First-Ever Indoor Hailstorm Created at IBHS Research Center PDF Print E-mail
News Releases - Environment & Weather
Written by Joseph King   
Friday, 22 February 2013 15:15

Tampa, Fla. (February 20, 2013) – Demonstrating innovative leadership in building science and property damage prevention, the Insurance Institute for Business & Home Safety (IBHS) is conducting the first-ever, full-scale indoor hailstorm at the world-class IBHS Research Center in South Carolina.

“IBHS is blazing a new trail in applied research – with ice and air cannons,” said Julie Rochman, IBHS president and CEO. “Meticulously recreating hailstorms at the IBHS Research Center will enable our scientists to conduct a multi-faceted, first-of-its kind research initiative, exploring several aspects of building material and assembly performance that researchers have never been able to explore before.”

Among the many unique aspects of IBHS hailstorms is the use of thousands of very highly realistic hailstones, which are painstakingly created by IBHS scientists. Dr. Tanya Brown, IBHS research engineer – and a meteorologist – uses a mixture of tap water and seltzer water to attain the appropriate shape, density and hardness that closely mimics hailstones produced by Mother Nature. This laboratory work is based on, and supplemented by, field research during which the IBHS team tracked several storms to gather extensive data on which to base hand-made hailstones.

Among the challenges facing IBHS researchers is the fact that – unlike size and density – there is no standard definition or measure for the compressive strength, or hardness, of hailstones.

“It makes sense that harder hailstones will cause more damage, but we need to explore that,” says Dr. Brown. “To do that, we had to create a compressive force device, and it had to be portable enough to take into the field, where we could find and measure actual hailstones.”

Research Center staff used a load cell (like those found in bathroom scales), vice, and balance to measure hailstone mass, and a caliper to measure stone dimensions. The vice was customized to include the load cell and was interfaced with a complex computer program to measure compressive force needed to crush different hailstones; they combined this data with GPS information about the location of where each hailstone fell in order to tie hail characteristics back to specific storm attributes.

Another distinctive aspect of IBHS laboratory work involved creating an effective system to properly deliver hailstones. After investigating numerous options, IBHS researchers determined there was no off-the-shelf solution. So, the engineers designed and built multi-barreled hail cannons, which they mounted on the Research Center catwalk, 60 feet above the test specimen house inside the center’s massive test chamber.

“Creating hailstones and designing and building the hail cannons were two of the greatest challenges we faced,” Dr. Brown said. “But, like every research project we undertake at IBHS, getting the science right is paramount. We thoroughly investigated many hailstone formulas and hailstone delivery prototypes to ensure our hailstorm capabilities provide the closest match possible to Mother Nature.”

During the full-scale IBHS hailstorm, multi-barreled hail cannons deliver approximately 8,000 to 10,000 hailstones (with diameters of 1”, 1.5” and 2”) at up to 76 miles per hour. The cannons are aimed a 20 ft. by 20 ft. residential-style test specimen featuring different types of roofing and siding materials. In the first-ever demonstration of this capability, to simulate a common residential space, IBHS will place a car and typical outdoor furniture, toys, and accessories near the structure.

Key construction features of the home used in the demonstration, to illustrate different levels of performance in a hailstorm, include:

  • Roofing – one plane of the roof is covered with standard, non-impact resistant 3-tab asphalt shingles; another plane is covered with impact-resistant architectural asphalt shingles. The other two planes of the roof is covered with standing seam metal roofing. In one case, the metal roofing is installed directly over the rood deck; in the other case, the metal roofing is installed over a layer of asphalt shingles – a common real world occurrence and one which may enable more hail damage.
  • Exterior walls – two sides are covered in fiber-cement siding; the other two feature standard vinyl siding.
  • Windows – both vinyl and aluminum windows are installed.
  • Gutters – both aluminum gutters and downspouts are installed.

“We are interested in all types of materials that are used on the exterior of buildings. While there are impact-resistant standards for roofing materials, there are absolutely no such standards for siding or fenestration, such as doors and windows,” Rochman said. “This is incredible, given the many millions of dollars consumers and insurers spend each year on repairing or replacing these materials. One of our goals is to advance development of such standards.”

IBHS’ hail research initiative also will:

  • investigate the impact of aging on the performance of building materials when subjected to hail impacts;
  • document differences between cosmetic and structural damage – and provide insights and guidance about best practices when it comes to evaluating, as well as repairing and replacing building components exposed to hail; and,
  • help people who manage and evaluate different types of risk, including high winds and hail, to understand how various building materials, systems and types are vulnerable to hail damage.

Editor’s note: IBHS has produced additional media assets for use with this story, including video and photos. To access and download extra assets please visit the IBHS Hailstorm Demonstration Resources page: http://www.disastersafety.org/research-center/hail-demo/#resources.

or via direct message on Twitter @jsalking.

for more information about how to make your buildings more resistant to a variety of disasters, big and small. Follow IBHS on Twitter at @DisasterSafety and on

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About the IBHS - IBHS is an independent, nonprofit, scientific research and communications organization supported by the property insurance industry. The organization works to reduce the social and economic effects of natural disasters and other risks on residential and commercial property by conducting building science research and advocating improved construction, maintenance and preparedness practices.


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