The difference
ZINCALUME® is a bare metallic alloy coating. New Zealand Steel says its current AM coating is about 55% aluminium, up to 3% magnesium, and the rest zinc 1. COLORSTEEL® puts factory-applied paint over a metallic-coated base, and you get a choice of colours.
Exposure categories decide
| Category | Typical distance (east coast) | ZINCALUME® | COLORSTEEL® |
|---|---|---|---|
| Mild | 5 km+ from breaking surf | Warranted (25 yrs roofing) | MAXAM® / ALTIMATE® |
| Moderate | 500 m–5 km | Warranted (20 yrs roofing) | MAXAM® / ALTIMATE® |
| Severe | 100–500 m, or harbour foreshores | Not recommended | MAXAM® / ALTIMATE® |
| Very Severe | 25–100 m | Not recommended | MAXAM® / ALTIMATE® |
| Extremely Severe | 0–25 m, breaking surf | Not recommended | ALTIMATE® |
Sources: 1 2. West-coast distances differ (e.g. Very Severe 50–500 m). Check the guide for your site.
Maintenance
Both warranties assume you wash the areas the rain doesn't, and you'll wash more often closer to the sea 12.
Wellington takeaway
Inland in Upper Hutt or up the valleys, you can often pick either. On the south coast, the harbour front or a Kāpiti beach, it usually ends up being a COLORSTEEL® product. See Kāpiti and Wellington City.
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Frequently asked questions
Does Zincalume rust?
Every metal coating breaks down in the end. The warranty depends on your exposure category and whether you wash it 1.
How long is the COLORSTEEL® warranty?
Depends on the product and your category. The manufacturer's environmental categories guide sets out the terms by exposure, so get the warranty for your address in writing 2.
Sources
- New Zealand Steel — ZINCALUME® (accessed 26 Oct 2026)
- COLORSTEEL® — Environmental categories & warranty guide (PDF) (accessed 26 Oct 2026)
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