When Hail Tests Your Roof's Mettle: Why Metal Roofs Are the Solution to Hailstorm Damage
Australia is no stranger to frequent, and often severe, hailstorms. The monstrous hailstorm that smashed Sydney in 1999 damaged over 45,000 houses and caused enough destruction to make it the world's costliest hailstorm ever recorded.
However, as terrible as that hailstorm was, it does demonstrate that the future of roofing in Australia, and especially New South Wales, revolves around metal. By using some of the details from the storm in 1999, and some from the present, this article will demonstrate that metal roofing is the sturdiest and most cost-effective solution to hailstorm damage.
Other Roofing Materials Are Easily Damaged
Some of the most common roofing materials, such as terracotta tiles and concrete tiles, are brittle. This means that even average-sized hailstones can cause considerable damage to them. After the Sydney storm of 1999, for instance, 72% of the roofing material needed for roof repair after the storm consisted of terracotta tiles, amounting to 12 million tiles.
Concrete tiles (13%), metal (11%) and slate tiles (4%) accounted for the rest of the materials needed for roof repair. When a large hailstone strikes a terracotta or concrete tile, it can crack or even break the material. The damage is both cosmetic and functional. In regards to metal roofs, a hailstone may dent the material, which causes mainly cosmetic damage.
Average-Sized Hailstones Are a Minor Threat
The hailstones that caused so much damage in the Sydney storm of 1999 were 7 centimetres in size, roughly the size of cricket balls. Such large hailstones will damage all roofing materials—even metal. However, since the average size of hailstones in Australia is about 4 centimetres, a metal roof can withstand all but the most severe hailstorms.
In the US, hailstorms are also a common problem. To better understand the performance of various roofing materials when exposed to hailstorms, The Roofing Industry Committee on Weather Issues Inc. (RICOWI) conducted two hail investigations.
They found that while most roofing materials were badly damaged by hailstones of between 1.25 and 2.0 inches in size, metal roofing could withstand hailstones of up to 2.5 inches. This demonstrates that while average-sized hailstones will damage most roofing materials, a metal roof will suffer only minor damage in the form of dents.
Older Metal Roofs May Not Fare so Well
Although a metal roof can last for decades, even when exposed to extreme weather, eventually corrosion may take its toll. Areas that are weakened by rust will no longer be able to withstand impacts from hailstones. That's why it is important to monitor your metal roof and to have it inspected after especially severe hailstorms.
The downside to repairing a metal roof rather than replacing it is that the colour of any newer roof sections may not match that of the existing roof.
Repair and Repaint, or Replace?
Whatever type of metal your roof is composed of, whether it is colorbond steel, zincalume steel or seaside grate steel, unusually large hailstones will pose a problem. The main issue will likely be moderate to severe denting. A large hailstone can leave a large dent and penetrate the upper layer of paint, stripping away the colour along with the paint's protective properties.
On roofs with minimal slopes, large dents can also cause water to pool, eventually leading to corrosion if the protective coating has been penetrated. After a severe hailstorm then, you should inspect your metal roof or hire a roofing contractor to do it for you.
In some cases, you can save money by repairing and repainting, but only a professional and reputable roofing contractor should make such a recommendation. While no other roofing material stands up to hail like metal, replacing a severely dented roof will save money that would otherwise be spent on mounting maintenance costs due to corrosion and water damage.
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