STEVE INSKEEP, HOST:
Bad weather can mean big losses for homeowners and insurance companies. So recently, the insurance industry built a laboratory in rural Richburg, South Carolina in hopes of developing more weather-resistant buildings. The latest experiment was a giant, indoor hailstorm.
Julie Rose of member station WFAE takes us inside.
JULIE ROSE, BYLINE: Tanya Brown has had a single obsession these past two years...
TANYA BROWN: I'm a research engineer and the lead engineer on this project.
ROSE: How to make hail.
BROWN: The standard tests that are out there use distilled water or tap water or even steel balls and we tried to take it to the next level to make sure that density was as realistic as possible. So we measured over 10,000 hailstones before we came up with the recipe that we use today.
ROSE: Brown and other scientists from the Insurance Institute for Business and Home Safety chased storms across the Midwest, weighing and crushing hail stones to see just how dense they were. Plain old frozen water turned out to be a bad match for the real deal, so Brown's team turned to a secret ingredient.
BROWN: The recipe is 80 percent seltzer, 20 percent tap water and we use that seltzer water to actually cause bubbles as the ice freezes, which actually helps us control the density to make it more realistic.
ROSE: They spent months injecting the concoction into molds - by hand - and using a deep freezer to create perfectly round hail stones ranging from one to two inches. And now, Brown is 60 feet up in the rafters of this cavernous warehouse, ready to unleash hail with a weapon made just for this occasion.
Engineer Ian Giammanco is in the control room, finger on the trigger.
IAN GIAMMANCO: It's, it's almost a glorified potato gun. I mean, it's very similar.
ROSE: A click of his mouse will force compressed air through about dozen of the cannons, firing some 9,000 hand-made hailstones at speeds up to 80 miles per hour.
GIAMMANCO: Safety off in three, two, one, one-inch fire. Group two, fire.
ROSE: We watch through a glass window as a small, but still full-size house - rotates slowly on a giant turntable. It's built with a patchwork of materials and techniques to test their resistance to hail. There's also a shiny black car, some patio furniture and a child's toy or two. From here, the cannon fire is muffled, but out in the lab?
(SOUNDBITE OF HAIL)
ROSE: Hail clatters off the roof, batters the rain gutter, shatters the car windshield. After four minutes of unrelenting ice fury...
(SOUNDBITE OF HAIL)
BROWN: All right, the artificial hail storm is finished and now everybody in their hardhats has moved in to inspect. There's a lot of folks here from the insurance industry, which funds this research institute. They are particularly interested in different types of building materials, how they hold up under extreme weather. And, of course, that plays into the kinds of coverage that they offer as well.
BRIAN COOK: My name is Brian Cook, with Amica Insurance. Really, the only way to really get a handle on insurance costs is to reduce the risk of loss. And if we can do things through mitigation and strengthening our homes, we accomplish that task and it's better for everybody.
ROSE: The Insurance Institute of Business and Home Safety uses these experiments to back up their fight for stronger building codes and better construction materials. Previous tests have simulated hurricanes, tornadoes and wildfire - funded entirely by the insurance industry.
JULIE ROCHMAN: We are the only multi-hazard lab of our kind. So we are obsessed equally with wind, water, fire and hail.
ROSE: Institute CEO Julie Rochman estimates the hail storm cost about half a million dollars to pull off.
ROCHMAN: I think we figured out that each hailstone probably cost about $2,000.
ROSE: Engineers will now detail every ding and dent in the house to figure out which types of shingles, siding and windows did best. Age of the materials is another key factor they'll be testing with a series of roofs already sprouting up in a field just outside the test chamber.
Will those get the homemade hail treatment too?
ROCHMAN: Hail, yes. As we like to say, hail yes.
ROSE: For NPR News, I'm Julie Rose.