Timber Door, Window and Ventilator Frames

IS 4021: Scope - Key Formulas, Tables & Specifications

Scope:
Covers timber frames for doors, windows, ventilators specifying material, dimensions, workmanship, and sampling.

1. Sampling (Clause 2.3 & Annex C)

• All sampled frames inspected for material (Clause 4), dimensions & tolerances (Clause 6), workmanship & finish (Clauses 5 & 8).

2. Dimensions & Tolerances (Clause 6.1, Table 2)

• Tolerances: +3 mm width, +2 mm thickness.

3. Designation (Clause 6.3)

• Format: Width Type Height (modules)
• Type codes:
  • D = Door
  • W = Window
  • V = Ventilator
  • S = Single shutter
  • T = Double shutter
• Example: 12 DT 20 = Double shutter door, 12 modules wide (119 cm), 20 modules high (199 cm).

4. Purch

IS 4021: Sampling and Inspection Key Points

Sampling Procedure (Clause 2.3 & C-2.3)

• Inspect all selected frames for:
  • Material quality (see Clause 4)
  • Dimensions & tolerances (Clause 6)
  • Workmanship & finish (Clauses 5 & 8)

Sample Size & Permissible Defectives (Table 3, Clause C-2.1)

• Samples must be randomly selected (per IS 4905:1968).

Criteria for Conformity (Clause 2.1 & 2.2)

• Number of frames inspected depends on lot size (see Table above).
• Random selection ensures unbiased inspection.

Additional Notes

• Purchaser must specify frame size, type, shutter thickness, opening direction, timber group/grade, finish, and ventilator details (Clause 11).
• Imported timber species require treatment as per IS 401:1982.

flowchart TD
    A[Lot Size] --> B[Determine Sample Size (Table 3)]
    B --> C[Random Selection of Frames (IS 4905)]
    C --> D[Inspection for Material, Dimensions, Workmanship]
    D --> E{Defectives ≤ Permissible?}
    E -->|Yes| F[Lot Accepted]
    E -->|No| G[Lot Rejected]

Summary: Use Table 3 for sample sizes and defect limits, ensure random sampling, inspect all selected frames per relevant clauses, and confirm conformity based on permissible defectives.

IS 4021: Criteria for Conformity - Key Points

Sampling & Inspection (Clause 2.3, Annex C)

• All sampled frames inspected for:
  • Material (Clause 4)
  • Dimensions & tolerances (Clause 6)
  • Workmanship & finish (Clauses 5 & 8)
• Acceptance Criteria:
  A lot conforms if defective frames ≤ permissible defectives (Table 3).

Timber Defects Permissible (Table 1, Clause 4.1.5)

Additional Notes:

• Imported timber species require treatment per IS 401:1982 unless heartwood is highly durable.
• Purchaser must specify frame size, type, opening direction, timber grade, finish, and ventilator details.

Summary Diagram: Sampling & Conformity Decision

flowchart TD
    A[Start

IS 4021: Materials and Defects - Key Formulas, Tables & Specifications

1. Sampling & Permissible Defectives (Clause 2.3, Table 3)

• All sampled frames inspected for material quality, dimensions, tolerances, workmanship, and finish.

2. Permissible Defects in Timber (Clause 4.1.5, Table 1)

3. Defects Prohibited (Clause 4.1.4)

• Decay, fungal growth, boxed heart, splits, pitch pockets/streaks on exposed faces are not allowed.
• **Knots not allowed at joints or

IS 4021 - Joinery and Assembly: Key Points

1. Permissible Defects in Timber (Clause 4.1.5, Table 5.2)

2. Joinery Types (Clause 5.2.1)

• Single dovetail joint (Fig. 2): Wedge-shaped, resists withdrawal except along assembly direction.
• Closed mortice and tenon joint (Fig. 3)
• Haunched mortice and tenon joint (Fig. 4)

3. Gluing of Joints (Clause 5.3)

• Joints must be glued properly for strength and durability.
• Use adhesives compatible with timber species.

4. Typical Joint Dimensions (from Figures 2 & 3)

• Thickness of tenon ≈ thickness of post/frame
• Width of tenon ≈ 1/3 to 1/2 width of post
• Shoulders: Full contact for strength
• Root of tenon: Avoid sharp corners to reduce stress concentration

Summary Diagram of Single Dovetail Joint:

graph TD
A[Post] -- Tenon --> B[Mortice in Frame]
B -- Dovetail shape --> C[Wedge fit]
C -- Resists withdrawal -->

Here are the key formulas, tables, and specifications from IS 4021 regarding Dimensions and Designation of timber door, window, and ventilator frames:

1. Designation of Frames (Clause 6.3)

• Format:
  Width (modules) + Type + Height (modules)
• Type Symbols:
  • D = Door
  • W = Window
  • V = Ventilator
  • S = Single shutter
  • T = Double shutter
• Double sets of shutters: Use DD, WW, VV
• Example:
  12 DT 20 = Double shutter door, 12 modules wide (119 cm), 20 modules high (199 cm)

2. Dimensions of Frames (Table 2, Clause 6.1)

• Shutter thickness (R): 25, 30, 35, or 40 mm
• Tolerances: +3 mm width, +2 mm thickness

3. Modular Size Reference (Clause 6.2)

• Width and height are expressed in modules for coordination.
• Non-modular sizes allowed only for width and height, cross-section remains per standard.

4. Typical Cross Sections

• Refer to

IS 4021: Location & Specifications of Metallic Fasteners / Holdfasts

Key Points from Clause 7 (Location of Holdfasts)

• Door Frames:

  • Minimum 3 holdfasts per side.
  • Locations:
    • 1 at center
    • 2 at 30 cm from top and bottom edges
  • Exception: For horned head frames, provide 2 equally spaced holdfasts per side.

• Window & Ventilator Frames:

  • Height ≤ 60 cm: 1 holdfast per side, centrally placed.
  • Height > 60 cm: 2 holdfasts per side, suitably spaced (with or without horns).

Fixing Details (Clause 5.4)

• Frames fixed during wall construction (built-in) or after wall completion.
• Use metallic fasteners or iron holdfasts.
• Door frames without sill: vertical members embedded full depth into flooring and anchored with metal pins.
• Frames must be wedged or strutted to prevent warping.

Summary Table for Holdfast Locations

Diagram: Holdfast Locations on Door Frame

graph TB
    top[Holdfast at 30 cm from Top]
    center[Holdfast at Center]
    bottom[Holdfast at 30 cm from Bottom]
    frame[Door Frame Side]

    frame --> top
    frame --> center
    frame --> bottom

This ensures secure fixing and prevents frame distortion during and after construction as per IS 4021.

IS 4021: Surface Finish and Priming - Key Points

• Priming Coat:

  • All timber door, window, and ventilator frames to be painted, polished, or varnished must receive a priming coat of suitable wood primer (per IS 3536:1966) before delivery.
  • Cut surfaces, especially end grains, must be primed before installation to prevent moisture ingress.

• Paint Finish:

  • Priming alone does not provide full weather protection. Frames should receive subsequent coats of paint, polish, or varnish within a reasonable time after priming.

• Aluminium Primer:

  • Use only special aluminium primers designed for timber frames to ensure a satisfactory finish.

• Unexposed Surfaces:

  • Surfaces in contact with walls or lintels must be coated with coal tar pitch (IS 216:1961) before delivery for moisture resistance.

• Reference Table (Fig. 9):

  • Provides preferred sizes of timber frames (in cm) for doors, windows, and ventilators (see IS 4021 Fig. 9).

Summary Table: Priming & Finishing Requirements

flowchart TD
    A[Timber Frame] --> B{Surface Type}
    B -->|Exposed| C[Apply wood primer (IS 3536) → Paint/varnish]
    B -->|Cut surface| D[Prime before fixing]
    B -->|Aluminium| E[Use special aluminium primer]
    B -->|Unexposed contact surfaces| F[Coat with coal tar pitch (IS 216)]

This ensures durability, weather resistance, and a quality finish per IS 4021.

IS 4021 - Information to be Supplied by the Purchaser (Clause 11)

When placing an order, the purchaser must provide:

• Frame size and type, including how the door-shutter opens (inward/outward).
• Shutter thickness and whether the frame is for exterior or interior use.
• For frames without sills, specify if pins are required.
• Group and grade of timber to be used.
• Finish details: whether the door is to be polished or painted.
• If a ventilator is present on top, specify if it is top hung, bottom hung, or centre hung to adjust the rebate accordingly.

Key Tables & Dimensions (Clause 6.1)

Designation Example (Clause 6.3)

• Format: Width Type Height
• Letters: D (Door), W (Window), V (Ventilator), S (Single shutter), T (Double shutter)
• Example: 12 DT 20 = Double shutter door, 12 modules wide, 20 modules high.

Sampling (Clause 2.3 & Table 3)

This ensures clarity in orders, quality control, and compliance with IS

Additional Requirements for ECO Mark (IS 4021:1995, Clause 10)

Key Points:

• Material Source: Door shutters must be made from:

  • Agricultural/industrial wastes
  • Wood residues
  • Wood from non-natural forests (e.g., industrial/social forestry plantations, shade trees from tea/coffee estates)
  • As per IS 12896:1990

• Quality & Performance: Must meet this standard's requirements and ECO Mark environmental criteria.

• Documentation: Manufacturers must submit:

  • Certificates/declarations proving eco-friendly material usage
  • Environmental consent clearance from State Pollution Control Board (Water & Air Acts)
  • Authorization under Environment (Protection) Act, 1986 if applicable

• Marking: Besides the BIS Standard Mark, the product shall carry the ECO Mark.

Important Specifications & References

Annex B: Selected Imported Timber Species for Frames (Examples)

*Species marked with * have durable heartwood; others require treatment per IS 401:2001.

Summary Diagram: ECO Mark Certification Process

flowchart TD
    A[Select Eco-friendly Material] --> B[Manufacture Door Shutters]
    B --> C[Meet IS 4021 Quality & Performance]
    C --> D[Submit Documentation to BIS]
    D --> E[Ob

IS 4021: List of Related Indian Standards

Key Notes:

• Imported timber species for frames require treatment per IS 401:1982.
• Heartwood of species marked '+' is durable without treatment.
• Species refractory to preservative treatment require PCP solvent system post-construction.
• Definitions as per IS 10428:1983 and IS 707:1976 apply.

This list ensures compliance with timber quality, treatment, and finishing for durable door and window frames.

flowchart LR
    A[IS 4021] --> B[Timber Preservation - IS 401]
    A --> C[Moisture Content - IS 287]
    A --> D[Seasoning - IS 1141]
    A --> E[Timber Classification - IS 12896]
    A --> F[Adhesives - Polyvinyl Acetate]
    A --> G[Paint & Primer - IS 3536 & IS 4835]

This diagram shows the interconnected standards supporting IS 4021.

IS 4021: Imported Timber Species Suitable for Frames

Key Imported Timber Species (Annex B, Clause 4.1.1)

(*) Heartwood species marked do not require preservative treatment due to high natural durability.

Treatment Requirements

• All species except those marked (*) must be treated as per IS 401:2001 (Code of Practice for Preservation of Timber).
• For species with poor treatability, use PCP solvent system after construction:
  • Soak in 5% PCP solution for 24 hours or pressure treat.
  • Ensure minimum preservative penetration of 2 mm in finished frames.

Dimensions & Tolerances (Clause 6.1)

• Finished timber section dimensions for frames must follow Table 2

IS 4021: Sampling Procedures for Timber Door & Window Frames

Key Clauses & Tables:

Sampling Size & Defectives (Clause 2.1, Table 3)

• Samples must be randomly selected (see IS 4905:1968 for randomization procedures).
• All selected frames are inspected for material quality, dimensions, tolerances, workmanship, and finish (Clauses 4, 5, 6, 8).

Criteria for Conformity (Clause C-3)

• Lot is accepted if number of defectives ≤ permissible number.
• Otherwise, lot is rejected.

Additional Notes:

• Sampling ensures quality control without inspecting every frame.
• Random selection avoids bias.
• Inspection covers:
  • Material properties (e.g., timber species, treatment)
  • Dimensional tolerances (critical for fitting)
  • Visual finish and workmanship defects.

Summary Flowchart of Sampling Procedure:

flowchart TD
    A[Start: Lot Received] --> B[Determine Lot Size]
    B --> C[Select Sample Size (Table 3)]
    C --> D[Randomly Select Frames (IS 4905)]
    D --> E[Inspect Frames for Material, Dimensions, Workmanship]
    E --> F{Number of Defectives ≤ Permissible?}
    F -- Yes --> G[Accept Lot]
    F -- No --> H[Reject Lot]

For detailed timber species, treatment, and purchaser info, refer to Annex B and Clause 11 of IS 4021.

IS 4021: Committee Composition & Key Specifications

Committee Composition (Annex D)

• Chairman: Brig Kulwant Singh (Engineer-in-Chief's Branch, Army HQ)
• Members: Representatives from industries, government departments, research institutes, and associations related to doors, windows, and shutters.
• Subcommittees: Wood and lignocellulosic materials handled by CED 11.1 with a Convener and members from Central PWD, Plywood institutes, and industry experts.

Sampling & Conformity (Clause 2.3, 3.2 & Table 3)

• A lot is conforming if defectives ≤ permissible number.

Designation & Dimensions (Clause 6.3 & Table 2)

• Designation Format:
  Width (modules) + Type + Height (modules)
  • Type: D (Door), W (Window), V (Ventilator), S (Single shutter), T (Double shutter)
  • Example: 12 DT 20 = Double shutter door, 12 modules wide, 20 modules high.

• For small windows & ventilators, thickness is 50 mm.

Summary Diagram: Frame Designation

graph LR
A[Width in Modules] --> B[Type (D/W/V + S/T)]
B --> C[Height in