Edie Howard Housel, who lost her husband, Russell Howard, and their two children, 5-year-old Harli Jace and 19-month-old Hayze Cole, during the storm, specifically cites the 100,000-pound concrete slabs that made up the store’s walls. All but 10 of the 73 tilt-up panels fell after the tornado ripped the roof off of the building, including some that fell inward and killed Housel’s family members and others.

Housel filed the lawsuit in May in Jasper County Circuit Court, but it was moved last month to U.S. District Court’s Western Missouri District. It names as defendants Home Depot USA, property owner HD Development of Maryland, Inc., and store designer Casco Diversified Corp., The Joplin Globe reported.

Home Depot USA, which is based in Atlanta, and HD Development denied all of the allegations, calling the EF-5 tornado that killed 161 people and destroyed thousands of buildings an “act of God.” Because of that, imposition of liability on the defendants is prohibited, the company’s attorneys said.

Casco also denies all allegations, saying the plaintiff is barred by Missouri’s 10-year law of repose from suing the company. Construction of the Home Depot was finished around March 1, 2001, and the lawsuit was filed more than 13 years after it was completed, Casco said.

The lawsuit alleges that as the tornado approached the store, Howard and his children were directed to Home Depot’s training room by employee Dean Wells. Before they could get there, the building’s unsupported wall panels collapsed on them after the roof was ripped away by winds estimated at 165 mph, plus or minus 20 mph, according to a National Institute of Standards and Technology study.

About 30 people who made it to the training room near the store’s northeast corner survived because the panels fell outward, the NIST study concluded.

After the storm, engineers criticized the tilt-up wall method used to construct the store, saying such buildings are prone to collapse in high winds if the roof fails.

In response to a Kansas City Star story a month after the tornado, the Tilt-Up Concrete Association formed a committee to examine the incident and challenge claims that the building was improperly constructed.

That probe found that the building was actually overbuilt when it was constructed in 2001 under the 1996 BOCA Basic Building Code, which said the building should be able to withstand wind loads of 70 mph. Instead, it was designed to handle 90 mph winds.

After examining what happened in Joplin, both NIST and the American Society of Civil Engineers recommended that storm shelters be installed in big-box structures because they lack the material strength to provide protection from tornadoes.

When Home Depot rebuilt its tilt-wall store in Joplin, it included a reinforced room, company spokesman Stephen Holmes said.

“What we’ve said all along about building the reinforced room is that we don’t hold our facilities out to be storm shelters, but we felt it was appropriate given the events of the past at this store and the sentiment of the community.”