14/08/2021
we looked at options available for walls when building a home or extension. But of course there’s more to a home than just the walls—roofing is equally important as it not only protects the rest of the building, but also has to withstand the most intense levels of solar radiation of any part of the home, as well as considerable forces from wind, rain and hail.
The roof must also be able to support added structures such as solar panels and solar hot water systems, satellite dishes, ventilation and air conditioning systems, as well as the weight of people walking on it while installing and maintaining such systems. Plus it’s used to collect rainwater for your home and garden.
There are many different roofing materials available, including corrugated iron and Colorbond steel, concrete, ceramic, metal and composite tiles, slate, shingles and even load-bearing panels such as SIPs (structural insulated panels). Each option has its advantages and disadvantages, each has its own particular look, and each comes in a range of options for that particular material.
Which roofing you go for will depend in part on the materials and the general look of the rest of the home, as well as your personal preference, which may be determined by a number of factors including appearance, the eco-credentials of the material, the range of colours and styles available, the building method (some roofing materials need more structural support than others), the level of maintenance you are willing to give to the roof, the fire resistance level required, and, of course, the location and hence surrounding environment of the home, including heritage or aesthetic requirements of your local council. Let’s look at each material in turn.
Sheet materials
1 Galvanised iron/Colorbond steel
These materials are made from thin steel sheet (typically less than 1 mm thick) and are coated in either zinc (galvanised iron), an aluminium/zinc/magnesium alloy (Zincalume) or paint over zinc alloy (Colorbond) coating. There’s also a stainless steel-based version of Colorbond for extreme coastal environments.
Steel sheet materials come in a wide range of profiles (the shape, corrugated or otherwise, when viewed end-on), including the common corrugated iron, the mini version (such as Lysaght Mini Orb, which is usually used on walls but can be used as a roofing material), as well as profiles more commonly used for commercial roofing although also suitable for some domestic projects, such as Trimdek, Klip-Lok and numerous others.
2 Insulated panels/SIPs
These consist of two sheets, usually coated or painted metal such as Colorbond sheeting, which are bonded to each side of a layer of insulating foam. They are similar to structural insulated panels (SIPs)—indeed SIPs can be used as roofing—but roofing panels such as Ritek’s Custom Roof Panel, Stratco’s Cooldek and Versiclad’s insulated panels range are specifically designed for roofing applications.
They are very strong, lightweight and easily installed, and may provide the first level of both thermal and acoustic insulation to a home. These types of panels are available in thicknesses of 125 mm or more, so insulation levels can be considerable. A quick look around will find domestic-grade SIPs ranging from around R2 to R5 or so.
Maintenance requirements are minimal, much the same as regular sheeting products.
Tiles
Tiles have been a popular option in Australia and the finished result is preferred by many homeowners. All tiles, regardless of the material they are made from, have the advantage that they can be easily replaced if they suffer damage, such as from falling tree limbs, being walked on etc. Unlike with sheet materials, you only need to replace the area that has been damaged, not an entire roof section from cap to gutter. There are quite a few materials used for tiles nowadays, so let’s look at the more common ones.
Concrete tiles
As you might expect, concrete tiles are made from cast/pressed concrete, which is a mixture of cement, sand and pigments. They are available in a wide range of colours and patterns, including traditional styles, flat slate-like tiles, bevelled and textured tiles.
Clay tiles
Clay tiles are usually made from terracotta clay fired to around 1100 °C, resulting in a waterproof vitrified tile. They are available in a range of colours and profiles and will have a very long life if cared for
Metal tiles
As you might expect, metal tiles are made from pressed sheet metal and designed to look like more traditional ceramic/concrete tiles. They have the advantages of being lightweight, stronger than masonry tiles and more easily replaced than sheet materials should they be damaged.
Slate tiles
Slate gives a nice look to a roof, but slate is relatively fragile and heavy and requires a skilled roofer with slate installation experience to install it. If considering slate, you should find a slate supplier/installer with long-term experience.
Composite tiles
These are made from reinforced plastic composites, much like recycled plastic decking that has become popular in recent years, although composite tiles use virgin resins (not recycled) for longevity.
Transparent/translucent sheeting
Often used for verandahs or garages, transparent or translucent materials transmit light into an area and fall into three common types: polycarbonate, PVC and fibreglass.
They are all used just like regular sheet products, and indeed have the same profiles, so that one or more sheets of steel roofing can simply be replaced with transparent sheets.
Because of their lower strength compared to steel sheets, they usually require load-spreading washers specifically designed for their profile to prevent screws pulling through the sheet during high winds.
