Corrugations Ahead

Corrugated iron buildings are nostalgic icons of the Australian landscape

Wherever you go in Australia, from the south coast to the Top End, and from the east coast to the west, you are likely to find buildings constructed of corrugated iron. Some are large, like barns and shearing sheds; while others are small, like water tanks, mail boxes and dunnies.

Some are new and tidy looking; while others are definitely showing what you might politely call the patina of age. Tumbledown shacks and farm sheds are bitter-sweet reminders that life on the land can be tough.

But somehow, all these corrugated iron structures seem to encapsulate a piece of Australia’s heritage. They are fundamental to the look of our country, and you can only hope that some of the older buildings are being heritage listed. They should be kept to remind future generations of what life was like back in the pioneering days.

Galvanising into Action

The terminology for corrugated iron can be a bit confusing, since you may also hear it being described as galvanised iron. In fact both names are correct; they just happen to describe two different aspects of the sheet metal, both of which make it useful as a building material.

People who are a bit pedantic, or maybe just a bit long-winded, sometimes cover all bases by calling it corrugated galvanised iron. You may even come across the term corrugated galvanised steel. All these names refer to the same material.

A quick update on the history and manufacture of corrugated iron makes these alternative names easier to understand. The material was invented in the early 19th century by Henry Palmer, a London engineer. He rolled wrought iron into thin sheets, which were light, but too flexible and rust prone for routine use as a building material. He then used specially shaped rollers to corrugate the sheets of iron. Those wavy folds stiffen the sheets along the direction of the ridges, making them more suitable for building.

To reduce the problem of rusting, he dipped the corrugated sheets into molten zinc. The zinc fuses onto the iron and protects it from oxygen in the air, thus preventing the iron from rusting. In fact, zinc is more reactive to oxygen than iron, so the zinc even helps to protect the iron at cuts and scratches, where the film of zinc is damaged. Later the iron was replaced with mild steel, which is an iron-carbon alloy. So the descriptive term “corrugated galvanised steel” is arguably the most appropriate name of all.

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