Have you just spotted a few rust-looking specks on your roof and thought, “Hang on there. I just paid good money for that Colorbond® roof!” “Does Colorbond® rust too?”
Or, are you considering re-roofing in a coastal area with high humidity and saline conditions? Then you’re right to be concerned about the possibility of rust on your Colorbond® roof.
Many Adelaide homeowners start to panic at the first sign of discolouration, especially those living closer to the coast. Salt air, rain, and debris make people worry their roof’s lifespan might be shorter than promised.
From experience working across South Australia for four generations, our experts at Roof and Render have seen every kind of roof issue imaginable, from genuine Colorbond® steel that’s lasted decades, to cheap imitations that rusted in months. With 100 years of industry trust, our team knows what causes corrosion, what prevents it, and how to make a Colorbond® roof last up to 45 years or more.
Colorbond® steel is a high-strength metal material used for roofing, walling and fencing, manufactured by BlueScope Steel®, and built for Australia’s harsh weather. Each sheet has five layers designed to protect against corrosion and fading.
Here’s what’s inside every genuine Colorbond® roofing sheet:
| Layer | Purpose |
| Steel base | Made from high-quality steel for strength and durability |
| Metallic coating (Zincalume®) | Combines aluminium, zinc, and magnesium for strong corrosion resistance |
| Conversion layer | Ensures perfect bonding between coating and paint |
| Primer coat | Adds adhesion and enhances long-term protection |
| Top coat | A baked-on Colorbond® coating that resists chalking, fading, and flaking |
These layers form a tight barrier. Oxygen and moisture can’t easily reach the steel beneath, which is why Colorbond® roofs are so durable even in coastal towns like Port Noarlunga or Glenelg.
That’s also what makes them different from galvanised steel roofs, which use a single zinc layer that can corrode faster under salt exposure.
Short answer: not if the right one is installed.
Genuine Colorbond® steel has exceptional corrosion resistance. This is one of the biggest benefits of Colorbond®. It’s tested across 12,000 Australian sites under different climate zones, from humid tropics to dry deserts, to prove it can withstand our conditions.
However, rust can occur when the protective layers are damaged or when non-genuine materials are used during installation.
Now, here’s something not every roofer tells you. While regular Colorbond® steel does a good job in most parts of South Australia, it’s not a one-size-fits-all material.
If you’re right near the coast (in Henley Beach, Moana or Aldinga), your roof faces a tougher job. The constant salt spray and humidity mean you’ll want a heavier-duty version to keep rust away. BlueScope Steel® makes a couple of upgraded types built exactly for these spots:
• Colorbond® Ultra steel: Perfect for homes about 100 to 200 metres from breaking surf. It’s made with an extra layer of protection to handle salty air and constant moisture. Great for coastal homes, beach shacks and seaside suburbs.
• SUPERDURA® Stainless steel: This one’s for the extreme cases. If you’re within 100 metres of the ocean and face direct salt spray. Instead of regular steel, SUPERDURA® is protected by a finish coat, corrosion primer, another coating and then a stainless steel underneath. So, it laughs off corrosion and lasts much longer.
For the rest of Adelaide, suburbs like Morphett Vale, Aberfoyle Park, or the foothills, standard Colorbond® roofing holds up well. But if you’re that close to the water that you can smell the sea breeze from your deck, it’s worth going the extra mile with Colorbond® Ultra or SUPERDURA® Stainless.
These options cost a bit more upfront, but they’ll save you plenty over the years in fewer touch-ups, no early rust, and way more peace of mind.
We’ve been up on more roofs than we can count, from the beachside suburbs down at Seaford and Port Noarlunga to the leafy streets of Belair. And when we spot rust, it’s rarely the fault of the Colorbond® roofing sheets themselves. It’s usually what’s around it or what’s been done to it.
Let’s talk about what really causes rust on Colorbond® and other metal roofs:
When sheets get cut on-site, they throw off hot metal shavings called swarf. Those tiny bits might not look like much, but if they’re left sitting on your roof, they’ll start rusting before you know it. One good rain and you’ll see brown streaks trickling down your shiny new Colorbond® panels.
We’ve seen it happen plenty of times and not just in old homes. One homeowner (from Victoria, not Adelaide) shared that they’d “just put up a new Colorbond® shed roof” and couldn’t believe how quickly rust stains appeared. They had even blown the roof clean afterwards, but because it had a low pitch and was in one of the wettest areas in the city, some of the swarf stuck. Within weeks, tiny rust marks showed up.
Another roofer jumped into the thread with a good point: it probably wasn’t the Colorbond® rusting at all. It was “small flecks of waste or grinding dust from screw holes” that had sat long enough to stain, then blown away in the wind. Someone else agreed, saying it looked like “grinding dust from trimming an edge, not actual rusting steel.”
The fix: Installers should always cut sheets on the ground (never on the roof) and brush or blow off every bit of metal debris before packing up. It might take an extra 10 minutes, but skipping it can cost you hundreds later in stain removal or even sheet replacement.
Colorbond® is tough as nails, but the protective coating can still get damaged. We see this all the time when tradies drag ladders or tools across the surface. Even one scratch deep enough to expose the metal can let water and oxygen in. That’s enough elements for the metal to start corroding.
Tips: If you ever have other service men up on the roof (sparkies, solar guys, air-con installers), remind them not to drag gear across the sheets, plus they must be on soft-soled boots.
This one’s a big deal. Use the wrong type of screw or flashing, and you’ll set off galvanic corrosion. Basically, one metal reacts with another when moisture hits. It happens a lot when people use cheap galvanised screws instead of Colorbond®-compatible Class 4 fasteners. You’ll spot it when rust rings start forming around the screw heads.
Best practice: Stick with genuine BlueScope®-approved fittings. Everything on the roof (screws, clips, and flashings) should match the same material type.
You’d be surprised how many roofs we see ruined by wet leaves and soil build-up. When muck sits in the gutters, it holds moisture against the steel and slowly eats into the coating. In Adelaide, gum leaves are a repeat offender, especially around the Hills where roofs cop it year-round.
Pro tip: Clean your gutters and roof valleys twice a year, or more often if you’ve got trees overhanging.
Sometimes the rust didn’t even start on your roof. Run-off from copper pipes, rusty TV antennas, or nearby metal fences can drip down and stain your Colorbond®. Even bore water, which often contains iron, can leave orange streaks if you’ve been using it to hose down the roof.
What to do: Check what’s running onto your roof and where the water’s going. You might only need to reroute a pipe or swap out an old fitting to stop the problem.
In most cases, these issues are fixable if you catch them early. Surface rust can often be cleaned off and sealed, but if it’s been sitting there for years, it may need a professional to assess whether it’s worked into the sheet.
We always tell Adelaide homeowners the same thing. Colorbond® itself doesn’t rust easily. It’s the little mistakes, shortcuts, and neglect that let the damage in. Keep an eye out, keep it clean, and it’ll be alright for decades.
You don’t need to overthink maintenance. A few simple steps can make a world of difference.
Colorbond® roof replacements add value to your home, and proper care helps you protect that investment.
Here’s how to keep rust at bay:
• Schedule roof cleaning: Wash every 6–12 months, especially near the coast, to remove dirt and salt deposits. Yes, rain can wash away some dirt. However, scheduled roof cleaning, especially in coastal areas, is still important to effectively remove stubborn dust, dirt and salt deposits that rain alone might not fully address.
• Use compatible fasteners: Only use materials recommended by BlueScope Steel®.
• Avoid walking on coated areas: Pressure or scratching weakens the surface.
• Keep gutters and valleys clear: Prevent pooling water or trapped debris.
• Inspect after storms: Look for scratches, dents, or foreign metal fragments.
Simple maintenance can help your Colorbond® roof look new for decades.
If you’re unsure what cleaning products are safe, use mild detergent and water. Avoid harsh chemicals that can strip protective layers away.
There’s a big difference between Colorbond® roof installations done by professionals and quick, cut-corner jobs.
Only genuine BlueScope Steel® products come with warranties up to 45 years. Imitations often fail within a few years, especially when the metallic coating or paint layers are thinner than required.
At Roof & Render SA, we only use certified materials and follow Australian standards for every roof replacement. Each project comes with:
• 10-year workmanship warranty
• 10-year Astec warranty
• 20-year watertight warranty
• Up to 45-year BlueScope® warranty
We keep building on a spotless reputation of over a century by doing things properly, never taking shortcuts. Our Lonsdale showroom is home to Australia’s #1 Colorbond® display, featuring popular colours like Southerly, Basalt, Woodland Grey, and Surfmist.
To see them in person, visit our Colorbond roof installation showroom in Lonsdale.
So, again, does Colorbond® rust? Under normal conditions, no.
Genuine Colorbond® roofing sheets are built for Australian conditions, and with proper care, they resist corrosion for decades.
The few cases of rust we’ve seen in Adelaide often trace back to improper installation, poor maintenance, or imitation products.
When you choose Roof & Render SA, you’re getting peace of mind backed by over 100 years of family expertise and South Australian craftsmanship.
Thinking about upgrading to a Colorbond® roof that lasts? Contact Roof & Render SA for expert installation and long-term protection.
You can also call us on 08 8451 6116 or visit our showroom at 2/22 O’Sullivan Beach Road, Lonsdale, SA to see genuine rust-free Colorbond® sheet options that hold their own against harsh weather or coastal elements.
Fill in the form below to book a free consultation at our Colorbond Showroom in Lonsdale.
We will give you a call within 24 hours to organise a time that suits you.
Fill in the form below to book a free consultation at our Colorbond Showroom in Lonsdale.
We will give you a call within 24 hours to organise a time that suits you.
