Wildfires are inevitable throughout most of California. But the losses to life and property from these fires can be minimized by using building construction methods that reduce the likelihood of building ignition in conjunction with, maintaining defensible space to reduce the severity of potential wildfire exposure. For more information, click on the subject areas listed below.

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When wildfires result in disastrous property losses they are referred to as “Wildland-Urban Interface” (WUI) fires, or simply “interface fires.” These fires may start as small vegetation fires in cities like Oakland and Los Angeles miles from “wildlands”, or be a part of large brush and forest fires. They usually happen on days of especially extreme weather conditions when wildfires threaten so many houses at once that California’s vast system of cooperative fire protection is overwhelmed. The three primary components required to reduce interface fire losses are: 1) building construction methods that reduce the hazard of building ignition, 2) “Defensible Space” to reduce hazardous vegetation around houses and reduce the potential severity of wildfire exposure, and 3) identification of areas where there is a significant risk of interface fires and a history of such disastrous losses.

For general information about reducing your risk of loss and maintaining your property look for the community specific “Ready-Set-Go” program in your area or click here for CALFIRE’s “Ready-Set-Go” material. For detailed information on the three components of interface fire loss reduction, see the “Wildfire Protection Building Construction,” “Defensible Space,” and “Fire Hazard Severity Zone” web pages below.

For more background information on the Wildland-Urban Interface fire problem click here.

Wildfire Protection Building Construction

Public fire-safety education, law enforcement and fire protection prevent 98% of California wildfires from becoming large or damaging. However, wildfires are inevitable in California’s fire-prone environments. It will not be possible to prevent all wildfires. Some wildland fires will escape the best fire suppression efforts and a few will become large conflagrations with disastrous. But experience shows us that the large losses of buildings can be substantially reduced. Large wildfires are inevitable, but the disastrous house loss associated with interface (WUI) fires can be prevented by reducing hazardous conditions at and immediately around buildings before the fires start. This will keep California’s fire protection systems from becoming overwhelmed and help reduce fire suppression costs as well as interface fire losses.

The most important step in mitigating interface fire hazards is building construction that reduces the risk of building ignition. This is especially true for existing buildings with old shake or shingle wood roof covering that is not fire-retardant-treated by the manufacturer and doesn’t have at least the “Class C” fire classification required for all new construction since the 1990’s.

For more detailed information on the following subject areas:

• State Building Construction Regulations and SFM Test Standards
• Wildfire ("CBC Chapter 7A") Code Compliance Policies and Accepted Products
• OSFM BML "Wildland-Urban Interface Products Handbook"
• OSFM Code Interpretations
• OSFM Information Bulletins

Click here to go to the OSFM “Wildfire Protection Building Construction” web page.

Defensible Space and Hazardous Vegetation Management

The second most important step in mitigating interface fire hazards is maintaining the “Defensible Space” that has been required by law in areas protected by CALFIRE since the 1960’s. The key to Defensible Space is managing the hazardous vegetation around houses and reduce the potential severity of wildfire exposure. For more information, click on the links below.

• 100 Feet for Defensible Space is the Law
• Be "Ready" for wildfire with adequate Defensible Space
• General Guidelines for Creating Denfensible Space

Areas at Risk From Interface Fires & California's Fire Hazard Severity Zones

State law requires CALFIRE to designate areas, or make recommendations for local agency designation of areas, that are at risk from significant fire hazards based on fuels, terrain, weather, and other relevant factors. These areas at risk of interface fire losses are referred to by law as “Fire Hazard Severity Zones” (FHSZ). The law requires different zones to be identified (Moderate to Very-High). But with limited exception, the same wildfire protection building construction and defensible space regulations apply to all “State Responsibility Areas” and any “Fire Hazard Severity Zone” designation. Click on the following links for more information:

• 2010 State Responsibility Area (SRA) Maps and Classification System
• 2008 Local Responsibility Area (LRA) Very-High FHSZ Map Recommendations and Hazard Model Background
• Fire Hazard Severity Zone Model – A Non Technical Primer 2007 Fact Sheet
• Fire Hazard Severity Zones 2007 Fact Sheet
• New WUI Building Codes Fact Sheet
• FHSZ and Calfironia's New WUI Building Codes 2007 FAQ's
• Building Standards Revision and Update - 2007 Project Background
• Stakeholder Briefing California's 2007 FHSZ and Building Standards Revision Update
• OSFM 2007 FHSZ Map Implementation and WUI Building Standards Rollout Project Scope v1 2

Additional Information

For more information on reducing wildfire losses, fire risk planning and analysis, and other wildfire protection state requirements click on the following links:

• Wildland Fire Prevention
• Wildland Fire Analysis and Planning
• Real Estate Disclosure and Land Development
• 2009 Code Change Project Archive - Wildfire Protection Building Construction "CBC 2010 CH7A" Task Force