Indian timbers for furniture and cabinets- Classification
1993 Edition

Overview of Scope and Essential Specifications in IS 13622

Scope (Clause 3.1):

• Applies to timber species enumerated in IS 707:1976 alongside additional species featured in this standard.

Group III Timbers (Clause 4.1.4 & Annex D):

• Standards include:
  • Strength coefficient not less than 50
  • Weight relative to teak (baseline 100)
  • Grain, texture, and finish suitable for polishing and visual appeal
• Representative species in Group III:

(Complete species listing available in Annex D of IS 13622)

General Criteria (Clause 5.2.5):

• Maximum permissible bow and spring deformation: 1 mm per meter length

Additional Highlights:

• BIS certification mark confirms compliance with prescribed quality and testing norms.
• Detailed species characteristics and treatment requirements are provided in annexures.
• For structural design, strength coefficients and species data from IS 707 and IS 13622 should be referenced.

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

Definitions and Timber Group Classification Summary in IS 13622

Clause 3.1:

• Adopts definitions from IS 707:1976.
• Timber species are categorized into groups based on their durability and physical properties.

Timber Groupings (Annexes A to D)

Notes:

• Timbers marked with * require preservative treatment.
• Species marked with ** have undetermined durability.
• Classification assists in choosing timber considering expected lifespan and exposure conditions.

Sample Table Format (Annex A - Super Group)

This classification is fundamental for specifying timber in furniture and cabinetry per IS 13622 to ensure performance and durability.

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]

IS 13622: Classification Parameters for Timber Species

Timbers are divided into four categories based on strength coefficient, weight relative to teak (100), and grain/finish quality:

Additional General Criterion (4.1.1):

• Shape retention value must exceed 60 (relative to teak at 100) for furniture-grade timbers.

Overview

• Quantitative factors: strength coefficient and weight compared to teak.
• Qualitative factors: grain texture and finishing quality.
• Species lists corresponding to each group are provided in annexures A through D.

flowchart TD
    A[Timber Species Input] --> B{Strength Coefficient}
    B -->|≥ 75| C{Weight 85-110}
    C -->|Yes| D[Assign Super Group or Group I]
    C -->|No| E[Group II or III]
    B -->|65 to <75| E
    B -->|50 to <65| F[Group III]
    D --> G[Check Grain & Finish]
    E --> G
    F --> G
    G --> H[Group Assignment & Annex Reference]

Grouping of Timber Species in Accordance with IS 13622

Timber species are segmented into four groups based on strength, specific gravity, and aesthetic qualities.

Grouping Criteria Summary

Sample Tables (Extract)

Annex B - Group I Timbers

Annex C - Group II Timbers

Notes:

• Strength coefficient indicates relative mechanical strength.
• Weight is benchmarked against teak (100).
• Species marked with * require preservative treatment; ** denotes unknown durability.
• Grain and finish quality assess suitability for furniture and cabinetry use.

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

IS 13622: Summary of General Requirements

1. Group Classifications (Clause 4.1)

• Group III (Clause 4.1.4):

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

• Group II (Clause 4.1.2):

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

2. Definitions (Clause 3.1)

• Wood terminology as per IS 707:1976 applies.

3. Defect Limits (Clause 5.2)

• Acceptable defect levels specified in Clause 5.2.

Key Parameters at a Glance

For detailed species lists and defect specifications, consult Annex B, Annex D, and Clause 5.2 of IS 13622.

flowchart LR
    A[Timber 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]

Key Points on Seasoning and Moisture Content from IS 13622

• Seasoning Requirements (Clauses 3.1 & 6):
  Timber must be dried to moisture levels specified in IS 287:1973, employing seasoning methods outlined in IS 1141:1973.

• Moisture Measurement Methods:

  • Oven drying technique
  • Electrical moisture meter as per IS 11215:1991

• Permissible Moisture Content:
  Refer IS 287:1973 for maximum moisture limits depending on timber application, generally between 12% to 15% for furniture.

• Wane Restrictions (Clause 5.2.7):

  • Maximum 4% of surface area affected by wane
  • No more than 25% of pieces in a batch should contain wane

• Preservative Treatments (Clause 7):
  Sapwood of durable and Class III species must be treated following IS 401:1982.

Typical Moisture Content Limits (IS 287:1973)

Moisture Content Calculation (Oven Drying Method):

[ MC = \frac{W_{green} - W_{dry}}{W_{dry}} \times 100 ]

• (W_{green}): Weight prior to drying
• (W_{dry}): Weight after oven drying

flowchart TD
    A[Fresh Timber] --> B[Seasoning per IS 1141]
    B --> C[Moisture Content Check (IS 11215)]
    C -->|MC ≤ Limit| D[Approved for Use]
    C -->|MC > Limit| B

Essential Points on Preservative Treatment in IS 13622

1. Moisture and Seasoning Compliance:

• Timber must meet seasoning requirements per IS 287:1973 (Clauses 3.1, 4.1).
• Seasoning methods conform to IS 1141:1973.
• Moisture determined by oven drying or electrical moisture meter (IS 11215:1991).

2. Treatment Necessity:

• Sapwood of all durable species and those classified as durability class III require preservative treatment (Clause 7).
• Treatments are to be administered as per IS 401:1982, which outlines preservation techniques.

3. Timber Groupings and Treatment:

• Group I (Annex B): Includes species like Albizia procera (Safed Siris), Pterocarpus marsupium (Bijasal), Fraxinus excelsior (Ash).
• Group II (Annex C): Species such as Acer spp. (Maple), Cedrus deodara (Deodar), Mangifera indica (Mango).
• Super Group (Annex A): Species including Albizia lebbeck (Kokko), Dalbergia latifolia (Rosewood), Tectona grandis (Teak).

Treatment Summary Table

Treatment Methods (IS 401:1982):

• Pressure impregnation, brushing, dipping
• Chemicals such as Copper Chrome Arsenate (CCA), creosote
• Specific retention and penetration depend on timber use and species

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

IS 13622: Details on Super Group Timbers

Clause 4.1.1 - Criteria:

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

Annex A Species List

Notes:

• Species marked with * indicate the need for preservative treatment.
• Durability and finish quality are critical for furniture and cabinetry.
• Teak serves as the benchmark for weight and shape retention.

Property Summary Table

IS 13622: Overview of Group I Timbers

Characteristics (Annex B, Clause 4.1.2)

• Strength coefficient ≥ 75
• Weight range: 85 to 110 (Teak = 100)
• Excellent grain, texture, finish, and polish
• Seasoned as per IS 287:1973 and IS 1141:1973
• Sapwood requires preservative treatment in accordance with IS 401:1982

Representative Species

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

Selection Criteria Summary

flowchart LR
    A[Timber Candidate] --> B{Meets Group I Criteria?}
    B --> C[Strength ≥ 75]
    B --> D[Weight 85-110 (Teak=100)]
    B --> E[Excellent Grain & Finish]
    B --> F[Meets Moisture Content Standards]
    B --> G[Requires Preservative Treatment]
    C & D & E & F & G --> H[Classify as Group I Timber]

Details on Group II Timbers in IS 13622

Group II (Annex C, Clause 4.1.3) consists of species with moderate strength and durability, appropriate for furniture and general use.

Common Examples:

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

Selection Parameters (Relative to Teak = 100):

• Strength coefficient approximately 50 to 75
• Weight ranging from 85 to 110
• Grain and finish quality from satisfactory to good

Seasoning and Treatment:

• Timber must be seasoned adhering to IS 287:1973
• Sapwood and Class III timbers require preservation as per IS 401:1982

Summary Table

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

Essential Information on Group III Timbers (IS 13622)

Classification Criteria (Clause 4.1.4):

• Strength coefficient minimum 50
• Weight compared relative to teak (100)
• Grain, texture, and finish adequate for satisfactory polish and appearance
• Species detailed in Annex D (list not included here)

Summary of Timber Group Characteristics

Additional Standards:

• Season timber in compliance with IS 287:1973 and IS 1141:1973.
• Apply preservative treatment to sapwood and Class III durability timbers as per IS 401:1982.
• Maintain shape retention value above 60 (teak = 100) for furniture-grade timbers.

Important Notes:

• Detailed species list and specifications are available in Annex D.
• Strength coefficient reflects mechanical properties such as modulus of rupture and elasticity.
• Weight comparison indicates relative density against teak.

For design strength formulas or values, please request specific details.