Nevada County, CA Accessory Structures: ADU Rules (2026)
ADU rules in Nevada County, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Approval type
- Ministerial (no hearing)
- Decision deadline
- 60 days or deemed approved
- Side/rear setback
- 4 feet
- State minimum size floor
- 850 sq ft (1,000 if 2+ bedroom)
- Owner occupancy
- Cannot be required (ADU)
- Primary authority
- CA Gov. Code 66310 et seq.
Summary
In unincorporated Nevada County, ADUs and JADUs are reviewed ministerially and are governed primarily by California State ADU Law (Gov. Code 66310 et seq.). A completed application must be approved or denied within 60 days, ADUs need only 4-foot side and rear setbacks, and no owner-occupancy may be required.
Section 12.03.190 Accessory and Second Dwelling Units. Accessory and junior accessory dwelling units provide an important source of affordable housing. By promoting the development of accessory, junior accessory, and second dwelling units, the County may ease a rental-housing deficit, maximize limited land resources and existing infrastructure and assist low and moderate-income homeowners with supplemental income. ... Section 12.03.191 Accessory and Junior Accessory Dwelling Units. A. Purpose. To maintain the social fabric of families and to improve affordable housing opportunities for the County's workforce, family members, students, senior citizens, in-home health providers, the disabled, and others at below-market prices in existing neighborhoods in the County of Nevada. B. Definitions: "Accessory dwelling unit" and "junior accessory dwelling unit" have the same meanings as defined in the California Government Code. C. Standards. An accessory dwelling unit or junior accessory dwelling unit shall be ministerially permitted, regardless of minimum parcel size and zoning densities, on all parcels where residential uses are permitted by-right or by conditional use, subject to zoning compliance and building permit issuance and the following standards: 1. Accessory dwelling units may be a conventionally on-site constructed attached or detached structure, a manufactured home or a converted area within a legally existing residential unit or accessory structure provided that building permits are obtained, and the following size limitations are satisfied...
Full Breakdown
Accessory dwelling units in unincorporated Nevada County are processed by the Community Development Agency Planning Department as a ministerial (non-discretionary) action, meaning no public hearing or design review. County guidance states ADUs must meet 4-foot rear and side yard setbacks and remain consistent with the zoning of the parcel. Because California ADU Law (Gov. Code 66310-66342) preempts most local standards, the County applies state rules: a local agency may not set a maximum ADU size below 850 sq ft (1,000 sq ft for a unit with more than one bedroom), and must approve an ADU of up to 800 sq ft regardless of other standards (Gov.
Code 66321). The County's general size cap referenced in materials is 1,200 sq ft. A completed ADU or JADU application is deemed approved if not acted on within 60 days (Gov. Code 66317). Owner occupancy may not be required for ADUs (Gov. Code 66315). Note: HCD advised the County in October 2025 that its 2019 ADU ordinance may be outdated; where a local ordinance conflicts with state law it is null and void and state standards control (Gov. Code 66316). ADUs require separate utility disconnects and a new address is assigned.
Violations & Fines
Building or occupying an ADU without required building permits, or failing to obtain ministerial planning approval, can trigger code enforcement; unpermitted units may be required to be permitted or removed, though state law (Gov. Code 66331/66332) provides delayed enforcement and amnesty paths for certain pre-2020 units.
Frequently Asked Questions
Can the County require me to live on-site if I build an ADU?
How long does the County have to act on my ADU application?
Sources & Official References
Other rules in Nevada County
How Nevada County compares: Easiest Cities to Build an ADU·California rules heatmap·Compare Nevada County to another location·View the California accessory structures overview
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