IBHS study shows parcel, community mitigation needed to limit devastation from conflagration events like Lahaina Fire

Research organization analyzes relative importance of structure separation, connective fuels, building materials 

News Release from Insurance Institute for Business & Home Safety

Richburg, SC, September 4, 2024 – A new report released today by the Insurance Institute for Business & Home Safety (IBHS) reinforces the need for action at both the parcel and community levels to reduce the likelihood of catastrophic conflagration during wildfires. The 2023 Lahaina Conflagration study concludes a system of mitigation strategies, including developing communities with greater structure separation, removing combustible connective fuels and hardening properties against ember and flame exposures, is needed to mitigate the devastation seen in the Lahaina Fire.     

“A single building and an entire community have one thing in common,“ said IBHS CEO Roy Wright. “They are only as strong as their weakest link. No vulnerability can be overlooked.”  

Working with Hawaii state officials, IBHS conducted an extensive post-disaster investigation to better understand the conflagration cause and unique pathway of the 2023 fire that destroyed three-quarters of Lahaina’s structures and caused $5.5 billion in estimated reconstruction costs, according to the University of Hawaii.  

Based on the investigation findings, IBHS researchers identified three main factors that contributed to the Lahaina wildfire’s rapid conflagration:   

• Structure density: Flames from burning homes often extended over twenty feet, rapidly igniting homes at closer distances downwind.  
• Connective fuels: Connective fuels acted as pathways that brought fire to and enabled its spread through the built environment, including plants, secondary buildings and vehicles.  
• Building materials: Fire-resistant building materials offer higher resistance against thermal exposures compared to traditional materials, but their effectiveness was diminished in Lahaina due to intense heat from nearby burning buildings with limited structure separation. 

“This study shows structure separation and connective fuels allow building materials to matter,” said Wright. “Otherwise, they are overwhelmed.” 

The report also highlights the importance of homes located at the periphery of communities surrounded by grasslands. 

“These homes serve as the first line of defense against spreading grassfires. If they are constructed with fire-resistant materials and given adequate defensible space, the hazard to other homes within the community is reduced,” said IBHS Lead Research Engineer Dr. Faraz Hedayati, the lead author of the report. “This is particularly important for homes surrounded by grassland, as grass fires are not likely to cause long-range spotting within the community.” 

IBHS wildfire researchers have identified actions that can be taken at the community level to reduce overall wildfire risk: 

• Maintaining fuel breaks: Fuel breaks are vegetation gaps designed to reduce or stop wildfire spread. Communities in wildfire-prone areas should develop and upkeep fuel breaks around developed areas to prevent grass fires from becoming conflagration events.  
• Expanding separation distances: Spacing buildings further apart can reduce the likelihood of building-to-building fire spread. Additionally, noncombustible privacy fencing materials can reduce the chances of wildfire spreading to other buildings when a home does ignite.   
• Promoting mitigation strategies: Communities should construct new buildings with wildfire resilience in mind. By constructing homes with fire-resistant materials using resilient construction methods, like the Wildfire Prepared Home Plus™ standard, structures have a higher chance of survival and can reduce the hazard for other homes within the community.    

Homeowners living in areas of elevated wildfire risk are not powerless and can take action to reduce the risk to their properties by educating themselves on the common contributing factors to fire spread and following science-based mitigation actions outlined in IBHS’s Wildfire Ready guide including: 

• Creating defensible space: Homeowners can most significantly reduce their wildfire risk by creating a 5-foot noncombustible buffer around their home, also known as Zone 0. This buffer reduces the chance of structural ignition from embers.  
• Reducing connective fuels: Reducing the number of connective fuels around a property, such as plants, combustible objects or vehicles, can help slow the spread of fire.  
• Using fire-resistant building materials: Homeowners interested in reducing wildfire risk can construct or retrofit their homes using fire-resistant building materials, such as metal fencing, brick or stucco siding and enclosed eaves. 

Hedayati noted actions across the community and individual parcels also improve the effectiveness of first responders’ suppression efforts, as fewer building ignitions allow for concentrated efforts. 

About the Insurance Institute for Business & Home Safety (IBHS)

The IBHS mission is to conduct objective, scientific research to identify and promote effective actions that strengthen homes, businesses and communities against natural disasters and other causes of loss. Learn more about IBHS at ibhs.org.   

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PDF: 2023 Lahaina Conflagration study

LINK: THE 2023 LAHAINA CONFLAGRATION WEBINAR  – Insurance Institute for Business & Home Safety (ibhs.org)

AP: Lahaina Wildfire Report Advises Communities On Avoiding Similar Disasters