SOUTHLAKE -- It's been a hail of a year for North Texas homeowners.

Three hail-producing storms raked the region in April. Then a monster lineup of supercell thunderstorms clobbered the Metroplex the evening of May 24, spawning 10 tornadoes, high winds and hail as big as baseballs in some areas.

Now a team of roofing experts has descended on the region to check out how homes withstood the barrage.

This week the trail of battered rooftops left by the May storm is being used as a laboratory for hail investigation by teams of researchers from the Insurance Institute for Business and Home Safety and the Roofing Industry Committee on Weather Issues.

Seven teams of engineers, meteorologists and roofing industry experts are climbing up on about 150 roofs across Dallas-Fort Worth to assess how well different types of roofing held up to the hail, investigation coordinator David Roodvoets, a roofing industry consultant from Montague, Mich., said Wednesday.

The teams target areas that had hailstones greater than 1.5 inches in diameter that caused significant damage over at least six square miles or more, Roodvoets said.

"There are plenty of those areas here. You guys do it big," Roodvoets said.

A similar investigation was done in Oklahoma City in 2004, and the two nonprofit industry groups have been "watching and waiting" for three years for a hailstorm of such magnitude in Dallas-Fort Worth, said Richard Herzog, chairman of the roofing industry group's hail task force.

The May storm damaged an estimated 356,000 homes and caused an estimated $300 million in damage to homes, autos and even dozens of jetliners, according to Texas insurance officials.

"It's been a really bad year; some Texas insurance companies have said they have paid more claims out of thunderstorms this year than they did in Hurricane Ike," said Mark Hanna, spokesman for the Insurance Council of Texas.

After checking out a roof in Southlake, Herzog said, the groups were particularly interested in North Texas because it has the nation's highest concentration of impact-resistant roofing.

Add in the broiling Texas heat, which also shortens a shingle's life, and you have the perfect setting for a rooftop investigation, he said.

"We're looking at all roof types but we really want to see how some of the new impact-resistant products performed," said Herzog, a meteorologist and engineer from Minneapolis.

So far, the initial survey results on impact-resistant roofs are encouraging, he said.

The 7-year-old roof on the two-story Southlake home was made with impact-resistant asphalt shingles, which were undamaged by 1.5-inch-diameter hail, Herzog said. But metal vents on the roof were peppered with large dents.

At another nearby home with a similar aged roof of regular asphalt roofing, the shingles were fractured or "bruised" and will need replacing, he said.

Texas is the southern anchor of "Hail Alley," which stretches north through Oklahoma, Kansas, Colorado, Iowa and Minnesota, said Wanda Edwards of Tampa, Fla., a home safety engineer with the business and home safety institute, which aims to reduce deaths, injuries, property damage and economic losses caused by natural disasters.

Texas homeowners who install impact-resistant roofing can get a certificate from the Texas Insurance Department that entitles them to a reduction in their home insurance premium.

"We're finding that the impact-resistant roofs are holding up really well. This will help us make citizens and the roofing industry more aware of the effectiveness of the materials," Edwards said.

The cost of impact-resistant roofing varies across the country but it generally costs about 10 percent more for materials and a little more for installation labor, she said.

For the Southlake homeowner whose roof survived, the impact-resistant materials "paid off," Herzog said.

Original:star-telegram.com