by David Klinghoffer
Properly constructed houses can withstand storms, earthquakes, and floods – but the situation is a lot murkier for those homes built with materials with a poor history of protecting their owners. That’s one of the keys to making sure that homes built with slow-release dents and shingles, undersized landscaping and poorly built foundations, aren’t destroyed by a hurricane.
Klinghoffer, a Certified Structural Engineer at an engineering firm in New York, runs the National Earthquake Center’s website, EarthquakeZones.org, where readers can find detailed information about their respective earthquake zones and hazards.
Q: What would be the impact of a hurricane on my house? Would I be able to withstand it?
A: Your house would be flattened. But if you really want to deal with such an event, you need to build the house for being blown around by storm winds, and have storm-resistant eaves and windows.
Before I tell you more about hurricanes, let’s talk about the worst kind of hurricane, which is a Category 5. It is capable of moving at nearly 90 miles per hour and up to 500 mph, and causes millions of dollars in damage in hours.
A heavy, swinging hurricane is like a pack of big, bad dogs walking at full speed around a house. The walls have to keep pace or the dogs will eat your house. If the walls can’t keep pace, the back of the house almost certainly will be blown off. If the back of the house is blown off, the roof will come through the front. If the roof is blown off, you’ll probably be living in a huge mess.
The best way to deal with hurricanes in your home is to build the house for high winds. The best way to make a safe house is to build the outside to withstand winds above 200 miles per hour, and to have construction systems that can prevent windows and doors from shattering when wind speeds exceed those limit.
Q: What are hurricane-resistant windows?
A: Your windows and doors are a good investment if they withstand winds at or above 205 miles per hour, but many homes have windows and doors that don’t have a frame that can withstand wind speeds. Here’s the main reason: Most windows and doors were engineered in the mid-20th century. Today, with the exception of those engineered-for-thrashing windows, new windows and doors use a shatter-proof, impact-resistant frame that is much tougher than anything the manufacturers made in the ’60s and ’70s. Also, your window or door isn’t going to be the worst thing that will happen to you. Three-quarters of the home and interior is going to be blown off in seconds by hurricane winds. (Although it may take several weeks for a home to be rebuilt.)
Q: What is a hurricane-resistant roof?
A: The interior of your home should be hurricane-resistant. Also, protect the roof with an impact-resistant frame and a crash-resistant deck or wall. You need to protect not only the roof but also the house, even if it means raising the roof to make it stronger. If you don’t finish the roof before a hurricane strikes, the damage will be worse, since the floors beneath the roof will be washed away or separated by debris.
Here’s the most important advice you’ll get from a contractor about your roof: Protect it from the rain. If you can’t patch a severe hole, use a roofing-type piece called a Kevlar and attach it to a piece of metal rebar, like the kind used in a security fence.
Q: What are certified structural engineers?
A: Certified structural engineers are trained to evaluate the strength and safety of structures. Most residential buildings have structural engineers whose job it is to look at the overall structure, determined by the strength and load of the structure. It is the structural engineer who will help you figure out what to do if the roof falls off in a hurricane.
David Klinghoffer is a certified structural engineer and engineer at Sandia Corporation in Albuquerque, N.M. He is the author of “Earthquake Zones for Every State” (Dutton.