Colorsteel grades compared
Four steels, one decision, and it is mostly decided by how far the house is from breaking surf. Here is what actually separates them.
The choice is driven by the coastal zone, not by colour. Colorsteel MAXAM is the premium coastal option; ColorCote is a comparable pre-painted range; Armorsteel ColorZen is a cheaper pre-painted steel that gives away corrosion protection near the sea; plain Zincalume is unpainted, self-weathering and the lowest cost where appearance does not matter. Distance to breaking surf sets the zone, the zone sets the warranty, and gauge — 0.40 mm or 0.55 mm — is a separate decision again.
The four, side by side
| Product | What it is | Where it belongs |
|---|---|---|
| Colorsteel MAXAM | NZ Steel's premium pre-painted line, built on the Activate™ aluminium-zinc-magnesium coating. Rolled and painted at Glenbrook from New Zealand iron sand. | The one to specify near the coast. The magnesium in the coating slows corrosion where salt is in the air. |
| ColorCote | A separate pre-painted range with comparable coastal performance, sold in its own colour and coating tiers. | A genuine alternative to MAXAM. Match the specific tier to the zone rather than treating the brand as one product. |
| Armorsteel ColorZen | A cheaper pre-painted steel with a solid coating and a full colour range. | Inland and sheltered work where budget matters. It gives away corrosion protection in coastal zones — that is the trade. |
| Zincalume | Unpainted aluminium-zinc alloy-coated steel — natural silver. The coating self-weathers, so it needs no painting. | Sheds, farm buildings, anywhere appearance is not the point. Lowest cost, and long-lived for what it is. |
Coastal zones — the number that decides it
New Zealand is a thin country and most of it is near the sea. Corrosion severity is set by distance to breaking surf — breaking surf, not just water, because it is the airborne salt from the break that does the damage. A sheltered harbour is a milder environment than an open west-coast beach at the same distance.
| Zone | Distance to breaking surf | What it means for the spec |
|---|---|---|
| Mild | 5 km or more | The full range is available. Warranties are at their longest. |
| Moderate | 500 m – 1 km | Pre-painted, and pay attention to the coating tier. |
| Severe | 100 – 500 m | Coastal-grade coating. Warranty periods shorten. |
| Very severe | 25 – 100 m | MAXAM or equivalent, heavier gauge worth considering, and check the warranty statement before you quote it. |
Closer to the coast means a shorter perforation warranty, on every product. That is not a catch — it is the manufacturer being honest about a harder environment. What it means for you is that the zone has to be established before the material is specified, because the two are the same decision.
What the warranties actually cover
Indicative figures, and they are the reason the zone matters:
- MAXAM — up to a 50-year perforation warranty in mild zones, reducing as the zone gets more severe.
- ColorZen — around 30 years in mild environments.
- Zincalume — a 20-year non-perforation warranty. Repainting at around twenty years extends its life further, though the whole point of it is that it does not need painting.
Check the current published warranty for the product, the tier and the specific zone before you put a number in a quote. Manufacturers revise these, they vary by colour and coating tier, and they are usually conditional on installation detail — compatible fixings, no dissimilar metals, and washing down where the roof is sheltered from rain. A warranty quoted from memory is a warranty you are personally underwriting.
Gauge: 0.40 or 0.55
A separate decision from grade, and a simpler one.
- 0.40 mm is standard on a normal residential roof.
- 0.55 mm buys stiffness underfoot, better performance across wider purlin spacings, and more metal between the weather and the inside. It is worth having in a severe coastal zone, in a high wind zone, and on any roof people will walk on regularly — a roof with a lot of servicing on it, or one you know you will be back to.
Wind zone feeds into this as well: high and very-high wind sites need closer fixing centres, and sometimes the heavier gauge is the cheaper way to get there.
Colour is not only appearance
Dark colours run hotter, which matters for thermal movement on long runs and for the expansion detail at the fixings. It is not a reason to talk a customer out of a dark roof — it is a reason to detail it properly and to mention it when they are choosing.
How to have the conversation
Homeowners ask which is the good one
. The honest answer is that the good one depends
on where they live, and it is worth saying so:
- Establish the distance to breaking surf. That gives the zone.
- The zone rules out what cannot go there and sets the warranty they will get.
- Within what is left, colour and price are their choice, and gauge is yours to recommend.
Put the grade, the gauge and the colour in the quote in writing. A quote that says
new Colorsteel roof
and nothing else is a quote that can be undercut by a cheaper
steel and lose on price to something that is not the same product.
What comes up most.
What is the difference between Colorsteel and Zincalume?
Zincalume is the unpainted aluminium-zinc alloy-coated steel — the natural silver one. Colorsteel is pre-painted steel, and MAXAM is its premium line, built on the Activate™ aluminium-zinc-magnesium coating.
Zincalume self-weathers and needs no painting; it is the cheapest option and it lasts well where looks are not the point. Colorsteel is what goes on a house.
How close to the sea can I use ColorZen?
It is a mild-environment product. In coastal zones it gives away corrosion protection compared with MAXAM or a coastal ColorCote tier, and that is the whole reason it is cheaper.
Establish the zone first, then check the manufacturer’s current warranty statement for that zone. If the warranty will not be written, the product does not belong there.
Does Zincalume need painting?
No. The aluminium-zinc coating self-weathers to resist corrosion, and it carries a 20-year non-perforation warranty unpainted.
Repainting at around twenty years extends its life further if you want it to, but the product is designed to be left alone.
What does "distance to breaking surf" mean exactly?
The straight-line distance from the building to where the waves break, not to the nearest water. Airborne salt comes off the break, so an open surf beach at 300 m is a far harder environment than a sheltered harbour edge at the same distance.
Prevailing wind matters too. A house downwind of an open coast sees more salt than one the same distance away in the lee of a hill.
Should I use 0.55 gauge?
On a normal residential roof, 0.40 is standard and fine. Go to 0.55 for stiffness underfoot, for wider purlin spacings, in a severe coastal zone, in a high wind zone, or on a roof that will be walked on regularly.
It is a small proportion of the job cost and it is the kind of upgrade a customer understands when you explain what it buys.
Can I mix brands on one roof?
Avoid it. Different coatings and different fixings sitting against each other is how you get a corrosion problem at the junction, and it complicates any warranty claim later — each manufacturer can point at the other.
Specify one system, with its own compatible flashings and fixings, and keep it consistent across the whole roof.
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