Karen Clark’s report shows that Ian failed to make it Florida’s costliest storm

A detailed review of the costliest hurricane in Florida history, written by reputable disaster modeling firm Karen Clark & ​​Co., highlights construction practices that had a major impact on the scale of insured losses:

• Contrary to what might seem like common sense, low-sloped roofs and flat roofs performed significantly worse than steeper-sloped roofs. With low roofs, the air pressure above is reduced compared to the pressure below, creating suction that completely ripped a number of roofs off buildings when Hurricane Ian hit southwest Florida in September 2022, the report said.
• But even flat and low-pitched roofs made of metal, reinforced concrete, or prefab wood decking suffered less damage than other types of roofs. “These integrated roof systems perform better because multiple layers add redundancy,” KCC engineers and analysts found.
• Cladding systems, a popular siding material for commercial buildings and apartment buildings, proved particularly vulnerable even in light winds during Yang. Sheets of heat-insulating plates are light and easily detached. “Winds can exploit small cracks and cause significant damage to the siding, which can lead to significant interior damage due to water ingress,” the report said.
• Soffits on site-built homes were also damaged in and around the affected Fort Myers area, but the damage is usually only visible from below, not from the air. Soffit damage can occur when high winds tear the face board away from the edge of the roof line and expose the soffit, the underside of the eaves, or the roof overhang. And the soffits in the corners of the houses are especially vulnerable to the wind, which is directed up the outer walls. “Damage to the soffit can necessitate a complete replacement of the building’s siding because the wind blows rain under the siding and into the walls. Rainwater can also seep through the exterior wall into wall cracks and attics. Water ingress can cause significant internal damage, increasing ultimate losses,” the report notes.
• Garage doors were a common point of failure in areas with only Category 3 winds during the storm. The wind can cause the door to bulge and buckle, increasing wind pressure on the overall structure of the property and increasing the likelihood of roof and wall collapse. .

Karen Clark, whose engineers and scientists surveyed Yang’s damage shortly after the storm and then again in March, found that newer homes and buildings survived Yang in much better shape than older structures. Other studies argue that it is due to new building codes and construction methods. Older, low-rise structures, especially those made of wood frame or masonry, suffered severe damage, while concrete and steel buildings experienced less wind and water damage.

Many of the older homes that were elevated were not elevated enough to handle Ian’s storm surge, which reached 12 feet on Fort Myers Beach. About 20% of the buildings on this beach were completely destroyed, and most of them were not raised. Those structures that sustained severe damage or total loss had broken foundation joints or collapsed foundations themselves, the report said.

“Anchor bolts create a much stronger connection than clips or nails because anchor bolts are often cast in place and bonded to the concrete surface, creating a higher load capacity,” the analysts noted. The report includes numerous photos of the damage, including one home that was completely moved off its foundation while others were completely destroyed by the flash.

“As coastal areas experience a combination of high wind speeds and inundation from storm surge, it can be difficult to determine the cause of loss, but damage must be assigned to the appropriate sub-peril to assess the insured loss,” KCC wrote. “Wind-related damage usually starts on the roof and progresses downward, while coastal flood damage starts on the ground and progresses to other parts of the building.”

Overall, Hurricane Ian, with winds of up to 160 miles per hour, caused more than $100 billion in economic damage. One number in the report shows just how devastating Ian was in Florida: Total privately insured losses from all U.S. storms in 2022 are expected to be about $64 billion. Almost $63 billion of that came from John, and most of it was in Florida. Damage estimates in Florida anticipate a large number of lawsuits, typical of recent storms in Florida’s litigious atmosphere, before some legislative reforms to court proceedings are enacted in 2022 and 2023.

Forecasts for the consequences of future hurricane seasons do not look rosier. A hurricane needs three main components to strengthen quickly, as Ian did twice as it swept through the Caribbean and Gulf of Mexico: weak vertical wind shear; high ocean temperatures and high sea surface temperatures.

Climate change is causing surface temperatures to rise and rapidly intensifying storms are likely to become even more frequent, the report predicts.

American meteorologists said last week that the weather phenomenon known as “El Niño” is likely to form off the west coast of South America. Historically, El Niño patterns have been associated with a lower-than-average number of hurricanes in the Atlantic basin. On Thursday, May 25, the US National Oceanic and Atmospheric Administration will release its forecast for the 2023 Atlantic hurricane season. Researchers from the two universities predict six to eight hurricanes for the season, which begins on June 1. It is a little less than last year.

But as Karen Clarke and other reports have pointed out, all it takes is one rapidly intensifying storm to cause record losses.

The firm was founded in 1987 by Karen Clark and Vivek Basrur and is building one of the nation’s first disaster simulation companies, according to the firm. Clark received the Nobel Prize in 2007 for her contribution to the work of the Intergovernmental Panel on Climate Change. The full report on the 2022 Atlantic hurricane season can be found here.

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