Assessing The Damage From Hurricane Charley (Metal Construction News, October 2004)

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Assessing The Damage From Hurricane Charley
By Kevin Corcoran
V.P. Of Business Development
Englert Inc.

When Hurricane Charley rampaged through southwest and central Florida August 13, pummeling Lee and Charlotte Counties with winds exceeding 145 mph, technical sales representative Charles “Butch” Dubecky wondered how Englert commercial and residential projects built over the past 10 years would fare against the Class Four storm.

Two days later, Dubecky and Keith Van Dyne, a local roofing supplier, had a small plane scouting Lee and Charlotte Counties to assess the damage from the air. By the end of the day, Dubecky was reporting back to us at Englert’s corporate offices that not one of the 39 projects surveilled had sustained damage.

While owners of buildings with standing seam roofs had suffered little or no damage whatsoever, officials were predicting damages to other insured structures alone would reach $14 billion. And materials, construction techniques and construction quality were being investigated throughout the damage zone in the hunt for evidence to see if code and building practices would have to be improved.

Roofing damage was extensive in the area where residential building codes mandated residents use asphalt tile roofing purely for aesthetic reasons. As Dubecky and Van Dyne’s plane flew over the massive damage that had left hundreds of thousands of Punta Gorda and Port Charlotte residents reeling from the damage or homeless, they noticed hundreds of bright blue tarps dotting the landscape as far as the eye could see.

The U.S. Army Corps of Engineers has been repairing more than 2,600 roofs through Operation Blue Roof, placing tarps for free on residents’ homes. More than 66,000 tarps had been distributed to various sites around the affected area by the time Dubecky and Van Dyne were in the air.

Tim Reinhold, vice president of engineering at the Institute for Building and Home Safety, Tampa, an insurance industry group, told reporters a lot of new construction designed and built to the new standards did well, but that there are still issues, even with some of the newer provisions of the code—such as where tile roofs are required. In a lot of homes at the higher end, Reinhold reportedly told the paper that in areas where ordinances required them to have tile roofs, the tiles were coming off and spraying through the neighborhoods and creating real problems for the houses downstream.

One resident of Port Charlotte with a degree in architectural design told a local newspaper “clay tile roofs in a hurricane zone are an architectural nightmare waiting to happen.” Clay tile roofs are the most impractical roof treatment in the building industry, especially in hurricane zones, he observed, adding, “The safest and most effective roof treatment in a hurricane zone is metal. Every other treatment is woefully inadequate by comparison.

” He would have had a lot of agreement from Dubecky and Van Dyne who saw an incredible contrast of the buildings shot from the air—tile-covered and asphalt shingle roofs and their buildings destroyed by the massive storm standing side by side with metal roofs with little or no damage.

Witness the community of Punta Gorda where every school suffered extensive damage–except for the 900-student Sallie Jones Elementary School, a two-story, 98,000-sq. ft., tilt-up concrete structure with a metal roof, steel floor and roof framing. Designed with a metal roofing system, architects had put an additional “importance factor” of 1.15, resulting in a structural design load of 138 mph for wind.

Dallas engineer Yoosef Lavi smiled when Dubecky called him and told him the school was unscathed by the storm. It was Lavi who had been commissioned to produce an ASCE engineering analysis of what would be required for the elementary school to withstand the high winds. A lot of factors went into producing the Sallie Jones School report including the required wind speed loads, the geometry and geography of the building, its exposure, area weather history and the pitch of the roof.

In this particular case, Lavi specified Englert Series 1300 1-½” double lock standing seam panel for the 110,000 sq. ft. roof. Over most of the surface he required that a custom-fabricated clip made to meet these standards be spaced every 2.9’. But around the eaves and ridge areas most susceptible to high wind, he mandated the clips be spaced at 1.3’.“I realize I’m conservative in my specifications and I know some contractors might wrinkle their noses at these requirements. But I can also tell you that being conservative and using quality products are the reason the school remained intact,” Lavi said.

The real proof of that, said Dubecky, came as he looked at the devastation around the Sallie Jones School. Only 100 yards away the town’s 1938 high school had lost its third floor and much of the building’s roof, he said. In contrast, Sallie Jones Elementary was used as an emergency center during the storm and today is the only school in the path of Hurricane Charley holding classes for its students and another school destroyed by the storm. “It’s about the only usable building on the south side of the Charlotte Harbor at this point,” noted one local construction executive two days after the storm.

Hurricane Charley Some of the most devastating destruction—aside from leveled mobile homes —happened in places where it could least be endured: hospitals, airports, fire stations, even a brand new metal-framed agricultural center that was designed as a hurricane shelter.

The plane flew over that facility, the Turner Agri-Civic Center in Arcadia, a two-year-old, steel frame building, designed for 140 mph winds, that was supposed to serve as a shelter for 1,400 people. The building was a twisted ruin that collapsed in estimated 100 to 110 mph winds. The windward corner of the roof separated first, and the building partially collapsed progressively along its length. Refugees inside were able to escape the facility, which had recently been upgraded for $2 million to make it a hurricane shelter.

Dubecky then looked just yards to the east of the mangled center where three buildings stood intact. Two were semi-enclosed storage buildings and one was an exhibition hall, all with metal roofs. Dubecky recognized the exhibition facility. Lavi had engineered it as well with an Englert Series 2000 1-3/4” structural snap lock system and the same kind of conservative fastening employed at the Sallie Jones School.

Fire stations in the direct path of the storm were desperately needed to house resources and equipment vital during and after the storm. Many with asphalt and tile roofs were torn to shreds—but not one in Fort Myers where divison chief Daniel Leffin was headquartered.

His station, Iona McGregor Fire Station #4, survived without losing a panel of its 38,000 sq. ft. 24-gauge Slate Gray roof. The 18”, 1-¾” snap-on panel stood like a lonely sentinel amidst the devastation around it, its fire vehicles and equipment untouched by the storm. The result was that 38 vehicles were saved because they had been brought into the building to last out the storm, including 32 staff vehicles and two trucks from nearby Sanibel and Captiva islands which had been evacuated.

Van Dyne, owner of ANCO Roofing Suppliers in Fort Myers, visited the station two days after Charley swept over it. Leffin did everything but hug Van Dyne when he showed up at the firehouse door. “When he heard we’d put the roof on his building, he came out of the firehouse to my one-ton dually Dodge truck and shook my hand,” said Van Dyne. “Sure it felt good to hear him tell us our roof helped save his building. But the fact of the matter is that the specifications and the way we installed the clips and the double lock seam is what helped keep his building intact in the high winds. That’s pretty impressive, particularly when you realize that some of those panels were up to 97’ long.”

As the small plane continued along the Florida coastline from Punta Gorda to Fort Myers, the picture repeated itself. Tile and asphalt roofs stripped from their undercoatings and million dollar homes below looked like dollhouses with their roofs ripped off.

Why did some buildings survive while others were torn to shreds? Engineers acknowledge it is too early to know whether failures were the fault of the systems themselves, inadequate codes, construction shortcuts or simply the power of Mother Nature. But the consensus among those same engineers is that tougher wind standards in the more restrictive building codes implemented after Hurricane Andrew probably saved property and lives.

These codes require architects who designed buildings to meet ASCE 7-98, the 1998 edition of the American Society of Civil Engineers standards for minimum design loads for buildings and other structures. This is the national standard to which building codes refer when specifying design load requirements for flood, wind, snow, rain, ice, and earthquake loads on buildings. The wind loading section of this standard is considered to contain the most up-to-date requirements available.

ASCE 7-98 only contains methods to calculate loads on structures. Professional engineers like Lavi are then hired to take the wind pressures specified in the standard, and apply them to the building being designed. These wind pressures determine how the building must be constructed. The specifications are then compiled in an analysis report that the contractor must follow in building a roof.

ASCE 7-98 has special requirements for Hurricane Charley buildings sited in areas called “wind-borne debris regions”, specifically those along the Atlantic and Gulf Coasts where the design wind speed is 120 mph or above, or within one mile of the coastal mean high water line where the wind speed is 110 mph or above. This includes the 150 mph requirements in certain coastal sections of Miami-Dade and Monroe County.

Interestingly enough, tough standards were being employed in roofing specified by conservative engineers like Yoosef Lavi long before Andrew changed things. And those buildings generally fared as well as if not better than those built with post-Andrew codes. And then there are installers whose projects fared well because they are just as conservative as Lavi in their craftsmanship.

“Engineers like Yoosef may indicate the clips and fasteners should be spaced every foot in a specific corner situation on an overhang,” noted Scott Shwenk of West Coast Roofing in Fort Myers. “We often take that specification and put the clip everywhere on the overhang. Some people might say that is overkill and it costs more money. But it vastly improves the odds of those buildings surviving.

” The roofing material itself is always an issue as well. And some metal roofing products—meeting certain industry benchmarks such as Dade County uplift testing, the new Florida Building Code requirement, FM uplift testing, UL uplift standards and ASTM uplift standards—have gone through rigorous, controlled performance examinations that make them more qualified than others to withstand the onslaught of Mother Nature.

“And it doesn’t make any sense for a contractor to try to save money by using a homemade clip and drywall screws that are cheaper but can’t withstand the wind loads and pressures of a hurricane that batters a building with 140-mile an hour gusts of wind for hours on end,” noted Van Dyne. Examples dot the southwest Florida landscape that properly-installed metal roofs have fared well in meeting the full brunt of a Force Four storm. And manufacturers, suppliers and installers of metal roofing are hopeful owners and architects will take a lesson from the experience.

“Our strongest hope is that builders and owners have been pounded enough by these storms to realize how closely related quality of materials and workmanship is to survival in an area where it is almost certain to happen again,” said Dubecky.