Laying of Asbestos Cement Sheets Code of practice, Part II: Semi-Corrugated Sheets

IS 3007 Part 2: Scope Summary

This part of IS 3007 focuses on efficient planning and execution of roofing work, specifically for metal sheet roofing.

Key Parameters to be Provided (Clause 4.1):

• Roof area to be covered
• Sub-structure details (supporting framework)
• Roof pitch (angle of slope)
• Openings (location & size) and roofing accessories
• Sheet sizes to be used
• Purlins: type, dimensions, and spacing
• Building height up to eaves
• End and side laps for sheet installation

Important Notes:

• Refer to Annex A for related Indian Standards (updated editions recommended).
• This standard ensures compatibility and quality control in roofing work.

Typical Data Table for Planning (Example):

flowchart TD
    A[Start: Project Planning] --> B[Collect Roof Area]
    B --> C[Assess Sub-structure]
    C --> D[Determine Roof Pitch]
    D --> E[Mark Openings & Accessories]
    E --> F[Select Sheet Sizes]
    F --> G[Specify Purlin Details]
    G --> H[Confirm Building Height]
    H --> I[Decide on End & Side Laps]
    I --> J[Execute Roofing Work]

This structured approach ensures compliance with IS 3007 Part 2 for metal sheet roofing.

IS 3007 Part 2: Key Definitions & Specifications

Definitions & Planning Data (Clause 4.1)

For efficient roofing work, detailed info on the following is essential:

• Roof area
• Sub-structure details
• Roof pitch
• Openings & roofing accessories
• Sheet sizes
• Purlin type, dimensions & spacing
• Building height to eaves
• End & side laps of sheets

Bolts & Washers Specifications (Table 2, Clause 9.2.7.1)

Important Notes:

• Check purlin spacing and sheet length before laying to ensure laps and overhangs.
• Bolt lengths depend on purlin depth plus a fixed allowance.
• Number of bolts varies with lap type and presence of filler pieces.

flowchart TD
    A[Roof Planning] --> B{Details Needed}
    B --> C[Roof Area]
    B --> D[Sub-structure]
    B --> E[Pitch]
    B --> F[Openings & Accessories]
    B --> G[Sheet Sizes]
    B --> H[Purlin Type & Spacing]
    B --> I[Building Height]
    B --> J[End & Side Laps]

This concise summary aligns with IS 3007 Part 2:1999 for roofing sheet installation.

IS 3007 Part 2: Materials and Accessories - Key Points

Fixing Accessories (Clause 5.3 & 9.2.1)

• Must conform to IS 730 (J-bolts, L-bolts, roof washers, etc.).
• Proper selection ensures roofing efficiency.
• Accessories include ridge cappings, ventilators, skylights, apron flashings, etc. (Clause 3.2).

Tools for Working Processes (Table 9.1.2)

Note: Avoid high-speed circular saws.

Bolts, Washers & Lengths (Table 9.2.7.1)

Summary Diagram: Fixing Accessories & Sheet Laying

flowchart TD
    A[Fixing Accessories] --> B[Conform to IS 730]
    A --> C[Proper Selection]
    C --> D[Bolts & Washers]
    D --> E[Number & Length per Table 9.2.7

IS 3007 Part 2: Roof Design and Planning Key Points

1. Roof Plan (Clause 6.1.1)

• Keep the roof plan simple.
• Avoid hips and valleys to reduce complexity.
• Avoid isolated projections to ensure weatherproof junctions.

2. Essential Planning Data (Clause 4.1)

Before design and execution, gather:

• Roof area to be covered.
• Sub-structure details (supporting members).
• Roof pitch (angle of slope).
• Location/size of openings and roofing accessories.
• Sheet sizes to be used.
• Purlin type, dimensions, and spacing.
• Building height to the eaves.
• End and side laps for sheet installation.

3. Roof Pitch (Clause 6.1.2)

• Pitch affects water runoff and wind resistance.
• Typical minimum pitch for metal sheet roofs is 5° to 10° depending on sheet type and weather conditions.

Typical Roof Pitch and Lap Guidelines (from general practice):

Summary Diagram of Roof Planning Inputs:

graph TD
A[Roof Design Planning] --> B[Roof Area]
A --> C[Sub-structure Details]
A --> D[Roof Pitch]
A --> E[Openings & Accessories]
A --> F[Sheet Sizes]
A --> G[Purlin Details]
A --> H[Building Height]
A --> I[Sheet Laps]

Ensure all inputs (Clause 4.1 & 4.2) are provided before roof sheeting work begins.

IS 3007 Part 2: Storage at Site (Clause 7)

• Stack Height: Sheets shall be stacked not more than 1 m high on firm, level ground.
• Base Protection: Use timber or suitable packing beneath sheets to avoid direct ground contact.
• Protection from Elements:
  • Protect sheets from wind damage if stored in exposed areas.
  • For long-term outdoor storage, provide covers to protect against sun exposure.
• Handling: Asbestos cement units must be carefully stacked near the building parts where they will be fixed, preferably in sheltered locations.
• Wind Precautions: Avoid laying sheets during high winds (Clause 8.7).

Key Specifications (Storage)

Expansion Joint Note (for reference):

• Max spacing: 35 m
• End lap: ≥ 150 mm
• Stitching with seam bolts if lap between purlins

flowchart LR
    A[Sheets delivered] --> B[Stack on firm, level ground]
    B --> C{Stack height ≤ 1 m?}
    C -- Yes --> D[Use timber packing below]
    C -- No --> E[Reduce stack height]
    D --> F{Exposed to sun/wind?}
    F -- Yes --> G[Provide protective cover]
    F -- No --> H[Store in sheltered place]
    G & H --> I[Ready for fixing]

This ensures sheet integrity and ease of installation per IS 3007 Part 2.

IS 3007 Part 2 — Laying Procedures (Clause 9.3)

Key Points on Laying Sheets (Clause 9.3 & 9.3.1)

• Check purlin spacing and sheet length before laying to ensure:

  • Correct lap lengths (side and end laps per Clause 9.1.6).
  • Specified overhang at eaves and ridge.

• Sheet orientation:

  • Smooth side upwards.
  • Corrugations aligned in continuous straight lines.

• Laying suspension:

  • Stop work during high winds (Clause 8.7).

Bolt and Washer Specifications (Table 2, Clause 9.2.7.1)

Summary Diagram of Laying Process

flowchart TD
    A[Start: Check purlin spacing & sheet length] --> B[Lay sheets smooth side up]
    B --> C[Align corrugations in straight lines]
    C --> D[Ensure laps & overhang as per Clause 9.1.6]
    D --> E{High wind?}
    E -- Yes --> F[Suspend laying]
    E -- No --> G[Fix sheets with bolts & washers as per Table 2]
    G --> H[Complete laying]

Remember: Proper bolt length and number ensure structural integrity and weather tightness. Always refer to the specific purlin depth and sheet arrangement for accurate bolt sizing.

IS 3007 (Part 2) - Safety Precautions Summary

Shade Protection for Stacks (Clause 1.5 & Fig. 7, 8)

• Use 1.5 m sheets laid at each end of the stack.
• Lay 1.5 m sheets leaning around the stack to provide shade from all directions.
• Use 3 Nos. 3 m sheets on top of the stack for additional protection.
• Secure sheets properly to prevent them from being blown away by wind.
• Suspend laying sheets during high winds (Clause 8.7).

Recommended Work Practices (Clause 9.1.2)

• Use appropriate tools for cutting sheets to minimize dust emission.
• Refer to Table 1 for tools suitable for sawing and drilling.
• Consult manufacturer if unsure about tool selection.

Key Safety Specifications:

flowchart LR
    A[Stack of Sheets] --> B[1.5m Sheets at Ends]
    A --> C[1.5m Sheets Leaning Around]
    A --> D[3 Nos. 3m Sheets on Top]
    B & C & D --> E[Shade Protection]
    E --> F[Secure Sheets to Prevent Wind Damage]
    F --> G[Suspend Work if High Winds]

Note: Always follow manufacturer guidelines and IS recommendations for safe handling and environmental control.

IS 3007 Part 2: Fixing and Fastening Key Points

1. Fixing Accessories (Clause 5.3 & 9.2.1)

• Must conform to IS 730 (for bolts, washers, J-bolts, L-bolts).
• Proper selection and use are critical for roofing performance.

2. Recommended Tools for Corrugated Sheets (Table 9.1.2)

Note: Avoid high-speed circular saws.

3. Bolt Length and Number (Table 9.2.7.1)

4. Special Fixing for Tubular Purlins (Clause 9.2.6)

• Bolt must encompass ≥ 50% of tube periphery.
• Prevent bolt rotation.
• Alternative hook bolts may be needed for non-angle/tube sections.

flowchart LR
    A[Select Fixing Accessories] --> B{Conform to IS 730?}
    B -- Yes --> C[Choose Bolt Type & Length]
    C --> D{P

IS 3007 Part 2: Cutting and Drilling of Sheets

Key Specifications (Clause 9.1 & 9.1.2)

• Cutting: Use a wood saw or recommended tools; avoid high-speed circular saws.
• Drilling: Holes must be drilled, never punched to prevent material weakening and fractures.
• Hole Size: Holes should be 2 mm larger than bolt diameter.
• Hole Location: Drill holes through the crown of the corrugation, not in valleys.

Recommended Tools (Table 1)

* Other mechanical saws may be used with precautions; avoid high-speed circular saws.

Important Notes:

• Fixing accessories must comply with IS 730.
• Proper cutting/drilling ensures durability and weather resistance.

flowchart LR
    A[Sheet Cutting] --> B{Process}
    B --> C[Mitring]
    B --> D[Cross Cutting]
    B --> E[Longitudinal Cutting]
    B --> F[Cut-outs]
    B --> G[Drilling]

    C --> H[Hand saw, Jig saw, Nibbler, Band saw]
    D --> I[Hand saw, Jig saw, Nibbler]
    E --> J[Scriber, Jig saw, Hand saw]
    F --> K[Jig saw, Hand saw]
    G --> L[Hand or power drill]

    style L fill:#f9f,stroke:#333,stroke-width:2px

This ensures correct workmanship and longevity of corrugated sheets in roofing applications.

Key Specifications for Roof Accessories and Flashings (IS 3007 Part 2)

1. Roof Accessories (Clause 3.2)

• Includes: ridge cappings, north light curves, ridge finials, apron flashing, eaves filler pieces, barge boards, expansion pieces, ventilators, skylights.
• Purpose-made fittings must match roof profile and ensure weather tightness.

2. Top Edges and Abutments (Clause 10.6)

• Apron Flashing: Use asbestos cement apron pieces at top edges against walls.
• For vertical sheeting walls: wall laps over flashing upstand; apron laps over roof sheeting; no metal flashing needed.
• For brick/masonry walls: apron fixed to sheeting + metal/felt over flashing over upstand.
• At sloping abutments:
  • Flashing width ≥ 150 mm covering at least one full corrugation.
  • Upstand must be covered or secured to wall.
  • If corrugations run into wall, keep sheeting edge ≥125 mm from wall and provide gutter.

3. Fixing Accessories (Clause 9.2.1)

• Fixings must conform to IS 730.
• Proper selection critical for serviceability.

4. Working Tools for Corrugated Sheets (Table 9.2)

Note: Avoid high-speed circular saws for cutting sheets.

Summary Diagram: Flashing at Wall Abutment

flowchart LR
    A[Wall (Brick/Masonry)] -->|Upstand| B[Apron Flashing]
    B -->|Lap over| C[Roof Sheeting]
    B -->|Metal/Felt Over Flashing| A
    C -->|Edge ≥

IS 3007 Part 2: Gutters and Rainwater Pipes - Key Points

1. Types of Gutters (Clause 10.3.2)

• Half-round gutters: Used if sufficient space is available in the valley.
• Flat gutters (plaster + lead sheets): Used when space is insufficient.

2. Definitions (Clause 3.10)

• A roof-water channel includes any gutter or rainwater pipe system for directing roof water.

3. Purlin Position (Clause 1.75)

• Purlins must be positioned to suit the overhang and support the gutter properly.

4. Material Availability (Clause 7.4)

• All materials including gutters, downpipes, brackets, and fixings must be onsite before installation.

Typical Design Considerations:

• Gutter size depends on roof area and rainfall intensity.
• Rainwater pipe diameter (D) can be estimated by:

[ D = \sqrt{\frac{4Q}{\pi V}} ]

Where:

• ( Q ) = Peak runoff (m³/s)
• ( V ) = Velocity of flow (m/s), typically 1.5 to 3 m/s

Example Table for Gutter Sizes (Indicative):

flowchart TD
    Roof[Roof Surface]
    Gutter[Gutter]
    Downpipe[Rainwater Pipe]
    Drain[Drainage System]

    Roof --> Gutter --> Downpipe --> Drain

Summary: Use half-round gutters where space permits; otherwise, flat plastered gutters with lead sheets. Ensure purlins support gutter overhang. Prepare all materials onsite before installation. Design gutter and pipe sizes based on roof area and rainfall.

IS 3007 Part 2 - Expansion Joints Key Points

1. Spacing & Location

• Max spacing for expansion joints: 35 m (Clause 6.1.7.1)
• Expansion joints must be provided on large roofs to accommodate structural movement due to climatic changes (Clause 6.1.7).

2. End Lap

• Minimum end lap for expansion joints: 150 mm (same as roofing sheets).
• If laps occur between purlins, they must be stitched with seam bolts (Clause 6.1.7.1).

3. Typical Details

• Expansion joints include asbestos-cement accessories as shown in Figures 3, 4, 5, 6, 7, and 8.
• Use bituminous felt washers and J-type hook bolts for fixing.
• Purlins are generally MS angle sections.

4. Installation Notes

• Protect asbestos-cement units during storage (Clause 7.1).
• Expansion joint details vary by roof type (semi-corrugated, serrated ridge, northlight curve).

Summary Table

flowchart LR
    A[Roof Structure] --> B[Expansion Joint]
    B --> C{Spacing ≤ 35 m}
    B --> D[End lap ≥ 150 mm]
    D --> E{Lap between purlins?}
    E -->|Yes| F[Stitch with seam bolts]
    E -->|No| G[Standard fixing]
    B --> H[Fix with J-type hook bolts & bituminous felt washer]

This ensures thermal movement is accommodated, preventing damage to roofing sheets.

Maintenance and Repainting - IS 3007 Part 2 (Summary)

1. Inspection before laying sheets (Clause 9.3.1):

• Check purlin spacing and sheet length to ensure correct laps and overhang at eaves and ridge.

2. Fixing accessories (Clause 9.2.1):

• Use fixing accessories conforming to IS 730.
• Proper tools for cutting and drilling sheets include:
  • Mitring: Hand saw, Jig saw, Nibbler, Band saw
  • Cross cutting: Hand saw, Jig saw, Nibbler
  • Longitudinal cutting: Scriber, Jig saw, Nibbler
  • Drilling: Hand or power-operated drill
  • Avoid high-speed circular saws for sheet cutting.

3. Bolt and washer specifications (Table 2, Clause 9.2.7.1):

Key Points for Maintenance & Repainting:

• Ensure laps and overhangs are maintained as per original design.
• Check and replace fixing accessories if corroded, using IS 730 compliant bolts and washers.
• Use recommended tools to avoid damage during repairs.
• Repaint with suitable protective coatings to prevent corrosion.

flowchart TD
    A[Check purlin spacing & sheet length] --> B[Ensure laps & overhang]
    B --> C[Inspect fixing accessories]
    C --> D{Accessories OK?}
    D -- Yes --> E[Proceed with maintenance]
    D -- No --> F[Replace bolts & washers (IS 730)]
    E --> G[Re

IS 3007 Part 2: References and Related Standards

• Annex A lists all Indian Standards referenced in IS 3007 Part 2, making them integral to this standard.
• Editions cited in Annex A were valid at publication; users should check for the latest revisions.
• The standard aligns with international codes to ensure global compatibility.
• Key related standards often include:
  • IS 456: Code of Practice for Plain and Reinforced Concrete
  • IS 800: Code of Practice for General Construction in Steel
  • IS 875: Code for Design Loads (Dead, Live, Wind, Seismic)
• No direct formulas or tables are specified under References; instead, these standards provide detailed design data, formulas, and tables.
• Users should consult the latest editions of referenced standards for design formulas, load factors, and material specifications.

flowchart LR
    A[IS 3007 Part 2] --> B[Annex A: Referenced IS Codes]
    B --> C[IS 456 - Concrete]
    B --> D[IS 800 - Steel]
    B --> E[IS 875 - Loads]
    B --> F[Other IS Codes]

Summary: IS 3007 Part 2 relies on a network of Indian Standards (Annex A). Always verify current editions for design formulas and specifications.

IS 3007 (Part 2): Annexures Key Points

1. Referenced Indian Standards (Annex A)

   • These standards form integral provisions of IS 3007 Part 2 and should be referred to for detailed specs:

     IS No.	Title
     459:1992	Unreinforced corrugated & semi-corrugated asbestos cement sheets
     730:1978	Hook bolts for corrugated sheet roofing
     1120:1975	Coach screws
     2098:1997	Asbestos cement building boards
     11769 (Part 1):1987	Safe use guidelines for asbestos cement products

2. Fixing Accessories (Clause 9.2.1 & Table 9.2)

   • Accessories must conform to IS 730.
   • Recommended tools for working processes on corrugated sheets:

   Process	Tools
   Mitring	Hand saw, Scriber, Jig saw, Nibbler, Band saw, Low speed circular saw
   Cross cutting	Hand saw, Jig saw, Nibbler, Low speed circular saw
   Longitudinal cut	Scriber, Jig saw, Nibbler, Hand saw, Low speed circular saw
   Cut-outs	Jig saw, Hand saw, Low speed circular saw
   Drilling	Hand or power drill

3. Fixing of Other Accessories (Clause 10.9)

   • Use roofing bolts (mushroom head type) with GI or bituminous felt washers for corner rolls, barge boards, etc.
   • Position pipe openings carefully to avoid extended flashing lengths.
   • Gutters & rainwater pipes to be fixed per relevant IS codes.

4. Typical Fixing Details (Figures 21-23)

   • Show semi-corrugated roof lights, roofing bolts, barge boards, and corner rolls.

Summary Diagram: Fixing Accessories Workflow

graph TD
  A[Select Fixing Accessories] --> B[Check IS 730 Compliance]
  B --> C[Choose Correct Tools]
  C --> D{Working Process}
  D -->|