Living In Hail Country: Choosing An Impact-Resistant Roof
If you live in a part of the country where hailstorms or severe thunderstorms are common, then having a roof that resists impact damage could be the difference between having to pay for frequent roof repairs versus having extra spending money.
In fact, getting the most impact-resistant roof possible can save you money in other ways, too. If a damaged roof leads to leaking inside the house, you may have to pay for attic repairs or water damage restoration. On the other hand, many homeowner's insurance companies will lower your premiums if you have a roof that can hold up to your area's severe weather.
Underwriters Laboratories Impact Testing
Underwriters Laboratories is a company that conducts independent safety testing of a wide range of objects and materials, from appliances to fire extinguishers to wireless telecommunications devices. For the impact resistance of roofing, they have a standard known as UL 2218, which involves hitting roofing materials with various sizes of steel balls from varying distances, and then measuring the damage done.
Roofing materials that have undergone UL 2218 testing are classified on a scale of 1-4 based on how much energy the steel ball must have before it cracks or damages the material. A Class 1 impact rating is the least impact-resistant, and Class 4 is the most. So if you're looking for residential roofing that can hold up to hailstone impact, look for roofing materials with a Class 4 impact rating.
The reason why impact rating is helpful is because roofing that is made from the same materials won't necessarily have the same resistance to impact. For example, asphalt shingles are generally not good at resisting hailstone damage. The granules on the surface can be worn off or broken, exposing the more fragile underlayer to the elements. And with larger hailstones, the entire shingle may crack under the pressure.
Yet there are also asphalt shingles that have a Class 4 impact rating. By reinforcing the asphalt with a fiberglass base and modifying the asphalt formula for added flexibility, asphalt shingles can be made that are much less prone to damage or cracking from hail and debris impact. This is why choosing a material based on its impact rating, rather than the base material type, is your best bet for a sturdy roof.
The greatest damage from impact is at a ninety-degree angle – when the hail or storm debris collides directly with the roof. Low-pitched roofs thus suffer a lot of hail damage when the hail is falling directly, while high-pitched roofs are most damaged during high winds. Knowing this, you may prefer a low-pitched roof if you live in a windy area or a high-pitched roof if storms are not often accompanied by severe winds.
Of course, if you are installing a roof on an existing house, it may not be an option to change the pitch dramatically; however, if you are in the market to purchase a new house, you might consider your desired roof pitch as a selling point.