IS 277:2018 is the BIS specification for hot-dip galvanized steel sheets in plain (GP) and corrugated (GC) form. The standard defines zinc coating weight classes, dimensional requirements, and quality conditions for sheets used in roofing, wall cladding, agricultural buildings, and industrial enclosures. It is the most referenced standard for galvanized sheets in the Indian construction market.
Technical Overview
Galvanizing applies a zinc coating to steel sheet by continuous hot-dip immersion, providing cathodic corrosion protection. IS 277 classifies sheets by coating weight (expressed as total zinc on both surfaces in g/m²) from Z100 (100 g/m²) to Z600 (600 g/m²). Higher coating weights provide longer service life in corrosive environments. The standard covers base metal requirements (typically IS 1079 or IS 513 quality), surface finish, spangle (zinc crystal) appearance, and dimensional tolerances for plain sheets and standard corrugation profiles. The 2018 revision aligned more closely with international coating weight designations.
Grades & Mechanical Properties
| Grade | Notes |
|---|---|
| Z100 | Light coating — interior, low-corrosion environments |
| Z150 | Standard interior / light exterior use |
| Z200 | General exterior use — common industrial standard |
| Z275 | Heavy exterior — roofing, cladding, agricultural (most common) |
| Z350 | Enhanced protection — coastal and industrial zones |
| Z450 | High corrosion resistance — marine or chemical environments |
| Z600 | Maximum protection — extreme exposure conditions |
Values are minimum requirements unless otherwise stated. Always verify with the current edition of the standard and the mill test certificate.
Common Applications
- Roofing sheets for industrial, commercial, and agricultural buildings
- Wall cladding and side-sheeting for warehouses and factories
- Purlins and secondary structural members
- Rural housing and poultry shed construction
- Cold storage panels and refrigerated enclosures
- HVAC ductwork substrate
International Equivalents
EN 10346 DX51D+Z
European continuously hot-dip coated steel — equivalent coating weight designations
ASTM A653
US specification for galvanized sheet — coating weight G90 ≈ Z275
JIS G3302 SGCC
Japanese galvanized steel sheet — common quality, equivalent to GP
Frequently Asked Questions
What is IS 277 galvanized sheet?
What does Z275 mean in IS 277?
What is the difference between GP and GC sheets?
What is the base metal standard for IS 277 sheets?
Related Standards
IS 14246:2013 — Hot Dip Zinc Coated Steel Sheets and Coils
IS 14246:2013 specifies continuously hot-dip zinc coated (galvanized) steel sheets and coils for structural, roofing, and general engineering applications. Unlike IS 277 which focuses on formed roofing sheets, IS 14246 covers the coil form supplied to downstream processors — colour coaters, profilers, roll formers, and fabricators — making it the reference standard for galvanized coil trade in India.
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IS 513:2008 — Cold Rolled Low Carbon Steel Sheets and Strips
IS 513:2008 is the Bureau of Indian Standards specification for cold rolled low carbon steel sheets and strips. It defines five grades (CR1 to CR5) based on formability — from commercial quality for general fabrication to ultra deep drawing quality for complex press-formed components. CR steel is characterised by its smooth surface finish, tighter dimensional tolerance, and superior formability compared to HR equivalents.
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IS 1079:2017 — Hot Rolled Carbon Steel Sheet and Strip
IS 1079:2017 specifies hot rolled carbon steel sheets and strips for general engineering purposes. It defines four commercial grades — HR1 through HR4 — based on forming characteristics, covering thicknesses from 1.6mm to 10mm in sheet form and strips up to 600mm wide. It is the foundational standard for the hot rolled coil and sheet supply chain in India.
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IS 2062:2011 — Hot Rolled Medium and High Tensile Structural Steel
IS 2062 is India's primary structural steel standard, specifying hot rolled medium and high tensile steel used in bridges, buildings, industrial structures, and fabricated assemblies. It defines six grades from E250 to E550, covering mild to high tensile performance. Published by the Bureau of Indian Standards (BIS), it is the most referenced steel specification in Indian construction and engineering.
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