By Jim Loney
MIAMI — With solid concrete walls and roofs and laminated glass windows protected by storm shutters, a house can be built to withstand nearly any hurricane. But very few are.
Even in the most vulnerable U.S. coastal areas, virtually no one builds homes or buildings to survive a Category 5 hurricane — a monster storm with winds higher than 155 miles per hour (250 km per hour) that can crush ordinary houses.
It costs too much.
“There’s a cost associated with every degree of wind resistance. It can be done physically but it would be tremendously expensive,” said Kurt Gurley, an associate professor of civil engineering at the University of Florida who has studied hurricanes and building codes.
With the number and cost of hurricanes rising — the damage from last season’s record 28 storms was more than $100 billion — Americans and their insurance companies are becoming more interested in hurricane-resistant homes and buildings.
The August 29 anniversary of Hurricane Katrina, which flooded New Orleans and killed about 1,500 people, according to the latest estimate from the U.S. National Hurricane Center, is a reminder of the terrible destruction these storms can bring to the unprepared.
But the cost puts a hurricane-proof home out of reach of most people.
POSSIBLE BUT PRICEY
Even tough new building codes enacted after Hurricane Andrew smashed greater Miami with 165 mph (265 kph) winds in 1992 don’t require builders to make houses that can withstand the most powerful type of storm on the five-stage Saffir-Simpson scale of hurricane intensity.
“It’s economically unfeasible,” said Charles Danger, building director of Florida’s Miami-Dade County, considered one of the nation’s most hurricane-prone areas. “We are very comfortable that the structures that are built now … will resist a mid-Category 4 hurricane.”
Miami-Dade’s code, the gold standard for building codes, demands resistance to 146 mph (235 kph) winds. The Florida Keys code raises the level to 150 mph (241 kph).
But Danger estimates only 4 to 6 percent of the buildings in the teeming Miami metropolitan area of 2.3 million people were built recently enough to meet the current code.
Some builders say it could cost 10 to 20 percent more to build for the worst hurricanes, or $25,000 to $50,000 for a median-priced Florida home.
Andrew, whose wind gusts may have topped 200 mph (320 kph) — it broke most of the wind-measuring instruments in south Florida — damaged or destroyed 140,000 homes and caused a then-record $25 billion in damage.
Only a handful of Miami buildings — hospitals, hurricane shelters and the National Hurricane Center — are considered strong enough for a Category 5.
The hurricane center, moved inland in 1995 after Andrew destroyed radar and other instruments at the old one, is widely regarded as a fortress.
It has 10-inch (25-cm) thick concrete walls, laminated windows and restrooms surrounded by 20 inches of concrete as “safe rooms” capable of defeating tornadoes. But the building was constructed to handle 130 mph (210 kph) winds, the top end of Category 3, according to government literature.
Although it’s too costly for most people to build hurricane-proof homes, that has not deterred some from trying to fortify existing dwellings, and there is a boom in the business of adding storm shutters to houses.
Builders and other experts say that while building for Category 5s is not cost effective, neither is it necessary.
Only three Category 5s have hit the United States in recorded history — Andrew in 1992, Camille in 1969 and an unnamed hurricane that struck the Florida Keys in 1935.
Any such hurricane will quickly lose some steam as it moves inland, making Category 5 construction unwarranted for homes farther from shore.
EXOTIC DESIGNS
A handful of homeowners have built hurricane-proof houses in southern states, using exotic techniques or designs. Poured, steel-reinforced concrete walls that can withstand wind-driven debris moving at 200 mph (320 kph) take the place of hollow concrete blocks, the favored Florida homebuilding method.
Laminated windows bolstered by layers of plastic and reinforced garage doors can help keep the house “envelope” intact. Some designers use rounded shapes to reduce wind resistance. Domes can eliminate the loss of roofs.
“You can make them bomb-proof,” said Douglas Buck of the Florida Home Builders Association. “Then the issue becomes, ‘Can you afford to live there?”‘
Experts say new homes and building codes have been put to the test by the extraordinary spate of hurricanes that hit Florida in the past two years. Hurricane Charley in particular pummeled the west coast in 2004 with 150 mph (240 kph) winds.
“The good news is that those (newer) homes, statistically speaking, were much, much more resistant to structural damage,” Gurley said. “Complete failure of walls and roofs, that’s not something we’re seeing with modern construction.”
Even a handful of screws used to secure the corners and other fragile areas of roofs can reduce damage significantly, engineers say. Some insurers are advising clients on ways to hurricane-proof their buildings in order to minimize claims.
“To put in a screw instead of a nail, that’s feasible. And it really helps,” Danger said.
(For more stories related to the anniversary of Hurricane Katrina, please go to http://today.reuters.com/news/GlobalCoverage.aspx?type=katrina&s rc=GLOBALCOVERAGE_wire)
Comments