by Bob Henson of Weather Underground · October 16, 2018, 2:37 PM EDT
South Florida has gotten plenty of accolades for the very strong building codes it has adopted and maintained since Hurricane Andrew laid waste to the southern Miami metro area in 1992. Florida is a big state, though, and it’s all hurricane-vulnerable. What about the northern stretches of Florida, including the Panhandle coast slammed by Hurricane Michael last week? The standard code for buildings in this region is much more lenient, and even that looser standard is now at risk of falling behind international code.
Make no mistake: Florida’s statewide building code, adopted in 2002, has made a real difference. A 2017 working paper for the University of Pennsylvania’s Wharton School, led by James Done (National Center for Atmospheric Research), concluded: “A multiple regression analysis finds homes built after implementing a statewide Florida Building Code (FBC) in the early 2000s experience significantly lower losses than homes built in the previous decade, in agreement with previous literature.” (This study has now been published in the ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems.)
Miami-Dade and Broward counties are part of a High-Velocity Hurricane Zone, where local code requires that a building’s entire envelope (including windows, doors, and eaves) incorporates lab-tested, wind-resistant design. Elsewhere in the state, the requirements vary, based on expectations of where peak winds will be the strongest.
Figure 1 (below) shows the 3-second wind gusts used in Florida since 2010 to set the minimum building code that applies to most homes and other structures apart from hospitals and other health care facilities. These values were calculated based on extensive computer modeling and observations, drawing in part on the state’s multiple hurricane landfalls in 2004. They’re designed to represent the highest gusts one would expect to recur at a given point in a typical 700-year period. In many cases, these values allow for a lower standard of protection than the comparable pre-2010 value. (The comparision is not apples-to-apples: the pre-2010 numbers were based on “nominal” wind speeds—essentially, sustained winds—rather than gusts, so in some cases, a slightly higher value in 2010 actually correlates to a weaker overall wind field.)
Figure 1. The strength of three-second wind gusts (“basic wind speed”) expected to recur on average every 700 years. The Florida Building Code uses these values in setting code for most structures except for health care facilities, where the code stipulates building for stronger winds (1700-year average recurrence intervals). The cross-hatched areas show where regions were added (green) or removed (red) in 2010 from the “wind-borne debris region” category. Image credit: Florida Department of Business & Professional Regulation.
The minimum in expected peak winds evident in the eastern Florida Panhandle/Big Bend region illustrates how few hurricanes have struck that area in recent decades. Even at the top of the Crescent Coast, in western Taylor County, the code assumes that the highest wind gust one might observe on average in a 700-year period is about 120 mph. This correlates to top sustained winds in the ballpark of 100 mph—in other words, a low-end Category 2 storm. If I lived in this stretch of coast, I wouldn’t count on getting to the year 2700 before a Cat 2 hurricane arrives!
The reddish cross-hatched areas show where the 2010 revision of the code removed parts of the state (all at least one mile inland) from the 140-mph top gusts that are used to define the “wind-borne debris zone”—the area where state-approved, impact-resistant windows, doors, and/or shutters are required in new construction. Likewise, the green area shows territory that was added to the wind-blown debris zone with the 2010 revision.
Note that the entire area more than one mile inland from the coast that was slammed by Michael’s inner core, from the Panama City area north and east, was removed from the wind-blown debris zone in 2010 or was never in the zone in the first place.
Figure 2. Ralph Swindler sent us these photos of two homes in Callaway, Florida, a community just southeast of Panama City that experienced some of Hurricane Michael’s worst winds over land. “We were in the west side eye wall of Michael,” Swindler said. “One house (left) was constructed in 2002 and up to the standards post-Andrew. It has minor roof damage and no other structural damage, including no windows blown out. It was built out of poured concrete. The other house is just down the block. As you can see, the roof is entirely compromised and the garage collapsed. This house was built in the 1960s/70s. Amazing.” Image credit: Courtesy Ralph Swindler.
For most of the last few years, Florida’s building code has used standards from the International Code Council as its foundation for reviews and updates every three years. In a nutshell, state planners took the latest ICC standards and used those as a starting point, deleting irrelevant parts (such as snow-related standards) and enhancing the code with Florida-specific measures as needed.
This changed in 2017, when the Florida legislature voted to step away from basing its code on ICC releases. Instead, the state is now free to pick and choose whatever code revisions it likes, whenever it likes, without changes being triggered by ICC code changes.
Florida’s 2017 process revisions were advocated by the Florida Home Builders Association but were criticized by many members of the emergency management community, including former FEMA head Craig Fugate.
As reported by Fred Grimm (Sun-Sentinel):
Fugate warned the 2017 National Hurricane Conference in April that the Florida legislature was hell bent on abandoning mandatory code upgrades. State builders, he said, were complaining that updating the codes every three years was inconvenient. “Who’s it inconvenient to?” Fugate asked, rhetorically. “The homeowner who’s going to be paying for a home for next 30 years, that will probably go through one, if not more, tropical systems? Or to the builder or developer who’d like to build faster and cheaper?”
In its article on a 2018 report from the Insurance Institute for Building & Home Safety on the status of codes in 18 Gulf and Atlantic states, Insurance Journal noted that “despite the increasing severity of natural disasters, [many states] have relaxed their approach to codes — or have yet to impose any whatsoever.” For example, Louisiana—hard hit by massive flooding in the “no-name” storm of 2016, that year’s most expensive U.S. disaster—declined to adopt the one-foot-above-base-flood elevation standard mandated by ICC. Insurance Journal added: “The shift toward less rigorous codes is driven by several factors, experts say: Rising anti-regulatory sentiment among state officials, and the desire to avoid anything that might hurt home sales and the tax revenue that goes with them. And fierce lobbying from home builders.”
Figure 3. Bryan Norcross.
Bryan Norcross has quite a bit to say about hurricane safety in Florida. Norcross gained national fame while at Miami’s WTVJ-TV for his nonstop, life-saving coverage on Aug. 23-24, 1992. On that night, Category 5 Andrew thrashed its way across the southern metro area, destroying some 25,000 structures. Norcross is now back on the air in Miami at WPLG-TV after several years serving as a hurricane specialist at The Weather Channel and an emergency communications consultant.
Here is Norcross’s take on the changes to the code revision process:
“I think that the Florida system of administering the building codes is flawed. I’m not accusing anyone of being dishonest. I’m saying their incentives are not the incentives that a consumer advocate would have in terms of deciding how the building code is going to be administered and adjusted.
“There’s no question that when the ICC code is updated, there’s work to be done in terms of deciding what fits the Florida situation. But the ICC code should be the minimum code in any case. Structural elements change, materials change, and the code should keep up. Connecting to the ICC code keeps Florida in step with the rest of the country.
“Builders want to build houses. They’re people for whom time is money, and if you do things to slow down the process, that’s a negative for them. They should have input into the process. But the final decision on how strong the code should be ought to come from representatives of the people based on what’s best for residents, not the construction industry.”
See weather.com for my full interview with Norcross, including his suggestions for straightforward steps that Floridians can take to help protect older buildings from hurricane damage. As Norcross puts it, “Miami-Dade County figured all this out in the 1990s. Now, other areas just need to use those hard-learned lessons. It’s just got to be done.”
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.
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