California ADU rules · Tuolumne County
Can I Build an ADU in Sonora?
Yes — you can build an ADU in Sonora. California's statewide ADU law requires every city, including Sonora, 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
Local rule1 ADU (attached or detached) + 1 JADU
Units on a multifamily lot
Local ruleJADUs prohibited; up to 2 detached ADUs plus conversions (>=1 or 25% of units)
JADUs not allowed on multifamily lots
Junior ADU (JADU)
Local ruleAllowed
JADUs allowed only on single-family lots
Size & height
Max detached ADU size
Local rule1,200 sq ft
Local cap is 1,200 sq ft for detached ADUs
Max attached ADU size
Local rule50% of primary dwelling, up to 1,000 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
Local rule500 sq ft
Minimum 150 sq ft
Max height
Local rule16 ft
No local exception above 16 ft for transit or two-story
Setbacks
Side setback
Local rule4 ft
4 ft for state-exempt ADUs; otherwise, underlying zone
Rear setback
Local rule4 ft
4 ft for state-exempt ADUs; otherwise, underlying zone
Front setback
Local ruleMust meet the front setback of the underlying zone; no reduction for ADUs
Separation from main house
Local rule10 ft
May be reduced to 6 ft with approval
Parking
Parking required
Local ruleUp to 1 space
No more than 1 per unit or bedroom; exemptions apply
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
CA state lawNot required
When a garage/carport is demolished or converted to build an ADU, replacement parking cannot be required.
Approval, timeline & cost
Approval path
CA state lawMinisterial (by right)
No public hearing or discretionary design review for a qualifying ADU.
Approval timeline
CA state law60 days
The agency must act within 60 days of a complete application — and the ADU is deemed approved if it does not.
Owner-occupancy
Local ruleOnly for a JADU
Owner must reside in main dwelling or JADU for JADUs
Impact-fee waiver
CA state lawWaived under 750 sq ft
An ADU of 750 sq ft or less pays no impact fees (the 750 sq ft threshold itself is exempt under § 66311.5); larger ADUs pay fees proportional to the primary dwelling. JADUs (≤ 500 sq ft) are exempt.
Permits required
CA state lawBuilding permit
Only a ministerial building permit — no conditional use permit or discretionary design review for a qualifying ADU.
Sonora-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Very High Fire Hazard Severity Zone (VHFHSZ)
Defensible space clearance (50 ft) required; sprinklers not required unless main dwelling requires them
Historic District
Exterior changes must not affect historic integrity; staff-level design review for compatibility
Sonora prohibits JADUs on multifamily lots, limits detached ADUs to 1,200 sq ft, and requires a minimum 10 ft separation between detached ADUs and other structures (may be reduced to 6 ft with approval). Historic and fire-hazard overlays impose additional requirements.
Frequently asked questions
Can I build an ADU in Sonora?
Yes. California's statewide ADU law requires Sonora 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 Sonora?
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 Sonora?
Side and rear setbacks are limited to 4 ft. Must meet the front setback of the underlying zone; no reduction for ADUs.
Is parking required for an ADU in Sonora?
Up to 1 space. 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 Sonora?
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 Sonora?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Sonora Municipal Code Chapter 17.55 (Accessory Dwelling Units), last amended by Ord. 897 on 10/3/2022
- Sonora Municipal Code § 17.55.040(A)
- Sonora Municipal Code § 17.55.040(B)
- Sonora Municipal Code § 17.55.100(D)
- Sonora Municipal Code § 17.55.060(C)(1)(a)
- Sonora Municipal Code § 17.55.050(B), § 17.55.060(C)(1)(c)
- Sonora Municipal Code § 17.55.060(C)(1)(c)
- Sonora Municipal Code § 17.55.060(B), § 17.55.080(D)
- Sonora Municipal Code § 17.55.100(I)
- Sonora Municipal Code § 17.55.080, § 17.55.100(J)
- Sonora Municipal Code § 17.55.080(C)-(E)
- Sonora Municipal Code § 17.55.080(E)
- 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 § 66321 (size minimums & height)
- Cal. Gov. Code § 66322 (ADU parking; § 66334 covers JADU parking)
- Cal. Gov. Code § 66314 (local ordinance standards)
- Cal. Gov. Code § 66311.5 (impact fees: none for an ADU ≤ 750 sq ft or JADU ≤ 500 sq ft)
Last updated 2026-06-25. This is an AI-assisted summary of Sonora'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 Sonora Planning before relying on it.
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