strength values and IS 13622 Annex D for species selection.

IS 13622 - Definitions & Timber Grouping Summary

Clause 3.1:

• Definitions as per IS 707:1976 apply.
• Timber species are classified into groups based on durability and properties.

Timber Group Classifications (Annex A-D)

Notes:

• *Timber species marked with * require treatment for durability.
• **Timber species marked with ** have unknown durability.
• The classification helps select timber based on expected service life and environmental exposure.

Reference Table Format Example (Annex A - Super Group)

This classification is essential for specifying timber in construction per IS 13622, ensuring durability and performance.

flowchart LR
    A[Timber Species] --> B{Durability Group}
    B -->|Super Group| C[Highly Durable]
    B -->|Group I| D[Durable]
    B -->|Group II| E[Moderately Durable]
    B -->|Group III| F[Less Durable]

For detailed species lists and treatment requirements, refer to Annexes A-D

IS 13622: Classification Criteria for Timber Species

Timber species are classified into 4 groups based on strength coefficient, weight (relative to teak = 100), and grain/finish quality:

Additional General Requirement (4.1.1):

• Retention of shape value > 60 (teak = 100) for furniture-grade timber.

Summary

• Strength coefficient and weight relative to teak are primary quantitative criteria.
• Grain and finish quality are qualitative criteria.
• Species lists are provided in respective Annexes A-D.

flowchart TD
    A[Start: Timber Species] --> B{Strength Coefficient}
    B -->|≥75| C{Weight (85-110)}
    C -->|Yes| D[Super Group / Group II]
    C -->|No| E[Group III or IV]
    B -->|65 to <75| E
    B -->|50 to <65| F[Group IV]
    D --> G[Check Grain & Finish Quality]
    E --> G
    F --> G
    G --> H[Assign Group & Refer Annex]

This classification aids in selecting appropriate timber for furniture and cabinets as per IS 13622.

Timber Species Grouping as per IS 13622

Timber species are classified into 4 groups based on strength, weight, and appearance.

Group Criteria Summary

Key Tables (Excerpt)

Annex B - Group I Timbers

Annex C - Group II Timbers

Notes:

• Strength coefficient is a relative measure of timber strength.
• Weight is relative to teak (100).
• Some species marked * require treatment; ** durability unknown.
• Grain and finish relate to suitability for furniture/cabinet making.

flowchart TD
    A[Timber Species] --> B[Super Group (Annex A)]
    A --> C[Group I (Annex B)]
    A --> D[Group II

IS 13622: General Requirements Summary

1. Species Grouping (Clause 4.1)

• Group III (Clause 4.1.4):

  • Strength coefficient ≥ 50
  • Weight relative to teak (teak = 100)
  • Grain, texture, finish: Satisfactory polish & appearance
  • Species list: Annex D

• Group II (Clause 4.1.2):

  • Strength coefficient ≥ 75
  • Weight relative to teak: 85 to 110
  • Grain, texture, finish: Very good polish & appearance
  • Species list: Annex B

2. Definitions (Clause 3.1)

• Refer IS 707:1976 for wood definitions.

3. Permissible Defects (Clause 5.2)

• Defects allowed to specified extents (detailed in Clause 5.2).

Key Parameters Table (Simplified)

For detailed species lists and defect limits, refer to Annex B, Annex D, and Clause 5.2 of IS 13622.

flowchart LR
    A[Wood Species Selection] --> B{Strength Coefficient}
    B -->|≥ 75| C[Group II]
    B -->|≥ 50 and <75| D[Group III]
    C --> E[Weight 85-110 (Teak=100)]
    D --> F[Weight relative to Teak]
    C --> G[Very Good Finish]
    D --> H[Satisfactory Finish]

This ensures selection based on strength, weight, and finish quality per IS 13622 general requirements.

IS 13622: Seasoning and Moisture Content Key Points

• Seasoning Requirement (Clause 6 & 3.1):
  Timber must be seasoned to moisture content as per IS 287:1973 (Clauses 3.1 & 4.1). Seasoning methods follow IS 1141:1973.

• Moisture Content Determination:

  • Oven drying method or
  • Electrical moisture meter method (IS 11215:1991).

• Moisture Content Limits:
  Refer IS 287:1973 for max permissible moisture content depending on timber use (typically 12-15% for furniture).

• Wane Limits (Clause 5.2.7):

  • Max 4% of surface area affected by wane.
  • Max 25% pieces in a lot with wane.

• Preservative Treatment (Clause 7):
  Sapwood of durable species and class III timbers treated as per IS 401:1982.

Typical Moisture Content Limits for Seasoned Timber (from IS 287:1973)

Moisture Content Calculation (Oven Drying Method):

[ \text{Moisture Content} , (MC) = \frac{W_{wet} - W_{dry}}{W_{dry}} \times 100 ]

• (W_{wet}) = Weight before drying
• (W_{dry}) = Weight after oven drying

flowchart TD
    A[Green Timber] --> B[Seasoning Process (IS 1141)]
    B --> C[Moisture Content Check (IS 11215)]
    C -->|MC ≤ Specified Limit| D[Ready for Use]
    C -->|MC > Specified Limit| B

Summary: Season timber to moisture content per IS 287, verify by oven or electrical method (IS 11215), control wane to ≤4% surface and ≤25% pieces, and treat sapwood as per IS 401.

Preservative Treatment - IS 13622 Key Points

1. Moisture Content & Seasoning:

• Timber must be seasoned to moisture content as per IS 287:1973 (Clauses 3.1, 4.1).
• Seasoning methods per IS 1141:1973.
• Moisture content measured by oven drying or electrical moisture meter (IS 11215:1991).

2. Preservative Treatment:

• Sapwood of all durable species and timber of durability class III require preservative treatment (Clause 7).
• Treatment as per IS 401:1982 (Code of practice for preservation of timber).

3. Timber Classification for Treatment:

• Group I Timbers (Annex B, Clause 4.1.2): Includes species like Albizia procera (safed siris), Pterocarpus marsupium (bijasal), Fraxinus excelsior (ash).
• Group II Timbers (Annex C, Clause 4.1.3): Includes species like Acer spp. (maple), Cedrus deodara (deodar), Mangifera indica (mango), etc.
• Super Group Timbers (Annex A, Clause 4.1.1): Includes Albizia lebbeck (kokko), Dalbergia latifolia (rosewood), Tectona grandis (teak).

Summary Table: Timber Groups & Treatment Requirement

Preservative Treatment Process (per IS 401:1982):

• Methods: Pressure impregnation, brushing, dipping.
• Chemicals: Copper Chrome Arsenate (CCA), creosote, etc.
• Retention levels and penetration depth as per timber use and species.

flowchart TD
    A[Timber Species] --> B{Durability Class}
    B -->|Class I & II| C[No Treatment or Minimal]
    B -->|Class III or Sapwood| D[Preservative Treatment]
    D --> E[

IS 13622: Super Group Timbers - Key Specifications & Tables

Clause 4.1.1 - Criteria for Super Group Timbers:

• Strength coefficient: ≥ 75
• Weight (relative to teak = 100): 85 to 110
• Grain, texture, finish: Excellent polish and general appearance
• Shape retention value: > 60 (teak = 100)

Annex A (Clause 4.1.1) — Super Group Timber Species

Additional Notes:

• Species marked with * require treatment.
• Durability and finish are key for furniture and cabinetry.
• Teak (Tectona grandis) is the benchmark for weight and shape retention.

Summary Table of Key Properties

IS 13622: Group I Timbers Key Details

Group I Timbers (Annex B, Clause 4.1.2)

• Characteristics:
  • Strength coefficient ≥ 75
  • Weight: 85 to 110 (Teak = 100)
  • Excellent grain, texture, finish, and polish
• Moisture Content: Seasoned as per IS 287:1973 and IS 1141:1973
• Preservative Treatment: Sapwood treated as per IS 401:1982

Typical Species in Group I

Note: Species marked with * require treatment; + indicates unknown durability.

Summary Table: Selection Criteria for Group I Timbers

flowchart LR
    A[Timber Selection] --> B{Group I Criteria}
    B --> C[Strength ≥ 75]
    B --> D[Weight 85-110 (Teak=100)]
    B --> E[Excellent Grain & Finish]
    B --> F[Moisture Content as per IS 287]
    B --> G[Preservative Treatment per IS 401]
    C & D & E & F & G --> H[Group I Timbers]

For detailed species and treatment, refer to Annex B of IS 13622.

IS 13622: Group II Timbers Key Data

Group II Timbers (Annex C, Clause 4.1.3) include species with moderate strength and durability, suitable for furniture and general construction.

Important Species Examples:

• Acer spp. (Maple)
• Acrocarpus fraxinifolius (Mundani)
• Adina cordifolia (Haldu)
• Mangifera indica (Mango)
• Cedrus deodara (Deodar)
• Hevea brasiliensis (Rubber wood)
• Toona ciliata (Toon)

Selection Criteria (Compared to Teak = 100):

• Strength coefficient: ~50-75 (moderate)
• Weight: 85 to 110
• Grain & Finish: Satisfactory to good polish and appearance

Moisture Content & Treatment:

• Season timber to moisture content as per IS 287:1973.
• Preserve sapwood and durability class III timbers per IS 401:1982.

Summary Table (Excerpt)

flowchart TD
    A[Group II Timbers] --> B[Moderate Strength (50-75)]
    A --> C[Weight 85-110 (Teak=100)]
    A --> D[Good Grain & Finish]
    A --> E[Seasoning per IS 287]
    A --> F[Preservative Treatment per IS 401]

Note: For detailed species list and exact durability, refer Annex C of IS 13622.

Group III Timbers - IS 13622 Key Points

Criteria (Clause 4.1.4):

• Strength coefficient: ≥ 50
• Weight: Compared to teak (100)
• Grain, texture, finish: Satisfactory polish & appearance
• Species listed in Annex D (not provided here).

Timber Group Classification Summary (from Clauses 4.1.1 to 4.1.4)

Additional Specifications:

• Moisture Content: Season timber to IS 287:1973 & IS 1141:1973 standards.
• Preservative Treatment: Sapwood of durable species & Class III durability timbers treated per IS 401:1982.
• Retention of Shape Value: > 60 (teak = 100) for furniture-grade timbers.

Important Notes:

• For detailed species list and properties, refer to Annex D of IS 13622.
• Strength coefficient relates to mechanical strength (modulus of rupture, modulus of elasticity).
• Weight comparison is relative density or specific gravity vs teak.

If you need formulas for strength or design values, please specify.