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 commercial 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

Installation of ISO Board and TPO on a Roof
Building Science

Roof Insulation: A Positive Investment to Reduce Total Carbon

Have you ever thought about building products reducing the carbon dioxide emissions caused by your building? When considered over their useful life, materials like insulation decrease total carbon emissions thanks to their performance benefits. Read on for an explanation of how this can work in your designs.What is Total Carbon?Total carbon captures the idea that the carbon impacts of buildings should be considered holistically across the building's entire life span and sometimes beyond. (In this context, "carbon" is shorthand for carbon dioxide (CO2) emissions.) Put simply, total carbon is calculated by adding a building's embodied carbon to its operational carbon.Total Carbon = Embodied Carbon + Operational CarbonWhat is Embodied Carbon?Embodied carbon is comprised of CO2 emissions from everything other than the operations phase of the building. This includes raw material supply, manufacturing, construction/installation, maintenance and repair, deconstruction/demolition, waste processing/disposal of building materials, and transport between each stage and the next. These embodied carbon phases are indicated by the gray CO2 clouds over the different sections of the life cycle in the image below.We often focus on "cradle-to-gate" embodied carbon because this is the simplest to calculate. "Cradle-to-gate" is the sum of carbon emissions from the energy consumed directly or indirectly to produce the construction materials used in a building. The "cradle to gate" approach neglects the remainder of the embodied carbon captured in the broader "cradle to grave" assessment, a more comprehensive view of a building's embodied carbon footprint.What is Operational Carbon?Operational carbon, on the other hand, is generated by energy used during a building's occupancy stage, by heating, cooling, and lighting systems; equipment and appliances; and other critical functions. This is the red CO2 cloud in the life-cycle graphic. It is larger than the gray CO2 clouds because, in most buildings, operational carbon is the largest contributor to total carbon.What is Carbon Dioxide Equivalent (CO2e)?Often, you will see the term CO2e used. According to the US Environmental Protection Agency (EPA), "CO2e is simply the combination of the pollutants that contribute to climate change adjusted using their global warming potential." In other words, it is a way to translate the effect of pollutants (e.g. methane, nitrous oxide) into the equivalent volume of CO2 that would have the same effect on the atmosphere.Today and the FutureToday, carbon from building operations (72%) is a much larger challenge than that from construction materials' embodied carbon (28%) (Architecture 2030, 2019). Projections into 2050 anticipate the operations/embodied carbon split will be closer to 50/50, but this hinges on building designs and renovations between now and 2050 making progress on improving building operations.Why Insulation?Insulation, and specifically continuous insulation on low-slope roofs, is especially relevant to the carbon discussion because, according to the Embodied Carbon 101: Envelope presentation by the Boston Society for Architecture: Insulation occupies the unique position at the intersection of embodied and operational carbon emissions for a building. Insulation is the only building material that directly offsets operational emissions. It can be said to pay back its embodied carbon debt with avoided emissions during the building's lifetime.A Thought Experiment on Reducing Total CarbonTo make progress on reducing the total carbon impact of buildings, it is best to start with the largest piece of today's pie, operational carbon. Within the range of choices made during building design and construction, not all selections have the same effect on operational carbon.When making decisions about carbon and energy reduction strategies, think about the problem as an "investment" rather than a "discretionary expense." Discretionary expenses are easier to reduce or eliminate by simply consuming less. In the example below, imagine you are flying to visit your client's building. Consider this a "discretionary expense." The input on the far left is a given number of kilograms of carbon dioxide equivalent (CO2e) generated for the flight, from the manufacturing of the airplane, to the fuel it burns, to its maintenance. The output is the flight itself, which creates CO2 emissions, but no durable good. In this case, the only CO2 reduction strategy you can make is to make fewer or shorter flights, perhaps by consolidating visits, employing a local designer of record, or visiting the building virtually whenever possible. Now consider the wallpaper you might specify for your client's building. It involves a discretionary expenditure of CO2e, in this case, used to produce a durable good. However, this durable good is a product without use-phase benefits. In other words, it cannot help to save energy during the operational phase of the building. It has other aesthetic and durability benefits, but no operational benefits to offset the CO2 emissions generated to create it. Your choices here are expanded over the previous example of an airplane flight. You can limit CO2 by choosing a product with a long useful life. You can also apply the three Rs: reduce the quantity of new product used, reuse existing material when possible, and recycle product scraps at installation and the rest at the end of its lifespan. In the final step in our thought experiment, consider the insulation in your client's building. As before, we must generate a certain amount of CO2e to create a durable good. In this case, it's one with use-phase benefits. Insulation can reduce operational energy by reducing heat flow through the building enclosure, reducing the need to burn fuel or use electricity to heat and cool the building. The good news is that, in addition to the other strategies considered for the flight and the wallpaper, here you can also maximize operational carbon savings to offset the initial embodied carbon input. And, unlike the discretionary nature of some flights and the often optional decision to use furnishings like wallpaper, heating and cooling are necessary for the functioning of almost all occupied buildings.Based on this example, you can consider building products with operational benefits, like insulation, as an "investment." It is appropriate to look at improving the building enclosure and understanding what the return on the investment is from a carbon perspective. As the comparison above demonstrates, if you have a limited supply of carbon to "invest", putting it into more roof insulation is a very smart move compared to "spending" it on a discretionary flight or on a product without use-phase carbon benefits, such as wallpaper.This means we should be careful not to measure products like insulation that save CO2e in the building use-phase savings only by their embodied carbon use, but by their total carbon profile. So, how do we calculate this?Putting It to the TestWe were curious to know just how much operational carbon roof insulation could save relative to the initial investment of embodied carbon required to include it in a building. To understand this, we modeled the US Department of Energy's (DOE) Standalone Retail Prototype Building located in Climate Zone 4A to comply with ASHRAE 90.1-2019 energy requirements. We took the insulation product's embodied energy and carbon data from the Polyisocyanurate Insulation Manufacturers Association's (PIMA) industry-wide environmental product declaration (EPD).To significantly reduce operational carbon, the largest carbon challenge facing buildings today, the returns on the investment of our building design strategies need to be consistent over time. This is where passive design strategies like building enclosure improvements really shine. They have much longer service lives than, for example, finish materials, leading to sustained returns.Specifically, we looked here at how our example building's roof insulation impacted both embodied and operational carbon and energy use. To do this, we calculated the cumulative carbon savings over the 75-year life of our model building. In our example, we assumed R-30 insulation installed at the outset, increased every 20 years by R-10, when the roof membrane is periodically replaced.In our analysis, the embodied CO2e associated with installing R-30 (shown by the brown curve in years -1 to 1), the embodied carbon of the additional R-10 of insulation added every 20 years (too small to show up in the graph), and the embodied carbon represented by end-of-life disposal (also too small to show up) are all taken into account. About five months after the building becomes operational, the embodied carbon investment of the roof insulation is dwarfed by the operational savings it provides. The initial and supplemental roof insulation ultimately saves a net of 705 metric tons of carbon over the life of the building.If you want to see more examples like the one above, check out PIMA's study, conducted by the consulting firm ICF. The research group looked at several DOE building prototypes across a range of climate zones, calculating how much carbon, energy, and money can be saved when roof insulation is upgraded from an existing baseline to current code compliance. Their results can be found here. Justin Koscher of PIMA also highlighted these savings, conveniently sorted by climate zone and building type, here.Support for Carbon Investment DecisionsSo how can you make sure you address both operational and embodied carbon when making "carbon investment" decisions? We've prepared a handy chart to help.First, when looking at lower-embodied-carbon substitutions for higher-embodied-carbon building materials or systems (moving from the upper-left red quadrant to the lower-left yellow quadrant in the chart), ensure that the alternatives you are considering have equivalent performance attributes in terms of resilience and longevity. If an alternative material or system has lower initial embodied carbon, but doesn't perform as well or last as long as the specified product, then it may not be a good carbon investment. Another consideration here is whether or not the embodied carbon of the alternative is released as emissions (i.e. as part of its raw material supply or manufacturing, or "cradle to gate" stages), or if it remains in the product throughout its useful life. In other words, can the alternative item be considered a carbon sink? If so, using it may be a good strategy.Next, determine if the alternative product or system can provide operational carbon savings, even if it has high embodied energy (upper-right yellow quadrant). If the alternative has positive operational carbon impacts over a long period, don't sacrifice operational carbon savings for the sake of avoiding an initial embodied product carbon investment when justified for strategic reasons.Last, if a product has high operational carbon savings and relatively low embodied carbon (lower-right green quadrant), include more of this product in your designs. The polyiso roof insulation in our example above fits into this category. You can utilize these carbon savings to offset the carbon use in other areas of the design, like aesthetic finishes, where the decision to use the product may be discretionary but desired.When designing buildings, we need to consider the whole picture, looking at building products' embodied carbon as a potential investment yielding improved operational and performance outcomes. Our design choices and product selection can have a significant impact on total carbon targets for the buildings we envision, build, and operate.Click these links to learn more about GAF's and Siplast's insulation solutions. Please also visit our design professional and architect resources page for guide specifications, details, innovative green building materials, continuing education, and expert guidance.We presented the findings in this blog in a presentation called "Carbon and Energy Impacts of Roof Insulation: The Whole[-Life] Story" given at the BEST6 Conference on March 19, 2024 in Austin, Texas.References:Architecture 2030. (2019). New Buildings: Embodied Carbon. https://web.archive.org/web/20190801031738/https://architecture2030.org/new-buildings-embodied/ Carbon Leadership Forum. (2023, April 2). 1 - Embodied Carbon 101. https://carbonleadershipforum.org/embodied-carbon-101/

By Authors Elizabeth Grant

September 13, 2024

GAF Burgaw VIBE Group in front of a Habitat for Humanity build
In Your Community

How GAF's VIBE ERG Supports Veteran Employees and Their Local Communities

A group of local GAF employees in Burgaw, North Carolina, is making a difference for veterans and the community as a whole. In 2024 alone, Veteran Involvement Brings Excellence (VIBE) has undertaken several initiatives to give back to Burgaw as well as all who live and work there.Bill Price, GAF production supervisor II at the Burgaw manufacturing plant, is the champion for the group. He recently sat down to discuss VIBE's latest projects and share insight into its motivations.What Is the VIBE ERG at GAF?VIBE is an employee resource group (ERG) available for all GAF employees. It focuses on the needs of veterans who work at GAF, provides a place for employees to share their experiences, and helps foster opportunities for them to give back to their communities.Each GAF plant has a VIBE group and facility leader that organizes the team. GAF leadership supports each group and its community efforts.The VIBE ERG's mission is to create a supportive environment for veterans and active duty members from all military branches. The group's core values are integrity, duty, honor, and respect. VIBE provides personal support for members and helps them manage the realities of being a veteran, such as applying for benefits.Each VIBE group can work on or be involved in whatever projects they wish. While their primary focus is to support veterans, they also strive to give back to the local communities they live and work in.VIBE Projects in BurgawThe VIBE ERG at the Burgaw plant meets regularly to discuss the activities they want to get involved in. This year, the group has participated in several projects:17 GAF-employed veterans volunteered for the second annual Habitat for Humanity veteran's build, which GAF donated roofing materials for.Team members participated in a food and clothing drive for a local women's shelter.A local veteran service officer visited the plant to help workers learn about—and gain access to—benefits and resources.In honor of Memorial Day, VIBE provided an opportunity for volunteers to place flags at veterans' tombstones at Coastal Carolina State Veterans Cemetery and Wilmington National Cemetery.That's not all the group has planned for. Future initiatives include hosting Toys for Tots at the plant, adopting a highway in honor of veterans, representing GAF at a booth for the Burgaw Blueberry Festival, and continuing to support local veterans in need.How VIBE Impacts GAF and the CommunityThe Burgaw facility, which employs about 247 people, has one of the largest veteran groups within GAF, totaling 28 members. The facility manufactures ventilation products, such as roof vents, foundation vents, turbines, and heating and cooling ductwork."The group has brought the veterans at the plant together to work toward a common goal and also given everyone the comradery they were accustomed to from when they were in the service," Price says. "I think this has had an impact not only on the employees involved but also on the plant as a whole. All of us involved enjoy being part of the team and giving back to those in need."Price notes that each project the group has been a part of has been well received. "We received many thanks from the families that were receiving assistance from the Habitat build and also from the staff at the local women's shelter during the food and clothing drive," he says. "I have no doubt that as we continue to be involved with more events within the community, it will only get better."Giving Back While Looking AheadGAF believes in giving back to its employees and the communities they work in. VIBE is just one of seven GAF ERGs making a difference in team members' lives and those most important to them.Curious to learn more about the opportunities and culture at GAF? Visit our GAF Careers page.

By Authors Dawn Killough

August 09, 2024

GAF Community Matters team members repair a storm-damaged roof on a home in Puerto Rico
In Your Community

GAF Supports Puerto Rico Hurricane Recovery

As part of its mission to build resilient communities, GAF Community Matters has supported Puerto Rico hurricane recovery efforts through roofing material donations, roof installation trainings, and team members' hard work. This has had a multifaceted impact on the island and the people who call it home.Hurricane Maria Hit HardHurricane recovery services are needed as urgently today as they were in 2017 when Hurricane Maria struck, leaving behind 15-foot deep floodwaters, about $90 billion in damage, an estimated 2,975 lives lost, and the longest power outage in US history. For 11 months, residents waited for electricity to be fully restored.Short-term disaster relief poured in post-storm. But years after the news cycles ended, Puerto Rico still remains—metaphorically—underwater. Schools and hospitals have fallen into hurricane-related disrepair, and insufficient fixes to the power grid cause frequent blackouts and brownouts.To make matters worse, hurricane-damaged homes that weren't repaired suffer compound damage from years of subsequent storms and exposure.Puerto Ricans Stand StrongThe people of Puerto Rico are strong and proud, determined to rebuild. However, the availability of needed resources poses a considerable challenge.For many, the funds needed to repair an unsafe roof are simply out of reach. Economic opportunities are scarce, and the government is heavily in debt. The US Census Bureau reported that 42% of Puerto Rican people are in poverty.Unfortunately, lower-income Puerto Rican households most vulnerable to Hurricane Maria were also least able to recover from the financial strain of repairing storm damage. With wind speeds up to 155 mph, extensive flash flooding, and wind tunnels ripping through the mountainous terrain, homes throughout this area were no match for the Category 4 hurricane.GAF Helps Build ResilienceTo help those impacted, GAF partnered with Team Rubicon, local nongovernmental organizations, and community members through the GAF Community Matters initiative to assist in Puerto Rico hurricane recovery. Since hurricane Maria recovery efforts began in 2017, GAF has donated materials for over 500 roofs and helped install them, bringing relief and shelter to families all over the island.This work has meant more to this community than just keeping their homes dry. Mr. Alfredo—a homeowner who received a new GAF roof—said, "There is nothing more important in life than to have a place to come home to, spend quality time in, sit, and be at peace."For all of Puerto Rico's strength and perseverance, many families still live in unsafe conditions due to hurricanes. GAF can't stop storms, but it can help build resilience.To that end, in addition to installing roofs, GAF, through the GAF Community Matters initiative and GAF Roofing Academy program, provided free roof installation trainings to local organizations in vulnerable Puerto Rican communities. Educating communities on roof installation creates a greater ability to adapt and bounce back when the next storm hits.Joining the Effort for GoodIn addition to its focus on roofing innovation, GAF remains committed to partnering with local organizations to build resilience in communities across the country. Team members will continue to donate time and materials to support and strengthen communities wherever the need may be.Curious to learn more about this project and other initiatives GAF is involved in? Explore GAF Community Matters.

By Authors Annie Crawford

August 07, 2024

Don't miss another GAF RoofViews post!

Subscribe now