Could Your Home Withstand Hurricane Winds?
Hurricanes can subject houses to immense wind loads. Could your house withstand the winds from a hurricane?
Many states adopt a modified version of the model building codes from the International Code Council. The “Florida Building Code” is specific to Florida though it’s quite similar to the code used in other states and many other countries.
Building codes for houses provide minimum design standards such as the wind, snow and seismic loads a house must withstand. The loads vary by location so they’re depicted with maps in the building code.
The following figure shows the wind speeds for which houses in Florida must be design and constructed. As you can see, the design speeds in south Florida are extremely high. That’s because hurricanes often draw energy from the warm open waters of the Gulf and Atlantic so they hit southern Florida with power that hasn’t been reduced from the hurricane making landfall.
Wind Speed Map from the 2020 Florida Building Code
The wind speed figure below is from the 2018 model building code. The wind speeds for which a home must be designed are significantly lower in much of the nation than in southern Florida.
Wind Speed Chart from the 2018 International Residential Building Code
As you can see in the figure above, the wind speeds are higher where you would expect to encounter a storm moving ashore - along the Atlantic and Gulf coasts. Despite the higher numbers along the coast, the speeds drop off quickly to 115 miles per hour for most of the inland United States.
The wind speeds in the figure below are from the 2012 building code. They’re significantly lower than the current values in the Florida Building Code or the model building code.
It’s remarkable that the wind speeds in southern Florida were increased by forty miles per hour. Even the inland area of the United States was increased from 90 miles per hour to 115 miles per hour.
A Change in the Building Code
The wind speeds in the building code increased in the 2015 version of the model codes. Most of American housing was built before the increase in 2015 so those homes didn’t have to meet the higher standard.
The model building codes that most states adopt (with revisions) are published every three years. In fact, all of the codes published by the International Code Council are revised every three years.
The codes are updated in response to changing conditions - such as data showing a trend of more powerful hurricanes. The huge amount of study and discussion that’s required to change something as important as wind speeds is an effort to balance the safety of building occupants with the cost of implementing the safety or performance measures.
Listen to Locals
We hope you’ll heed the advice of local officials when a storm approaches. They should be considering the quality of buildings in their decisions to call for an evacuation from the path of a hurricane.
For example, the U.S. Census Bureau collects data on the age of homes. Building officials also have access to tax assessor and building permit data they can use to understand the quality of their housing stock.
A building official who knows the average age of the house in her jurisdiction then knows (or can easily look up) the building code requirements for things like wind speed at the time the average-aged house was constructed. If the threats from a weather event exceed the construction of the local housing stock then an evacuation may be necessary.
It’s easy to dismiss calls to evacuate as over cautious or reactionary though decisions may be much more informed than you think. There are also other concerns that trump criteria like wind speeds.
Should You Stay or Should You Go?
Even if your home can handle the wind loads from a hurricane, there are other risks such as airborne debris and storm surges that can cause catastrophic damage. Other buildings and infrastructure such as roads and bridges may be damaged to the point that travel becomes unsafe, utilities are not available and emergency services are overwhelmed.
Evacuating early can be a tough decision. Evacuating can be very disruptive yet it’s better to be safe than caught in the event and aftermath of a severe weather event.
Back To Our Question
At the outset of this blog post, we asked if your home could withstand the winds from a hurricane. The Saffir-Simpson Hurricane Wind Scale is used to rate hurricanes.
The lowest category on the scale is a Category One hurricane - winds from 74 to 95 miles per hour. Most of American housing stock was designed for wind speeds up to 90 miles per hour: inland houses built prior to 2015.
So, the answer to whether your house could withstand the winds from a hurricane is probably no. Even a Category One hurricane could cause most American houses to fail and that failure could lead to loss of life. This is of particular issue when a powerful storm makes landfall and retains winds above 90 miles per hour as it moves inland.
Leave a comment below to let us know if you’d evacuate from the path of a hurricane or try to shelter in place until it passes. What were the top priorities in your decision?