Protecting
your home from the mighty twister.
What can you do to shelter your home from a direct hit by a tornado? Not much, once the house is built. But there are some things you can do if you are building a new house or remodeling.
- No Stopping a Direct Hit
Ron Wolfe, a research engineer at the U.S. Forest Products Laboratory, has investigated storm damage after hurricanes tornadoes. Wolfe says that almost nothing will save a house from a direct tornado hit.
- "The drop in pressure can be quite dramatic,"
Wolfe says, "and the house will just blow apart."
A direct hit is rare, however, since a tornado only hits any given square mile in tornado alley once in 700 years. "It's not economically feasible to build a house to resist that kind of wind," Wolfe says. "That's why you get insurance."
Blow me away... Isn't there something I can do?
Homes can benefit from simple, cheap measures that will help reduce
damage caused by debris impacts or the intense winds around a funnel cloud,
Wolfe adds.
Unfortunately,
most of these measures must be taken during construction, Wolfe notes.
His advice focuses on the roof. If it fails during a storm, heavy rain
can soak the insulation and drywall, and destroy the interior.
Take a look at the roof in this photo. The roof held together, even through an F-5 tornado in Barneveld, Wisconsin. Too bad the builders didn't securely fasten the rafters to the house! The roof lifted off the home and flipped off.
There are other steps that builders can take, including taking special steps to be sure shingles stay on.
But the problem isn't just on top of the house. The whole house must be well anchored to the foundation.
When the house in this photo was blown off its foundation during
the 1984 Barneveld tornado, the required anchors were absent.
Look at the top of the cement foundation. Anchor bolts should be sticking up every four to eight feet along the top of this foundation, as required by common sense (and usually by building code). These bolts would have helped keep the house attached to the foundation.
What about mobile homes?
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This
lesson created by "The Why
Files," a NISE project funded by the NSF. Lesson used by permission.
Original lesson and graphics copyright NISE. Modifications copyright BPNM.
Photo courtesy Ron Wolfe, U.S. Forest Products Laboratory.