IS 459:1992 is the Indian Standard (BIS) for corrugated and semi-corrugated asbestos cement sheets. This standard lays down the requirements regarding composition, dimensions, and physical properties (like load-bearing capacity and impermeability) for corrugated and semi-corrugated asbestos cement sheets used primarily for roofing and cladding.
Specifies requirements for corrugated and semi-corrugated asbestos cement sheets for roofing and cladding.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Reinforcing Fibre | Chrysotile Asbestos (min. 8% by mass) | Prohibited. Typically uses cellulose and synthetic fibres (e.g., PVA). | BS EN 494 |
| Transverse Strength (Typical AC sheet) | Minimum Breaking Load: ≥ 2750 N/m (for Type B sheets) | Minimum Bending Moment: ≥ 40 Nm/m (for Class 1 sheets). Note: Different units and test principles. | BS EN 494 |
| Length Tolerance | +10 mm, -5 mm | ± 10 mm | BS EN 494 |
| Width Tolerance | +10 mm, -5 mm | +10 mm, -10 mm | BS EN 494 |
| Water Tightness/Permeability Test | No leakage under a 250 mm head of water for 24 hours. | No formation of water droplets on the underside after 24 hours under specified test rig conditions. | BS EN 494 |
| Apparent Density | Not explicitly specified as a primary requirement. | Required to be ≥ 1400 kg/m³ for certain product types/classes. | BS EN 494 |
| Durability Test (Freeze-Thaw) | Not required. | Required for sheets intended for use in climates with freeze-thaw cycles (e.g., 100 cycles with strength retention checks). | BS EN 494 |