Wildfire Hazard

Humboldt County is particularly prone to wildfires due to a combination of its unique geography, climate, and vegetation. In response to this wildfire hazard, California has established the Wildland-Urban Interface (WUI) and State Responsibility Area (SRA) Fire Safe regulations. These regulations are designed to reduce the risk of property loss and life safety due to wildfires. Here's a brief summary of these regulations:

California Wildland-Urban Interface (WUI) Building Standards:

In simple terms, these regulations (CBC 7A and CRC 337) are designed to help protect homes and buildings located near wildland areas from wildfires. The "Wildland-Urban Interface" is a term used to describe areas where homes and other human-made structures are close to or within natural areas that are prone to wildfires (see Humboldt GIS and Important GIS Layers).

Here are the main things you should know about California's WUI regulations:

  • Fire-Resistant Materials: When building or renovating homes in these areas, certain materials must be used that are less likely to catch fire. This includes things like the roof, walls, and decks of your home. For example, wood shake roofs are not allowed because they can easily catch fire (see WUI Listed Products Handbook). Below are some examples of WUI requirements.
    • Roof Coverings CRC §R337.5.2 – A Class A fire rated roof underlayment, tested in accordance with ASTM E108, shall be permitted to be used. If the sheathing consists of exterior fire retardant-treated wood, the underlayment shall not be required to comply with a Class A classification. Bird stops shall be used at the eaves when the profile fits, to prevent debris at the eave. Hip and ridge caps shall be mudded in to prevent intrusion of fire or embers.
    • Exterior Wall Coverings CRC §R337.7.3 – The exterior wall covering shall be of noncombustible material (see code section for alternatives). Exterior wall coverings shall extend from the top of the foundation to the roof and terminate at 2 inch (50.8 mm) nominal solid wood blocking between rafters at all roof overhangs, or in the case of enclosed eaves, terminate at the enclosure.
    • Exterior Wall Assemblies CRC §R337.7.4 – Exterior wall assemblies of buildings or structures shall be suitable for exterior fire exposure containing one layer of 5/8-inch (16 mm) Type X gypsum sheathing applied behind the exterior wall covering or cladding on the exterior side of the framing (see code section for alternatives).
    • Open Roof Eaves CRC §R337.7.5 – The exposed roof deck on the underside of unenclosed roof eaves shall consist of noncombustible material (see code section for alternatives).
    • Enclosed Roof Eaves CRC §R337.7.5 – The exposed underside of enclosed roof eaves having either a boxed-in roof eave soffit with a horizontal underside, or sloping rafter tails with an exterior covering applied to the underside of the rafter tails, shall be protected by noncombustible material (see code section for alternatives).
    • Decking Surfaces CRC §R337.9.3 – The walking surface material of decks, porches, balconies and stairs shall be constructed with material that complies with the performance requirements of Section R337.9.4 when tested in accordance with both ASTM E2632 and ASTM E2726 (see code section for alternatives).
  • Protected Openings: The regulations require that openings, such as vents, windows, and doors, be designed to prevent burning embers from getting into the building. For instance, vents must be covered with a metal mesh to keep embers out.
    • Ventilation Openings CRC §R337.6.2 – Ventilation openings shall be fully covered with Wildfire Flame and Ember Resistant vents approved and listed by the California State Fire Marshal, or WUI vents tested to ASTM E2886.
    • Off Ridge and Ridge Vents CRC §R337.6.2 – Vents that are installed on a sloped roof, such as dormer vents shall be covered with a mesh where the dimensions of the mesh therein shall be a minimum of 1/16 inch (1.6 mm) and shall not exceed 1/8 inch (3.2 mm) in diameter. Additionally, the mesh material shall be noncombustible and corrosion resistant.
    • Exterior Windows, Skylights and Exterior Glazed Door Assembly Requirements CRC §R337.8.2.1 – Exterior windows, skylights and exterior glazed door assemblies shall be constructed of multipane glazing with a minimum of one tempered pane meeting the requirements of Section R308 Safety Glazing (see code section for alternatives).
    • Exterior Doors CRC §R337.8.3 – Exterior doors shall have the exterior surface or cladding be of noncombustible material (see code section for alternatives).
  • Defensible Space: The space around a building, known as the 'defensible space,' must be maintained in a way that reduces the likelihood of the building catching fire. This often involves removing or reducing vegetation that could easily catch fire and spread it to the building.
    • Vegetation Management Compliance CRC §R337.1.5 – A person who owns a building or structure in, upon, or adjoining land that is covered with flammable material shall maintain defensible space of 100 feet from each side and from the front and rear of the structure. See CA Public Resource Code §4291 for more information.
  • Accessory Structures: Any accessory structures, such as fences and carports, should be made from materials that resist ignition, because these can potentially transfer fire to the main building.

California Board of Forestry and Fire Protection's State Responsibility Area (SRA) Fire Safe Regulations:

In simple terms, these regulations (see SRA Fire Safe Regulations) are guidelines designed to protect lives, property, and natural resources in areas where the state has financial responsibility for the prevention and suppression of wildfires. These areas are typically rural, forested, or grassy regions, and are referred to as State Responsibility Areas (SRAs).

Here are the main points you need to know:

  • Access: Your property should be easily accessible for emergency vehicles. This includes standards for driveway and road widths, grades, and surfaces. Roads should be able to support the weight of fire trucks and other emergency vehicles, and there should be enough space for them to turn around.
    • Humboldt County Code (HCC) 3112-1 Road and Driveway Access – Road and street networks, whether public or private, unless exempted under Section 3111-3(b), shall provide for safe access for emergency wildland fire equipment and civilian evacuation concurrently, and shall provide unobstructed traffic circulation during a wildfire emergency consistent with Sections 3112-2 through 3112-13.
  • Address Visibility: Your address should be clearly visible from the road, even at night or in smoky conditions. This ensures that emergency responders can quickly locate your property in case of a fire.
    • Humboldt County Code (HCC) 3113-11 Visibility of Addresses – All buildings shall have a permanently posted address, which shall be placed at each driveway entrance and visible from both directions of travel along the road fronting the property. In all cases, the address shall be posted at the beginning of construction and shall be maintained thereafter, and the address shall be visible and legible from the road on which the address is located.
  • Water Supply: Adequate water supply should be available for fire protection. This could be a connection to a public water supply, a private water source like a well or pond, or a dedicated fire protection water tank.
    • Humboldt County Code (HCC) 331.5-13(h) Water Supply – In addition to the domestic water supply, a firefighting water supply of at least 2,500 gallons (pond, tank or equivalent) shall be maintained on the property. If access to the supply is by pipe, such pipe shall be at least 1-1/2 inches in diameter and shall have at least one hose outlet no less than fifty (50) feet from the primary dwelling. If the water storage facility is below the fire equipment access level, then the firefighting equipment must be able to get within fifteen (15) feet of a water supply which is not piped to the primary dwelling.
  • Defensible Space: The area around your home should be cleared of vegetation and other materials that could catch fire easily, creating a 'defensible space'. This helps to slow or stop the spread of fire and gives firefighters a safer place to defend your home from.

Related Regulations:

  • Humboldt County General Plan: Every city and county in California is required to adopt a comprehensive, long-term general plan for its physical development. This includes a safety element that addresses fire hazards, among other things. If your property is in a high fire hazard severity zone, additional building and site design standards may apply under the safety element of your local general plan (see Humboldt County General Plan).
  • California Fire Code: The California Fire Code sets out minimum requirements for fire prevention and fire protection systems, which can help protect buildings and their occupants from fire. It includes requirements for things like fire sprinkler systems, fire alarms, and fire extinguishers (see California Fire Code).

Remember, while these rules can help make your home more resistant to wildfires and other fires, they cannot guarantee complete protection. It's always important to have a personal emergency plan and to follow evacuation orders when given.

Frequently Asked Questions:

  • How do I determine if my construction project is subject to WUI requirements?

One option is to just ask a permit technician. Alternatively, you can use the Humboldt GIS and Important GIS Layers to see if you are located in the SRA. If you are located in the SRA, then reference California Residential Code (CRC) R337.1.3 or California Building Code (CBC) 701A.3 to see if your development is within the Scope of the WUI requirements. Typically, all new construction within an SRA needs to comply with WUI requirements.

  • How do I determine if my construction project is subject to SRA Fire Safe requirements?

One option is to just ask a permit technician. Alternatively, you can use the Humboldt GIS and Important GIS Layers to see if you are located in the SRA. If you are located in the SRA, then reference Humboldt County Code 3111-3 Scope to see if your development is within the Scope of these requirements. Typically, all new construction within an SRA needs to comply with SRA Fire Safe requirements.

  • What do I do if my project is subject to the WUI and SRA Fire Safe requirements?

You will need to integrate these requirements into your proposed design and reflect these requirements on your construction plans. The site plan will show Fire Safe requirements (see Site Plan Checklist and SRA Checklist) while the elevations and floor plan often show WUI requirements. Remember, if your development is subject to WUI you will need to use products listed on the WUI Listed Products Handbook.

  • I am building an alternative-owner builder (AOB) residence. Do I still need to comply with WUI and Fire Safe requirements?

Yes. As of April 4th, 2023, the Building Division is requiring new construction of Alternative-Owner Builder (AOB) dwellings built in high and very high fire severity zones to comply with the Wildland-Urban Interface (WUI) requirements described in CRC R337 and CBC 7A. This requirement comes from the Humboldt County General Plan Chapter 14 S-P27.

  • What specific inspection requirements are applicable to WUI and SRA Fire Safe?

We will inspect the exterior of the structure at the rough-framing inspection for all required WUI features, including doors and windows. We will follow up at the final inspection to ensure compliance. Make sure to leave WUI elements accessible for inspection and have product specification sheets, UL Listings, and other ratings available for the inspector.