A new report on the Deadliest US wildfire in a century describes steps communities can take to reduce the likelihood of grassland wildfires developing into urban fires.
The report, from a nonprofit scientific research organization supported by insurance companies, examined the ways in which a wildfire on August 8, 2023, historic Maui town of Lahaina, killing 102 people.
The Insurance Institute for Business & Home Safety has the summary of Wednesday’s report. The IBHS researchers found that a multifaceted approach to fire protection — including creating fuel breaks around a city, using fire-resistant building materials and reducing flammable compounds between houses, such as wooden fences, can give firefighters valuable time to fight fires and even help prevent them from happening. spread of flames through a community.
“It’s a multi-layered problem. Everyone needs to work together,” said IBHS lead researcher and report author Faraz Hedayati, including government leaders, community groups and individual homeowners.
“We can start by fortifying homes on the edge of the community so that a fast-moving grass fire never has the chance to become embers” that can ignite other fires, as happened in Lahainahe said.
Grass fires grow quickly, but typically send embers only a few feet into the air and a short distance along the ground, Hedayati said. Burning buildings, however, create large, buoyant embers that can travel long distances, he said.
It was the building of cinders, combined with strong wind that ravaged Maui on the day of the fire, sending flames in Lahaina in all directions, the report said. The embers sparked new spot fires in the town. Winds extended the flames — sometimes reaching more than 20 feet (6.10 meters) — and bent them toward the ground, where they could ignite vehicles, landscaping and other flammable materials.
The flames often exceeded the distance between structures, causing homes and buildings in the wind direction to catch fire directly, the report said. The fires grew so hot that temperatures likely exceeded the tolerance of even fire-resistant building materials.
More than 2,100 buildings were destroyed in Lahaina, with an estimated rebuilding cost of about $5.5 billion, according to the report. Still, some homes remained largely or partially unburned amid the devastation. The researchers used those homes as case studies, examining factors that helped protect the buildings.
One home that survived the fire was surrounded by about 35 feet of short, well-maintained grass and a paved driveway, virtually eliminating a flammable path for the flames.
A nearby home was partially protected by a fence. Some of the fence was flammable and was damaged in the fire, but most of it was stone, including the part of the fence attached to the home. The stone fence helped break the path of the fire, the report found, and prevented the home from catching fire.
Other homes surrounded by defensible spaces and fireproof fences were not spared, however. In some cases, flying embers from nearby burning homes landed on roofs or siding. In other cases, the fire was so hot that radiant heat from the flames ignited nearby building materials.
“Structural separation is the driver of many aspects of risk,” Hedayati said.
The researchers found that hardening homes on the edge of a community can help prevent wildfires from becoming urban fires. Hardening homes within a community can help slow or limit the spread of a fire that has already crossed the wildland-urban boundary.
The key takeaways? It’s all about connections and pathways, according to the report: Is the natural area surrounding a community directly connected to homes because there isn’t a large enough break in the vegetation? Are there flammable pathways like wooden fences, sheds, or vehicles that could easily allow flames to spread from building to building? If flames do reach a home, is it built with fire-resistant materials or easily ignited fuels?
For homeowners, it can be expensive to make these changes individually. But in some cases, neighbors can work together, Hedayati said, perhaps sharing the cost of installing a stone fence along a shared property line.
“The survival of one or two houses can lead to breaking the chain of fire in a community. That is something that is important to reduce exposure,” Hedayati said.
