Maui wildfire report shows communities how to avoid similar disasters

A new report on the deadliest wildfire in the United States in a century details steps communities can take to reduce the likelihood that grassland wildfires will turn into urban blazes.

A report prepared by a non-profit scientific research group supported by insurance companies examined how a wildfire that broke out on August 8, 2023, destroyed the historic town of Lahaina on Maui and caused the deaths of 102 people.

The Insurance Institute for Business and Home Safety released an executive summary of the report on Wednesday. IBHS researchers found that a multifaceted approach to fire protection — including installing fuel breaks around a town, using fire-resistant building materials and reducing flammable connections between homes, such as wooden fences — can buy firefighters valuable time to fight fires and even help stop flames from spreading within a community.

“This is a multi-layered issue. Everyone has to work together,” said IBHS principal investigator and report author Faraz Hedayati, including government leaders, community groups and individual property owners.

“We can start by reinforcing homes on the edge of communities so that a rapidly spreading grass fire doesn’t have the opportunity to turn into embers that could ignite other fires like what happened in Lahaina,” he said.

Grass fires grow quickly but typically send embers only a few feet into the air and a short distance toward the ground, Hedayati said. But burning buildings create large embers with a lot of buoyancy that can travel long distances, he said.

According to the report, embers, combined with high winds that hit Maui on the day of the fire, caused the flames in Lahaina to spread in all directions. The ash started new fires throughout the town. The winds fanned the flames — at times allowing them to extend more than 20 feet — and fan them toward the ground, where they could ignite vehicles, landscaping and other flammable materials.

The size of the flames often exceeded the distance between structures, directly igniting downwind homes and buildings, the report said. The fire grew so large that temperatures likely exceeded the tolerance of even fire-resistant building materials.

More than 2,100 structures in Lahaina were destroyed, the report said, with the cost of rebuilding estimated at about $5.5 billion. Still, amid the destruction, some homes were left mostly or partially intact. Using those homes as case studies, researchers examined the factors that helped preserve the structures.

One house that survived the fire was surrounded by about 30 feet of short, well-kept grass and a paved driveway, eliminating any path for the flames to burn.

A nearby home was partially protected by a fence. Some of the fence was flammable and damaged by the fire, but most of it was made of stone — including the section of the fence that was attached to the house. The report found that the stone fence helped block the fire’s path and prevented the house from catching fire.

However, defensible areas and other homes surrounded by fireproof fences were not spared. In some cases, flying embers from nearby burning homes fell on roofs or siding. In other cases, the fire was so hot that the radiant heat from the flames caused nearby building materials to ignite.

“Structural segregation is a driver of many aspects of risk,” Hedayati said.

Researchers found that retrofitting homes on the edge of a community can help prevent wildfires from turning into urban fires. Retrofitting homes within a community can help slow or limit the spread of a fire that has penetrated the forest-urban interface.

The takeaways? The report says it’s all about connections and pathways: Is the wilderness surrounding a community directly connected to homes because there isn’t a big enough gap in the vegetation? Are there flammable pathways, such as wooden fences, sheds or vehicles that allow flames to easily spread from building to building? If flames do reach a home, is it made of fire-resistant materials or flammable fuels?

It can be expensive for homeowners to make these changes one at a time, but in some cases, neighbors can work together, Hedayati said, perhaps splitting the cost of installing stone fencing along a common property boundary.

“The survival of one or two houses can lead to breaking the fire chain in a community. This is an important thing to reduce exposure,” Hedayati said.