Hurricane Ian’s aftermath: Code-approved lessons and results

by arslan_ahmed | August 17, 2023 2:08 pm

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By Vinu J. Abraham

Advancements in hurricane building science, continuous code improvements, and the success of code-approved products have made it possible to design more resilient structures in hurricane zones. The widely acclaimed success of Babcock Ranch, a solar-powered community 32 km (20 miles) inland from Ft. Myers, is a testament to how far the building and testing industry has come.  Hurricane Ian hit the community with 160 km/h  (100 mph) winds, yet Babcock Ranch never lost power or even internet.

The southwest Florida community survived Ian with minimal damage, due to state-of-the-art planning and design. The community was built 9 m (30 ft) above sea level and all power lines are buried underground to protect them from strong winds. The infrastructure is designed to work with nature rather than against it. Small lakes around the neighborhood protect houses from flooding, and houses are built to the latest codes.

All buildings at Babcock Ranch must be certified by the Florida Green Building Coalition’s Green Home or Commercial standards,¹ which is similar to the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) rating, but specifically designed for hot-humid climates. This is the only certification program with a disaster mitigation section. Under the building code, “homes are required to be designed to 160-mph wind loads.” The voluntary standard also provides guidelines for commercial property, land development, and governmental structures.

The average Home Energy Rating Score (HERS)² for homes at Babcock Ranch is 58—which is approximately 25 percent more efficient than the Florida Building Code (FBC): Energy Conservation, which is fairly stringent. Electric heat pumps are used for all heating and cooling, though natural gas is used in some houses for cooking and water heating.

Babcock Ranch represents a shining example of how science and good design can offer resiliency, instead of billions of dollars in destruction. For today’s architects, engineers, and builders, the progress and learning from the past 30 years will lead to the design of more resilient homes and businesses.

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Ft. Myers feels the brunt of Ian

While Babcock Ranch represents what good design can offer, other areas hit by the hurricane suffered devastating losses. Months after Hurricane Ian made landfall in Cayo Costa, Florida, on September 28, 2022, a ride along the Ft. Myers beachfront still feels like a scene from an Armageddon-themed Hollywood movie. As of June 2023, only 25 percent of restaurants are open and vacation rentals are still difficult to find.³ Debris is still piled on roadsides. The divide between older and newer construction is evident. Many newer buildings are still standing and being repaired. Newer roofs remained intact, which is a departure from earlier storms where roofs commonly blew off, resulting in devastation to the interiors. Impact-resistant windows withstood flying debris. Reinforced garage doors braved the wind. The FBC proved its value after Ian and other recent natural disasters such as Hurricane Irma (2017) and Hurricane Michael (2018).

For buildings constructed to the code, structural damage was nearly eliminated, underscoring a significant success story for the wind science and engineering community. While damage from Ian was estimated to be between $47 and $70 billion, according to disaster analytics firm Core Logic,⁴ it could have been worse if Florida had not begun the long road toward tougher building codes following Hurricane Andrew in 1992. Better building practices, improved construction products, and vigorous testing protocols for materials saved many buildings constructed after the new codes began to take full effect in the early 2000s.

However, there is much to improve, especially when considering the staggering loss of properties and people. Older, wood-framed buildings were sometimes demolished, and giant piles of debris stand like ghostly tributes to former beach restaurants, churches, and shops. Not only did Ian cause immense structural damage, but more than 5,000 homes and 300 businesses in Lee County
alone were damaged or destroyed.⁵

What went wrong?

Hurricane Ian was the confluence of several unfortunate factors. There was a very high tide when the storm hit two densely populated centers, Sanibel and Ft. Myers. The high tide, combined with a catastrophic storm surge, hit at the same time for maximum flooding. The storm surge caused some houses and concrete swimming pools to act as boats, as they floated off their foundations. Irma, by contrast, hit the less populated Everglades hard in terms of storm surge and rising waters from rain, causing flooding along the rivers more than the coastal locations. This is a major reason why storm surge damage from Ian was greater than the storm surge damage left behind from Irma.

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Path of destruction

After plowing a path of destruction through the Caribbean, bringing heavy rainfall and dangerous surf to Jamaica, the Cayman Islands, and western Cuba, Hurricane Ian made landfall in southwestern Florida as a dangerous Category 4 storm. After crossing over the Florida peninsula, it strengthened again over the water to a Category 1 hurricane and made a second landfall near Georgetown, South Carolina.⁶

On September 28^th, Ian intensified into a Category 4 hurricane over the Gulf of Mexico, with maximum sustained winds of 249 km/h (155 mph), just shy of a Category 5 storm. Ian came ashore near Cayo Costa, Florida, at 3:05 p.m. EDT with maximum sustained winds of 241 km/h (150 mph), tying the record for the fifth-strongest hurricane on record to strike the U.S. It was the strongest hurricane to hit Florida since Michael in 2018. It was also the first Category 4 hurricane to impact southwest Florida since Charley in 2004, and it was the strongest September hurricane in the Gulf of Mexico since Irma in 2017.

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What made Ian unique was its deadly combination of storm surge and catastrophic high winds. A storm surge with an inundation of an unprecedented 3 to 5.4 m (12 to 18 ft) above-ground level was reported along the southwestern Florida coast, and Ft. Myers itself was hit particularly hard with a record-high surge. High watermarks on Ft. Myers Beach reached nearly 4.8 (16 ft) in spots, according to a study by the U.S. Geological Survey. According to the Insurance Institute for Business & Home Safety (IBHS), water surge is always far more damaging than wind.  “Water simply weighs more than wind. Complete structural failure can be common in the surge zone, leading to far more damage than wind alone,” says Dr. Ian Giammanco, managing director of standards and analytics at IBHS.

Designing better structures for the future

Following the aftermath of Hurricane Andrew in 1992, an entirely new category of products testing was born. In hurricane-prone regions, architects, engineers, and owners face multiple design and safety challenges related to the building envelope and its ability to withstand severe storm and hurricane-force winds and water intrusion. The combination of intense wind, storm surge flooding, and heavy rainfall can lead to the type of damage seen during Hurricane Ian and many other recent hurricanes.

Many advances in understanding how high winds and water affect structures begin at the test lab. Manufacturers must ensure their building products meet code compliance to be used in hurricane-prone areas, including the high-velocity hurricane zone (HVHZ). Hurricane zones are typically defined by the geographical location of the building, which is defined in part by The American Society of Civil Engineers’ (ASCE’) wind speed map—ASCE 7. Florida has implemented some of the toughest product approvals in the world, specifically Miami-Dade County, and the need to receive either a notice of approval (NOA) or a Florida Product Approval (FPA).

The FBC are administered by the Florida Building Commission. The FBC is based on the International Building Code (IBC), which is used across the U.S. As a result of the destruction caused by Hurricane Andrew in 1992, the state of Florida designates various wind zones to mandate product approvals. The FBC created the HVHZ and includes Miami-Dade and Broward counties with ultimate design wind speeds higher than 273 km/h (170 mph). Wind zones 1, 2, and 3 are defined for ultimate wind speeds ranging from 209 to 273 km/h (130 to 170 mph).

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The most common test for the hurricane market is the impact and cycling test, designed to simulate windborne debris striking a window or an element of the building during a hurricane.  Providing protection from flying debris that breaches the building envelope is critical. If a structure’s envelope is breached, wind can enter the building, creating pressure changes that can lead to destruction of the contents in a building and to the building structure itself. Also, a breached opening can allow water into the building causing water damage throughout. Impact and cycling tests simulate the hurricane act of flying debris and the rapid increase and decrease in pressure.

The weakest links in a building envelope are windows, doors, soffits, and ridges vents on roofs. For windows and doors, the impact test consists of firing a 2×4 projectile at predetermined locations. The cycling portion of the test is conducted after the impact test with no penetrations and consists of 9,000 cycles of positive and negative pressures.

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How well did code-approved products perform during Ian?

Following Hurricane Ian, Intertek, a global provider of testing, inspection, and certification services, sent a large team to evaluate buildings after the storm.
By the early 2000s, many aspects of the first versions of the FBC had begun to take effect and the benefits were clear.  Here are some of the key learnings:

 Roofs

Roofs in high-velocity wind hurricanes represented one of the most challenging building components for engineers to tackle following Andrew, which was a Category 5 storm. Investigations after Andrew revealed the most damage was caused by building envelope failure due to blow-off of roof coverings, including the roof structure in many cases. Glass breakage and collapse of large doors were also primary contributors to building damage.

Ever since, roofing codes have gone through many refinements, as subsequent hurricanes were studied and laboratory testing of roofing products advanced. Roof attachment to the building, especially hip and ridge tiles, presented a challenge. These tiles were not adequately addressed by the code. Many roofers were still setting hip and ridge tiles on a bed of mortar, even where they had nailed or screwed the field tiles. Over time, the mortar’s grip on the hip and ridge tiles can weaken, leaving them without adequate attachment. The tiles would blow off and become airborne, essentially becoming small wind-driven missiles. This problem has been addressed using hip and ridge nailers attached these tiles, providing a more secure attachment method. Florida adopted the 2020 FBC, requiring a fully sealed roof deck, which will also help minimize interior damage from future hurricanes.

The roof-to-wall connection is also significant. A strong connection between the two is essential to prevent the roof from flying off the building, exposing its interior to significant water damage.  Roof straps need to be fully wrapped around the roof trusses and wall structure. In addition, structures with continuous load path construction performed well. Tying the roof to the foundation with metal connectors and fasteners (such as straps, nails, and screws) means better resistance to high winds.

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Intertek’s teams on the ground inspected hundreds of roofs and found those that were installed recently often performed extremely well. In addition to anchors, the use of adhesive foam instead of mortar was another impactful improvement. In general, metal roofs performed the best after Ian, but other newer roofing types and installation matters and newer roofs fared well.

According to Dr. Murray Morrison, managing director of research at IBHS, there is still room for improvement in the performance of asphalt shingles, the most common roof cover material. However, the performance of roofs now compared to 30 years ago is significantly better, thanks to improved materials, testing, and quality control (QC) codes. Many newer roofs installed in southwest Florida did not lose even a single shingle during the storm.

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The Florida Legislature passed Senate Bill 4D (SB-4D) in May 2022, which creates new requirements for condominiums and buildings three or more stories tall. SB-4D establishes a statewide inspection program that requires associations to conduct milestone structure inspections and perform structural integrity reserve studies to ensure safety in these building types—roofs are included in these requirements. Since SB-4D is a new law and still open to interpretation and commentary through the end of 2023, additional work may be required to comply with changes to the law as new information becomes available.

Windows and doors

Hurricane shutters or impact-resistant windows and doors, adhering to the FBC, performed extremely well. Impact-resistant windows are especially effective since they do not need to be put in place in the hectic hours before the storm. Ian’s sudden southward track gave many people little time to prepare.

Conclusion

There has been significant progress in strengthening codes since Hurricane Andrew. According to the Institute for Home and Business Safety, in the aftermath of Hurricane Ian, new science may emerge and be translated into future code adoptions.⁷ As evidenced by the success in Babcock Ranch, architects and specifiers along the coasts can see the benefits of Florida’s tough building codes and what is possible when designing beyond the code.

Notes

¹ See Florida’s Green Building Coalition’s certifications, www.floridagreenbuilding.org/certification[9].

² Learn about the Home Energy Rating System (HERS), www.hersindex.com/hers-index/what-is-the-hers-index/[10].

³ Update on Ft. Myers after Hurricane Ian, weather.com/storms/hurricane/video/fort-myers-beach-still-recovering-from-ian[11].

⁴ Visit www.nesdis.noaa.gov/news/hurricane-ians-path-of-destruction[12].

⁵ Read more at www.eenews.net/articles/weak-florida-planning-law-boosted-ians-destructive-power[13].

⁶ Consult www.census.gov/library/stories/2018/08/coastal-county-population-rises.html[14].

⁷ Visit The Insurance Institute for Business
& Home Safety (IBHS) to learn more, ibhs.org/[15].

Author

Civil engineer, Vinu J. Abraham, is one of the pioneers of the hurricane testing market. He began his 31-year career in a test lab at Texas Tech University, where this type of testing was in its initial stages of development. His expertise as a test engineer landed him as a site manager with Intertek.Today, Abraham is vice-president of products for Intertek’s building and construction business units and oversees more than 25 Intertek locations globally. His expertise helps clients address stringent windborne debris requirements and aid in the development of protective glazing products that safeguard homes, businesses, and communities from the effects of severe windstorms. Abraham holds a degree from Texas Tech in civil engineering, B.Sc. and M.Sc. He has appeared in numerous television and print news media outlets, discussing how properly certified products can help save lives and protect property during severe windstorms.

Source URL: https://www.constructionspecifier.com/hurricane-ians-aftermath-code-approved-lessons-and-results/

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