Gulfport, Miss. – A few more nails and extra bolts could have made a big difference for some homes that were destroyed by Hurricane Katrina.
An initial engineering review found that most of the wood- frame houses that survived the storm’s 130-mph gusts held up because of little things: plenty of nails, metal straps attaching rafters to frames and bolts anchoring frames and porches to concrete.
The review was completed by a five-person team organized by the University of Alabama. University researchers, building- code specialists, engineers and wood-industry experts spent three days inspecting 30 locations in southern Mississippi and eastern Louisiana. The goal was to explain why some homes survived and others were left uninhabitable.
“The lesson to be learned is attention to detail,” said John van de Lindt, a Colorado State University professor who was part of the team. “If the (building) code was followed, things seemed to do really well.”
The group didn’t spend much time looking at the rubble of homes nearest the coast, where structures were washed away by a storm surge topping 35 feet. Instead, it focused on homes just a little inland.
“Designing against surge can be done, but it would be so expensive that no one could afford it,” said Andrew Graettinger, an associate professor of civil and environmental engineering at Alabama.
The research group determined that new homes fared better than older ones, but porches were a problem area.
“The columns supporting them were just resting on the concrete, and the wind would just pick it up,” van de Lindt said. “That led to roof failures on both homes and light industrial buildings.”
The group also found evidence of spotty quality among builders. But rather than purposely skirting building codes, builders apparently didn’t understand all the requirements of constructing hurricane-proof homes, the team believes.
Dave Johnson, a building inspector in Harrison County, said most of the area’s coastal towns operate under a building code that requires that structures withstand winds up to 130 mph. Farther inland, buildings are rated to weather 100-mph winds, he said.
Johnson said code inspectors ensure there are only “very minor differences” in construction from one contractor to the next.
The Home Builders Association of Mississippi, a trade group with about 4,000 members, said it supports adoption of a statewide building code, which Mississippi doesn’t have. The group did not respond to other questions about the damage review.
The National Science Foundation funded the research and will use the findings, along with the American Society of Civil Engineers, to improve standards for wood-frame structures.
Nick Jones, an engineer who has studied the way wind flows around buildings during hurricanes, said the construction industry isn’t using all the techniques it could to reduce damage in storms like Katrina.
