In light of last night’s deadly tornadoes in Illinois, I am raising (again) the issue of building in tornado zones using the new, groundbreaking construction philosophy that emerged after the catastrophic Tuscaloosa, Joplin and Moore outbreaks from recent years. The engineering case is strong, and last week Dr. Kevin Simmons, an Austin College economist, added to the economic case as well – http://bit.ly/1auWHdu.
Clearly, it is time to spread the word to leaders that by adding $1 per square foot to the cost of construction and incorporating tornado safe rooms to homes in high-wind zones, we can forever alter the deadly pattern of death and destruction that follow the annual, typical tornado outbreaks that will continue.
Below are excerpts from our May 2013 paper, “Building Codes: The Foundation for Resilience” that describe the engineering breakthrough.
For more than three years, the American Society of Civil Engineers (ASCE), Federal Emergency Management Agency (FEMA) building science engineers, and leading academic researchers have called for a new way of building to meet the challenge of saving lives while also preserving property in the face of tornado outbreaks. Their work, published as the Dual-Objective-Based Tornado Design Philosophy, is landmark in that it defies traditional assertions that “there is nothing you can affordably build to withstand tornadoes.”
The research-informed effort comes in response to field investigations that documented a pattern of disproportionate structure collapse in tornado outbreaks. They point out how even small design changes can make a difference, and they have developed guidelines to estimate the tornado-induced loads. This will provide reasonable targets for designers to use in their future work. Homes built to these newer, research-informed guidelines will have the advantage of better wall bracing, improved roof tie-downs and overall stronger connections.
According to Dr. David O. Prevatt, Associate Professor of the University of Florida, Department of Civil and Coastal Engineering, “If we can put a man on the moon, we can keep a roof on a house, and our research demonstrates it is possible to design and build houses that protect people and structures from deadly winds. Techniques developed and implemented in Florida that have reduced hurricane losses can be applied and used in houses to also reduce tornado losses.”
This novel new approach is buoyed by the finding by the National Climatic Data Center (NCDC) that even if a tornado is EF-4 or EF-5, 95 percent of the damage generated occurs at EF-3 and below. What this means is that the enhanced practices can bring material increases in home strength. Moreover, since 90 percent of all tornadoes never exceed EF-2 with winds of up to 135 mph, wind-resistant building practices like those included in the code can save lives and dramatically improve building performance in nearly every tornado event.
We believe that this is possibly one of the most important breakthroughs in high wind design during the past two decades as it offers an affordable innovation that can potentially improve life safety and economic well-being for millions of residents throughout the U.S.
Homes are a long-term investment. Eighty percent of our homes are more than 20 years old, and most of them will be around for at least another 30 years. Thus, it’s important not only for individual families to make careful choices now as they rebuild, but each community must acknowledge its responsibility to rebuild in a resilient way.
In January of 2015, during the International Builders Show, we analyzed and released updated NOAA Storm Prediction Center data showing that nearly 90% of U.S. counties experience tornado watches. This information underscores the point that the impact of building differently is not just beneficial to those who are directly hit by tornadoes. Having a stronger home and a safe room will bring beneficial peace of mind to all in harm’s way as they hunker down, worry, and wonder if their town will be next.
 Van de Lindt, John W., et al. 2013. “Dual-Objective-Based Tornado Design Philosophy.” Available: http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29ST.1943-541X.0000622