RoofViews

Commercial Roofing

Protecting Your Building from Hail Roof Damage

By Dawn Killough

May 13, 2022

Close-up of hail impacting dark shingles.

Up to 25% of the United States experiences large hail episodes—and when they do, hail can cause severe damage to roofs and the HVAC equipment stored there. Hailstorms account for 70% of the average annual property losses from severe convective storms in the US. Building owners can protect their buildings and equipment by designing their buildings and roofs to withstand the damage caused by large hailstones.

FM Global, an insurance company that specializes in loss prevention and testing, provides a standard for testing and approving assemblies that provide greater hail resistance. Building owners and designers often rely on FM Global's resources to specify desired roofing assemblies and construction methods. These resources include RoofNav assemblies from FM Approvals as well as loss prevention data sheets and Approvals Standards. Well-maintained roofs that meet FM's hail testing and approval requirements are better equipped to protect buildings from hail and water damage that occurs during storms.

Assessing Risks from Hail Roof Damage

Hail can cause physical damage to a building's roof and the equipment stored there, including dents, cracking, mineral loss on modified bitumen sheets, and compound delamination. Older roofs or those in poor condition may be more susceptible to damage from hail. Roof equipment, including cooling fins and condenser coils, can also be damaged from falling hail. Skylights are subject to hail punctures, which are the main cause of water damage to buildings and their contents.

In the US, the most severe hail generally occurs in the Midwest and central contiguous states. According to FM, very severe hail can be found in the region from North Dakota to Texas and Colorado to Missouri. Roofs, roof assemblies, and equipment in this region should be designed to meet FM's specific hail requirements to better withstand hail roof damage.

Defining Very Severe Hail

FM Approvals has recognized three classes of hail: moderate, severe, and very severe.

Moderate hail (MH) is less than 1.75 inches in diameter, which is about the size of a cherry. Severe hail (SH) is 1.75 inches to 2 inches in diameter, similar in size to a golf ball. Very severe hail (VSH) is 2 inches or greater in diameter, similar in size to a billiard ball (or larger).

FM's Very Severe Hail (VSH) certification was added in 2016 based on data from the National Oceanic and Atmospheric Administration's National Weather Service and National Center for Environmental Protection's Storm Prediction Center. This data showed a concentration of reports of hail larger than 2 inches in diameter in the very severe hail region.

Passing a Very Severe Hail Test

FM tests assemblies in accordance with FM 4470:

  • To test an assembly for moderate hail, a 2-inch-diameter steel ball weighing 1.19 pounds is dropped from 81 inches above the assembly. Two samples, unweathered and weathered, are tested 10 times each. This test provides an impact energy of 8 foot-pounds.
  • Testing for severe hail, the same 2-inch-diameter steel ball is dropped from a height of 141.5 inches above the assembly. This test provides an impact energy of 14 foot-pounds.
  • When testing whether a roof assembly can withstand very severe hail, a 2-inch-diameter preformed ice ball is launched at the assembly using compressed air. Three samples are used in this test: one unconditioned, one UV weathered, and the third UV weathered and heat aged for 42 days prior to testing. This test provides an impact energy of between 53 and 58 foot-pounds.

After the test is performed, the roof assembly is inspected for dents, cracking, and delamination. Assemblies that pass the test are certified as meeting the FM criteria. You can find an online database of VSH-rated roofing assemblies here; GAF has over 1600 single ply VSH-listed assemblies.

The FM standard recommends that building owners inspect their roofs on a regular basis and repair deficiencies; the standard also advises replacing roofs where deficiencies cover a large area or when the roof is nearing the end of its useful life. An owner should also inspect heat and smoke vents and skylights for cracking, yellowing or discoloration, cloudiness, or other indications of damage due to weathering and aging. Skylights showing damage should be replaced as needed, and hail guards on HVAC equipment require inspections to ensure they are in place and free of damage.

For more information about GAF and very severe hail, contact your local roofing contractor or complete our very severe hail contact form.

About the Author

Dawn Killough is a freelance writer in the construction, finance, and accounting fields. She is the author of an ebook about green building and writes for construction tech and green building websites. She lives in Salem, Oregon with her husband and four cats.

Related Articles

GAF Sustainability Award winners holding their award.
In Your Community

GAF Celebrates Major Strides in Manufacturing Sustainability

Manufacturing sustainability is a top priority for GAF. In 2022, the company announced its 2030 Planet Goals to "focus on operational improvements, product transparency, and the introduction of circularity in the asphaltic shingle industry."Looking to lead positive change while considering the long-term impact of its business on the planet, GAF identified several goals, including:Diverting 1 million tons of roofing materials from landfills while integrating recycled shingle materials into new shingle productsDiverting 80% of manufacturing waste from landfills, recycling all shingle and TPO scrap that results from the manufacturing process, and recycling or reusing fiberglass mat scraps and coresReducing embodied carbon and operation carbon throughout its manufacturing and operationsAchieving Environmental Product Declarations for its core products, conducting life cycle assessments, and generating 2.5 GW of power from solar roofs in partnership with GAF EnergyMeeting these goals takes time, resources, innovation, and ingenuity, all backed by a team working to build a better world. Every GAF location is striving to meet the company's goals. Looking back on the progress made in 2023, some impressive accomplishments are bringing the company closer to achieving full manufacturing sustainability.Residential ManufacturingThe GAF Mt. Vernon, Indiana, shingle manufacturing plant worked toward achieving sustainable operations through robust recycling efforts. The team established a shingle recycling outlet estimated to divert thousands of tons of asphalt shingles from landfills annually. This has eliminated thousands of dollars in disposal fees and reduced transportation costs.The Mt. Vernon staff found creative ways to keep complex waste materials out of landfills, including working with a local golf course that could take the plant's waste sand. The team implemented an internal recycling program that includes cardboard and packaging materials, increasing its waste diversion score.Commercial ManufacturingAt the Gainesville, Texas, plant that manufactures TPO and Polyiso, team members earned the area's first waste diversion certification for both products' waste streams. They also earned a recycled content certification for each.The plant established a trial program with a plastics recycler to reprocess TPO skin material for reuse in manufacturing new material. Recycling and reusing would divert thousands of tons of waste from landfills and use recycled materials in manufacturing flexible TPO for flashings.The plant also developed a program with a local recycling company that serves as a single source to take its pallets, large cardboard boxes, facers, paper, and plastics.Sustainability All-StarsRecycling and manufacturing sustainability programs wouldn't be possible without the people behind the initiatives. GAF is proud to spotlight these individuals who went above and beyond to meet the company's sustainability goals.Ben AnselmanAs part of the Mt. Vernon team, Anselman was critical to starting the plant's core recycling program. He initiated repairs to an existing baler and established a program for recycling the super sacks. His creativity sparked the partnership with the local golf course to divert aggregate waste from landfills. In addition, he was the champion for the shingle recycling outlet project and repurposed an existing compactor to reinstate a cardboard recycling initiative.Christina Talladira and Amy WilsonThese teammates lead the core recycling program at the Tampa, Florida, manufacturing plant. They worked together to establish aggregate and shingle recycling programs with their local recycling company. Talladira and Wilson consistently look for ways to divert waste streams from landfills. They also handle the administrative needs accompanying these programs, including scheduling loads and tracking waste.Jeremy TisdaleAt the Tuscaloosa, Alabama, plant, Tisdale took the initiative to improve its core recycling program and set up a cardboard recycling program. He also championed a baler trial for glass mat cover and core waste, developing standard operating procedures and a job safety analysis. He was the innovator behind diverting the plant's plastic waste from landfills. He created a program where stretch film and shingle bundle packaging waste is saved in Gaylord boxes and then baled whenever the plant has downtime.Pete WeyrensIn Gainesville, Texas, Weyrens is the champion behind the plant's recycling efforts, establishing relationships with the local recycling company. He also organized the flexible TPO skin material trials. This effort will divert thousands of tons of waste from landfills and use recycled materials to manufacture flexible TPO for flashings.Leslie PeelsAfter the plant in Cumming, Georgia, saw a drop in its year-over-year waste diversion rate, Peels stepped in to turn those numbers around. Leading the effort to separate recyclable materials from regular waste, the Cumming location saw an impressive increase in keeping waste out of the landfill. Peels also set an example in data collection and analysis to keep the plant's sustainability goals on track.TJ Jenkins and Todd WinsteadJenkins and Winstead represent the TPO team at the Mt. Vernon manufacturing plant. Working together, they used their knowledge and experience in the TPO manufacturing process to help earn the plant's recycled content certifications. They also found a way to divert calcium chloride from local landfills and continue to work closely with the sustainability team to support waste diversion efforts.Sustainability PromiseGAF is committed to "Protect What Matters Most," and that includes people, communities, and the planet. Its sustainability promise is an opportunity to invest in a healthy future for everyone. Learn more about that commitment in its sustainability report.

By Authors Karen L Edwards

April 11, 2024

GAF volunteers gather in front of the Ennis, TX plant to celebrate Breast Cancer Awareness.
In Your Community

How GAF Team Members Are Making an Impact in Ennis, Texas

Ennis, Texas, might be best known for hosting the National Polka Festival every year, but it's also home to many GAF professionals who support the community.GAF has been part of the Ennis community for over 45 years, where its footprint has grown to include a research and development center and two manufacturing plants. In addition to the work GAF employees complete onsite, many have used their connections to champion local organizations' efforts. GAF knows how important it is to build resilient, thriving communities, and its continued commitments in Ennis offer proof of what's possible.The GAF Ennis Facility's Tradition of Giving BackWith over 260 employees at the Ennis facility, it has a significant impact on the surrounding area. Many team members have worked there for 30 to 40 years, or more, and are lifelong residents of the city. One of the plants manufactures fiberglass mat rolls, a critical component used in roofing materials, while the other plant manufactures shingles. The shingle plant recently expanded to include recycled asphalt briquettes, which will be used in manufacturing recycled asphalt shingles to divert 300,000 tons of waste from landfills.David Tuttle, Senior Director of Residential Operations at GAF, joined the community in 2004 and in 2012 set out to help his friends and neighbors flourish with increased community engagement. He first joined the board of the Ellis County Children's Advocacy Center and has since expanded his service to other organizations, including two local United Way chapters, and the Ennis Boys and Girls Club.Tuttle's work started a legacy of community leadership. For instance, Joe Glanton, the GAF plant's community engagement ambassador, is now President of the Board of Directors of Greater Ennis United Way. Other GAF associates quickly followed suit, demonstrating their commitment to the community by working on local projects as well as joining the board of the Ennis Boys and Girls Club.Today, the tradition of giving back still runs strong. Many local groups and charitable organizations continue to benefit, and the community keeps growing stronger.GAF Ennis Facility's Community ImpactProviding justice, hope, and healingTuttle was instrumental in setting an example for community engagement. After joining the board of the Ellis County Children's Advocacy Center more than a decade ago, he eventually served as Board President. The nonprofit responds to child abuse and sexual assault reports, providing advocacy, forensic interviews, and mental health services to those affected."Our charge is to provide justice, hope, and healing for every child," Tuttle explains. After serving two years as Board President, and two as Past President, his 12-year tenure on the board is ending, but Tuttle has been working to bring other GAF team members into the organization and maintain support for Ennis's youngest residents.Stepping upGAF team member, Angela Adams, who is also an Ennis Boys and Girls Club board member, serves as a mentor through the Mentors Care program. After a Mentors Care representative was invited to speak at the Ennis plant, three of her colleagues signed up to volunteer as mentors. "I was so impressed by the number of employees who showed up to listen to what Mentors Care had to say," Adams notes.Mentors Care matches struggling high school students with mentors who serve as positive role models to help students manage their day-to-day challenges. The nonprofit recently reported that 100% of seniors in the program graduated, 92% of mentored students achieved a 90% school attendance rate, and 89% of students advanced to the next grade level.Unique solutions for unique challengesMatt Neal, GAF engineering manager, serves as Board President of Runnin' Free Ranch, which serves area veterans, at-risk youth, and individuals with special needs through counseling with horses. The organization is working to change the lives of Ennis residents who face unique challenges.A local US Navy veteran who participates in the program wrote that he was "a prisoner of rage and unending bitterness" after he departed from serving. Though he doubted a horse could help him, he eventually realized that "our therapy sessions have comprised of laughter, tears, frustration, and a release of tension that I've never experienced before."Making a direct impact when it's needed mostJoe Glanton has been involved in the evolution of many community organizations, including serving as a board-level leader for the Ennis CARES organization. Founded during the COVID-19 pandemic, Ennis CARES was developed to help community members with non-emergency needs, including food, health care, and other services. Glanton notes that "it's a natural extension of our work to be as supportive and active as possible with organizations that have a direct impact on protecting what matters most."Ennis CARES will soon break ground on a new community center and "combat multiplier" for local charities, opening space to house a food bank and provide services such as health care for women and seniors.Disaster ResponseRandy Brumley, GAF mat plant Production Process Manager, met Team Rubicon—a disaster response organization—when they visited the Ennis plant. He instantly decided to become a greyshirt volunteer alongside several other team members.Brumley wrote about his first operation, where he responded to Houston neighborhoods affected by Hurricane Harvey. "Team Rubicon is a diamond class organization held together by volunteers—veterans and civilians—and respect at its core," he explains. "For anyone who has the chance, I would say: Step into the arenal!" Brumley has been a part of the Ennis community, and a GAF employee for over 40 years, and also serves as a member of the Ennis Boys and Girls Club.Becoming Part of the CommunityTuttle shares that he and his teammates appreciate that GAF affords them the flexibility and opportunity to give back to their communities. "It's exciting that GAF provides the support and encouragement to go and serve," he says. "We owe it to our communities; we're really blessed and privileged with our jobs and careers and the benefit to go volunteer. Everyone has the ability to go and find a place to serve."With a total of 34 manufacturing locations spread throughout 26 communities across the US, GAF and its team members are well positioned to change lives and help build resiliency nationwide. Curious to learn more about joining the GAF team? Explore the available career options and opportunities to get involved.

By Authors Karen L Edwards

April 09, 2024

Community Matters GAF Employees and Volunteers
In Your Community

2023 Social Impact: GAF Roofing

As industry leaders, we have a responsibility to use our expertise and resources to leave our communities and our planet better than we found it. We are making strategic investments to achieve our goals and have made great progress in partnership with our employees, non-profit partners and contractors. Visit gaf.com/sustainability to learn more and join our efforts.

By Authors GAF Roof Views

December 12, 2023

Don't miss another GAF RoofViews post!

Subscribe now