Structures in Luzerne County — or most of Pennsylvania, for that matter — cannot be expected to hold up if they are in the direct path of an EF2 tornado like the one that hit Wilkes-Barre Township last week, a local architect said.
Construction in the state must comply with International Building Code wind load requirements, which are based on an extensive review of historic wind speed data, said Rick Williams, a registered architect and former county councilman.
The requirement that must be met here: 90 mph, Williams said. That means buildings and houses are designed and built to remain intact in winds up to that speed.
Wind speeds in Wednesday’s twister are believed to have reached 130 mph.
“There appears to be no evidence that buildings damaged Wednesday were under-designed,” Williams said. “They were not designed to withstand a tornado and did not have to be.”
Stores and restaurants in The Arena Hub Plaza and surrounding commercial areas along Mundy Street were directly in the path of Wednesday’s storm, which touched down around 10 p.m. Eight buildings have been condemned as a result and 14 are listed as unsafe, officials said Friday.
In comparison with the local requirements, structures along much of the East Coast must withstand winds up to 140 mph, Williams said.
The bar is set even higher elsewhere, at 170 mph in Guam, 145 mph in Puerto Rico and 150 mph on the southern tip of Florida, he said. A lower speed of 85 mph is imposed for portions of Washington, California and Oregon, he said.
While reviewing weather data, building code crafters must weigh both public safety and the costs to meet standards, Williams said.
“It’s not realistic to design every structure to resist every conceivable possible force to which it might be subjected,” he said.
The code is regularly updated based on a review of past and current weather events and technological advances, said Williams.
Engineer Jim Brozena, a consultant and prior county Flood Protection Authority executive director, concurred.
The codes for each region reflect the most frequent and likely hazard occurrences, he said, which could also include earthquakes, flooding, wildfires, mudslides, hurricanes and snowstorms that dump additional weight atop structures.
“You can’t design structures to withstand everything. You’d never build anything,” Brozena said.
Northeastern Pennsylvania may also have another vulnerability, however. Because code requirements are triggered for new construction or significant renovations, many legacy buildings may not meet contemporary standards.
“The biggest problem may be older housing stock constructed well before building codes,” Brozena explained.
Buildings in areas with higher wind load requirements have larger and more frequent fasteners, cross-braced walls and other components to resist collapse, Williams said.
The goal is trying to ensure a structure is tied down to the foundation and connected together in a way that different parts, such as the roof, don’t break free, said county Planning/Zoning Office Transportation Planner Tanis Manseau, a licensed professional engineer in both Pennsylvania and South Carolina.
For example, structures along the East Coast often require special “hurricane clips” to prevent roof panels from ripping loose, said Manseau, who is also a certified building official through the International Code Council.
Stronger doors and windows — and their frames — also are necessary.
“If the whole thing stays together, there’s less chance of injury,” Manseau said.
There are no guarantees with tornadoes because they subject structures to both the force of wind and extreme low pressure that makes the walls “suck in and suck out,” he said.
Some property owners in tornado-prone regions have purchased dome-shaped concrete residential structures designed to reduce the vertical surface taking a direct hit.
Manseau, who hails from Charleston, S.C., said he’s observed many Northeastern Pennsylvania residents are fortunate to have basements for shelter if a tornado comes.
“In the coastal plains, the groundwater table is much higher. You really can’t have a basement because it will stay flooded all the time,” he said.
While the Wilkes-Barre Township tornado was shocking to many, Williams doesn’t expect property owners to invest in precautionary building modifications at this time.
He advises those concerned about high winds to regularly check signs, antennas and other things attached to their structures to make sure they are securely attached.
“Much of the harm that can be done to individuals is through flying objects,” he said.
Reach Jennifer Learn-Andes at 570-991-6388 or on Twitter @TLJenLearnAndes.