Selection and Use of Various Types of Lignocellulosic Panel Products - Code of Practice, Part 2: Hardboards

IS 15973 Part 2: Scope Overview

• Scope Definition: IS 15973 Part 2 covers specifications related to hardboards and fibre insulation boards used in construction.
• Reference Standards: The standard refers to IS 1658 for definitions and IS 3348:1965 for fibre insulation board specifications.
• Annex A: Provides useful data on physical and mechanical properties of hardboards, such as density, moisture content, and strength.
• Application: Used for quality control and material selection in structural and non-structural building elements involving hardboards.

Key Points:

Typical Properties (from Annex A):

• Density: ~800-1200 kg/m³
• Moisture Content: 5-12%
• Modulus of Rupture: 15-30 MPa (typical range)

flowchart LR
    A[IS 15973 Part 2] --> B[Definitions from IS 1658]
    A --> C[Fibre Insulation Boards - IS 3348]
    A --> D[Annex A: Hardboard Properties]
    D --> E[Density, Strength, Moisture Content]

For detailed design or material selection, refer to the latest editions of referenced standards.

IS 15973 Part 2 – References Summary

• Referenced Standards:

  • IS 1658: Definitions related to hardboards and fibreboards.
  • IS 3348:1965: Specification for fibre insulation boards.

• Key Notes:

  • These referenced standards form an integral part of IS 15973 Part 2.
  • Users should consult the latest editions for updated provisions.
  • Annex A in IS 15973 Part 2 provides useful data on physical and mechanical properties of hardboards.

Typical Properties from Annex A (Example)

Usage Tip:

Always cross-check definitions and material specs with IS 1658 and IS 3348 for consistency in design and procurement.

IS 15973 Part 2 - Definitions Summary

• Definitions: As per IS 15973 Part 2, all definitions are referenced from IS 1658 (Specification for Hardboards). This means the terms and their meanings used in IS 15973 Part 2 strictly follow IS 1658.

• Annex A: Contains additional useful data on properties of hardboards, such as density, moisture content, and mechanical properties.

• Referenced Standards:

  • IS 1658: Main source for definitions.
  • IS 3348:1965: Specification for fibre insulation boards, relevant for related materials.

Key points from IS 1658 (Definitions context):

• Hardboard: A panel product made by pressing wood fibers under heat and pressure.
• Density: Typically ranges from 800 to 1100 kg/m³.
• Moisture Content: Usually maintained between 4% and 8%.

Typical properties table (from Annex A / IS 1658 context):

If you need specific formulas or detailed property values, consult IS 1658 directly, as IS 15973 Part 2 defers definitions and specifications to it.

IS 15973 Part 2 - Types of Hardboards: Key Specifications & Properties

Types of Fibre Hardboards (Based on Density)

• Standard Hardboard
• Tempered Hardboard
• Other variants (not explicitly detailed in the provided context)

Handling & Conditioning (Clause 8.2)

• Moistening back side with 0.5 to 1 litre water per board (2440 × 1220 mm, 3 mm thick)
• Stack back-to-back for 24 hours before fixing
• Fix immediately after conditioning to avoid warping

Mechanical Properties (Annex A)

Moulding (Clause 14)

• Radii: 20 to 80 mm
• Preheat & mould temp: 300 to 400 °C
• Moulding time: 5 to 150 seconds
• Wire side as convex surface improves mouldability

Fixing Recommendations

• Fixings spaced 100 to 150 mm apart
• Screws/nails placed 12 mm from edges
• Nailing/screwing from center outward, avoid forcing

flowchart TD
    A[Hardboard Types] --> B(Standard Hardboard)
    A --> C(Tempered Hardboard)
    B --> D[Properties: Screw Holding 250-320 kg, Nail Holding 130-150 kg]
    C --> E[Properties: Screw Holding 300-350 kg, Nail Holding 140-150 kg]
    F[Handling] --> G[Moisten Back Side 0.5

Applications of Hardboards (IS 15973 Part 2)

Key Specifications & Properties (Annex A)

Handling & Installation

• Conditioning: Moisten back side with 0.5–1 litre water/board (2440×1220×3 mm), stack back-to-back for 24h to avoid warping.
• Cutting: Use panel saw, fibreboard cutter, or fine saw at low angle with face up.
• Fixing: Frame spacing evenly along length & width; fixings ~12 mm from edges.
• Screw/Nail Spacing: 100–150 mm apart, start from center outward; rails paired, not staggered.

Moulding

• Radii: 20–80 mm.
• Preheat & mould temp: 300–400 °C, time 5–150 s.
• Wire side convex for better mouldability.

Finishing

• Use timber-compatible paints.
• Avoid water-based finishes if drying is slow.
• Follow manufacturer’s primer and coat recommendations.

flowchart TD
    A[Hardboard] --> B[Conditioning]
    B --> C[Cutting & Shaping]
    C --> D[Fixing (Screwing/Nailing)]
    D --> E[Finishing & Painting]
    A --> F[Moulding (Heat & Pressure)]

This summary aids in proper selection, handling, fixing, and finishing of hardboards per IS 15973 Part 2.

IS 15973 (Part 2): 2013 - Type Selection for Hardboards

Though Clause 6 and Annex A provide guidelines, key points for Type Selection of hardboards under IS 15973 (Part 2) are:

Key Specifications for Type Selection:

• Type A: General purpose, interior use, moderate moisture conditions.
• Type B: Suitable for humid conditions, interior/exterior protected applications.
• Type C: Exterior use, high moisture resistance, weatherproof.

Annex A Highlights (Typical Properties):

Selection Criteria:

• Moisture exposure: Choose Type B or C for humid/wet environments.
• Mechanical strength: Type C offers highest strength and durability.
• Application: Interior dry use suits Type A.

flowchart LR
    A[Type Selection] --> B[Type A: Interior, Dry]
    A --> C[Type B: Interior, Humid]
    A --> D[Type C: Exterior, Weatherproof]
    B --> E[Lower moisture resistance]
    C --> F[Moderate moisture resistance]
    D --> G[High moisture & strength]

For detailed property values and test methods, refer to Annex A of IS 15973 (Part 2): 2013.

IS 15973 (Part 2): Fasteners and Fixings Summary

Key Specifications:

• Fastener length & thickness: Selected based on panel type and thickness (Clause 7.2).
• Rust resistance: Fasteners must be rust-resistant (Clause 7.3).
• Fixing spacing: Screws/nails spaced 100–150 mm apart; fix near edges ~12 mm from board edges (Clause 13, 12).
• Fixing method: Nail/screw from center outward without forcing; rails on adjoining edges paired, not staggered.

Holding Strength (Annex A):

Additional Notes:

• Boards should be conditioned before fixing to avoid warping (water 0.5–1 litre/board, 24h stacking).
• Use appropriate metal types considering thermal expansion differences (wood > steel > aluminium > plastics).
• Hardboards can be moulded at 300–400°C with radii 20–80 mm.

Quick Reference Diagram: Fixing Layout

flowchart LR
    A[Board Edge] -->|~12 mm| B(Fixing Point)
    B -->|Spacing 100-150 mm| C(Next Fixing Point)
    C --> D(Along Length/Width)

Summary: Use rust-resistant screws/nails sized per panel thickness, spaced 100–150 mm, fixed 12 mm from edges, with screw/nail holding strengths as above for design.

Storage and Handling of Hardboards (IS 15973 Part 2)

Key Specifications & Guidelines:

• Storage (Clause 8.1):

  • Stack boards flat on closely spaced bearers or vertically along long edges with proper support.
  • Avoid termite-infested areas, wet/loose ground.
  • Store under cover to protect from rain and high humidity.
  • Retain protective packing until use.

• Handling (Clause 8.2):

  • Avoid edge damage; pack tightly with edge protection during transport.
  • Conditioning: Moisten back side with 0.5 to 1 litre water per board (2440×1220×3 mm), stack back-to-back for 24h before fixing.
  • Cut with ordinary panel saw or fibreboard cutter; use low-angle fine saw or circular saw blades set low.

Fasteners (Clause 7.3 & Annex A):

• Use rust-resistant fasteners.
• Screw holding strength:
  • Standard hardboard: 250–320 kg
  • Tempered hardboard: 300–350 kg
• Nail holding strength:
  • Standard hardboard: 130–150 kg
  • Tempered hardboard: 140–150 kg

Fixing (Clauses 11-13):

• Fix boards with screws/nails spaced 100–150 mm apart.
• Fix near edges at ~12 mm from edges.
• Nail/screw from center outward without forcing.
• Framework should run lengthwise and widthwise evenly spaced.

Moulding (Clause 14):

• Mould radius: 20–80 mm using heat (300–400°C) and pressure.
• Pre-heat and keep wire side convex.
• Moulding time: 5–150 seconds.

Useful Properties (Annex A):

flowchart TD
    A[Storage

Cutting and Machining of Hardboards (IS 15973 Part 2:2013)

Key Specifications:

• Conditioning: Moisten back side with 0.5 to 1 litre water per board (2440 × 1220 mm, 3 mm thick), stack back-to-back for 24h before fixing.
• Cutting Tools:
  • Ordinary panel saw (board face side up).
  • Fibreboard cutter for clean edges.
  • Fibreboard plane for grooving, beveling, scoring.
  • Fine saw for hand sawing at low angle, face supported uppermost.
  • Circular saw blades for machine sawing; cut into face side, blade set low for correct angle.

Fixing and Joining:

• Use wood-working adhesives; surface prep needed for plastics/metal bonding.
• Fix boards with screws/nails spaced 100–150 mm apart, 12 mm from edges.
• Nail/screw from center outward; rails on adjoining edges paired, not staggered.

Mechanical Properties (Annex A):

Moulding:

• Radius: 20–80 mm.
• Preheat at 300–400 ℃ for 5–150 s.
• Wire side convex during moulding.

flowchart TD
    A[Board Conditioning] --> B[Cutting]
    B --> C{Cutting Tools}
    C -->|Panel Saw| D[Face Up]
    C -->|Fibreboard Cutter| E[Clean Edge]
    C -->|Circular Saw| F[Blade Low]
    B --> G[Fixing]
    G --> H[Screw/Nail Spacing 100-150 mm]
    G --> I[Edge Distance 12 mm]
    G --> J[Center Outward Fixing]

This summary ensures proper handling, cutting,

IS 15973 Part 2: Bonding and Adhesives for Hardboards

Key Specifications & Recommendations:

• Adhesives: Use common woodworking adhesives suitable for wood products.
• Surface Preparation: Essential when bonding to plastics or metals for good adhesion.
• Metal Choice: Consider thermal expansion differences (Wood > Steel > Aluminium > Plastics) to avoid bond failure.
• Fixing:
  • Fixings near edges at ~12 mm distance.
  • Screws/nails spaced 100-150 mm apart, installed from center outward gently.

Handling & Conditioning:

• Condition boards by moistening back side with 0.5 to 1 litre water per 2440×1220×3 mm board, stack back-to-back for 24h before fixing.
• Cut with fine saw or fiberboard cutter; support board face up.

Mechanical Properties (Annex A):

Thermal Properties:

• Thermal conductivity: 0.124 kcal/h/°C/m
• Continuous thermal resistance: ≥ 150 °C

Moulding:

• Radii: 20 to 80 mm
• Preheat & mould temp: 300 to 400 °C
• Moulding time: 5 to 150 s

flowchart LR
    A[Surface Preparation] --> B[Adhesive Application]
    B --> C[Fixing: Screws/Nails]
    C --> D[Conditioning: Moistening & Stacking]
    D --> E[Final Installation]

Summary: Use appropriate adhesives, prepare surfaces well, consider thermal expansion differences, condition boards before fixing, and follow spacing guidelines for screws/nails for durable bonding and fixing of hardboards.

IS 15973 Part 2: Joining and Fixing of Hardboards

Key Specifications & Guidelines

• Conditioning:

  • Moisten back side with 0.5 to 1 litre water per board (2440×1220×3 mm)
  • Stack back-to-back for ≥24 hours before fixing
  • Fix immediately after conditioning to avoid warping

• Fixing Framework:

  • Use wooden, metallic, or plastic frames
  • Frame members spaced evenly along length and width
  • Fixings placed ~12 mm from board edges

• Screwing & Nailing:

  • Start fixing from center outward
  • Spacing: 100 to 150 mm between screws/nails
  • Rails on adjoining edges should be paired, not staggered
  • Use rust-resistant fasteners
  • Length/thickness of screws/nails depends on panel thickness

• Adhesives:

  • Use wood-working adhesives suitable for substrate
  • Surface preparation required, especially for plastics/metal
  • Consider differential thermal expansion: Wood > Steel > Aluminium > Plastics

Mechanical Properties (Annex A)

Summary Diagram: Fixing Layout

graph LR
A[Board] --> B[Frame members evenly spaced]
B --> C[Fixings ~12 mm from edges]
C --> D[Screws/Nails spaced 100-150 mm]
D --> E[Start fixing center outward]

Note: Avoid water-based finishes unless panels can dry quickly. Use recommended primers and multiple coats as per manufacturer instructions.

IS 15973 Part 2: Key Specifications for Partitions and Paneling

1. Fixing & Framework (Clause 12)

• Hardboards can be fixed on wooden, metallic, or plastic frameworks.
• Frame members should run along the length and width of the board.
• Fixings must be placed ~12 mm from board edges.
• Fixings spaced 100-150 mm apart (Clause 13).
• Screws/nails installed from center outward, not forced.
• Rails on adjoining edges should be paired, not staggered.

2. Handling & Conditioning (Clause 8.2)

• Condition boards by moistening the back with 0.5 to 1 litre water per 2440×1220×3 mm board.
• Stack back-to-back for 24 hours before fixing.
• Cut with panel saw, fibreboard cutter, or fine saw at low angles.

3. Mechanical Properties (Annex A)

4. Moulding (Clause 14)

• Mould radius: 20 to 80 mm.
• Preheat & mould temp: 300 to 400 °C, time 5 to 150 s.
• Keep wire side convex for better moulding.

flowchart LR
    A[Hardboard Panel] --> B[Framework]
    B --> C{Material}
    C -->|Wood| D[Fixings @ 12mm from edges]
    C -->|Metal| D
    C -->|

IS 15973 Part 2: Screwing and Nailing Key Points

1. Types of Fasteners (Clause 7.1)

• Use normal woodworking hardware: clout nails, wire nails, annular ringed shank nails, proprietary gun-driven nails.
• For metal/plastic substrates: non-corroding self-tapping screws or proprietary clips/hooks.

2. Fastener Dimensions (Clause 7.2)

• Length and thickness depend on panel type and thickness.
• Fixings should be near edges (~12 mm from edges) and spaced 100 to 150 mm apart (Clause 13).

3. Fixing Procedure (Clause 13)

• Nail/screw from center outward.
• Do not force fasteners.
• Rails on adjoining edges are paired, not staggered.

4. Holding Strength (Annex A)

5. Additional Tips

• Condition boards before fixing (moisten back, stack 24h).
• Avoid damage to edges during handling.
• Use appropriate saws for clean cuts.

flowchart LR
    A[Select Fastener Type] --> B{Substrate Type}
    B -->|Wood| C[Use standard nails/screws]
    B -->|Metal/Plastic| D[Use non-corroding self-tapping screws]
    C --> E[Fix near edges (~12mm)]
    D --> E
    E --> F[Spacing 100-150 mm]
    F --> G[Fix from center outward]

This ensures optimal fixing strength and durability per IS 15973 Part 2.

Moulding of Fibre Hardboards (IS 15973 Part 2, Clause 14)

• Moulding Radius: 20 to 80 mm
• Process: Application of heat and pressure
• Pre-heating: Recommended, with wire side as convex surface for better mouldability
• Mould Temperature: 300 to 400 °C
• Moulding Time: 5 to 150 seconds
• Finish: Usual timber paints/finishes; avoid water-based finishes unless panels dry quickly
• Manufacturer's Guidelines: Follow for primers, coats, and drying times

Key Specifications & Properties (Annex A)

Handling & Cutting Summary

• Condition boards by moistening back side (0.5 to 1 litre water per 2440×1220×3 mm board) and stack back-to-back for 24 h before fixing.
• Cut with ordinary panel saw or fibreboard cutter for clean edges.
• Use low-angle fine saw or circular saw blades set low for machine cutting.

flowchart LR
    A[Pre-heat Hardboard] --> B{Moulding Radius 20-80 mm}
    B --> C[Apply Heat & Pressure]
    C --> D[Mould Temp 300-400°C]
    D --> E[Moulding Time 5-150 s]
    E --> F[Cooling & Finishing]
    F --> G[Apply Paint/Finish]

This ensures proper shaping and surface finish of fibre hardboards as per IS

IS 15973 Part 2: Finishing & Surface Treatment of Hardboards

Key Specifications & Guidelines

• Handling & Conditioning (Clause 8.2):

  • Moistening back side with 0.5 to 1 litre water per board (2440×1220×3 mm).
  • Stack back-to-back for ≥24 hours before fixing to avoid warping.
  • Fix boards immediately after conditioning.

• Cutting & Edge Finishing:

  • Use ordinary panel saw or fibreboard cutter for clean edges.
  • Saw at low angle with face side up.
  • Circular saw blades set low for machine cutting.

• Joining & Fixing (Clause 11, 13):

  • Use wood-working adhesives; surface prep needed for plastics/metal.
  • Fixings near edges at ~12 mm from edge.
  • Screws/nails spaced 100-150 mm apart, from center outward.
  • Use rust-resistant fasteners (Clause 7.3).

• Moulding (Clause 14):

  • Radii: 20-80 mm.
  • Preheat & mould at 300-400°C for 5-150 s.
  • Wire side as convex surface for better results.

• Finishing:

  • Use usual timber paints/finishes.
  • Avoid water-based finishes if drying is slow.
  • Follow manufacturer’s primer, coat, and drying recommendations.

Useful Properties (Annex A)

Summary Diagram: Fixing & Edge