While a tornado was destroying homes in Dexter on March 15, builder Ken Trever and a worker were just a few miles away, in the garage of an unfinished home in the Polo Fields subdivision. When the worker’s wife called anxiously to check on him, he told her he’d be fine: the garage–in fact, the entire house–was built of concrete.

Trever, sixty-three, has been a builder for forty-one years. But he says he had a revelation on a very cold day twenty years ago, when he touched the foundation of a home he was building and realized it felt warm: he’d built it using insulating concrete forms (ICF), hollow foam blocks into which concrete is poured. For the last dozen years, he’s been building entire homes from ICF. “My whole house [in Milford] is made of concrete, every level, including the garage,” he says. “It’s mold, insect, sound, and tornado proof.”

Since the Dexter tornado, Trever says, he’s heard from dozens of potential clients who mentioned the storms here and elsewhere in the Midwest. He figures the 6,000-square-foot Polo Fields house contains “a couple of hundred yards of concrete, give or take a few yards,” and can withstand winds up to 220 mph. Trever says the walls cost only about 10 percent more than the heavy-duty wood framing he previously used–his homes start at around $400,000–but afterthoughts do cost extra. Cutting one additional window through the six-inch concrete walls of the Polo Fields house, he says, “took us about a day.”