The way a community is designed, from construction materials to escape routes, can impact how quickly and dangerously a wildfire spreads.
(Bloomberg) — It took about a day for a wildfire to tear through the Maui town of Lahaina, turning the onetime capital of the Kingdom of Hawaii into mostly rubble and ash. Houses burned down to their foundations, cars melted and at least 115 people perished in the deadliest wildfire in modern US history. It’s a sobering example of how devastating a wildfire can be when a community is not prepared.
All summer long, wildfires have raged out of control worldwide, claiming lives and doing billions of dollars in damage. Greece has had so many recent fires that Civil Protection minister Vasilis Kikilias described it as “a not-seen-before situation.” Canada is dealing with its worst wildfire season ever, which has burned at least 15.4 million hectares (38 million acres).
In the US, more people are living in the possible path of wildfires today than did a few decades ago. The population exposed to large fires grew 125% from 2000 to 2019, according to a study published in July in the journal Nature Sustainability. That’s in part because development is expanding into wildlands with a history of fires, and in larger part because climate change makes conditions favorable to fires more likely.
“The number of dry, hot, windy days is increasing,” says Mojtaba Sadegh, co-author of the recent paper and an associate professor of civil engineering at Boise State University. “We call them recipes for megafires.”
The best way to change those ingredients is to cut carbon emissions. But the way a community is designed can impact how much a fire spreads and the amount of damage it does. “We can get rid of the disasters,” Sadegh says. “We can prevent the impact.”
Looking at lessons from past disastrous fires, here are steps that can help reduce fire risk at the home and community level.
Create a vegetation buffer
Whether a community abuts forest or grassland, wildfire and building experts recommend a vegetation-free layer between any wild landscape and the outskirts of town. “What you like is to create a buffer without fuel around the community so you can slow the fire down, at least, but hopefully stop it,” says Thomas Cova, a professor at the University of Utah’s geography department who studies wildfire evacuation. In the case of Lahaina, invasive grasses — fuel for fire — came right up to the edge of town. “They had fuel adjacent to the community, which gives the fire the ability to go straight into the community like a rocket,” Cova says.Buffer zones can also help protect individual homes. “One of the real critical pieces is keeping fuel out of the five-foot zone around the house,” says Ian Giammanco, lead research meteorologist at the Insurance Institute for Business and Home Safety (IBHS). “We call it the home ignition zone. In California, it’s referred to as zone zero.” Fuel can include vegetation, woodpiles, or a kid’s plastic playset.
Increase the space between buildings
Spacing homes and other buildings at least 25 to 30 feet (roughly eight meters) apart can help prevent the spread of fire. At this distance, it’s more difficult for flames from one building to jump to another, and for the radiant heat or embers coming off a burning home or business to extend to neighboring structures.Tight building spacing likely contributed to the spread of the Maui wildfire. “When the structures are that close together and they start burning that high in the wind, it’s like each structure ignites the next structure or two structures away,” Cova says.
Avoid building with wood
Fires commonly spread from embers flying off one building and landing on the roof of another. Constructing roofs using fire-resistant material can protect against this risk. Materials with a Class A fire rating are best, says Giammanco, and include metal, certain tile and most modern shingles. “The worst are the wood shake shingles,” he says. “A lot of times there’s a fire-retardant treatment put on them, but that coating does not age very well.”
Building walls out of noncombustible concrete masonry or cinder blocks — or at least building homes atop concrete slabs that are lifted off the ground — can also help fireproof a structure. “One of the most important parts of the wall is really the lowest six inches where it meets the ground,” says Giammanco. “Embers like to accumulate right there.”
Make sure there are multiple ways out of town
When a wildfire is threatening a community, people need to be able to get away, fast. The more exits there are out of a town, the better. There were only two main roads out of Lahaina, and the combination of downed power lines and fire further limited people’s ability to leave quickly, contributing to the high death toll.
“Because everyone’s pouring downhill, even if you could get a few blocks, you’re eventually going to hit the brake lights. And so that’s why there were so many fatalities in cars,” says Cova. “People couldn’t go anywhere and the fire came down.”
Build fire refuges
If evacuating a wildfire-threatened community becomes impossible, pre-made shelters are a good backup. These can be community centers, schools, parks or golf courses — ideally places made of fire-resistant material and with a fire break or vegetation break to keep a blaze out. “Manicured athletic fields — they’re accidentally not bad places to stay in a fire, especially if you’re in a car,” Cova says. “In some cases, what you do is you drive a car onto a football field, and they turn the water and sprinklers on.”
Having multiple shelter options is best, says Alexander Maranghides, a fire protection engineer at the National Institute of Standards and Technology, so people can get to them from wherever they are in a community. During the Camp Fire that impacted the California communities of Concow, Paradise and Magalia, he explains, more than 1,000 people waited out the fire in shelters that had been identified ahead of time as well as those established as the disaster unfolded.
Read More: Four Home Designs for Climate Resiliency
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