North Carolina Sea Grant
Coastwatch Currents

Coastwatch Currents

October 13, 2014 | Katie Mosher

By Pam Smith

Coastal buildings have an open lowest level — so that the living areas are above most storm surges. Photo by Spencer Rogers.

Coastal buildings have an open lowest level — so that the living areas are above most storm surges. Photo by Spencer Rogers.

Has the 60th anniversary of Hurricane Hazel on Oct. 15 prompted you to think about current coastal construction?

Spencer Rogers, North Carolina Sea Grant’s coastal construction and erosion specialist, has good advice for anyone living — or considering living — on the coast: Remember, there is no such thing as a hurricane-proof building on a barrier island.

The good news, though, is that the evolution of hurricane-resistant construction methods has improved the odds of a code-compliant structure surviving a major storm event.

Still, Rogers told an audience at a recent North Carolina Coastal Federation event in Wrightsville Beach: “Hurricane-resistance is not an alternative to evacuation. Nothing is worth betting your life on. Get to higher ground and chances are you will have something to come back to after evacuation.”

Rogers, an expert on coastal dynamics, noted that robust building codes are not arbitrary. They take into account natural forces at work in the ever-changing coastal environment — winds, waves, storm surge, dunes, erosion, and seasonal fluctuations in sand transport to and from dunes and beaches.

During a major hurricane or nor’easter, dunes can provide the first line of defense from storm surges to structures set behind vegetated dune habitat. In recent years, dune walkovers have replaced dune cutout walkways that can channel storm surge into structures behind the dunes.

Rogers noted that erosion rates differ from place to place along the coast. Dune recovery from a major storm may range from several seasons to never — beach and dune sand transported far offshore cannot be recovered and is a net loss from the system.

Therefore, it’s prudent to check the erosion rate of a specific locale before investing in beachfront properties, Rogers suggests.

roof-anchor-web

Roof connections can be inexpensive to put in during construction but valuable when winds come. Photo by Spencer Rogers.

Since the mid-1960s, North Carolina building codes have pushed coastal construction to higher ground, elevating the height of the first floor on pilings driven deep into its building site. The open design enables storm surge to push inland without major structural damage.

Wind resistance is another matter. Designing or retrofitting a building for hurricane wind resistance need not be budget busting, Rogers asserts. A supply of galvanized steel connection plates and straps, wind anchors and roof ties is mandatory, but not expensive.

Sinking an extra row of galvanized nails into the plywood sub-roofing can be a smart $10 investment in the way a roof performs during a major wind event.

For more information about the latest technologies that protect coastal residents from hurricane hazards, check out the Autumn 2014 issue of Coastwatch magazine at www.nccoastwatch.org.

Knowing your code-compliant quotient may make a difference in the cost of National Flood Insurance premiums. For information on the proposed changes in the program, go to: http://fris.nc.gov/fris/ and click on North Carolina.

 

 

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