How long has corrugated iron been around for?
Corrugated galvanised iron was invented in the 1820s in Britain by Henry Robinson Palmer, architect and engineer to the London Dock Company. It was originally made from wrought iron.

Who made it popular/trendy?
Corrugated iron was invented in London in 1829 by Henry Palmer, an assistant to the great industrial engineer Telford, as a means to roof a new warehouse in the London docks. The idea was simplicity itself.

Putting flat sheets of wrought iron through rollers created a corrugated effect that strengthened and stiffened them.

They were quick to install on a basic wooden frame while remaining lightweight, strong and weatherproof, especially if painted. Within a few decades corrugated iron was being used to cover everything from railway stations to factory workshops, so that William Morris was moved to complain that it had become 'a pestilence' on the British countryside.

But it was the prefect material, especially when rust potential was minimised by dipping the sheets in molten zinc using the galvanising process invented in France in 1836.

After the patent ran out in 1843, other manufacturers rushed in with their own versions, many showcased at the Great Exhibition of 1851.

Prince Albert was so excited that he had a ballroom constructed entirely of the material at Balmoral, which still survives as a workshop on the estate. It was ideal for temporary buildings, and much of it was shipped to the new gold rush settlements in California, South Africa and, of course, Australia.

It was even possible to order complete buildings, like a church or a grand house complete with wallpapered walls. In the 1850s, the first rabbit-proof fence used sheets of corrugated metal to stop the critters burrowing below the visible barrier.

Indigenous Australians called it man-made bark, such was its ubiquity in rural areas, used for everything from shearing sheds to water tanks. It thus became identified with Australian rural life. By the end of the 19th century, steel took over from iron, and from 1915, most sheets were made in Australia's own factories rather than imported and were steel sheeting as opposed to corrugated iron sheets. These were most commonly used for roofing exterior wall cladding depending on sheeting sizes. These trends have transgressed to outdoor wall panelling for shed-converted homes.

It was still viewed as a touch basic for the aspirational in the city, who used it only on parts that weren't visible to the street. That changed in the late 1970s and 1980s, when architects like Richard Leplastrier and Glenn Murcutt created buildings made almost entirely from the stuff that were lightweight and elegant.

Suddenly corrugated metal was respectable, even fashionable, and today's aerial views of our outer suburbs show a veritable sea of corrugated metal roofs, a new vernacular of sorts. Its corrugations have visual strength in strong Australian sunlight, celebrated in paintings by Drysdale and others.

Just as Australians made decorative swans from car tyres and turned old toilets into floral displays, corrugated iron reflects a curiously Australian reverence for things (and people) that lack pretension. It speaks to all of us, the imagery seared into the collective memory, a hero that was born out of necessity. As resilient and iconic as any gum tree.

What is the different between corrugated iron, corrugated steel and corrugated zinc?
The coating on galvanised metal roofing is coated with almost 100-percent zinc. In comparison the alloy coating of Zincalume® metal roofing is approximately one-percent silicon, 43.5-percent zinc and 55-percent aluminium. Even though both are coated using a hot dip method, these two roofing products perform a bit differently from each other.

Since the galvanised metal roof primarily depends on sacrificial protection from corrosion and Zincalume® uses both sacrificial and barrier protection to keep from corroded, these two products have different levels of corrosion resistance. Zincalume® resists rust and corrosion in a superior fashion in test sessions. In fact, its protection lasts four times as long as, if not longer, than that of galvanised metal does in the same tests. Tests also show that both metals start off almost equal but the rate of corrosion with Zincalume® slows down as it is exposed to the weather elements since its coating forms additional barrier protection over time.

Is corrugated iron the same as Colorbond?
Colorbond is a coated steel roofing material which has quickly gained popularity over the past years, and is now used in many Australian homes. It is long lasting, resistant to different weather conditions, and makes any home look good.

How is corrugated iron made?

Corrugated iron is a building material composed of sheets of hot-dip galvanised mild steel, cold-rolled to produce a linear corrugated pattern in them. Although it is still popularly called "iron" in the UK, the material used is actually steel (which is iron alloyed with carbon for strength, commonly 0.3% carbon), and only the surviving vintage sheets may actually be made up of 100% iron. The corrugations increase the bending strength of the sheet in the direction perpendicular to the corrugations, but not parallel to them, because the steel must be stretched to bend perpendicular to the corrugations. Normally each sheet is manufactured longer in its strong direction.

What are the different profiles?

Bluescope Steel for instance offers:

Corrugated roofing

Ribbed, reliable and now comes in 3 sizes.

Corrugated roofing is a reliable product that’s stood the test of time. Corrugated roofing can be used as either a roofing or walling product. The profile can reflect a modern or traditional architecture depending on the application.

Corrugated roofing is now offered in 3 gauges – 0.42, 0.48 and the new 0.60. The popular 0.42BMT is used predominantly for domestic roofing, the 0.48BMT is used mostly for commercial applications and the 0.60BMT now provides a heavier and stronger profile in the range.

Corrugated roofing, with improved technology and manufactured from the highest quality Bluescope Steel, is now the smart choice when considering your roofing or walling requirements.

Trimdek

Economical steel wall panel, cladding or short span roofing.

Trimdek can be used for domestic and commercial applications as either a roof or walling product.

Trimdek’s 760mm sheet coverage is economical and quick to install. The 28mm rib height and specially designed capillary groove ensures watertightness down to a two degree roof pitch. Available in long lasting Zincalume® and Colorbond®.

Kliplok 700

When it comes to commercial concealed-fix roofing, nothing comes bigger or better than 100% Australian Kliplok 700® (Kliplok 700). At 700mm, it is amongst the widest concealed-fix deckings available. As to length, the only limit is your imagination, thanks to our mobile roofing mill. Plus, it’s available in the full range of light and heavy gauge Colorbond® colours. And don’t think concealed-fix steel roofing is only good on the flat. In addition to its unbeatable size, strength and watertightness, Kliplok 700® is also amazingly flexible and well-suited to curved roofs, making it the perfect solution to any commercial roofing project.

No screws, no holes, no leaks – plus a watertight guarantee.

Best of all, when it comes to installation we don’t screw around. An average 6000m2 screw-fix deck will have about 36,000 screw holes – each one a possible source of leakage and corrosion over time. But revolutionary full-width heavy duty KL75 clips provide incredible holding strength and stability without puncturing the sheeting. The clips are also self locating to ensure perfect accuracy. No screws, no holes, no leaks. In fact, we’re so confident in our Kliplok 700® roofs that we back them with this Watertight Installation Guarantee.

Pays for itself with savings in labour, time and supplies.

Kliplok 700® may cost a bit more than conventional screw-fix decking. But wider sheets mean fewer sheets, fewer laps and faster installation, and the 42mm profile adds incredible strength so you also need fewer purlins. Kliplok 700’s unique spring-tensioned clips and sliding brackets allow the sheets to move with temperature changes, eliminating the need for expansion joints. In fact, when you compare total costs with traditional screw-fix roofs, you’ll see just how cost effective Kliplok 700® can be. Factor in the long-term benefits of a concealed-fix roof and you have value that’s hard to beat.

Spandek

Spandek is a multi-rib design that offers great spanning qualities, greater trafficability and durability in steel roofing and walling applications.

Not unlike Corrugated Steel in its appearance, Spandek’s higher, squarer ribs offer greater strength. Available in long lasting Zincalume® and Colorbond®, suitable as either a roofing or walling product.

What colours are available?

This varies depending on what you choose. Colorbond is known to accompany more of an Australian/rural colour palette, whereas Zincalume has a glossy, zinc finish.

Is it durable?

Corrugated iron roofing is extremely durable and they are completely weather resistant. We find that the metal plates in the roofing system come with a galvanized iron coating. This coating helps in creating a protective layer for the metal plates and ensures that the windows do not succumb to the forces of nature. Therefore, they add another great layer of protection to your roof which is otherwise impossible to provide for. Hence this shouldn’t be overlooked when you are trying to find the perfect roof for your house. You can easily maintain this roofing in a normal way and corrugated iron roofing is very cost-effective.

High or low maintenance?

Low maintenance. Generally speaking, a properly installed metal roof will last the lifetime of your home – think 60+ years. Unlike asphalt shingles which can require re-roofing every 10-20 years, a metal roof won’t crack, peel, fade or disintegrate. Metal roofs require significantly less maintenance than other roof types because they’re built to withstand extreme weather conditions as well as repel pests and complement rainwater capture systems.

How do you install corrugated iron?

A metal roof is not a DIY job.

There is a definite step-by-step process to installing a metal roof, whether it overlap or be a clean sheet, but don’t despair if your roof was installed without due adherence to this system. A DIY job can mean you’ll be facing more maintenance and repairs in the long-term.

How much does corrugated iron cost?

Corrugated iron is one of the least expensive roofing products, but can cost more than zincalume and some types of Colorbond. Expect to pay: $19.50 per metre for galvanised corrugated iron at 0.42 BMT (base metal thickness) $12.40 per metre for zincalume at 0.42 BMT, prices may vary on colour and shape.

What else can you use corrugated iron for?

You can use corrugated iron for just about anything. Whether it be siding for your shed or a headboard for your bed, it’s both practical and all the rage aesthically these days thanks to the likes of architects such as Glenn Murcutt and online websites providing cladding ideas, whether it be tin cladding, zincalume cladding, custom orb, mini corrugated iron or bunnings corrugated iron. Whether it be for sale from a supplier or the list below, here is some help below on who to go to for your most trusted and reliable product.

This is a list of the top two corrugated iron options currently available in Australia:

1. Colorbond

Strong, secure and energy smart, COLORBOND® steel is tried and tested in Australian conditions to look great and deliver outstanding, long life performance. With 22 colours in the range, you can choose a roof colour that sets the theme for your whole home, or complements your other building material choices. In particular, you can 'mix and match' colours with your gutter, fascia and downpipes made from COLORBOND® steel. Furthermore, the range of thermally efficient light colours can help to keep your home cooler on hot, sunny days.

Adapting to the demands of the building market, Colorbond profiles have changed a great deal since its introduction in Australia in 1966. Not only has the colour range evolved, so too has the technology involved in Colorbond cladding, its price per metre and it's steel’s production. The most recent innovation, ACTIVATE® technology was introduced in 2013 and BlueScope holds numerous patents on the technology, both in Australia and around the world. No wonder we’re now seeing COLORBOND® steel being used on roofs for anything from homes all around Australia, to large commercial buildings like the Adelaide Velodrome and the Margaret Court Arena.

2. Zincalume

ZINCALUME® steel has been used with striking effect by leading architects to create the latest in modern building designs, through to classic roofing styles and rural sheds.

BlueScope’s ZINCALUME® steel with Activate® technology has a unique aluminium/ zinc/ magnesium alloy coating (AM) which acts in three ways:

• Magnesium, aluminium and zinc compounds are strategically positioned in the coating to provide sacrificial protection

• Magnesium compounds encourage the formation of a robust barrier, slowing the rate of subsequent corrosion

• Magnesium compounds also ‘activate’ the metal coating.

The result is a tough protective coating that provides enhanced corrosion resistance.

Sarah Buckley

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