California ADU rules · Stanislaus County
Can I Build an ADU in Riverbank?
Yes — you can build an ADU in Riverbank. California's statewide ADU law requires every city, including Riverbank, 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
Riverbank limits detached ADUs on multifamily lots to 2 per lot, less than the state default of 8.
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; included for explicit local confirmation.
Max attached ADU size
Local rule50% of primary dwelling
No local minimums stated; follows state for minimums.
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 rule16 ft
16 ft and 1 story for detached ADUs; up to 35 ft if above a garage.
Setbacks
Side setback
Local rule4 ft
Street side setback is 10 ft; standard side/rear is 4 ft.
Rear setback
CA state law4 ft
Front setback
Local ruleADUs not allowed in front yard setback
ADUs prohibited in front yard setback, which is more restrictive than state default.
Separation from main house
Local ruleNone required
No specific minimum separation in zoning code; must comply with building code.
Parking
Parking required
Local ruleUp to 1 space
1 off-street space per ADU or per bedroom, whichever is less; exemptions per state law.
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 required for parking lost due to ADU 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
No owner-occupancy for ADUs approved Jan 2020–Jan 2025; required 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
Local ruleBuilding permit, JADU deed restriction
JADUs require a deed restriction in addition to building permit.
Riverbank-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 compliance
Must meet city-adopted building/fire code; sprinklers not required if not required for primary dwelling.
Historic district parking exemption
No parking required for ADUs in historic districts.
Riverbank limits detached ADUs on multifamily lots to 2 per lot and prohibits ADUs in the front yard setback. JADUs require a deed restriction and owner-occupancy, while ADUs do not (through Jan 2025).
Frequently asked questions
Can I build an ADU in Riverbank?
Yes. California's statewide ADU law requires Riverbank 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 Riverbank?
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 Riverbank?
Side and rear setbacks are limited to 4 ft. ADUs not allowed in front yard setback.
Is parking required for an ADU in Riverbank?
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 Riverbank?
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 Riverbank?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Riverbank Municipal Code, Chapter 153, Sections 153.325–153.330 (Ord. 2021-007, passed 12-14-21)
- § 153.326(F)
- § 153.327(A)(1)(b)
- § 153.327(A)(1)(a)
- § 153.327(A)(4)
- § 153.327(A)(3)
- § 153.327(A)(5)
- § 153.327(A)(3)(c)
- § 153.327(D), (E)
- § 153.327(D)(3)
- § 153.329(A)
- § 153.327(A)(2)(e)
- § 153.327(A)(1)(d)
- 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 Riverbank'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 Riverbank Planning before relying on it.
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