Short answer: Colorbond is Zincalume with paint on it. Everything else follows from that.
They are not competing products from rival manufacturers. Colorbond is made by taking Zincalume steel and applying a factory-baked paint system to it. So the question is never really “which steel”, it is “does this job need the paint system, and can it justify the cost of it”.
Here is how we answer that at the counter, on the roofs we supply across Sydney.
The one-line difference
Zincalume is steel with an aluminium and zinc alloy coating: 55 per cent aluminium, 43.5 per cent zinc, 1.5 per cent silicon. It goes on the roof as a bare metallic finish.
Colorbond is that same Zincalume steel, plus a corrosion-inhibiting primer and a baked-on topcoat in a range of colours.
That extra paint system does three things: it gives you colour, it adds another barrier layer over the metallic coating, and it changes how the roof handles heat.
Side by side
| Zincalume | Colorbond | |
|---|---|---|
| Finish | Bare metallic, weathers to a soft grey | Painted, PLACEHOLDER_COLOUR_COUNT standard colours |
| Base steel | Aluminium-zinc alloy coated steel | The same steel, with primer and topcoat |
| Cost | Lower | Higher (PLACEHOLDER_PRICE_GAP) |
| Corrosion protection | Metallic coating only | Metallic coating plus paint system |
| Coastal suitability | Reduces sharply near breaking surf | Better, but still has limits. Check the environmental guidance. |
| Heat | Highly reflective when new, reflectivity falls as it weathers | Thermatech solar reflectance technology in the current range; light colours reflect far more than dark |
| Scratch and cut edges | Sacrificial zinc protects cut edges | Same base protection, plus paint that can be touched up |
| Where it fits | Sheds, warehouses, carports, industrial, raw architectural | Residential, commercial, anywhere colour is specified or a covenant applies |
| Fading | Nothing to fade, it patinas | Paint chalks and fades slowly, faster in darker colours |
When Zincalume is the right choice
- Sheds, carports, patios and outbuildings. The bare finish is expected and nobody is paying for colour.
- Industrial and warehouse roofs where appearance is not part of the brief.
- Deliberate raw-metal architecture. Some designers specify Zincalume precisely because it weathers and does not stay factory-fresh.
- Concealed work. Sub-structure, hidden flashings, anything that will not be seen.
- Tight budgets on large areas. On a big shed roof, the saving is real.
When Colorbond is the right choice
- Anything residential where the roof is visible. Which is nearly all of it.
- Where a development approval or covenant specifies a colour. Common on newer Sydney estates.
- Coastal and near-coastal jobs, where the additional paint system helps, though it does not make a roof suitable for every marine exposure.
- Where you want the heat performance of a light colour. A light Colorbond roof over a habitable space in Sydney’s western suburbs is a materially different summer to a dark one.
- Where the roof, gutters, fascias and flashings all need to match. Colour matching across the whole rainwater and flashing package is far easier in Colorbond.
The three things people get wrong
“Zincalume is cheaper so it is the value choice.” On a shed, yes. On a house where the client will look at it every day for twenty five years, the paint system is not the expensive part of the decision. Labour is.
“Colorbond is fine at the beach.” Both products have environmental limits, and both have exclusions close to breaking surf. Get the specific site classified against BlueScope’s current environmental suitability guidance before you specify either one. Where the exposure is severe, the answer may be stainless steel, aluminium, KME copper or VM Zinc rather than either of these.
“A metallic roof is always cooler than a coloured one.” Bare Zincalume is highly reflective when it is new. It gets less reflective as it weathers and picks up dirt. A light Colorbond roof with the current solar reflectance technology holds its performance better over time. If summer heat load is the driver, compare the current published solar absorptance figures for the specific colour rather than assuming the metallic finish wins.
Warranty
Both products carry BlueScope warranties, and both are conditional on the environment, the application, the fixings used and correct installation and maintenance. There is no single warranty period that applies to every job. PLACEHOLDER_WARRANTY. Read the current warranty terms for the specific product and site before you make a promise to a client.
Whichever you pick, these apply
- Do not cut over an installed roof with an angle grinder. Hot swarf embeds and rusts, on both products.
- Use compatible fixings. Incompatible fasteners corrode at every screw regardless of the sheet.
- Keep copper run-off, lead and wet concrete off both.
- Wash down the parts of the roof that rain does not reach. Sheltered areas are where both products fail first.
- Install roof sarking where condensation control is required.
- Order the flashings in the same material and the same batch as the sheet.
We supply both
HMR Supplies rolls Zincalume and Colorbond at Revesby, in corrugated, Longspan, Monoclade, SpeedDeck and the concealed-fix architectural profiles, with matching flashings folded from the same coil.
If you are not sure which one the job needs, call 02 9771 3777 with the site address, the exposure and the brief, and we will tell you straight. Text an order through on 0499 935 654, or use the contact form.
See the full materials range or the areas we service.
FAQs
Is Colorbond the same as Zincalume?
Not the same, but closely related. Colorbond is Zincalume steel with a factory-applied primer and baked-on topcoat. Zincalume is the unpainted aluminium-zinc alloy coated steel underneath.
Is Zincalume cheaper than Colorbond?
Yes, because it does not carry the paint system. The size of the difference varies with profile, gauge and quantity, so ask for a quote on your actual schedule rather than working from a rule of thumb.
Which lasts longer, Zincalume or Colorbond?
In the same environment, correctly installed and maintained, Colorbond’s additional paint system gives it an advantage over bare Zincalume. Both are strongly dependent on environment, fixings and maintenance, and both have exclusions in severe marine and industrial atmospheres.
Which is cooler in summer?
It depends more on colour than on product. Bare Zincalume is very reflective when new but loses reflectivity as it weathers. A light Colorbond colour with current solar reflectance technology holds its performance better. Compare published solar absorptance figures for the specific colour.
Can I use Zincalume flashings on a Colorbond roof?
Physically yes, visually no. The two finishes read as different materials from the street and they weather differently. Match the flashings to the sheet.
Which should I use on a Sydney beachside home?
Neither, without checking the site first. Both products have reduced suitability near breaking surf. Have the exposure classified against the manufacturer’s current environmental guidance, and be prepared for the answer to be stainless steel, aluminium, copper or zinc instead.