Wildfire Study Finds Structure Spacing and Home Hardening Significantly Reduce Losses

A groundbreaking Nature study analyzing five major California wildfires provides strong quantitative backing for what many insurers and mitigation experts have long advocated: creating defensible space and hardening homes dramatically increases wildfire resilience. By examining post-fire damage data and simulation modeling from the Tubbs, Thomas, Camp, Kincade, and Glass fires, researchers found that homeowners who cleared vegetation within 1.5 meters (Zone 0) and installed fire-resistant building features could reduce potential losses by as much as 48%.

Key to these findings was the use of machine learning tools like XGBoost and SHAP analysis, which confirmed that structure separation, exterior building materials, and construction year are major predictors of survivability. Homes built after California’s 1997 building code updates consistently fared better than older structures.

These insights align with recent findings from Triple-I and Guidewire’s HazardHub platform, which showed that granular property-level data can help insurers identify lower-risk parcels even within wildfire-prone ZIP codes. By layering mitigation measures and structural attributes into underwriting models, insurers could more accurately price risk and expand availability in high-exposure regions.

For adjusters and insurers alike, the implications are clear: promoting and verifying mitigation steps like vegetation clearance, fire-rated materials, and structure spacing isn’t just about safety—it’s critical to managing loss ratios and ensuring sustainable market participation in high-risk wildfire zones.