Laying of Asbestos Cement Sheets - Code of Practice, Part 1: Corrugated Sheets

IS 3007 Part 1 — Scope Summary

This standard covers efficient planning and execution of roofing work, focusing on:

• Roof area to be covered
• Sub-structure details of the roof
• Roof pitch
• Location, size of openings, and roofing accessories

Key Specifications:

• Applies to roofing design & installation with SI units.
• Includes provisions for purlin spacing, expansion joints, shade protection, and safety.
• Refers to related Indian Standards (Annex A) for comprehensive requirements.
• Encourages use of latest editions of referenced standards.

Important Notes:

• Originally published in 1964; revised for practical experience and SI unit consistency.
• Emphasizes detailed information collection for planning.

No direct formulas or tables in the scope section, but these details guide design calculations and material selection per the standard.

flowchart LR
    A[Start: Roofing Project] --> B[Collect Roof Area]
    B --> C[Assess Sub-structure]
    C --> D[Determine Roof Pitch]
    D --> E[Mark Openings & Accessories]
    E --> F[Plan Execution per IS 3007]

IS 3007 Part 1: Key Definitions & Specifications

• Purlin Spacing (Clause 6.1.3.1, Table 6.1.3.1) for roof and side cladding depends on sheet thickness and corrugation type:

• These spacings ensure adequate support for corrugated metal sheets used in roofing and cladding.

• The standard aligns with international norms to maintain consistency in structural steel design.

Summary:

• Use 0.8 m spacing for 4 mm shallow corrugated sheets on roofs.
• Use 1.35 m spacing for 4 mm sheets on side cladding.
• Use 1.4 m and 1.7 m respectively for 6 mm medium corrugated sheets.

This ensures structural integrity and serviceability of roofing systems according to IS 3007 Part 1.

IS 3007 Part 1: Necessary Information for Roof Sheeting

Key Information (Clause 4)

For efficient planning and execution, the following must be provided before starting roof sheeting work:

• a) Roof area to be covered
• b) Details of sub-structure of roof
• c) Pitch of the roof
• d) Location and size of openings and roofing accessories

This info must be supplied by the authority responsible for the building (Clause 4.2).

Purlin Spacing (Clause 6.1.3.1)

Additional Notes:

• Pitch of roof affects water drainage and load distribution.
• Sub-structure details include purlins, rafters, and trusses.
• Openings impact sheet layout and fixing details.

flowchart TD
    A[Start: Planning Roof Sheeting] --> B[Gather Necessary Info]
    B --> C{Info Required}
    C -->|Roof Area| D[Calculate Sheet Quantity]
    C -->|Sub-structure Details| E[Plan Fixing & Support]
    C -->|Pitch of Roof| F[Design Drainage & Load]
    C -->|Openings & Accessories| G[Layout Sheets & Accessories]
    D & E & F & G --> H[Execute Roof Sheeting Work]

This ensures proper material selection, structural safety, and efficient installation.

IS 3007 Part 1 - Materials and Accessories Key Points

Fixing Accessories (Clause 9.2 & 9.3.7)

• Must conform to IS 730 standards.
• Proper selection and use are critical for roofing performance.
• Accessories include ridge cappings, filler pieces, ventilators, skylights, etc.

Washers Specifications (Clause 9.2.8)

Bolts, Washers & Length (Table 2, Clause 9.2.7.1)

Notes

• Other washer sizes may be used if approved by the engineer-in-charge.
• Accessories must be purpose-made and suitable for the roofing system.

flowchart TD
    A[Roofing Accessories] --> B[Fixing Accessories (IS 730)]
    A --> C[Washers]
    C --> D[Galvanized Iron Washer: 25mm dia, 1.6mm thick]
    C --> E[Bitumen Washer: 35mm dia, 1.5mm thick]
    A --> F[Bolt Length & Quantity]
    F --> G[Depends on location & number of sheets]
    G --> H[Length = Depth of purlin + 75 or 90 mm]

This summary ensures compliance with IS 3007 Part 1 for materials and fixing accessories.

IS 3007 Part 1 — Design Considerations: Key Points

1. Coach Screws

• Must conform to IS 1120 (Clause 5.3.1).

2. Spacing of Purlins (Clause 6.1.3.1)

• Based on sheet thickness and corrugation type (from IS 3001 Part 1:1999):

3. Other Design Considerations (Clause 6)

• Includes spacing of supports, strength of sheeting, expansion joints, shade protection, storage, handling, and safety precautions.
• The standard emphasizes SI units and improved work practices.

Summary Diagram: Purlin Spacing Concept

flowchart LR
    A[Sheet Thickness] --> B{Corrugation Type}
    B -->|Shallow (4mm)| C[Roof: 0.8m]
    B -->|Shallow (4mm)| D[Side: 1.35m]
    B -->|Medium (6mm)| E[Roof: 1.4m]
    B -->|Medium (6mm)| F[Side: 1.7m]

Use these spacing values to ensure proper load distribution and structural integrity of roofing and cladding systems.

IS 3007 Part 1: Storage and Handling of Asbestos Cement Sheets

Key Specifications (Clause 7)

• Stacking Height: Max 1 m high on firm, level ground.
• Support: Use timber or suitable packing beneath sheets.
• Location: Store in sheltered positions near installation points.
• Protection: If exposed, protect sheets from wind damage.
• Stacking Orientation:
  • All uplap edges on one side.
  • All downlap edges on the opposite side.
  • Do not mix uplap and downlap in the same stack.

Safety Measures (Clause 7.6)

• Follow IS 11769 (Part 1), Clause 4 for handling to minimize airborne asbestos dust.
• Use recommended protective equipment and dust control during receiving and storage.

Expansion Joint Summary (Clause 6.4)

Diagram: Stacking Orientation

flowchart LR
    A[Stack Base] --> B[Timber Packing]
    B --> C[Sheets with Uplap Edges (all on one side)]
    B --> D[Sheets with Downlap Edges (all on opposite side)]
    style C fill:#b3d9ff,stroke:#333,stroke-width:1px
    style D fill:#ffcccc,stroke:#333,stroke-width:1px

Summary: Proper stacking and protection prevent damage and ensure safety. Expansion joints must be aligned with structural joints to accommodate thermal movement.

IS 3007 (Part 1) - Safety Measures Summary

Shade Protection (Clauses 1.5 & Figures 3-5)

• Use 1.5 m sheets at each end of the asbestos cement (AC) sheet stack for shade.
• Sheets should lean against the stack from all sides to prevent heat damage.
• Secure sheets properly to prevent them from being blown away.

Roof Work Safety (Clause 8.2)

• Use cat ladders or roof boards for safe access and working on roofs.
• Roof boards must be:
  • At least 375 mm wide.
  • Well-constructed to avoid tilting.
  • Battens/crosspieces must not project beyond board edges and must be securely fixed.

Handling Precautions (Clause 8.3)

• Workers must walk/work only on planks or ladders; avoid stepping directly on AC sheets.
• Display safety posters warning against stepping on roofing sheets to prevent damage and accidents.

Key Dimensions & Recommendations

flowchart LR
    A[Stack of AC Sheets] --> B(Shade Sheets 1.5 m)
    B --> C[Lean sheets on all sides]
    C --> D[Secure sheets against wind]
    E[Workers] --> F[Use cat ladders/roof boards]
    F --> G[Boards ≥ 375 mm wide]
    E --> H[Walk on planks/ladders only]
    H --> I[Display safety posters]

This ensures worker safety and material protection during roofing work per IS 3007 (Part 1).

IS 3007 Part 1: Laying and Fixing of Sheets - Key Points

1. Sheet Orientation & Laps (Clause 9.3.2)

• Smooth side upwards.
• Corrugations run in continuous straight lines.
• Side and end laps as per Clause 6.1.6 (typically, side lap = 1 corrugation, end lap = 150 mm or as specified).

2. Order of Cutting and Fixing (Clause 9.3.4.1)

• Laying direction: Left to right (reverse for right to left side of ridge).
• First tier, first course: Fix sheet A (no mitre), cut B & C at bottom right corner, fix upwards.
• Intermediate tiers: Mitre sheets D (top left corner), E (top left & bottom right), F (bottom right).
• Finishing tier: Mitre sheets G & H (top left corner), fix sheet I without mitre.
• Fixing method must avoid induced stresses to prevent sheet fracture.

3. Stacking of Sheets (Clause 7.2)

• Stack max 1 m height on firm, level ground.
• Use timber/packing underneath.
• Protect from wind damage if exposed.
• Keep uplap on one side, downlap on the other; do not mix.

4. Support Spacing & Strength (Clause 6.2)

• Support spacing depends on sheet thickness, profile, and loading.
• Refer to IS 3007 tables for max span (e.g., for 6 mm thick corrugated sheets, typical support spacing ~1.2 to 1.5 m).

Typical Side & End Lap Dimensions (from IS 3007 Table 6.1.6)

Fixing Stress Avoidance Tips:

• Use proper fasteners with washers.
• Avoid over-tightening.
• Allow for thermal expansion.

flowchart LR
    A[Start Laying] --> B{First Tier?}
    B -- Yes --> C[Fix Sheet A (no mitre)]
    C --> D[Cut B & C (bottom right

IS 3007 Part 1: Roofing Accessories and Cappings - Key Points

1. Accessories (Clause 3.2)

• Includes ridge cappings, finials, apron flashings, eaves fillers, barge boards, ventilators, skylights.
• Purpose-made fittings to complement roofing sheets.

2. Close Fitting Adjustable Ridge Capping (Clause 10.2.1)

• Designed to fit corrugation with sidelap = half corrugation.
• Fix with same bolts as roof sheets to ridge purlins.
• Corrugation pitch at side lap = 134 mm.
• Installation starts at left verge; wings fit into valleys of roof sheets.
• Use a template for accurate fitting.

3. Fixing Specifications (Clause 9.2.9)

• Ridge cappings secured by bolts used for sheeting.
• Other accessories fixed to structure or sheeting by roofing bolts.

4. Top Edges and Abutments (Clause 10.6)

• Use asbestos cement apron flashing at wall edges.
• For vertical sheeting walls: wall laps over flashing upstand; apron laps over roof sheeting.
• For brick/masonry walls: apron secured to sheeting; metal/felt flashing over upstand.
• At sloping abutments parallel to corrugations, metal/felt flashings dressed as apron.

5. Dimensions & Recommendations

Typical Fixing Bolt Types:

• Mushroom Head Roofing Bolt with Bituminous & GI Washers
• J-Type Hook Bolt

Installation Flow (Simplified):

flowchart TD
    A[Start at Left Verge] --> B[Place Small Roll Wing Inner]
    B --> C[Fit Ridge Wing Valley into Roof Sheet Valley]
    C --> D[Secure with Roofing Bolts]
    D --> E[Trim Ridge Wing at Verge]
    E --> F[Continue Along Ridge]

For detailed figures and bolt specifications, refer to IS 3007 Part 1 Figures 9-17.

IS 3007 Part 1: Gutters and Rainwater Pipes - Key Points

Relevant IS Codes & Specifications

• Gutters & fittings: Must conform to IS 1626 (Part 2) for asbestos cement gutters.
• Fixing: Follow recommendations in relevant IS codes (e.g., IS 1626, IS 456 for RCC pipes).
• Pipe penetrations: Use soaker flange sheets matching pipe diameter and roof pitch to prevent leakage.
• Accessories: Secure corner rolls, barge boards, ridges, and apron pieces with roofing bolts as per IS 3007 figs.

Design Considerations

• Sizing gutters and pipes: Based on rainfall intensity and roof area.
• Formula for Rainwater Discharge (Q):

[ Q = C \times I \times A ]

Where:

• (Q) = Discharge (liters/sec)
• (C) = Runoff coefficient (typically 0.8–0.95)
• (I) = Rainfall intensity (mm/hr)
• (A) = Catchment area (m²)

Typical Dimensions (As per IS 1626)

Fixing & Flashing

• Position pipe perforations considering end laps to avoid extended flashing length.
• Use roofing bolts for secure fixing of accessories.

flowchart TD
    Roof -->|Rainwater| Gutter
    Gutter -->|Flow| RainwaterPipe
    RainwaterPipe --> GroundDrain
    Roof -.->|Soaker flange sheet| PipePenetration
    PipePenetration -.->|Flashing & Seal| RoofSheeting

Summary: Use IS 1626 for sizing and materials, ensure proper fixing with roofing bolts, and use soaker flanges for waterproof pipe penetrations. Design gutters and pipes based on rainfall and catchment area using the discharge formula.