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Tougher Building Codes Strengthen New Homes

Jan 10, 2012 | News

Good fences make good neighbors. But good roofs might make even better ones, according to a new study by Sea Grant researcher WeiChiang Pang, a civil engineer at Clemson University.

“Your home will likely have less damage from flying debris during a hurricane if your neighbors have retrofitted their roofs or built new homes under current codes,” Pang said.

Coastal building codes have been improved since Hurricane Hugo struck South Carolina in 1989. For instance, builders in coastal areas are now required to attach a home’s roof sheathing to rafters with additional nails, which helps prevent roof losses.

Pang and his colleague, Scott Schiff, also of Clemson University, have created computer models to test the degree to which stronger building codes have improved the structural integrity of coastal housing.

Intense hurricane winds can rip plywood sheathing off a roof and carry it airborne as a dangerous missile through a neighborhood, where it can crash through windows and walls.

When intense wind enters a house’s protective “envelope,” it increases air pressure inside like blowing up a balloon beyond its capacity. If enough pressure builds in the house, the structure will break at its weakest point, usually the roof, which can fly off and create additional airborne debris.

Pang and Schiff have created a computer model that simulates a Hurricane Hugo-sized catastrophic storm hitting northern Charleston County—the same location where Hugo made landfall in 1989. The simulated storm was directed into a simulated subdivision including a few dozen homes built under today’s coast-al construction code. Then the same storm was directed through a similar simulated neighborhood but with homes built under typical construction practices of 1989.

Today’s tougher building codes, it turns out, have made roofs stronger in high winds.

“If another storm the size of Hugo hits the coast, we would see less roof failure and less debris because of today’s improved roofing practices,” Pang said.

The scientists, moreover, have created a computer model that will be used to analyze the trajectories of wind-borne debris and their impacts on buildings.

This product could eventually be used to design better impact-resistant windows and shutters, determine the orientation of buildings and placement of windows in respect to the coastline and typical hurricane paths, and refine building codes to make structures stronger.