California ADU rules · Yuba County
Can I Build an ADU in Marysville?
Yes — you can build an ADU in Marysville. California's statewide ADU law requires every city, including Marysville, 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 ruleup to 2 detached ADUs per lot with a proposed multifamily dwelling, or up to 8 detached ADUs per lot with an existing multifamily dwelling (not to exceed the number of existing units); multiple conversion ADUs allowed
City sets a lower cap (2) for detached ADUs on lots with a proposed multifamily dwelling, and up to 8 for existing multifamily, not to exceed number of existing units.
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 rule1,000 sq ft
Detached ADUs: 850 sq ft (studio/1-bed), 1,000 sq ft (2+ bedrooms); this is a local cap.
Max attached ADU size
Local rule850 sq ft (studio/1-bed), 1,000 sq ft (2+ bedrooms), but also limited to less than 50% of the primary dwelling’s floor area; must allow at least 850/1,000 sq ft regardless of percentage
City sets explicit sq ft caps and a 50% rule, but must allow at least 850/1,000 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
CA state law500 sq ft
Max height
CA state law16 ft
16 ft baseline; cities must allow 18 ft within ½ mi of a major transit stop or where the primary dwelling is two-story, and 20 ft on a lot with a multistory multifamily building.
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 ruleNot allowed in the front yard unless converting an existing structure in that location
New ADUs not allowed in front yard unless conversion of existing structure.
Separation from main house
CA state lawNone required
No statewide separation requirement between the ADU and the primary dwelling.
Parking
Parking required
CA state lawUp to 1 space
At most 1 space per ADU (or per bedroom, whichever is less) — and waived in the common cases below.
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 primary dwelling parking if garage/carport/covered parking is demolished or converted for an ADU.
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
CA state lawOnly for a JADU
No owner-occupancy requirement for ADUs (the prior sunset was removed). A JADU may require owner-occupancy, principally where it shares sanitation with the main house.
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.
Marysville-specific factors that can change the answer
State law sets the floor, but these local conditions often decide whether a specific parcel works.
Downtown Historic District
ADUs inside the historic district may have additional review; outside are ministerially approved.
Sprinkler requirements
ADUs not required to provide sprinklers if not required for primary dwelling.
Marysville sets a local maximum size for detached and attached ADUs (850/1,000 sq ft), limits detached ADUs on proposed multifamily lots to 2, and requires no parking for studios. ADUs in the historic district may face additional review.
Frequently asked questions
Can I build an ADU in Marysville?
Yes. California's statewide ADU law requires Marysville 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 Marysville?
A detached ADU of at least 1,000 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 Marysville?
Side and rear setbacks are limited to 4 ft. Not allowed in the front yard unless converting an existing structure in that location.
Is parking required for an ADU in Marysville?
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 Marysville?
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 Marysville?
Owner-occupancy: only for a jadu. ADUs under 750 sq ft are also exempt from impact fees.
Sources
- Marysville Municipal Code Chapter 18.90 (Ord. 1463, 10/7/2025)
- § 18.90.070(m), (n)
- § 18.90.070(e)
- § 18.90.070(e), Development Standards Table
- § 18.90.070(c), Development Standards Table
- § 18.90.070(h)(2)
- § 18.90.040
- § 18.90.070(j)
- 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 § 66315 (owner-occupancy)
- 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 Marysville'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 Marysville Planning before relying on it.
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