Wildfires and the Wildlife Urban Interface
Wildfires are not just a problem for Los Angeles. They present a growing challenge across North America, and they are being driven by hotter, drier conditions. The National Interagency Coordination Center reports that the United States has experienced an average of over 62,400 wildfires each year between 2015 and 2024, affecting an annual average of approximately 7.5 million acres. Canada has faced similar challenges, particularly in 2023, when over 6,000 wildfires burned more than 37 million acres in that year alone.
When combined with the continued incursion of development into previously wild spaces, the results can be both tragic and costly, since the fires cause significant ecological damage and affect communities in the Wildlife Urban Interface (WUI). WUI areas are defined as places where the built environment and wildfire-prone ecosystems intersect, and it is currently estimated that one in three houses in the U.S. stand in WUI zones, placing them on the front lines in the event of wildfire. A September 2025 report from Realtor.com claims, “Approximately 5.6% of homes (worth $3.2 trillion) in the United States face severe or extreme risk of fire damage, and nearly 39% of these high-risk homes (worth $1.8 trillion) are in California.”
As the fires in Los Angeles earlier this year demonstrated, homes can be at a high risk even if they are in suburban or even urban areas. Without fire-resilient strategies in place, these homes become fuel for wildfires and allow them to spread deeper into communities, even threatening dense urban cores.
Comprehensive Mitigation Strategies
Wildfire resilience relies on a mix of planning, construction practices, and community participation. Central to resiliency strategies is the creation of defensible space around the built environment. By reducing vegetation and combustible materials around homes, communities can slow the advance of flames and provide firefighters safer zones from which to work. Landscaping choices, routine maintenance, and setbacks between structures and flammable vegetation all play a role.
Outdoor features such as decks, patios, and fences also require attention. Choosing ignition-resistant composites or treated wood, enclosing the underside of decks, and breaking up combustible fence lines all help to prevent fire spread.
Construction materials are equally critical. Roofing is often the first point of failure, so Class A rated roof coverings, combined with ignition-resistant underlayment, can significantly reduce vulnerability. Similarly, soffits, vents, and eaves can act as gateways for embers, particularly in areas that experience high winds. Using non-combustible materials and ember-resistant venting minimizes these risks. Walls and siding made from stucco, fiber cement, or brick resist ignition better than untreated wood, while tempered glass, triple-glazing, and fire-rated doors add further protection.
The importance of fire-resistant design and construction in WUI zones led the U.S., the International Code Council to create the International Wildland–Urban Interface Code (IWUIC) in 2003. The IWUIC offers a standardized, enforceable framework that local and state governments can adopt to regulate building practices, vegetation management, and community design. Nearly 200 jurisdictions across 24 states have adopted some form of this code, with full state-level adoption in Colorado, Washington, and Nevada. In addition, an executive order requires federal buildings larger than 5,000 square feet in WUI areas to comply. Some states, like California and Oregon, have gone further, introducing stricter rules tailored to their elevated fire risks.
Community Impact
Wildfire-resistant codes and practices have demonstrated real-world benefits. For example, nearly 60% of structures built to the 2008 building code survived the 2018 Camp Fire in California. Of the older structures, only 21% survived. This striking contrast underscores how modern requirements for fire-resistant roofs, walls, and defensible space directly save homes and lives.
Economic analyses further support adoption. Research from the Institute for Catastrophic Loss Reduction shows that new buildings in high-risk areas built to wildfire-resistant standards achieve a benefit-cost ratio of 34:1, meaning each dollar spent saves an estimated $34 in avoided losses. Retrofitting existing structures also shows strong returns, with a ratio of 14:1.
Stone Wool Insulation and Fire Resistance
More rigorous codes translate into safer communities, preserved property, and reduced recovery costs. Underlying these codes are material choices which can further strengthen resilience. Stone wool insulation like ROCKWOOL is particularly effective in fire-prone regions. Derived from volcanic rock, stone wool is noncombustible and withstands temperatures exceeding 1,000°C. ROCKWOOL products satisfy the lowest in class values for smoke development and spread (per ASTM E84and CAN/ULC S114), making them a critical safeguard for walls, roofs, and other vulnerable assemblies. By combining stone wool insulation with ignition-resistant siding, roofing, and ember-resistant detailing, project teams can achieve a robust envelope that is fire-resistant and capable of achieving Passive House levels of performance.
ROCKWOOL products like Comfortbatt®, Comfortboard®, and Toprock® DD meet rigorous fire-safety standards in both the U.S. and Canada, with flame-spread and smoke-developed indices of zero. Approval extends to California, where the California State Fire Marshall has approved the use of ROCKWOOL products in WUI zones after Lake Tahoe-based Sagan Design Group and ROCKWOOL teamed up to demonstrate mineral wool’s fire and ignition resistance (learn their story here). The list of ROCKWOOL products certified by the California State Fire Marshall’s Building Materials Listing (BLM) program now includes:
