Sonoma County
Healdsburg ADU rules
Research summary of local ADU rules on file for City of Healdsburg in Sonoma County. Not a determination for a specific lot.
City or county ADU page
Check any California address for freeCity of Healdsburg rules on file
Local rules recorded in this project for this jurisdiction. Where a city figure on file is stricter than the state baseline on file, both are shown.
ADU size
ADUs may be up to 1,200 sq ft, attached, detached or converted from existing space, in any zone that allows homes.
Source: City of Healdsburg ADUs and JADUs page, Healdsburg Land Use Code § 20.20.010, accessed 2026-10-23.
Permits
A building permit is required for every ADU, including garage and other conversions; building fees are based on construction valuation. Additions and new construction that need fire sprinklers need separate sprinkler plans submitted to the Fire Department ((707) 431-3360).
Source: City of Healdsburg ADUs and JADUs page, Healdsburg Land Use Code § 20.20.010, accessed 2026-10-23.
School and impact fees
Additions or new construction over 500 sq ft may owe school fees (Healdsburg Unified School District). City impact fees apply only to a new ADU over 850 sq ft and are based on the ADU's size compared with the main home.
Source: City of Healdsburg ADUs and JADUs page, Healdsburg Land Use Code § 20.20.010, accessed 2026-10-23.
Free One-Stop meetings
The City's One-Stop Assistance Center meets Thursday afternoons at no cost, with Planning, Building, Public Works and Fire staff; book through the Community Development Center at (707) 431-3346.
Source: City of Healdsburg ADUs and JADUs page, Resources, accessed 2026-10-23.
Pre-reviewed ADU plans
Healdsburg's Pre-Reviewed ADU Plans Program lists plans reviewed for Building Code compliance, from a 340 sq ft studio to a 1,175 sq ft unit; you contact the designer listed for each plan. Using them should lower plan check fees, though site engineering and soils work will likely still be needed. Healdsburg is part of a countywide group, so a plan reviewed here may be usable in other Sonoma County cities.
Source: City of Healdsburg ADUs and JADUs page, Pre-Reviewed ADU Plans Program, accessed 2026-10-23.
California state rules on file
The statewide baseline recorded from state law and the HCD ADU Handbook.
Detached size cap described in state law
1,200 sq ft. Recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Side and rear setback cap for a new ADU
4 ft. Recorded in this rules file from Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Setback for a conversion of an existing structure
No additional setback, as recorded in this rules file from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum lot size
A city may not impose a minimum lot size for an ADU, as recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.
Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.
Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.
Permit decision deadline
60 days. Recorded in this rules file from Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.
Owner-occupancy requirement
None. Recorded in this rules file from Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.
Parking near public transit
No parking standards within one-half mile walking distance of public transit. Recorded in this rules file from Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.
Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. This rules file does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.
Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.
State baseline on the directory → · State ADU rules on the homepage →
Can I build an ADU in Healdsburg?
State law sets a baseline for ADUs in Healdsburg, and the local standards on file are listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with the City of Healdsburg Community Development Department, or run a free address summary.
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