Tornado damage in the Midwest highlighted the lack of national building standards

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Last week's tornadoes in the South and Midwest ripped apart factories and commercial buildings. Eight people died inside a candle factory in Kentucky when that building collapsed. And in Illinois, six others were killed inside an Amazon warehouse. Engineers say the way these warehouses are built can make them unstable during tornadoes. Local officials may need to update their building codes. From St. Louis Public Radio, Shahla Farzan reports.

SHAHLA FARZAN, BYLINE: Craig Yost was just finishing his shift at an Amazon warehouse in Edwardsville, Ill., when the winds started to pick up. Yost works as a delivery driver, and he says he took shelter shortly after parking his van at the warehouse. He told TV station KMOV that he and other workers were huddled inside a bathroom when a powerful tornado struck the building.

CRAIG YOST: The walls caved in, and I got pinned to the ground by a giant block of concrete. It was like a slow trash compactor.

FARZAN: The tornado had lifted part of the roof from the warehouse, and a 40-foot-high concrete wall collapsed. There were six other people on the south side of the building with Yost. He suffered multiple injuries, but he was the only one who survived. We've seen warehouse collapses during tornadoes before. In 2011, an extreme tornado leveled a Home Depot in Joplin, Mo., killing eight people inside.

MARC LEVITAN: If we're going to reduce the impacts of the tornadoes, then we need to start designing for tornadoes.

FARZAN: That's engineer Marc Levitan, who was one of the researchers at the National Institute of Standards and Technology who investigated the aftermath of the Joplin tornado. One of their findings was that the physical structure of warehouses and big-box stores in tornado-prone areas should be strengthened. Part of the issue is just how these buildings are constructed. They're often built using a method called tilt-up construction, where concrete walls are poured on site, then lifted into position and connected to the foundation.

Grace Yan, a structural engineer at Missouri University of Science and Technology, says the first part of a building that's usually ripped off during a tornado is the roof, and that's significant.

GRACE YAN: In a lot of cases, the roof damage can further lead to the collapse of the entire building. So installing a stronger roof is very, very important.

FARZAN: Yan says national building code standards do not require warehouses to have tornado-resistant features unless they're storing hazardous waste or chemicals. Amazon officials say the warehouse did meet local building codes, but Illinois Governor J.B. Pritzker questions whether that's enough.

J B PRITZKER: So it makes us wonder. I have to say - and I've spoken with the legislators that are here, too - about whether or not we need to change code based upon the climate change that we're seeing all around us.

FARZAN: Like many states, Illinois does not have a statewide building code, leading to a patchwork of local regulations. Municipalities that try to enact more stringent building codes can face pushback from builders and industry groups because of increased costs. But engineer Marc Levitan says early research shows making buildings safer isn't that much more costly, and it can help prevent a catastrophic collapse.

LEVITAN: Anything that you do to increase the wind load resistance for the tornado, as a result of designing for tornado, also increases your wind load resistance for any other kind of windstorm that you're going to have.

FARZAN: These most recent tornadoes may help convince communities that it's time to start updating their codes, so commercial buildings have a better chance of staying intact during a violent storm.

For NPR News, I'm Shahla Farzan in St. Louis.

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