As a structural engineer whose expertise is fortifying buildings against severe wind events, Timothy Reinhold has traveled the country examining the wreckage incurred by powerful hurricanes, from the wide swaths carved in 1992 by Andrew to the strips of aluminum siding left dangling in trees like Christmas tinsel after Charley in 2004.
In lectures, the former Clemson University professor likes to include a picture taken in Miami-Dade County after Andrew. Taken from above by a Miami Herald photographer, it shows a woman staring up from her roofless house, its four walls completely intact and the furniture still neatly arranged around her. The shot, he explains, perfectly demonstrates what can happen when a house is properly anchored. Her walls, made of concrete and secured with tie beams as required by code, held. Even though she lost her roof, it could have been much worse.
It also suggests how we should prepare for storms: in the short term and for the long haul.
At the start of every hurricane season, the Federal Emergency Management Agency (www.ready.gov) advises taking some basic steps.
• Have shutters or 5/8-inch marine plywood to cover windows and doors.
• Trim trees and shrubs, clear rain gutters and, if you have a flat roof, make sure rainwater doesn’t pond and drain openings are clear.
• Also consider securing roofs with additional straps or clips. If you can keep the wind out of your house, Reinhold explained, the risk of severe damage shrinks dramatically. “We’ve had cases where the house took up to 130 mph winds. But then you break a window on the front face, and suddenly the whole house is coming apart at 105 mph,” he said. “So that’s pretty dramatic.”
• Once a warning is issued, the National Hurricane Center (www.nws.noaa.gov) says it’s time to cover windows and doors and move light objects like garbage cans, plants and outdoor furniture indoors. (And never mind taping windows. It’s pointless.)
• If you’re riding out the storm in your homes, set the refrigerator on high and keep the door closed, turn off propane tanks, unplug small appliances and fill the bathtub with water.
• Then, if winds become strong, close interior doors, stay away from windows and, in a multistory building, go to the first or second floor, FEMA advises. In a flood zone, keep an ax in the attic.
While we often think of hurricane preparation as these hurried, last-minute steps, we should also begin to prepare long in advance, experts say.
Structural integrity, the kind usually hidden from view but what insures a house is properly secured, can make all the difference, Reinhold said.
Take Andrew, the Category 5 storm that destroyed 25,000 homes and severely damaged another 100,000 across South Florida. Coral Gables suffered a third of the damage inflicted on surrounding communities, Reinhold said. That wasn’t just due to the storm’s path, but because Herb Saffir worked and lived in the city. Saffir, the famed structural engineer who calculated the Saffir-Simpson scale used to measure storms, insisted on the city’s strict enforcement of its building code, he said.
How a house is reinforced can depend on its age and construction. Houses built in the 20s tend to be poured concrete and many builders used straps to secure roofs. By the 1970s and 80s, houses were built less soundly. Engineers generally agree the best place to begin is the roof. “There’s been a flipping of what’s the biggest weakness. Is it the roof or the openings?” Reinhold said. “We usually start with the roof because what we see time and time again is 95 percent of the time the roof is involved in the (insurance) claim.”
At the Insurance Institute for Business & Home Safety in South Carolina, where Reinhold is a chief engineer and senior vice president, scientists for the insurance industry’s nonprofit research arm spend a lot of time trying to blow down houses.
The 90-acre campus includes a 21,000-square-foot testing facility, where structures are built and tested. In dramatic videos (http://vimeo.com/ 17764719 and http://vimeo.com/17299430) scientists demonstrate how twin houses, one fortified and one typical of those found in hurricane zones, perform in winds generated by 350-horsepower fans. The unfortified house collapses like a sand castle.
Each storm, engineers say, gives them new evidence of what works and what doesn’t. For example, Charley revealed the weakness of aluminum soffits. Also, engineers have noticed a growing problem with double-entry doors like French doors. The doors, typically anchored by a lock and sliding bolts at the top and bottom, tend to fly open.
“A lot of people in Charley were trying to hold on to them and were pushing furniture up against them. But then they had tile floors and that furniture just slid,” he said.
Reinhold suggests shuttering them from the outside and, if you can’t, install sliding latches at the top and bottom that extend at least an inch into the frame. He also warned that if you’re adding straps to anchor your roof to your house, ensure the walls are anchored to the foundation. And when installing hurricane-proof windows, you need to make sure the frame is also impact-rated. Anchors are only effective when they’re part of a total structure system.
“If you can keep the wind pressure out of the house by protecting the openings,” Reinhold explained, “you can raise the threshold for loading up the house one to two categories of storms.”