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Tornadoes, other disasters ‘drive the codes’

Boards, shingles and personal items litter the front yard of the home of Sidney and Hilda Ford of Jim Shack Road on Thursday in Cave Spring, Ga. Building specialists say buildings that fail during a natural disaster "become the case studies for better" practices. (AP photo by Daniel Varnado, The Rome News-Tribune)

By Brian Johnson
Dolan Media Newswires

Minneapolis — As survivors across the South continue to pick up the pieces from the deadliest tornado outburst in nearly four decades, building specialists are sure to be exploring ways to minimize damage and loss of life in future storms.

Lessons from natural disasters, such as tornadoes and earthquakes, play an important role in the shaping of building codes, said Olene Bigelow, former Minnesota and North Dakota area director for the International Masonry Institute.

“Each disaster with which we are confronted,” she said, “provides us with more information to make building codes better.”

The Sept. 11, 2001, attack on New York’s World Trade Center, for instance, led to changes designed to prevent “progressive collapse” in buildings, Bigelow said.

The 1994 earthquake in the Los Angeles suburb of Northridge changed people’s thoughts about how structures behave, said Carol Shield, a professor in the University of Minnesota’s Civil Engineering Department.

Those types of instances become case studies in the search for ways to improve practices, said J. Stephen Weeks, associate professor emeritus with the University of Minnesota’s School of Architecture.

“Failures drive the codes,” he said.

There are challenges to making homes and buildings more tornado-proof, Weeks said, primarily that costs would be prohibitive to build a completely tornado-resistant structure.

Moreover, when you get to the F5 category of tornadoes, which involve winds in excess of 260 mph, even the best-built homes are laid to waste.

“Rarely does anything survive” such disasters, Weeks said.

Even so, one of the main concerns in tornadoes is the damage caused by flying objects and debris, and masonry systems tend to stand up well to those pressures, he said.

While some components in homes — such as roofs, doors and garage doors — especially are vulnerable to tornadic winds and debris, masonry will “provide a first line of defense against flying objects,” Weeks said.

Weeks said some cities have proposed changes to lessen the effect of tornadoes on lives and property.

After a May 25, 2008, tornado in Hugo, Minn., for example, city leaders considered an ordinance that would have required all new residential construction have a Federal Emergency Management Agency-approved tornado safe room.

The Hugo tornado damaged or destroyed hundreds of homes and killed a 2-year-old boy.

Ultimately, the city made the safe rooms an option for new homes rather than a requirement.

Builders now have to “provide an option in the building plans for a safe room, and the buyer can make a choice as to whether they want to have a safe room or not,” said Bryan Bear, Hugo’s community development director.

An 8-foot-by-8-foot FEMA-approved safe room, which also can be used as a bedroom or utility room, ranges in cost from about $6,500 to $8,500, according to FEMA’s website. Typically, the price tag is 20 percent more to add a safe room to an existing home.

“The downside of requiring it in every case is it elevates the cost of housing and there was not enough concern” to justify that, Bear said. “But at least there is an effort to provide it as a viable option.”

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