In areas prone to tornadoes, protecting oneself from strong winds is of utmost importance. As one of the strongest roofing materials on the market, stone-coated metal roofing is an ideal choice for homeowners in tornado-prone areas because it can withstand rain, snow, hail, and tornadoes.
In this article, we will introduce what homeowners need to know about tornado-resistant roofs and the benefits of stone-coated metal roofing, including:
What should be noted for tornado-resistant roofs?
How do traditional roofing materials withstand tornadoes?
Why is stone-coated metal roofing considered one of the best roofing materials for tornadoes!
Points to note for tornado-resistant roofs
Tornadoes are usually caused by strong thunderstorms. In addition to hurricane-strength winds, these storms also bring hail, wind-driven debris, and wind-driven rain. Therefore, you want to find a roof that can withstand all these conditions.
Impact of hail and wind-driven storm debris
The impact of hail or storm debris, including asphalt shingles flying out from home, can be as destructive as the strong winds of a tornado. Be sure to find a roofing material with a UL2218 Class 4 impact rating.
The Underwriters Laboratories (UL) in the United States is an independent laboratory that tests and certifies roofing products. The UL2218 impact rating is considered the industry standard for a roof’s ability to withstand damage from hail or storm debris.
The impact resistance of a roof is tested by repeatedly dropping a 2-inch steel ball from 20 feet above onto exactly the same spot. According to the test results, roofs are rated from Class 1 to Class 4. To achieve a Class 4 rating, the highest possible rating, the roof must not show any signs of breakage during the test.
Strong winds
Tornadoes can generate winds comparable to hurricanes. Therefore, it is wise for homeowners to find a roofing material approved for use in high-velocity hurricane zones (HVHZ). For example, Miami-Dade County has the strictest building codes in the country due to frequent hurricane landfalls. Even if your home is not in a hurricane-prone area, look for a roof that meets the strict building codes of HVHZ.
Wind-driven rain
Wind-driven rain can enter the house through the roof, causing leaks, mold, and other types of expensive water damage. Look for roofing materials that pass the TAS-100 test. Verified by an independent third-party laboratory, the TAS-100 sprays the equivalent of 8 inches of rain per hour on the roof to confirm that the roof can prevent rain from penetrating the underlying roof deck.
In addition to looking for a roof that can resist wind, hail, and impact damage, many homeowners are surprised to find that lightweight roofs are very important for protecting houses from tornadoes.
When it comes to roofs, heavier is not always better.
Shear strength refers to the ability to resist forces that cause the internal structure to slide on its own. For example, in reinforced concrete beams, the role of steel bars is to increase shear strength. On roofs, the forces that push the structure are usually caused by hurricanes, tornadoes, earthquakes, and severe storms. Houses with excessive roof loads are considered top-heavy and are vulnerable to lateral forces.
Lightweight roofs actually help enhance the shear strength of the roof without piling up excess weight on top of the building, which is least desirable.
How traditional roofing materials withstand tornadoes
As mentioned earlier, tornado-resistant roofs need to protect against more than just strong winds. However, not all roofing materials are designed to withstand hail, impact from storm debris, and wind and rain.
Traditional roofing materials, such as asphalt shingles, clay or concrete tiles, wood shingles or shakes, have shortcomings in some or all categories of tornado-resistant roofs.
Even a weak tornado can easily peel off warped or fish-mouthed asphalt shingles. The wind speed of an EF-1 tornado is 73-112 miles per hour, within the hurricane range. Once the wind speed reaches 90 miles per hour, it exceeds the rated wind resistance of a typical asphalt shingle roof. Asphalt roofs are prone to cracking and splitting after exposure to the natural environment, leading to loosening around fasteners.
Clay tiles, wood shakes, or wood shingle roofs provide insufficient impact protection against hail and storm debris. Most roofs cannot guarantee their impact resistance at all.
Why are metal roofs better in tornadoes?
One of the biggest advantages of metal roofs is their ability to resist cracking or splitting around fasteners. When the wind blows over the roof surface, the edges of metal panels do not curl up to form air inlets like asphalt shingles.
This is because metal roofs do not rely on nails, staples, or adhesives to be fixed. Instead, they are designed to withstand strong winds, using high-quality, corrosion-resistant screw fasteners and interlocking technology to firmly fix the roof in strong winds.
Most metal roofs, such as stone-coated metal roofs, have some of the highest wind uplift ratings, which are key safety indicators for building and testing the wind performance of roofing systems. This enables metal roofs to meet the strict building codes of HVHZ and pass the wind and rain test of TAS-100.
When it comes to hail or storm debris impact, metal roofs have the highest UL2218 hail impact rating. Manufacturers like SKW metal Roofing provide a comprehensive lifetime limited warranty for their roofs, covering hail impacts up to 2.5 inches in diameter and wind speeds up to 120 miles per hour.
Metal roofs are also one of the lightest roofing materials on the market, helping to enhance the shear strength of the roof.
Metal roof: weighs up to 1.6 pounds per square foot.
Wood strips/shakes: weigh up to 4.5 pounds per square foot.
Asphalt tape: weighs up to 5 pounds per square foot.
Clay or concrete tiles: weigh up to 10 pounds per square foot.
The benefits of metal roofs go far beyond protection against tornadoes. Homeowners can expect other benefits of metal, including:
A lifespan two to three times longer than traditional roofing materials such as asphalt shingles.
Providing up to 25% energy savings.
Getting insurance discounts. For example, in Texas, metal roofs can reduce homeowners’ insurance by up to 35% (consult your local insurance company for available discounts).
Increasing the value of the house by 6%.
SKW tornado-resistant metal roofing
SKW metal roofing products are renowned for their quality, durability, and longevity. SKW stone-coated metal roofing is manufactured in our factory in Dezhou, Shandong, China. It has been tested and exceeds requirements to ensure that every panel we produce has the quality that SKW is known for. Since SKW was established 20 years ago, SKW roofs have protected houses and buildings from tornadoes and almost everything else that nature has to offer.
Ready to see and feel the difference of SKW? Click here to order a free sample.