Corrugated iron is distinctly Australian. We associate it with "the Queenslander", the shearing shed, the woolshed, the outdoor dunny, and the water tank. It’s in our blood.
But unfortunately our corrugated iron is very susceptible to rust. If you have metal roofs that are more than 15 years old, you might find that bits of corrosion have started to show. It’s one of the biggest enemies of metal.
Rust happens when the metal comes into contact with moisture in the air, causing a chemical reaction. The longer the metal is exposed, the larger the corrosion will grow.
Most corrugated iron is treated with corrosion protectant, or galvanised, which is a process of applying a protective zinc coating to steel or iron. But over time and in harsh environments, protecting layers can wear off and corrosion can start to take hold.
If you’re situated in a highly corrosive environment, ie, coastal or heavy industrial, you should try to rinse your roof with potable water on a regular basis, the same way you would with your car. This is particularly important for parts that are sheltered from rain or sun.
But if you’ve already noticed corrosion, what can you do about it?
There are several options for combatting rust:
There are mechanical methods like sanding and wire brushing, which can be done by hand but it’s far easier to attempt with a power tool.
You should only attempt to wash the metal with an abrasive cleaner when it’s already rusty. If you do this for general cleaning, you will scrub away the protective patina on the surface of the metal and actually make it more susceptible to rust.
There is also rust removing chemicals, which can strip the rust from the iron to prepare the surface before painting with a corrosion resistant paint.
Products like Chemtech Rust-Off can help with small areas, but remember to be careful when using any dangerous substances.
If your corrugated iron is quite old and the corrosion is more widespread, then it may be difficult and dangerous to remove yourself. In these cases, it’s best to get a professional for a roof restoration or replacement.
Roo Roofing can restore Galvanised, Zincalume, Colorbond, Aluminium or even metal tiles.
If you find you need to replace your metal roof, then Colorbond is one of your best options. It’s tested in harsh conditions all over Australia and has 5 layers of corrosion resistant coating.