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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.

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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