The Fundamental Problem
Most homes in the U.S. were built to withstand a maximum straight-line wind of 90 mph. That’s a very small storm. While your home might hold up to a small twister and offers some protection in stronger tornadoes, an F5 tornado generates wind strong enough to rip pavement from highways and leaves very little behind.
Surprisingly, houses are not always secured solidly to foundations, and roofs aren’t well connected to walls. In a high wind a roof built on rafters toe-nailed onto the wooden wall plates could pull loose and fly away. Without the roof trusses to stabilize the walls, the walls collapse inward. That’s one of the reasons an interior hallway or bathroom is one of the safest places in the home. A windstorm topples wreckage over it but usually leaves the inner room intact.
Hurricane force winds exceed 90 mph frequently, which is why in hurricane areas homes are built to higher standards. Builders in hurricane-prone areas often tie the wooden framework to the foundation with rods or cables running the full height of the wall. Rafters connect solidly to wall plates with hurricane clips — metal fittings which bolt the rafters to the rest of the building. External hurricane clips aren’t too difficult to install, and do increase the survivability of any home. Homeowners won’t be able to change the basic framework of the building. Instead, you could turn the safest part of your home into a stronger storm shelter.
The Safe Room
Storm shelters were standard features of older farmsteads in the mid-west. I’ve spent enough time in them that the thought instantly pulls up the scent of storage apples and potato bins. A windowless root cellar with a strong door built flat to the ground provided very good protection from even the worst tornadic winds.
Today people head for the basement if possible, but in modern buildings small windows in basement walls leave residents vulnerable to storm debris. If the worst happens and the house above you blows away, you’re nearly completely exposed. A modern basement isn’t as safe as that old root cellar.
FEMA recommends a new shelter called a “safe room.” Safe rooms might be built in the corners of basements; in the interior of the home above ground; or built as independent structures. Researchers at Texas Tech University tested different types of wall materials against wind-blown missiles and decided on either reinforced concrete or wood-frame designs, built to survive 250 mph winds and the impact of a 15 pound 2×4 traveling end-on at 100 mph. Any small interior room might be converted to a safe room.
Improving the safest place in the house only makes good sense. In an emergency a cozy family could tolerate an 8×8 space — FEMA recommends 7 square feet of floor space per person. An interior bathroom is a good choice, since you’ll definitely need the facilities to outlast a storm as strong as Hurricane Andrew, which centered on Dade County, Florida, in 1992 and left 250,000 people homeless.
You’ll need to plan for 24 hours in a tiny windowless room, and if you’re part of a typical American family you’ll have your spouse, three kids, the family dog and a parakeet for company. Not only that, you’ll need to somehow fit in the emergency kit, which isn’t a small chore.
Next Steps
External Resources
- Detailed account of Hurricane Andrew
- Storm Shelters
