Apr 20, 2006 6:15 pm US/Central
New Homes Designed To Withstand Tornadoes, Fire
by Steve Baskerville
BOLINGBROOK (CBS) ―
April is the beginning of the tornado season in the Midwest, and the second anniversary of the Utica tornado has arrived, providing a reminder of just how destructive these storms can be.
CBS 2's Steve Baskerville reports on new help for homeowners.
Two years ago, a late afternoon storm developed into an F-3 tornado, with winds of nearly 200 miles per hour. It touched down in nearby Utica, killing eight and destroying dozens of homes.
Now, insurance companies and cement manufacturers are partnering up to design homes to withstand these awesome forces of nature.
Homes in one Bolingbrook subdivision look just like any other suburban development. But on closer inspection, there is something quite remarkable about them: They're fortified.
"This house and others on it are made out of pre-cast concrete," said DuKane Pre-Cast's Brian Bock. "This particular home is built with a double-wall, reinforced, concrete, panelized system for the walls and the floors all the way up to the ceiling of the second floor."
The walls are eight inches thick and consist of a pair of two-and-a-half-inch reinforced concrete sides, separated by three inches of high density foam.
In laboratory tests, the difference in durability between this concrete sandwich-style and typical building materials is quite dramatic.
In the test, a tornado canon fires a wooden two-by-four missile at 120 miles per hour at different wall materials. These conditions replicate the force that debris would be propelled by an F-4 tornado.
The test damages a typical two-by-four and plywood construction. The same wall with brick veneer is also damaged, but the missile only bounces off the pre-cast concrete wall.
In addition to the nearly impervious walls and impact-resistant windows, fortified houses use metal ties known as "hurricane strapping" to hold down the roof.
"It prevents the lift and the twist of the roof rafters when it's engaged in high wind application," said Dave Bender with Mustand Construction.
The insurance companies point out that these fortified homes are also very fire safe.
"If there is a fire, it's not going to burn as long, and it's going cause less damage," said AAA Insurance's Sasha Marcinczyk.
Outside of the fortified house, the exterior concrete surface is pre-formed in the shape of brick and painted to look like the real thing.
Amazingly, the weather resistant, fire safe and energy efficient homes are erected in only two weeks.
"When we put the walls up, it's done. You're not having to stud it out, insulate it and dry wall it. It's all done at the factory under controlled conditions," Bock said.
Brian Bock tells us that additional cost for these fortified homes is typically only 10 percent more than a conventional home.
(© MMVI, CBS Broadcasting Inc. All Rights Reserved.)
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