Jack Burns knows ICFs are durable. They may have saved his life early one morning when a 500,000-pound boulder crashed through the rear of his house, plowed through the bathroom, and stopped a few feet from his bed. 

Burns’ home lies just outside Zion National Park, across the street from the towering cliffs that attract millions of visitors each year. The walls of the home are made from Arxx ICFs, with a 6-inch concrete core; the roof is made of R-Control SIPs.

On that summer night in 2002, a light rain was falling, probably causing enough erosion to loosen a massive boulder atop the red sandstone bluff nearby.

By about 5:30 a.m., gravity took its inevitable course and the huge rock tumbled down the 600-foot cliff. It apparently bounced a few times like a rubber ball before careening into the back wall of the house. Observers measured the boulder after the fact at about 12 feet by 16 feet by 16 feet—taller than the ranch-style home in its path.

A half-million-pound boulder fell from a 600-ft. cliff and rolled into Burns’ home. Luckily the ICF walls stopped the massive rock just feet from his bed.

Frank Palmer, a supplier to the project, said, “If that rear wall hadn’t been reinforced concrete I suspect the boulder would have made it to the bed. As it was, the impact shifted the SIP panels to the left and the right, disconnecting them from the walls, and flattened the wall in back. But the rest of the walls stayed up.”

“I love that house,” says Burns, who now lives in nearby Springdale, Utah. “Its just fabulous to live in, for energy-efficiency as well as safety.”

Burns says that after some effort, the boulder was eventually removed. “They first attempted to use dynamite, but that didn’t even crack it,” he says. Crews eventually broke it apart with a ram hoe—a backhoe with a jackhammer attachment—and hauled it off. 

Once the rock was gone, the home was relatively easy to restore. “We just poured a new wall and replaced a few SIPs,” he says. “Right now I have it rented out, but I hope to move back into it.” 

Allen Staker, the local ICF contractor, is using Arxx to create an ICF development called Gifford Park. Exteriors are finished with native rock and interiors feature heavy wooden beams, in a style reminiscent of the 1930’s era National Park lodges. 

“I like high quality construction,” says Staker, “and ICFs lend themselves to that.”