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 they are in California. Thus, for the vast majority of the approximately fifty million homes in the United States WUIFire prevention is the responsibility of individual homeowners—it is a voluntary and one-time process. “The approach that's been taken over the last quarter century has been, 'Hey, something is better than nothing,'” Marangides told me. “And from the point of view of fire, this is absolutely not true. Fire does not work that way.” A homeowner could complete eighty percent of fire protection measures, potentially spending many tens of thousands of dollars on upgrades, and lose their home to the twenty percent that remain unfinished—in no small part due to uncontrolled 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. In order for homes to survive wildfires on their own, he said, people living on the wildlife frontier must not only clean up fuel sources around their properties, but also make 100 percent of the potential improvements to fortify the home. Even these emergency measures, he continued, are not enough. No home is an island, and dense housing can only protect itself if every neighbor does the same job. Such recommendations are so strict that they may seem impossible; Some of Marangides' colleagues in the fire safety field are concerned that the message will deter the public from trying. “You can’t choose,” Marangides told me. “Science tells us to do everything.”
For much of the twentieth century, wildfires threatened rural communities. Over time, a special approach to fire prevention has emerged: If your home is located on or near a large area of wooded land, you can protect it by creating a buffer around it. In the sixties, California law, supported by the state fire agency, put forth the fundamental concept of defensible space—a zone up to a hundred feet high where fuels such as brush and trees are strategically trimmed and managed. The U.S. Forest Service eventually recommended the practice. But over the decades, housing development has moved closer to wild lands, the climate has warmed, and fires have increasingly become uncontrollable urban conflagrations. Over the past decade, California's most destructive fires have burned more than fifty-seven thousand homes, businesses, and other structures. And when the closest source of fuel is not the forest, but the house next door, a broader strategy is needed. The houses had to be strengthened to reduce the likelihood of fire.
Last spring I visited Marangides at the National Fire Research Laboratory, which is studying defense strategies in a huge warehouse-like structure on the island. NISTCampus in Gaithersburg, Maryland. Huge ventilation pipes curled like snakes on the roof of the building. Marangides, wearing glasses and jeans, met me in the lobby, where we grabbed our white helmets. From there we entered a spacious room with a reinforced concrete floor. Hanging from the ceiling was a roughly fifty-square-foot hood, an industrial version of what you might find in home kitchens.
About a dozen researchers gathered around a model of a one-story dwelling. The beige cement-fiberboard façade featured double-glazed windows, an asphalt tile roof and metal guttering. It was designed to be highly fire resistant in accordance with Chapter 7A and the International Wildlife-Urban Interface Code. (The house resembled a stage set, with scaffolding in place of the other three walls; sensors monitored things like temperature and heat flow.) But all eyes were on a small corrugated steel shed located five feet from the house. The open door facing the dwelling revealed stacks of firewood inside.
“Wait for ignition,” announced a voice over the loudspeaker. A man in firefighting gear walked up to the barn, lit it with a propane torch, and left. A few minutes later, a bright flame shot out of the door towards the wall. We could hear a loud crash; the coals flew. Soon orange-red flames began to lick the wall and the exposed eaves of the roof. The smoke spiraled upward. The window frame, made of white vinyl, began to melt and then caught fire. About ten minutes after the start of the experiment, the cornice caught fire. A glass window pane fell to the ground.
