Gulf Coast Construction ‘Woefully Inadequate’ to Survive Storm Flooding

September 17, 2009

Government minimum flood elevation requirements for properties vulnerable to storm surge throughout the Gulf Coast region are “woefully inadequate,” according to a new study of property damage caused by Hurricane Ike, which struck the Bolivar Peninsula near Galveston, Texas one year ago yesterday, Sept. 13, 2008.

The study reveals that significantly more Gulf Coast homes and businesses are imperiled by disastrous flooding from storm surge than previously recognized by property owners or policymakers.

The authors say that the National Flood Insurance Program (NFIP) should do a better job of encouraging building at higher elevations to avoid flooding.The NFIP, which provides flood insurance to homes and businesses, also establishes base flood elevation (BFE) levels for properties.

The report, Hurricane Ike: Nature’s Force vs. Structural Strength, was issued by the Institute for Business & Home Safety (IBHS), a not-for-profit research organization supported by property insurers and reinsurers.

“Lessons learned from Hurricane Ike, which is the third-costliest hurricane on record, should be used by vulnerable communities from Texas to Maine to effectively reduce property damage in all hurricane-exposed areas,” said IBHS President and CEO Julie Rochman.

“Simply put, the study found that many properties are not built high enough to withstand storm surges, tightly enough to prevent water from causing interior damage or strongly enough to prevent damage when high winds strike.”

IBHS questions the current basis for elevating properties along the Gulf Coast and urges the NFIP to provide greater incentives for building well above the minimum elevations now in place. More than 50 percent of the nation’s population lives within 50 miles of the coast, with more than $9 trillion of insured coastal property vulnerable to hurricanes.

According to the study’s findings, the BFE requirement for homes on Texas’ Bolivar Peninsula ranged between 13 feet for homes built in the 1970s and 17 feet to 19 feet for homes built beginning in 1983. All but a handful of properties within the first few rows of houses from the coast, built to even the highest elevation requirements, were washed away during Hurricane Ike.

By contrast, the study found that 10 homes on the Bolivar Peninsula designed and built under IBHS’s building code-plus new construction program, Fortified…for safer living, survived the storm sustaining minor damage. The Fortified homes had outdoor decks at 18 feet that were destroyed, but the homes, which were elevated to 26 feet, survived.

According to IBHS Senior Vice President of Research and Chief Engineer Dr. Tim Reinhold, most homes in coastal areas are built to or slightly above 100-year base flood elevations. “A 100-year flood means that the level of flood water has a 1 percent chance of being equaled or exceeded in any single year. However, it is well recognized in the engineering community that coastal homes built to this level have a 26 percent chance of being flooded or demolished over the life of a 30-year mortgage. This chance increases to about 40 percent in a 50-year period,” Reinhold said.

“All it takes is a breaking wave about 2 feet above the base of a house to knock out the bottom floor or destroy a frame house,” explained Reinhold. “The chances of destruction can be significantly reduced by employing what has been learned about the importance of proper elevation, which can be relatively inexpensive when building a coastal home,” he continued. “For example, building to a 500-year base flood elevation reduces the chance of storm surge exceeding the base elevation to about 10 percent in a 50-year period.”

The IBHS study also provides a detailed, real world performance evaluation of superior construction techniques when tested by a truly extreme weather event;

It also includes a retrofit guide for Texans in coastal areas to use. The guide takes into account the current Texas building code requirements and outlines specific retrofit options that homeowners and residents can use to harden their property by doing things such as strengthening their roofs, accoroding to Rochman.

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