Fire · Glossary

Wildland-Urban Interface

Updated 2026-07-18

Wildland-Urban Interface is the area where buildings meet or intermingle with wildland vegetation and wildfire can threaten communities. In California, WUI conditions can trigger ignition-resistant construction and heightened review even when a parcel's exact regulatory classification requires local confirmation.

What it means

WUI includes interface and intermix development exposed to flames, radiant heat, and embers from vegetation fires.

Why it matters for land decisions

WUI exposure affects structure design, evacuation, road standards, water supply, vegetation management, and insurance.

  • Check adopted WUI and FHSZ maps.
  • Evaluate emergency access early.

People also ask

Is every rural parcel in the WUI?

No. Mapping and code definitions vary; verify the applicable state and local designation.

What building features address WUI exposure?

California standards can address roofs, vents, siding, glazing, decks, and other ember- or flame-exposed components.

Official sources

Related terms

Fire Hazard Severity Zone Defensible Space Public Right-of-Way

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