Napa County, CA Fire Regulations: Wildfire Zones (2026)
Key Facts
- WUI Building Code
- Cal. Building Code Chapter 7A
- Local Adoption
- Napa County Code Ch. 15.32
- Atlas Fire (2017)
- 51,624 acres, 783 structures
- Glass Fire (2020)
- 67,484 acres, 1,555 structures
- Fire Weather
- Diablo winds drive extreme risk
Summary
Napa County contains extensive Very High Fire Hazard Severity Zones across the Vaca Mountains, Howell Mountain, Mount Veeder, and the Mayacamas Range, mapped by CAL FIRE under the 2025 Fire Hazard Severity Zone update. New construction in mapped zones must comply with California Building Code Chapter 7A wildfire-exposure standards, adopted locally through Napa County Code Chapter 15.32.
California's seasonally dry Mediterranean climate lends itself to wildfires, and in an effort to better prepare, CAL FIRE is required to classify the severity of fire hazard in areas of California. The History of Fire Hazard Severity Zone Maps Fire Hazard Severity Zone maps arose from major destructive fires, prompting the recognition of these areas and strategies to reduce wildfire risks. Legislative response led to mandated mapping across California under the California Public Resources Code 4201-4204, encompassing all State Responsibility Areas (SRA). What are Fire Hazard Severity Zones? The State Fire Marshal is mandated to classify lands within State Responsibility Areas into Fire Hazard Severity Zones (FHSZ).
Full Breakdown
CAL FIRE's 2025 Fire Hazard Severity Zone maps designate most of mountainous Napa County as VHFHSZ in either the State Responsibility Area or Local Responsibility Area. Properties in these zones must comply with California Building Code Chapter 7A (Materials and Construction Methods for Exterior Wildfire Exposure) when constructing or substantially remodeling, including ignition-resistant siding, dual-pane tempered windows, ember-resistant vents, Class A roof assemblies, and noncombustible decks within 10 feet of structures. 32 adopts the California Fire Code with local amendments and implements the WUI Fire Conformance Checklist through the Napa County Fire Marshal's Office.
The October 2017 Atlas Fire burned 51,624 acres and destroyed 783 structures, the Tubbs Fire crossed from Napa into Sonoma, the 2020 Glass Fire burned 67,484 acres and 1,555 structures including Meadowood and numerous wineries, and the 2020 LNU Lightning Complex burned over 363,000 acres. Diablo winds drive extreme fire weather. 36 and PRC 4291 is required in addition to Chapter 7A.
Violations & Fines
Construction or substantial remodel in a CAL FIRE-mapped VHFHSZ without Chapter 7A-compliant materials violates Napa County Code Chapter 15.32 and California Building Code Chapter 7A, triggering stop-work orders, denial of final inspection, and required removal or replacement of non-conforming assemblies. Defensible space failures under Chapter 8.36 lead to county abatement and tax liens, and PRC 4291 fines of up to $500 per day apply in the SRA.
Frequently Asked Questions
How do I find out if my Napa County property is in a Very High Fire Hazard Severity Zone?
What building requirements apply in a Napa County VHFHSZ?
What happened in the 2020 Glass Fire?
Sources & Official References
Other rules in Napa County
California rules heatmap·Compare Napa County to another location·View the California fire regulations overview
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