When most people think of roofs, traditional shingle or tile roofs often spring to mind. But in Australia’s harsh climate, metal roofs have long been favoured by homeowners thanks to their durability and versatile nature. But, contrary to popular belief, the traditional corrugated iron roof isn’t the only type of metal roof available in Australia.
In this article on types of metal roofs we discuss the most common types of metal roofing materials used in Australia, as well as the different types of metal roof sheets these are available in.
Types of metal roofing materials
When it comes to selecting a metal roof, the first thing to consider is what type of material is right for your home. Numerous factors should be considered when making this decision, including your home’s location, its technical design and the aesthetic you’re after. Below we step through the four most common types of metal roofing materials you have to choose from, including their pros and cons.
COLORBOND steel roofing. Image from COLORBOND
Loved for its hardwearing nature, steel is one of the best roofing options in Australia. It’s also the material people most commonly associate with metal roofs. Steel is an alloy composed of iron and carbon. This combination of carbon and iron is what makes steel one of the strongest and most durable building materials available. Because steel is prone to rusting, specific types of steel are typically used for roofing. These include:
- Galvanised steel, which is steel with a zinc coating. Adding the zinc coating helps to prevent corrosion, making it more weather resistant than regular steel.
- Stainless steel, which is another form of alloy that includes chromium to prevent rusting and corrosion. Stainless steel is stronger than galvanised steel and will be more expensive.
- Coated steels, such as COLORBOND® Steel and ZINCALUME® Steel, which consist of a steel core and corrosion resistant coating.
Steel has numerous advantages, including:
- It is a strong material, which makes it durable and dent resistant. Steel roofs stand up better to the elements—such as strong winds and hail—than shingles or tiles.
- It is long-lasting. Steel roofs typically have a lifespan of at least 50 years, which is significantly higher than other roofing materials such as asphalt tiles.
- It is good at reflecting heat away from the building. Unlike some other roofing materials which absorb heat from the sun, steel reflects sunshine away from the building, helping to keep it cool in hot weather.
- It is recyclable, which makes it a relatively environmentally friendly option.
- It is a relatively low-cost roofing option, on par with other roofing materials. On average, steel roofing costs around $55 per square metre, which is the same as asphalt shingles, and only slightly more than concrete shingles. Considering steel is significantly more durable, this makes it great value for money.
- It is available in an extensive range of colours.
While the advantages of steel outweigh the disadvantages, there are some cons of steel roofing to keep in mind:
- Steel will rust over time, particularly if exposed to high levels of salt water, making it less suitable for coastal environments. While using galvanised steel can prevent this, the coating may come off after several decades of wear.
- Steel is harder than most other roofing materials, so if listening to rain on a metal roof isn’t something you enjoy, it may be worth choosing a slightly softer metal such as copper or zinc which will dampen the noise.
Aluminium may be one of the lightest types of metal roofs available, but it is also one of the strongest, making it a popular alternative to steel roofing. One of its main advantages over steel is its natural rust resistance—because aluminium is a chemical element and does not contain iron, it does not rust like steel does. It is therefore a great roofing option for homes in high rainfall or coastal areas.
Other benefits of aluminium roofing include:
- Its long lifespan of between 50 and 70 years.
- It retains less heat than steel, which can help to keep your home cooler.
- It is lighter weight than steel, so will place less stress on your building’s structure.
The downsides of aluminium roofing include its cost—it is typically more expensive than steel—and the fact that it is more prone to denting than steel as it is a lighter metal. It will also expand and contract more with temperature variations than steel so requires careful installation.
Famed for its striking visual appearance, copper has been used to build roofs for centuries. Unlike steel, which is an alloy, copper is a chemical element. While it starts out as a shiny pinkish-orange in colour, it gradually turns a green-blue over time as it develops a patina.
Copper is relatively uncommon in residential Australian houses, however it is a highly durable, low-maintenance roofing product that can add an elegant touch to a high-end build. Copper roofing has the following advantages:
- It is extremely durable. Copper is corrosion and rust resistant, and if properly installed and maintained, can have a lifespan well in excess of 50 years.
- It is low maintenance as it is naturally mould and rust resistant.
- It is a lightweight building material, which will place less stress on your building structure.
- It develops a blue-green patina over time, as it is exposed to the elements, making it an ideal choice as a statement roof.
There are some downsides to copper roofs, however. Specifically:
- Copper is one of the more expensive types of metal roofing material. This is due to a number of factors including the relatively high cost of the copper, and the specialised installation required.
- Copper is prone to expanding and contracting more than steel with temperature variation. It is therefore important to ensure it is installed by an experienced tradesperson.
Like copper, zinc is a chemical element that makes for a long-lasting, low-maintenance roofing option. While it is commonly used to galvanise steel, it is also used by itself as it has the following advantages:
- It is long-lasting, second only to copper in terms of its durability.
- It has great aesthetic appeal. Zinc maintains an elegant grey colour, which darkens over time as it develops a patina.
- It is low-maintenance as its patina forms a protective coating that resists mould and rust formation.
- It is environmentally friendly. Like copper, zinc is 100% recyclable and requires a relatively low amount of energy in the production process due to its low melting point.
Like copper, zinc is a premium building material and is therefore at the pricier end of the roofing material spectrum. It is therefore important to ensure it is installed by a zinc roofing expert.
Types of metal roof sheets
In addition to selecting the type of metal roofing material you want to use, you’ll need to select the most appropriate type of metal roof sheet for your house. The most common types of metal roof sheets include:
1. Corrugated sheeting
Widely used on Australian houses since the early 1900s, corrugated sheeting is one of the most common types of metal roof sheets. It was invented in 1829 by Henry Robinson Palmer and remains a highly popular metal roofing option today as it’s quick to install and a relatively low-cost option. While it is most commonly associated with steel roofing, it is available in all types of roofing material.
It is metal sheeting with ‘S’ shaped wavy and round corrugations, and is suitable for roofs with a pitch above 5 degrees. The main advantage of corrugated sheeting is that it is stronger than flat sheeting, making it a good option for softer metals like aluminium and zinc.
Unlike standing seam metal roofing, corrugated sheets are attached to the roof’s pylons with visible fasteners. Each sheet is overlapped with the next by several corrugations to ensure a watertight seal, and screwed into place.
2. Standing seam metal roofing
Standing seam metal roofing is fast gaining popularity as an elegant, modern looking alternative to traditional corrugated sheeting in Australia, and is commonly used for zinc and copper roofs. In a standing seam roof, each sheet of metal is secured to the roof frame with clamps, so that no roof fastenings are visible from the outside. Each panel is then crimped to the next, forming a watertight seal.
Aside from the visual appeal of a standing seam roof’s clean lines, its main advantage over a corrugated roof is its superior watertightness. Because of the way the sheets are joined together, minimal overlap is required to achieve a watertight seal, helping to reduce the amount of material required.
3. Trimdek and Kliplok
Sitting between round corrugated sheeting and typical standing seam metal sheeting, are a series of modern roofing sheets with ribs with a trapezoidal appearance. Depending on the type chosen, they are either fixed with screws or concealed clips. The primary advantage of these types of metal roof sheets is that they can be used on roofs with smaller pitches than corrugated roofs. These are typically used for steel roofs.