While the Denver area receives at least some hail each year, the occurrence of Very Severe Hail has increased in recent decades. Hailstorms damage commercial and residential property such as buildings, crops, cars, and more, resulting in billions of dollars in losses. But more important than the economic losses are the people that are impacted. Your roof provides your first line of defense against threats like hailstorms. That’s why we take our roof construction so seriously at Sol Vista Roofing.
Very Severe Hail Research
Nature Research, a leading research journal, reported that “In the past decade, average annual insured losses due to hail are estimated at $8–13 billion in the U.S., and losses have increased dramatically over the last few decades.”
The frequency and severity of hail storms has continued to increase. Roofing contractors have a responsibility to assist property owners in guiding them to plan and build a roof that provides the best level of protection for them.
Factory Manual (FM) is a leading expert in loss prevention and testing. They have rated United States regions as either Moderate, Severe, or Very Severe Hail (VSH) Prone Zones.
FM’s hail rating consists of:
- Moderate: < 1.75 inches (44 mm) hail
- Severe: < 1.75 (44 mm) & < 2 in. (51 mm) hail
- Very Severe: ≥ 2 in. (51 mm) hail
Very Severe Hail in Denver
Moderate hail is approximately golf ball sized. Severe hail is closer to the size of an egg. Very severe hail is even larger, approaching the size of a baseball. FM first introduced the Very Severe Hail rating in 2017. As the map demonstrates, Colorado is highly exposed to severe and very severe hail, including the large metropolitan areas of the front range.
Per FM, the new rating and map were updated based on research on new methods for analyzing the impact resistant capabilities of roofing products. Formerly the highest rating available for impact resistance was known as “Class IV” impact resistance (as opposed to unclassified or Class III ratings). The difference between the Class IV testing and Very Severe Hail testing is the use of two-inch ice balls, and the use of a cannon to fire the simulated hail instead of dropping from a prescribed height.
To earn a Very Severe Hail (Class 1-VSH) rating, three roof assembly samples are submitted to FM by roofing manufacturers. One sample is to be in new condition, one sample is to be UV weathered, and the third sample is to be UV weathered receive 42 days of heat aging to be eligible for testing. For the VSH testing, 2 inch ice balls are shot using a cannon at the test samples using compressed air up to an impact energy of 53-58 ft-lbs.
Hail Resistant Roofing Options
Properties insured by FM in high-hail areas like Colorado need to ensure their roofs meet VSH requirements. Sol Vista Roofing installs VSH rated products, including certain stone-coated steel roof products and properly designed/installed single-ply commercial roofing systems.
The FM team tests and rates roof products under its Approval Standard 4470. It was updated in 2017 when the Very Severe Hail rating was added to the prior ratings of Moderate Hail (MH) and Severe Hail (SH).
