Choosing a roofing sheet isn't just about price per square foot — the coating type, base metal, and profile all affect how long your roof lasts and how much maintenance it needs. Here's what to check before you place a bulk order.
1. Base Metal: GI vs Galvalume
Most colour coated sheets start as either Galvanized Iron (GI) or Galvalume Steel (Aluminium-Zinc Alloy Steel).
- GI is more affordable and widely available, suited for standard residential/commercial roofing in moderate climates.
- Galvalume offers better corrosion resistance and heat reflectivity — recommended for coastal areas or industrial sheds exposed to chemical fumes.
2. Coating Type: PPGI vs PPGL
Pre-painted sheets (PPGI/PPGL) add a polymer top coat over the base metal for colour, UV resistance, and an extra corrosion barrier. PPGL (Galvalume base) generally outlasts PPGI in harsh environments.
3. Sheet Gauge & Thickness
Thicker sheets (lower gauge number) cost more upfront but resist denting from hail, foot traffic during installation, and wind uplift. For industrial sheds, we typically recommend 0.45mm–0.50mm TCT; for residential, 0.35mm–0.40mm is common.
4. Profile
Trapezoidal profiles handle longer spans with fewer purlins; corrugated/crimped profiles are better suited for curved roofs and aesthetic finishes.
Need Help Choosing?
Our team can recommend the right specification based on your span, location, and budget — get in touch for a factory-direct quote.
