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Accessory Dwelling Units (ADUs) – Fire Prevention

Permit Sonoma Fire Prevention

Information about how Accessory Dwelling Units (ADUs) relate to Fire Prevention efforts, particularly automatic residential fire sprinkler system requirements.

Senate Bill 1069, Wieckowski (Chapter 720, Statues 2016) Land use: zoning, amends section 65852 of the Government Code to provide reform and incentives to facilitate and expedite the construction of affordable housing. The law was created to allow the construction of additional dwelling units associated with existing housing. An accessory dwelling unit may be attached of unattached to the existing house. The changes in the statue affect the automatic residential fire sprinkler system requirements for accessory dwelling units by exempting the requirement in some situations, noted below.

The Government Code is part of California statute and the bill has an effective date of January 1, 2017. The statute and the bill has effective date of January 1, 2017. The statue takes precedence over local regulations or ordinances. The information of SB 1069 can be found at:

CA Legislative Information- Senate Bill No. 1069

Fire Department Requirements

  • Site Plan
  • Fire Access
  • Construction
  • Fire protection water supplies
  • Vegetation management
  • Addressing
  • Automatic fire sprinklers

Other Documents and Information

Site Plan

Every site plan shall include the following items.

  • Location of ADU on property
  • location of  ADU to all property lines
  • location of ADU to other buildings
  • Location of utilities
    • Natural gas or LPG
    • Electrical
    • Solar Photovoltaic 
  • Gates
  • Fire protection water supplies
    • Public fire hydrant 
    • On-Site water storage
  • Addressing

Fire Department Access

All ADU structures shall be accessible to fire department apparatus access with in one hundred and fifty feet to all four sides of the structure. If access can not be provide by an approved route then a mitigation may be required.

All existing fire department access roads and driveways shall meet or exceed minimums set by the Sonoma County Fire Safe Standards. This information shall be included on the required site plan.


ADU structures located on properties over one acre and located in the State Responsibility Area (SRA) shall have minimum setbacks from other buildings and property lines. The minimum setback is thirty feet unless constructed per the adopted code section 13-55 sprinklered and non-sprinklered buildings. No ADU will be permitted less then ten feet from property lines unless approved by mitigation.

All newly constructed ADU shall be designed and constructed per California Residential Code, Section  R337. To see if your property address is located in the State Responsibility Area (SRA) please use the State Board of Forestry: SRA Viewer

Fire Protection Water Supplies

All newly constructed ADU buildings shall have access to a approved fire protection water supplies on site or provided by a local water purveyor. This minimum fire protection requirement shall be shown on the submitted plans for approval and shall meet minimum standards set in the Sonoma County Fire Safety Ordinance chapter 13.

Vegetation Management

Properties located in the SRA shall have by by final inspection a minimum clearance to vegetation of one hundred feet from all structures and property lines.

Vegetation clearance shall meet minimum guidelines set by Public Resources Code 4291 and Sonoma County Fire Safety Ordinance, Chapter 13 and 13A. For more information please visit: Wildfire Preparedness


All Qualified ADU structures shall receive a new address number per Sonoma County Fire Safe Standards, assigned by Permit Sonoma. The new address number shall be indicated on the approved plans. All permit data relating to the ADU shall be corrected and combined to the the newly assigned address number.

The approved plan shall include the location of the new address number for inspection and installed in accordance with the Sonoma County Fire Safe Standards. Compliant address numbers are required to be completed by final fire inspection occupancy approval.

Automatic Fire Protection Systems

Automatic Fire Protection Systems (fire sprinklers) are required by the California Residential Code Section 313, including Sonoma County Fire Safety Ordinance Chapter 13.

In order to apply for mitigation to exempt a ADU structure 1200 sq ft and less from fire sprinklers. The application will be reviewed on a case by case submittal. The applicant shall apply in writing for the exemption indicating the request and reason associated with the newly constructed ADU. The written request shall include how the property allows for fire department access and provides for fire protection requirements based on minimum codes and standards adopted by the State of California and County of Sonoma.  A review and possible site inspection by the fire code official shall indicate existing conditions such as fire access roads, vegetation management, onsite or available water supplies, addressing and building set backs to property lines. Once the review is completed the applicant will be able to make the necessary changes to meet the fire sprinkler exemption.

FIR-002 Accessory Dwelling Unit State Law Fire Sprinkler Exemption (PDF)

The minimum 1 hour fee for the review will be invoiced to the permit application requesting the exemption status.