California ADU rules · Sonoma County
Can I Build an ADU in Healdsburg?
Yes — you can build an ADU in Healdsburg. California's statewide ADU law requires every city, including Healdsburg, to approve a qualifying accessory dwelling unit by right, plus a junior ADU (JADU) on a single-family lot. What varies city to city are the local specifics below.
Can you build one?
ADUs allowed
CA state lawYes — by right
ADUs and JADUs are allowed by right in all residential and mixed-use zones; ministerial approval, no hearing.
Units on a single-family lot
CA state law1 ADU + 1 JADU
At least one ADU and one JADU per single-family lot (a conversion ADU may also be possible).
Units on a multifamily lot
Local ruleconversions (up to 25% of units, min 1) + up to 8 detached (not to exceed number of existing units; up to 2 on proposed multifamily)
Detached ADUs on multifamily lots capped at number of existing units; up to 2 on proposed multifamily.
Junior ADU (JADU)
CA state lawAllowed
Up to 500 sq ft, within the walls of an existing single-family home (single-family lots only).
Size & height
Max detached ADU size
Local rule1,200 sq ft
Local maximum for detached ADUs is 1,200 sq ft.
Max attached ADU size
Local rule1,200 sq ft local maximum
Local maximum for attached ADUs is 1,200 sq ft.
Guaranteed minimum size
CA state law800 sq ft
An 800 sq ft ADU must be allowed regardless of FAR/lot-coverage caps; a city also cannot cap an attached ADU below 850 sq ft (1,000 for 2+ bedrooms).
Max JADU size
CA state law500 sq ft
Max height
Local rule18 ft
Detached ADUs: 18 ft max; attached ADUs: up to 2 stories or 25 ft.
Setbacks
Side setback
CA state law4 ft
A city cannot require more than 4 ft side or rear setback; conversions of existing structures are exempt.
Rear setback
CA state law4 ft
Front setback
Local ruleper base zone; ADUs ≤800 sq ft exempt from front setback
ADUs ≤800 sq ft do not have to meet front setback.
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
Local ruleNone
No parking required for new ADUs or conversions.
Transit parking exemption
CA state lawYes — no parking required near transit & for conversions
No parking may be required within ½ mi walking distance of transit, in a historic district, for an ADU within an existing structure, within one block of car-share, or in certain permit-parking areas.
Garage-conversion replacement parking
Local ruleNot required
No replacement parking required when garage is converted.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
Local rule60 days
30 days for completeness review; 60 days for approval/denial after complete application.
Owner-occupancy
Local ruleOnly for a JADU
Owner-occupancy required for JADUs only.
Impact-fee waiver
Local ruleWaived under 850 sq ft
ADUs up to 850 sq ft are exempt from impact fees.
Permits required
Local ruleBuilding permit
Building permit required; city form and documentation needed.
Healdsburg-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire code/defensible space
Sprinklers not required in ADU if not required for primary; landscaping must comply with fire code for defensible space.
Healdsburg sets a local ADU size maximum of 1,200 sq ft and requires no parking for ADUs. ADUs up to 850 sq ft are exempt from impact fees, and owner-occupancy is required only for JADUs.
Frequently asked questions
Can I build an ADU in Healdsburg?
Yes. California's statewide ADU law requires Healdsburg to approve a qualifying accessory dwelling unit ministerial (by right), plus a junior ADU (JADU) on a single-family lot.
How big can an ADU be in Healdsburg?
A detached ADU of at least 1,200 sq ft must be allowed, and an ADU of 800 sq ft can never be zoned out by floor-area or lot-coverage limits. A JADU can be up to 500 sq ft.
What are the setback requirements for an ADU in Healdsburg?
Side and rear setbacks are limited to 4 ft. per base zone; ADUs ≤800 sq ft exempt from front setback.
Is parking required for an ADU in Healdsburg?
None. No parking can be required within ½ mile of transit, for conversions, or for units inside the primary home. When a garage is converted, replacement parking is not required.
How long does ADU approval take in Healdsburg?
A complete application must be acted on within 60 days, with ministerial (by right) — no public hearing or discretionary design review for a qualifying ADU.
Do I have to live on the property to build an ADU in Healdsburg?
Owner-occupancy: only for a jadu. ADUs under 850 sq ft are also exempt from impact fees.
Sources
- Healdsburg Municipal Code § 20.20.010 (Accessory Dwelling Units and Junior Accessory Dwelling Units)
- HMC § 20.20.010(E)(1)-(4), Table 20
- HMC § 20.20.010(C), Table 20, Table 20a
- HMC § 20.20.010(C), Table 20
- HMC § 20.20.010(E)(2)(c), Table 20, Table 20a
- HMC § 20.20.010(E)(2)(a), Table 20, Table 20a
- HMC § 20.20.010(G)(2)-(3)
- HMC § 20.20.010(G)(2)-(3), (B)(1)
- HMC § 20.20.010(F)(4)-(5)
- HMC § 20.20.010(F)(5), (G)(1)
- HMC § 20.20.010(F)(3), (D)(3)
- Cal. Gov. Code §§ 66310–66342 (ADU Law)
- HCD 2025 Accessory Dwelling Unit Handbook
- Cal. Gov. Code § 66317 (ministerial approval, 60-day deadline)
- Cal. Gov. Code § 66323 (by-right ADU/JADU, 800 sq ft, 4-ft setbacks)
- Cal. Gov. Code § 66333 (junior ADUs)
- Cal. Gov. Code § 66321 (size minimums & height)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
Last updated 2026-06-25. This is an AI-assisted summary of Healdsburg's ADU rules, drawn from its published ordinance and California ADU law — general information, not legal advice, and it may be incomplete or out of date. Verify the controlling rule for your specific parcel with Healdsburg Planning before relying on it.
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