Colour Coated vs Bare Galvalume Roofing Sheets
Quick Answer
Colour coated sheets (PPGI/PPGL) offer a painted finish with wider colour choices and strong corrosion resistance. Bare galvalume sheets provide superior heat reflectivity and slightly better corrosion performance for the same coating mass, at a lower cost, but with a plain silver-grey finish.
Side-by-Side Comparison
| Attribute | Colour Coated Roofing Sheets | Bare Galvalume Sheets |
|---|---|---|
| Base Coating | Zinc (PPGI) or Al-Zn alloy (PPGL) | Aluminium-zinc alloy (AZ) |
| Finish | Painted — multiple colour options | Bare silver-grey (weathers naturally) |
| Corrosion Resistance | Very good (PPGL better than PPGI) | Excellent — strong cut-edge resistance |
| Heat Reflectivity | Depends on paint colour | High (bare aluminium-zinc surface) |
| Lifespan | 15–25 years | 15–25+ years (AZ150 grade) |
| Available Brands | JSW, Tata, Jindal, Essar, AM/NS | Available across grades AZ70–AZ150 |
| Aesthetics | High — colour and shade options | Functional — plain industrial finish |
| Cost | Moderate to higher | Lower |
| Can be painted later? | N/A — already painted | Possible but not recommended |
| Best For | Visible roofs, colour-matched projects | Industrial sheds, budget projects, hot climates |
Which Should You Choose?
Colour Coated Roofing Sheets
Metal sheets coated with protective paint layers over a PPGI or PPGL base. Available in multiple colours, offering strong corrosion resistance and an attractive finish for industrial and commercial roofing.
Choose this when
- Aesthetics matter — colour matching an existing building
- The roof is visible and a finished appearance is needed
- You need a branded coil (JSW Durashine, Tata, Jindal Pragati+)
- Standard industrial roofing with corrosion protection is the brief
Bare Galvalume Sheets
High-strength steel sheets coated with an aluminium-zinc alloy. Distinguished by their silver finish that weathers naturally to grey. Offer excellent heat reflectivity and superior corrosion resistance in aggressive environments.
Choose this when
- Heat reflectivity is a priority — reduces building temperature
- The roof is not visible and appearance is secondary
- You are in a coastal or chemically aggressive environment (AZ150 grade)
- Budget is a priority and a plain industrial finish is acceptable
Frequently Asked Questions
- What is the difference between PPGI and PPGL?
- Both are painted steel. PPGI uses a zinc galvanised base while PPGL uses a galvalume (aluminium-zinc alloy) base. PPGL generally offers better corrosion resistance for the same coating mass, making it the common choice for industrial roofing.
- Does bare galvalume stay silver?
- No. It dulls to a soft grey over the first one to two years of weathering. This is normal and expected, not a defect.
- Which is better for coastal environments?
- Bare galvalume in AZ150 grade offers the best corrosion resistance for coastal and chemically loaded sites. For colour coated sheets, PPGL (galvalume base) significantly outperforms PPGI at the coast.
- Can I get colour coated sheets in the same thickness as bare galvalume?
- Yes. Both are available across standard thickness ranges. Specify the thickness, coating mass, and — for colour coated — the brand and shade when requesting a quote.
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