Frequently Asked Questions

Fire Hazard Severity Zoning and
New Building Codes for
California's Wildland Urban Interface

Questions about designation of Very High Fire Hazard Severity Zones in local responsibility areas

General Questions

Questions about Fire Hazard Severity Zones

Questions about Fire Hazard Severity Zones and Building Standards in state responsibility areas

Questions about the Fire Hazard Severity Zone model used by CAL FIRE

Questions about Wildland-Urban Interface Building Standards

Other questions should be directed to your local building department or fire officials.

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General Questions

What can be done to reduce buildings loss from wildfire?
Answer: Years of experience by fire agencies and others have led to a statutory strategy for reducing the chance of building loss or damage. It is a two-pronged approach: 1) defensible space – reduce flammable material around homes to keep direct flames and heat away from the side of the building. (The law already requires property owners to create 100 feet of defensible space around buildings); 2) exterior wildfire exposure protection - construct buildings so that they have less chance of catching fire from burning embers. We have learned that we must make changes to the surrounding property and to the buildings themselves.

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What do the new building codes do?
Answer: Recently adopted building codes and standards reduce the risk of burning embers igniting buildings. Codes already in effect place standards on roofing construction and attic venting. The new building codes require siding, exterior doors, decking, windows, eaves wall vents, and enclosed overhanging decks to meet new test standards.

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Do the building codes apply equally in the different Fire Hazard Severity Zones?
Answer: Yes. The new ignition resistant codes apply to all fire hazard zones in the state responsibility area and in very high Fire Hazard Severity Zones in local responsibility areas.

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Why are fire hazard severity maps being updated?
Answer:  The hazard maps are being updated to more accurately reflect the zones in California that are susceptible to wildfire.  The hazard mapping process incorporates new science and technology in determining hazard ratings.

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How was the fire hazard severity determined?
Answer: Using the latest fire science, CAL FIRE has developed and field tested a model that serves as the basis of zone assignments. The model evaluates properties using characteristics that affect the probability of the area burning and potential fire behavior in the area. Many factors are considered such as fire history, existing and potential fuel, flame length, blowing embers, terrain, weather and the likelihood of buildings igniting.

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Can the new building codes protect my home from fire?
Answer: Fire safe building practices can’t make your home fire proof but they can improve the chances that it will still be standing after the wildfire is out.

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How will the new building codes affect me as a property owner?
Answer: It depends on your specific situation.  Always check with your local building department for specific information. 

If your property is in state responsibility area and:

You applied for a building permit for your home before January 1, 2008 – You need only concern yourself with the fire safety practices that are already on the books. That means you must clear a defensible space around your property, keep your roof clear of flammable material like twigs and leaves, trim tree branches away from your chimney and keep a spark arrester on your chimney. Visit the CALFIRE website at www.fire.ca.gov for information on living safely in California’s fire prone areas.  Use appropriate roofing assembly for your hazard zone

  • You applied for a building permit on or after January 1, 2008 – In addition to complying with the fire safety requirements mentioned above you must:
    • Use approved building products and construction methods. That information is available from the Office of the State Fire Marshal’s Building Materials Listing Program .
    • Use exterior wildfire exposure protection materials and construction methods for exterior siding, windows, eaves vents, exterior doors, decks
    • Enclose all under-floor areas and the underside of decks to within six inches of the ground
  • You are remodeling a home on your property after January 1, 2008

    The new codes apply to the design and construction of new buildings located in the wildland-urban interface fire area.  Local ordinances may require improved exterior wildfire exposure protection materials and construction methods for remodel projects.  Check with your local building department to determine which ignition resistant building codes apply to your project.

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Is there an easy way to determine the Fire Hazard Severity Zone of my property?
Answer: If you know your address or the address of a nearby property, you can find the designation for state responsibility area lands on the web at: This Location

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Questions about fire hazard severity zones

What is a “Fire Hazard Severity Zone,” or FHSZ?
Answer: California law requires CAL FIRE to identify areas based on the severity of fire hazard that is expected to prevail there.  These areas, or “zones,” are based on factors such as fuel (material that can burn), slope and fire weather.  There are three zones, based on increasing fire hazard…medium, high and very high.

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How is a FHSZ determined?
Answer: Using the latest fire science, CAL FIRE has developed and field tested a model that serves as the basis of zone assignments. The model evaluates property using characteristics that affect the probability of the area burning and potential fire behavior in the area.  Many factors are considered such as fire history, existing and potential fuel, flame length, blowing embers, terrain, weather and the likelihood of buildings igniting.

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What does FHSZ measure?
Answer: Fire Hazard Severity Zone maps evaluate “hazard,” not “risk”.  They are like flood zone maps.  “Hazard” is based on the physical conditions that create a likelihood that an area will burn over a 30 to 50-year period without considering modifications such as fuel reduction efforts. “Risk” is the potential damage a fire can do to the area under existing conditions, including any modifications such as defensible space, irrigation and sprinklers, and ignition resistant building construction. 

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How have the Fire Hazard Severity Zone Maps changed?
Answer: Statewide, the acreage designated as very high Fire Hazard Severity Zones is reduced by 25 percent, the acreage designated as high Fire Hazard Severity Zones is increased by 57 percent, and the acreage designated as moderate Fire Hazard Severity Zones is increased by 33 percent. For detailed information on acreage changes by county, visit Publications. These changes are largely due to the ability to be more precise. In the previous map version, typically a minimum 10,000-acre zone size was used resulting in large areas of land being designated based on the highest hazard level found in that entire area. Refined modeling techniques and new, more precise data describing the potential fire environment has enabled the use of 200-acre parcel sizes in many cases which makes mapping more spatially refined. In addition, improved mapping science and a thorough model allowed for more consistency in how zones are rated.

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Where do Fire Hazard Severity Zones apply?
Answer: Fire Hazard Severity Zones are found in areas where the State has financial responsibility for fire protection, called State Responsibility Areas.  More than 31 million acres are in this area. Very high Fire Hazard Severity Zones are found in local jurisdictions as well.

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What are the uses of Fire Hazard Severity Zones?
Answer: The zones serve several purposes.  They are used to designate areas where exterior wildfire exposure protection building codes apply to new buildings.  It can be a factor in real estate disclosure.  Local government considers fire hazard severity in the safety element of the general plan.

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What difference do the Fire Hazard Severity Zones make?

Answer: In areas designated as Very High Fire Hazard Severity Zones, the roofing standards change. Please see the details on roofing requirements (165K PDF).
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Can I find my street address on the map?
Answer: Yes.  The University of California Berkeley Center for Fire Research and Outreach has developed an interactive mapping tool for the internet.  Fire hazard is shown for individual properties identified by street address. This mapping tool can be accessed through the Wildland Hazard & Building Codes section.

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What if I disagree with the Fire Hazard Severity Zone designation of my property?
Answer: The CAL FIRE Director will conduct public hearings in every county with state responsibility areas in June and July 2007.  You may comment about Fire Hazard Severity Zone designations at these hearings or you may send in a written comment via mail or e-mail. The public notice of the regulation includes the address for submitting written comments.  The Director will respond to all comments before making final adoption of the maps in state responsibility areas.

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How often will the Fire Hazard Severity Zone Maps be updated?
Answer:
Approximately every five years.

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Questions about Fire Hazard Severity Zones and Building Standards in state responsibility areas

What is “State Responsibility Area," or SRA?
Answer: State responsibility area is a legal term defining the area where the State has financial responsibility for wildland fire protection.  Incorporated cities and federal ownership are not included.  The prevention and suppression of fires in all areas that are not state responsibility areas are primarily the responsibility of local or federal agencies. There are more than 31 million acres in state responsibility area with an estimated 1.7 million people and 750,000 existing homes.

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How is state responsibility area determined?
Answer: The Board of Forestry and Fire Protection (Board) classifies land as state responsibility area. The legal definition of state responsibility area is found in the Public Resources Code Section 4125. The Board has developed detailed procedures to classify lands as state responsibility area. Lands are removed from state responsibility area when they become incorporated by a city, change in ownership to the federal government, become more densely populated, or are converted to intensive agriculture that minimizes the risk of wildfire.  While some lands are removed from state responsibility area automatically, the Board typically reviews changes every five years.

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Can I request that my land be taken out of state responsibility area?
Answer:  Yes. While not common, property owners can petition the Board to remove their land from state responsibility area.

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What Fire Hazard Severity Zones are in state responsibility area?
Answer: All of state responsibility area is in a Fire Hazard Severity Zone.  Lands are either ranked as moderate, high or very high Fire Hazard Severity Zones. 

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What is the impact of new building codes in state responsibility area?
Answer: Recently adopted building codes reduce the risk of burning embers pushed by wind-blown wildfires from igniting buildings.  Roofing standards vary by the fire hazard zone rating of the site.  The new codes for siding, decking, windows, and vents apply throughout all state responsibility area regardless of the fire hazard severity ranking.

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Questions about the fire hazard severity zone model used by CAL FIRE

What are the key elements of the Fire Hazard Severity Zone model? 
Answer: The fire hazard severity model for wildland fire has two key elements: probability of burning and probable fire behavior. Hence, the factors considered in determining fire hazard are how often an area will burn and, when it does burn, what characteristics might lead to buildings being ignited.

In the model, Fire Hazard Severity Zones are areas that have similar burn probabilities and fire behavior characteristics that result in damage to buildings.

In wildland areas, expected fire behavior is based on typical fire intensity on a normally severe fire weather day. The calculation also incorporates the potential of vegetation to be ignited by an ember and expectations based on fire history over the last 50 years.

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What is the difference between moderate, high, and very high Fire Hazard Severity Zones as ranked in the model?
Answer: Classification of a zone as moderate, high or very high fire hazard is based on a combination of how a fire will behave and the probability of flames and embers threatening buildings. Each area of the map gets a score for flame length, embers, and the likelihood of the area burning. Scores are then averaged over the zone areas.  Final zone class (moderate, high and very high) is based on the averaged scores for the zone.

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Why does the model place an emphasis on the spread of burning embers?
Answer: Embers spread wildfire because they can travel long distances in the wind and ignite vegetation, roofs, attics (by getting into vents), and decks.

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Why don't the maps reflect the fuel reduction and defensible space work done in an area?
Answer: Fire hazard and fire risk are not the same. Actions such as creating defensible space around buildings or thinning a forest reduce the fire risk to that area but they do not significantly change the fire hazard. Hazard + Mitigations = Risk.

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How do model elements relate to the law that requires Fire Hazard Severity Zones to be designated?
Answer: The Public Resources Code Section 4202 calls for zones to embrace relatively homogenous lands and shall be based on fuel loading, slope, fire weather, and other relevant factors present. The zone model considers these elements by zoning homogenous vegetation and slopes and considers fire behavior within these zones.  Fire behavior is based on fuel type, slope, and severe fire weather.

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Has the model been tested and verified to be accurate locally by CAL FIRE or other fire agencies?
Answer: The model uses on nationally accepted fire behavior calculation systems.  Model results were reviewed extensively in four counties:  Butte, Calaveras, Sonoma, and San Diego.  These four counties were selected to represent the different fuel conditions found in California.  Further, results were reviewed and field validated in the 56 counties with state responsibility areas.

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Questions about designation of very high fire hazard severity zones in local responsibility areas

NOTE:  The Fire Hazard Severity Zone maps for Local Responsibility Area will be rolled out in 2008. An expanded question/answer sheet will be provided in this space at that time.  This Q and A contains a limited amount of detail and is provided as an introduction to next year’s program.

What is “Local Responsibility Area”, or LRA?
Answer:  Wildland fire protection in California is the responsibility of either the State, local government, or the federal government.  Local responsibility areas include incorporated cities, cultivated agriculture lands, and portions of the desert. Local responsibility area fire protection is typically provided by city fire departments, fire protection districts, counties, and by CAL FIRE under contract to local government.

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What is the “Bates” bill?
Answer: The “Bates” bill, Government Code Section 51175, was prompted by the devastating Oakland Hills Fire of 1991.  This mid-1990s legislation calls for the CAL FIRE Director to evaluate fire hazard severity in local responsibility area and to make a recommendation to the local jurisdiction where very high Fire Hazard Severity Zones exist.  The Government Code then provides direction for the local jurisdiction to take appropriate action.

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How are Fire Hazard Severity Zones determined in local responsibility areas?
Answer: CAL FIRE uses an extension of the state responsibility area Fire Hazard Severity Zone model as the basis for evaluating fire hazard in local responsibility area.  The local responsibility area hazard rating reflects flame and ember intrusion from adjacent wildlands and from flammable vegetation in the urban area.  Scientists at the U. C. Berkeley Center for Fire Research and Outreach provided an urban fuels model that was incorporated in the hazard rating.

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When will CAL FIRE recommend very high Fire Hazard Severity Zones to local agencies?
Answer:  CALFIRE will prepare draft very high Fire Hazard Severity Zone recommendations for local responsibility areas during the summer of 2007.  These recommendations are scheduled to reflect hazard ratings in adjacent state responsibility area zones.  CAL FIRE anticipates reviewing and validating these draft local responsibility area recommendations with local agencies during the fall of 2007. 

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What are the requirements for landowners in Very High Fire Hazard Severity Zones in local responsibility areas?
Answer: The exterior wildfire exposure protection codes apply to the design and construction of new buildings located in very high Fire Hazard Severity Zones in local responsibility areas.  Local ordinances may require ignition resistant construction for remodel projects.  Check with your local building department to determine which ignition resistant building codes apply to your project.  In addition, Government Code Section 51182 calls for flammable vegetation clearance and other wildland fire safety practices for buildings.  Owners are also required to make a natural hazard disclosure as part of a real estate transfer. For information regarding clearance around buildings see the Homeowners Checklist at www.fire.ca.gov.

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Does the designation of Very High Fire Hazard Severity Zone in the local responsibility area trigger the 100 foot clearance requirement?
Answer: Yes, unless exempted by local government under specified conditions, the 100 foot clearance requirements apply.

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When is the effective date for Chapter 7A of the California Building Code (CBC)?  
Answer: The Building Standards Commission re-set the Local Responsibility Area (LRA) adoption date of Chapter 7A from January 1, 2008 to July 1, 2008. Contact your local agency for more detailed information on the timing of the adoption within your specific jurisdiction.

Chapter 7A became effective in State Responsibility Area (SRA) on January 1, 2008.

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Will the CBC Chapter 7A effective date change to July 1, 2008, have any affect on the LRA FHSZ mapping process?
Answer: No

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Can the CAL FIRE Director’s recommendation be modified by the local agency?
Answer: A local agency may increase the area designated as Very High Fire Hazard Severity Zone (VH FHSZ) following a finding supported by substantial evidence in the record that the requirements of Section 51182 are necessary for effective fire protection within the area. No provision is made in the Government Code for a local agency to reduce the area recommended for designation as a VH FHSZ.

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How will updates to the map occur after the VH FHSZ is adopted by a local jurisdiction?
Answer: This is a subject of a pending information bulletin being developed by the State Fire Marshal.

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After CAL FIRE transmits the officially recommended LRA VH FHSZ map to the local agency, how much time does the local agency have to make this map available for public review?  
Answer: Government Code Section 51178.5 states, ”… within 30 days after receiving a transmittal from the director that identifies very high fire hazard severity zones, a local agency shall make the information available for public review. The information shall be presented in a format that is understandable and accessible to the general public, including, but not limited to, maps”

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What is the CAL FIRE’s responsibility for mapping fire hazards in local responsibility jurisdictions?
Answer: CAL FIRE is required to identify VH FHSZ and to transmit this information to local agencies. CAL FIRE is also required to periodically review the recommendations.

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What does the Government Code say about fire hazards in local responsibility areas?
Answer: Government Code Sections 51175 – 51189 cover fire hazards in local responsibility areas.

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What is the local agency’s responsibility regarding the Director’s recommendation for VH FHSZ rating in the local responsibility area?  
Answer: It is the local agency’s responsibility to make the recommendation available for public review and to designate, by ordinance, VH FHSZs in its jurisdiction.

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How are LRA VH FHSZ used by local agencies?
Answer: LRA VH FHSZ maps are used to identify areas where ignition resistant building standards will be required for new construction, to identify properties requiring defensible space maintenance, and by sellers to disclose natural hazards at the time of property sale. It is strongly recommended that local governments use the LRA VH FHSZ’s as they update the safety elements of their general plans.

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What is CAL FIRE doing to ensure that the LRA FHSZ map recommendations are accurate?  
Answer: CAL FIRE has made draft maps available to local agencies through its website http://frap.fire.ca.gov/projects/hazard/draft_info.html. Local agencies have had the opportunity to comment on these draft maps and have requested changes, based on supporting data. CAL FIRE is reviewing the recommended changes and is updating the LRA VH FHSZ were appropriate. Local agencies will have further opportunities for input before the Director issues a formal recommendation. CA FIRE will post a “change map” indicating how local suggestions have been processed. Links to the change maps can be found on the Fire Hazard Severity Zone Mapping web page.

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What if the local entity does not have the geographic information system (GIS) capability to evaluate the draft data for FHSZ?  
Answer: CAL FIRE will assist that local agency by providing GIS technical support. This support can be requested by contacting CAL FIRE’s Northern Region FHSZ Mapping Coordinator at (530) 224-2445 or Southern Region FHSZ Mapping Coordinator at (559) 222-3714.

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Which law defines the roles and responsibilities of local agencies to adopt LRA VH-FHSZ?
Answer: Government Code Sections 51175 – 51182 defines the roles and responsibilities for LRA Very High Fire Hazard Severity Zone adoption.

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What happens if the local jurisdiction does not adopt CAL FIRE’s recommendation?  
Answer: Local jurisdictions should consult their legal counsel regarding responsibilities defined in the Government Code Sections 51175 - 51982.

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When will CAL FIRE transmit the officially recommend LRA VH FHSZ maps to the local agencies?  
Answer: CAL FIRE will transmit the official recommendations to local agencies between April and June, 2008.

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What process is being used to develop the recommended VH FHSZ ratings in local responsibility areas?
Answer: CAL FIRE has submitted draft maps to a number of counties and over 200 cities for review. The maps show suggested LRA VH FHSZ and, for background, also indicate suggested High and Moderate FHSZ. Cities and counties are in the process of reviewing suggested FHSZ ratings and submitting their input to CAL FIRE. CAL FIRE is reviewing the proposed input and posting “change maps” and other information on the web. These change maps indicate how local suggestions have been processed. Links to the change maps can be found on the Fire Hazard Severity Zone Mapping web page.

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What do the “change maps” show?
Answer: The “change maps” show information related just to LRA VH FHSZ rankings. The LRA Very High ranking is the only zone for which the law requires CAL FIRE to provide a recommendation to local government.

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Can the public comment on the “change maps”? 
Answer: CAL FIRE has made provisions for local agencies to comment on the maps over the web. Public questions should be directed to the local fire department or governing body.

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18. Can local agencies obtain maps of High and Moderate FHSZ ranking?  
Answer: Changes in LRA Very High ratings from the original draft map will affect the location of high and moderate rankings. At this time, CAL FIRE is not recalculating the hazard model to reflect those changes in the high and moderate hazard rankings. Local agencies can request this information. However, CAL FIRE will not be able to provide the information until after recommendations for LRA VH FHSZ are developed.

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19. Will the Very High Fire Hazard Severity Zone in Local Responsibility Area affect the cost and availability of fire insurance?
Answer: Insurance rates are determined by a variety of factors, including Fire Risk. Fire Risk is different from Fire Hazard. Fire Hazard is the focus of the FHSZ maps, not Fire Risk. Fire Hazard is based on factors such as fuel (material that can burn), slope and fire weather. Fire Risk considers the potential for damage based on factors such as the ability of a fire to ignite the structure, the flammability of the construction material, and mitigation measures that reduce the risk. These mitigation measures include defensible space, building design, ignition resistant building materials, and ignition resistant construction techniques.

Ultimately, it is not possible to state that insurers will ignore the limitations of the focus of FHSZ maps.  However, to respond to such issues, the California Department of Insurance and CAL FIRE have established a partnership and joint commitment to protecting Californians from fire losses. A Memorandum of Understanding was signed by the Insurance Commissioner and the Director of CAL FIRE, October, 2007 to mutually promote awareness and collaboration among fire officials, the insurance industry, and the public to prevent and mitigate fire losses.

The MOU can be found at http://www.insurance.ca.gov/0400-news/0100-press-releases/0060-2007/upload/Insurance_CDI_CALFIRE_MOU_091007TC.pdf.

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Questions about Wildland-Urban Interface Building Standards

Do the new construction standards apply to modular homes and mobile homes?
Answer:
For information regarding the application of Wildland-Urban Interface Building Standards to manufactured homes, mobilehomes, multifamily manufactured homes and commercial modular units see the State Fire Marshal Information Bulletin issued August 13, 2008.

Can you use quarter-inch mesh?
Answer:
All attic ventilation, other than eave and cornice vents, may use quarter-inch wire mesh as an alternative to special flame and ember-resistant vents.

Can you have eave vents in Fire Hazard Severity Zones?
Answer:
No, vents shall not be installed in eaves and cornices unless they resist the intrusion of flame and burning embers into the attic area of the structure.

 

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