Hurricane 101, Part II: Hide from the Wind

In my last post, I talked about the importance of hurricane evacuation zones, storm surge, and running from the water. Today, we're going to talk about the second rule of hurricane survival, hide from the wind.

As I demonstrated in my last post, buildings are simply not designed to withstand the hydraulic forces associated with storm surge and the tremendous weight of water associated with surge and wind driven waves. Most well-built structures can, however, withstand hurricane force winds.

"If you live in a well-built home that is not located in a storm surge area, often the best thing you can do is stay home and shelter in place."

Shadow evacuations are a major
cause of traffic jams
during a hurricane evacuation.

If you live in a well-built home that is not located in a storm surge area, often the best thing you can do is stay home and shelter in place. Emergency managers refer to people who evacuate when they don't need to as shadow evacuees, and shadow evacuations are one of the primary causes of the traffic jams we've all seen on TV preceding a hurricane.

In most hurricane prone areas, 20 to 40% of the population lives in an evacuation zone. Many of these areas can successfully move 20 to 40% of their population using their existing transportation infrastructure. After all, they do it every day at rush hour! But when you add in a shadow evacuation, the result is a dangerous gridlock.

If you do shelter in place during a hurricane, you should take some steps to protect your home beforehand and ensure it is safe for you and your family. These steps include:

• Have your home inspected. In particular, you want to ensure your home is structurally sound, and your roof meets acceptable standards for uplift resistance. In many cases, there are mitigation steps you can take to strengthen your home's structure and roof. Check with your local building officials.
• Secure any potential wind-borne projectiles. Things like lawn furniture, lumber, and barbeque grills can become deadly missiles in extremely high winds.
• Protect the exterior openings of your home. Your windows and exterior doors need to be covered with a protective material that meets acceptable standards for positive and negative wind load and impact resistance. Note that some so-called "hurricane windows" may not meet the impact resistance standard.
• Protect your garage door. I list this separately because your garage door is your main vulnerability and one of the most overlooked protective actions when it comes to wind damage. 

You may be wondering:

Why is covering my windows and doors so important?

If the exterior 'shell' of your home is penetrated, this results in increased atmospheric pressure inside the structure. This, combined with the uplift created by the high winds, often results in your home's roof literally popping off and being ripped off by the wind. And once the roof goes, the walls no longer have structural stability and a total collapse of the structure is possible.

What should I use to cover my windows and doors?

There is a wide variety of materials available ranging from plywood (cheap but heavy, difficult and dangerous to install, and hard to store and reuse) to custom fabric vinyl, metal, and fiberglass shutters that you can install yourself or have installed by a reputable company. 

Wouldn't we be better off just leaving, even if we're not in an evacuation zone?

Not necessarily. The National Hurricane Center has made great strides over the past decade in forecasting the track of storms. But even with the best science has to offer, at 24 hours out (when evacuation decisions must be made by your local government), the best "cone of uncertainty" the National Hurricane Center can offer is plus or minus eighty miles. 

Often, shadow evacuees leave their home unnecessarily, only to find themselves in the path of the storm the following day. Such was the case for many evacuees from the Tampa Bay area who fled to Orlando in 2004, only to have Hurricane Charley turn and race through the center of the state.

I want to stress that if you don't feel safe in your home, you should certainly plan on leaving. But take the time to educate yourself on your evacuation zone and wind vulnerability, and take some steps to protect your home. In some cases, your home may just be the safest place to be!