If global warming predictions for weather come true, there will be a greater frequency of hurricanes, tornadoes, and strong storms throughout the coming years. So designing homes to sustain minimal damage resulting from natural disasters will be increasingly important.

Building codes prescribe a design wind speed for every location in the United States, and for hurricane-prone areas, the codes define in detail how buildings should be constructed.

Although wood homes can be modified to resist the prescribed wind and seismic forces, it's a lot more difficult and costly than building concrete homes. And it's very difficult to protect the inhabitants of a wood built home from debris carried by high winds. Concrete walls don't have the debris problem. Just providing the concrete and reinforcement needed to build the walls and decks (ceilings or floors) of a house is usually all that's needed to provide the strength against wind and seismic forces and to protect from debris. So design issues for concrete homes are more related to connections for doors, windows, roofs, and garage doors—locations where different materials meet. This is where some additional costs come into play.

Defining Weather Terms

Hurricanes originate over water and are byproducts of the tropical ocean and the atmosphere. Powered by heat from the sea, Atlantic hurricanes are steered by the easterly trade winds and the temperate westerlys, as well as by their own ferocious energy. When the winds reach speeds of 23–39 mph they are referred to as “tropical depressions.” Storms with sustained winds exceeding 39 mph often are referred to as “tropical storms.” When sustained wind speeds reach 74 mph, the storms are called hurricanes, typhoons, or tropical cyclones depending on where they occur in the world—in the Gulf of Mexico and along the eastern United States seaboard, they are called hurricanes. In order to provide an estimate of potential damage, a scale was developed to describe hurricanes in categories. The Saffir-Simpson scale places hurricanes in five categories (see Figure 1).

Hurricanes cover large areas and often, in addition to wind damage, involve flood damage due to storm surges.

Relatively small diameter rotating columns of wind are called tornadoes when they occur over land and waterspouts when they occur over water. They extend from a cloud base to the ground and can be either visible or invisible. No place is safe from a tornado, however, there are areas where their frequency is higher. They can last between a few seconds to more than an hour; most commonly lasting about 10 minutes. A scale originally developed by Dr. Ted Fujita and known as the F-scale was modified in 2006 to become the “Enhanced Fujita Scale” (EF-scale). This is now what we use to describe a tornado's intensity. The EF-scale rating for a particular event is assigned by looking at the damage from the storm. It's essentially a damage scale because no one knows what the wind speeds are as it is almost impossible to measure the exact winds inside a funnel. The scale also rates the strength of a tornado in relation to the potential damage it can do. The scale is measured in numbers from 0 to 5 and as you can see in Figure 2, wind speeds can surpass 200 mph, making tornadoes the most formidable wind event.