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Community-scale WUI Fire Hazards

Properties tightly spaced within a high-density community allow fire to spread easily.

Fuel agglomeration and the proximity of many fuels can become a significant fire hazard in moderate- and high-density communities. Short Structure Separation Distances (SSD) of 8 ft between residential structures, common in high-density communities, pose significant potential for structure-to-structure fire spread. The addition of parcel-level fuels (including fences, decks, sheds, wood piles, and parked vehicles) further contribute fire spread pathways enabling a single ignition to destroy a community. Controlling the spread of fire among homes within dense communities is difficult and can result in heavy losses to the community.

This illustration, based on an actual WUI community, show real world fuel agglomeration and nominal 8 ft SSD on high-density parcels. The illustrated conditions extend across the street and throughout the community (not pictured). Fuel continuity is present across the community of hundreds of homes. For existing high-density communities where structures cannot be moved, as shown here, multi-parcel fuel reduction and targeted structure hardening must be implemented.
Created July 6, 2023, Updated August 28, 2023