Insulated concrete forms—combined with flame-resistant roofing and siding—make for one safe house

As thousands of Southern Californians contemplate how they’ll rebuild their homes charred by the wildfires ripping through the region, they’ll undoubtedly look for materials that won’t burn.

The answer for many of them will be ICFs (insulated concrete forms)—polystyrene blocks that fit together like Legos to form a house’s shell. Filled with concrete—one of the most fire—and heat—resistant of construction materials—ICFs create solid insulated walls that lock out sound and weather. They can reportedly withstand a fire for up to four hours.

While ICFs have been around for decades, their use has mostly been limited to commercial and institutional buildings, such as hotels and schools. But nationwide training camps sponsored by the United Brotherhood of Carpenters and Joiners of America now teach carpenters to build houses out of the stuff. Using ICFs costs 1 to 4 percent more than what you would pay for a bare bones wood-frame house with no built—in fire protection, says Vera Novak, Technical Services Manager for the Insulating Concrete Form Association. The material can save money in the long run because it helps prevent heated and cooled air from escaping through the walls; it’s a primary building block in many Energy Star rated homes.

ICFs mean little, however, without flame-resistant roofing and siding. “You can’t just put on a regular wood roof and expect the wildfires to go around you,” Novak says. “You must make sure that your roofing choices are equally fire resistant. That can be done with metal, concrete, and various types of tiles.” Safe bets for siding are stucco, stone, and brick. For the traditional look of wood, choose the fiber cement clapboards or shingles manufactured by CertainTeed Certain Teed and JamesHardie.