California ADU rules · Amador County
Can I Build an ADU in Ione?
Yes — you can build an ADU in Ione. California's statewide ADU law requires every city, including Ione, 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 (>=1 or 25% of units) + up to 2 detached
Local cap of 2 detached ADUs on multifamily lots, not 8 as in state baseline.
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 matches state cap, but is explicitly codified.
Max attached ADU size
Local rule50% of primary, >=850
No 1,000 sq ft minimum for 2+ bedrooms specified.
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
JADU minimum 220 sq ft, maximum 500 sq ft.
Max height
Local rule16 ft
16 ft max for detached ADUs; attached must comply with primary dwelling height.
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 (must comply with front yard setback of zoning district)
Front setback must comply with base zone; cannot block state-mandated ADU.
Separation from main house
Local rule5 ft
Detached ADU must be at least 5 ft from primary dwelling.
Parking
Parking required
Local ruleUp to 1 space
1 space per ADU or per bedroom, whichever is less; exemptions per state.
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 for garage/carport conversion.
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 occupancy required for JADU only.
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
Local rulePlanning review (unless exempt), Building permit, Other construction permits
Planning review required unless ADU/JADU qualifies for direct building permit under state law.
Ione-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Fire sprinklers
If fire sprinklers are required for the primary dwelling, they are also required for the ADU/JADU.
Historic resource
ADUs/JADUs on historic resources must comply with Secretary of the Interior standards.
Ione limits multifamily lots to 2 detached ADUs and requires a 5-foot separation between detached ADUs and the primary dwelling. Fire sprinklers and historic standards may apply in special cases.
Frequently asked questions
Can I build an ADU in Ione?
Yes. California's statewide ADU law requires Ione 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 Ione?
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 Ione?
Side and rear setbacks are limited to 4 ft. per base zone (must comply with front yard setback of zoning district).
Is parking required for an ADU in Ione?
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 Ione?
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 Ione?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Ione Municipal Code § 17.112.030, Ord. No. 528, 2-15-2022
- § 17.112.030(B)(1)(a)(ii)-(iii), (A)(3)
- § 17.112.030(B)(2)(a)(ii)
- § 17.112.030(B)(2)(a)(i)
- § 17.112.030(B)(4)(c)
- § 17.112.030(B)(2)(a)(iii)
- § 17.112.030(B)(2)(b)
- § 17.112.030(B)(2)(b)(iii)
- § 17.112.030(G)
- § 17.112.030(G)(2)
- § 17.112.030(B)(4)(b)
- § 17.112.030(D)(5), (F)(1)(c)
- § 17.112.030(A)(4)
- § 17.112.030(A)(5)
- 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)
- 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 Ione'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 Ione Planning before relying on it.
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