A New Paradigm for Protecting Homes from Disastrous Fires
But the new paradigm for fighting these fires contains an inconvenient truth. Most people don’t live in new homes, and most building codes aren’t as strict as California’s. Thus, for the vast majority of some fifty million American households WUIfire prevention is the responsibility of individual owners – it is voluntary and ad hoc. “The approach that’s been taken over the last quarter century has been, ‘Hey, something is better than nothing,'” Maranghides told me. “And from a fire perspective, that’s absolutely not true. Fire doesn’t work that way.” A homeowner could complete eighty percent of fire protection measures, potentially spending tens of thousands of dollars on renovations, and lose their home because of the twenty percent that remains unfinished – largely due to uncontrollable and unpredictable embers.
This reality led Maranghides to a position so logical that it reminded me of Spock, the ultra-rational character from “Star Trek.” For homes to survive fires on their own, he said, people who live on the wildland border should not only eliminate fuel sources around their properties, but also make 100 percent of potential improvements to strengthen their homes. Even these extraordinary measures, he continued, are insufficient. No house is an island, and dense housing developments can only protect themselves if every neighbor does the same job. Such recommendations are so strict that they may seem impossible; Some of Maranghides’ colleagues in the fire prevention world worry that this message will dissuade the public from trying. “You can’t choose,” Maranghides told me. “Science tells us you have to do everything.”
For much of the 20th century, wildfires tended to threaten rural communities. Over time, a particular approach to fire prevention has emerged: If your home is located on a spacious plot in or near the woods, you can protect it by creating a buffer zone around it. In the 1960s, a California law supported by the state’s fire service advanced the fundamental concept of defensible space, an area of up to a hundred feet where combustibles such as brush and trees are cut down and strategically managed. The United States Forest Service ultimately recommended this practice. But over the decades, housing developments expanded into wildlands, the climate warmed, and fires increasingly turned into unstoppable urban conflagrations. Over the past decade, California’s most destructive wildfires have incinerated more than fifty-seven thousand homes, commercial properties, and other structures. And when the closest fuel source isn’t wood but rather the house next door, a broader strategy is needed. Houses had to be reinforced to make them less likely to catch fire.
Last spring, I visited Maranghides at the National Fire Research Laboratory, which studies hardening strategies in a towering warehouse-like structure on NISTin Gaithersburg, Maryland. Huge ventilation pipes coiled like snakes on the roof of the building. Maranghides, wearing glasses and jeans, met me in the foyer, where we grabbed white hard hats. From there we entered a cavernous room with a reinforced concrete floor. A roughly fifty-square-foot extractor hood—an industrial version of what you’d find in domestic kitchens—hung from the ceiling.
A dozen researchers were gathered around a model of a single-storey dwelling. A beige fiber cement board facade featured a double-glazed sliding window, an asphalt shingle roof and a metal gutter. It has been designed to be highly fire resistant in accordance with Chapter 7A and the International Wildland-Urban Interface Code. (The house was like a stage set, with scaffolding in place of the other three walls; sensors tracked measurements such as temperature and heat flow.) But all eyes were on a small corrugated iron shed five feet from the house. Its open door, facing the house, revealed piles of wood inside.
“Wait for ignition,” a voice announced through a loudspeaker. A man in firefighter gear approached the shed, used a propane torch to light the fire, and walked away. Within minutes, an incandescent flame burst from the door toward the wall. We could hear loud crackling sounds; the embers were flying. Soon, orange-red flames began licking the wall and open eaves. The smoke was spiraling up. The window frame, made of white vinyl, began to melt and then catch fire. About ten minutes into the experiment, the eaves were burning. A window fell to the ground.
