A Bright Idea: Protect Historic Properties from Lightning

In 2018, architects from Martin Gardner Architecture in Marion replaced the lightning protection system, including copper rods and conducting cables, on the Winneshiek County Courthouse in Decorah. (Photo: Martin Gardner Architecture)

Many Iowans love a spring or summer rainstorm — unless it causes damage.

Lightning accounts for 5 percent of all insurance claims across the country, with annual damage estimated as high as $1 billion, according to Underwriters Laboratories, Inc. And certain buildings are prime targets: Nearly a third of all church fires start with a dramatic bolt from above.

That’s why Cedar Rapids architect Bethany Jordan is leading a session about lightning protection at the upcoming Preserve Iowa Summit, which the State Historic Preservation Office has planned for June 6–8 in Newton. She’ll discuss how to determine which historic properties are at highest risk and how to protect them.

“A lot of it is common sense,” she said. “If it’s the tallest building out in the middle of nowhere, maybe. If there’s a tree that’s taller than your house, the tree will probably get struck first.”

The National Fire Protection Association publishes a list of other factors that can help property owners assess their risk, including a building’s geography (hilltops are risky), architecture (towers are targets), materials (wood is flammable) and contents (barns full of hay are highly combustible).

In most cases, installing lightning protection is voluntary, but property owners with concerns should consult their insurance agent or local fire marshal. For large or historic buildings, owners may also want to hire an architect or engineer to assess the risks.

When Jordan and her firm, Martin Gardner Architecture, were hired to install a new roof on the Winneshiek County Courthouse in Decorah, they took a close look at the 1904 building’s old lightning protection. The copper spikes on the roof were OK, but some of the braided copper cables running down the exterior walls were frayed. After consulting a forensic engineer, Jordan and her colleagues decided to replace the components to minimize the courthouse’s risk.

“It’s one of the biggest buildings in Decorah, with a big copper dome on top,” she said. “It’s essentially a giant lightning rod sticking up in the sky.”

New copper cables line the walls of the Winneshiek County Courthouse. (Martin Gardner Architecture)

Fortunately, the technology to protect buildings from lightning damage hasn’t changed much since Benjamin Franklin designed one of the first systems back in the 1750s. It doesn’t actually prevent lightning from striking, but it gives all that electrical power somewhere to go — from a spike on the roof and down through cables to another spike embedded deep in the ground.

New lighting rods line the roof of the Winneshiek County Courthouse. (Martin Gardner Architecture)

Lighting protection caught on fairly quickly during the late 1700s — including Independence Hall in Franklin’s Philadelphia — and was commonplace by the late 1800s.

But public opinion turned against lighting protection during the early 20th century, even as scientists produced more proof that they worked. The culprits: door-to-door salesmen.

“Using scare techniques, parlor tricks to simulate lightning, testimonials, and flashy advertising, unscrupulous traveling salesmen frequently gave little consideration as to whether a structure was at risk and merited lighting protection,” according to a recent brief Charles Fisher published in 2017 for the National Park Service, which promotes historic preservation and oversees the National Register of Historic Places.

Fisher’s report explained that aggressive marketing and shoddy workmanship eventually eroded public confidence in lightning protection.

But today, most architects and engineers agree with Benjamin Franklin. Lighting protection can make a difference — if it’s correctly installed and maintained.

“We encourage Iowans to take a look at their historic properties and take intentional, practical steps to protect them,” said Steve King, who leads the State Historic Preservation Office. “As Franklin himself advised, an ounce of prevention is worth a pound of cure.”

Michael Morain, Iowa Department of Cultural Affairs