Tornados

How Tornados Damage Roofs

Tornados create a vacuum that sucks the materials right off your home, and the fierce accompanying winds turn branches, building materials, rocks, and debris into high-velocity missiles. The supercell thunderstorms that form tornados also bring lightning, hail, high winds, and heavy rains with them, so if your home is within a mile of a tornado, it can still be affected by the storm.

While there have been improvements in tornado-proof building materials over the years, science has not figured out how to tornado-proof homes. This makes homes in a tornado’s path highly susceptible to not only roof damage, but other structural or foundational issues as well—if not total loss.

How to Prepare and Recover From Tornados 

There are preparations you can make to fortify your home. Pay attention to local weather reports and purchase an NOAA-approved weather radio for your home. Meteorologists can predict when conditions are right for a tornado, and an NOAA-approved radio set to the proper county code can give you and your family enough time to get to a safe location. Choose a small, interior, windowless area in the lowest part of your home, such as a basement. Identify this area before a storm hits. If you live in an area with frequent tornados, consider constructing a shelter built to ICC 500 standards.

Make sure to inspect your roof after every major storm. Be sure to assess your roof vents, gutter, and chimneys for heavy damage. Tornados can also produce hail, so visit our page on hailstorms for more information on spotting hail damage.

If your roof is badly damaged, FEMA’s Operation Blue Roof may be able to provide a tarp to help protect your roof while you seek repairs. FEMA can be reached at 888-ROOF-BLU (1-888-766-3258). For more information on dealing with tornados, visit FEMA’s website.

Selecting a wind-resistant roofing product that can stand up to vertical drafts can help limit the damage to your roof—and possibly to neighboring homes—during a tornado. Most contemporary roofing materials offer a high level of wind protection when installed according to manufacturer specifications. Some offer specific instructions, such as the use of additional fasteners or an adhesive for installation in high-wind zones. Slate and metal roofing, while typically more expensive than asphalt, provide excellent protection against wind. Slate is extremely heavy, however, and may require additional structural roof supports. Metal, alternatively, provides excellent wind-resistance without the heavy weight of slate. Clay tile is also a heavy roofing material with strong wind-resistance, yet it is susceptible to cracks—which can spell trouble when hit by flying debris or falling branches.

Tornado Facts

According to the National Severe Storms Laboratory (NSSL), tornados causing roughly $400 million in wind damage and killing approximately 70 people every year¹.
The worst tornado in U.S. history, the “Tri-State Tornado” of 1925, passed through eastern Missouri, southern Illinois and southern Indiana, killing 695 people, injuring some 13,000 people and causing $17 million in property damage². Southern Illinois was hit the hardest, accounting for more than 500 of the casualties.

The wind speed of a tornado can top out at a frightening 250 miles per hour – faster than a Formula One car – and can leave a path of destruction 50 miles long.

There’s evidence to suggest that changes in the climate are making tornado activity in the U.S. more frequent³. A recent study by the National Severe Storms Laboratory noted a significant increase in tornado frequency in parts of the Southeast, Midwest, and Northeast between 1979 and 2017⁴. While 77 percent of tornados in the U.S. are considered weak (EF-0 or EF-1), scientists expect climate change to increase America’s propensity for warm moist air, meaning more thunderstorms and tornados⁵.

How Tornados Form

These vertical funnels of fast-spinning air occur in the U.S. more than any other region in the world. To create a tornado, a severe thunderstorm (called a supercell) needs to be layered with hot, moist air on the bottom and cool dry air on top. The area between the Rocky Mountains and the Gulf of Mexico produces ideal conditions for tornados to form. The Rockies provide the cool, arid air from the high desert in the Southwest, which collides with warm, wet air that travels from the Gulf in the Southeast.

Sources

1. https://www.nationalgeographic.com/environment/natural-disasters/tornadoes/#close
2. https://timelines.ws/subjects/Disasters.HTML
3. https://www.pbs.org/newshour/science/is-climate-change-making-u-s-tornadoes-worse
4. https://www.weather.gov/lmk/niu_tornado_frequency_study
5. https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology/tornado-alley