But communities in the Florida Panhandle were given an exemption to the impact-protection provisions for homes built beyond one mile of the coast. This exemption was granted on grounds that the Panhandle was not likely to experience violent hurricanes like Andrew. And then there was Michael.
The code was fully enacted in 2002, but new homes in the Panhandle were exempt from impact provisions until 2007. Beyond the use of hurricane straps and enhanced anchoring of exterior walls, the coastal provisions require impact-resistant windows and doors or hurricane shutters.
Census data show that Bay County, where Panama City and Mexico Beach are located, added almost 25,000 residential units after the enactment of the code. Based on permit data, more than 60 percent were built during the time of the exemption, meaning that many homes lacked the impact protection required in other coastal communities.
As Hurricane Michael maintained at least Category 3 winds across the state and into Georgia, homes deep in Florida’s interior would have benefited from impact protection.
There is little doubt that homes built to the code show less damage even without impact protection. But the intent of the coastal standards is to prevent flying debris from penetrating the home, allowing wind to put upward pressure on the roof. This pressure, in combination with the lift effect of the wind as it passes over the roof, makes failure more likely.
A last-minute effort to minimize that possibility is to purchase plywood and nail it over all windows and doors. But Michael developed quickly, forcing residents to evacuate without much time to protect their homes. Installing permanent shutters or impact-resistant glass, as the code intended, makes last-minute precautions unnecessary.
A new paper I co-authored with Jeffrey Czajkowski of the University of Pennsylvania’s Wharton Risk Center and James Done of the National Center for Atmospheric Research shows that homes built in coastal areas of Florida, after the implementation of the code, suffer 64 percent less damage than homes built before. Our study used realized insured loss data across 10 years from more than 1 million homes. Loss data for the study included seven landfalling hurricanes, three of which were Category 3 or higher.
The results make a clear statement concerning the wisdom of requiring construction methods based on wind engineering principles. Last year’s hurricanes shattered records, but when Hurricane Irma hit Florida, the stronger codes limited the wind damage for homes built to the code.
Building resilient homes does add cost, and the most expensive part of the code is the impact-protection provision. So it’s understandable that communities wanting to protect affordability would resist actions that make building a home more expensive. But another result from our research finds the code is cost-effective.
Statewide, we find a benefit-to-cost ratio of $6 in reduced damage for every $1 in increased cost. The cost effectiveness is highest in the interior of the state, but coastal communities that must utilize more expensive impact protection still show impressive benefit-to-cost ratios. Even the most expensive option (impact-resistant windows) provides a benefit of $2.20 in reduced damage for each $1 of increased cost. Ratios are higher when the lower-cost option (hurricane shutters) is used.
Since 1980, wind storms have caused almost $1 trillion in damage, with 85 percent of that amount since 2000. Increased population in coastal areas combined with the effects of a warming climate suggest that damage exceeding even that number will occur during the next 40 years.
While it’s not possible to eliminate all damage from natural disasters, we can begin making wise and cost-effective decisions. There will always be the temptation to discount the need for better protection from the wrath of nature. But if Hurricane Michael has taught us anything, it is that the unthinkable can and probably will happen, someday.