California Government Code, Title 7, Division 1, Chapter 13 — Accessory Dwelling Units (§§66310–66342). Consolidated state ADU/JADU law (relocated by SB 477, operative 2025-01-01) that preempts and sets the floor for local ADU regulation.
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Standards for 'state-exempt' ('66323') ADUs and JADUs — units a jurisdiction must approve ministerially regardless of local ADU ordinance. A jurisdiction may allow more. Source: Cal. Gov. Code §66323 via ABAG State ADU Law Summary (2025-07-01).
| Standard | Requirement for State-Exempt ADUs |
|---|---|
| Zones allowed | All residential and mixed-use zones, with limited exceptions based on traffic flow, water, sewer, or public safety. |
| Size — Detached ADU | Up to 800 square feet. |
| Size — Conversion ADU | Within the converted space of a proposed/existing single-family home or accessory structure, or the converted non-livable space of an existing multi-family dwelling. On a single-family property an existing accessory structure may be expanded by no more than 150 sf for ingress/egress. |
| Size — JADU | Up to 500 square feet; must be within an existing or proposed single-family home (including an attached garage). |
| Setbacks — Detached | No more than 4-foot side or rear setbacks for new construction. |
| Setbacks — Conversion ADU / JADU | Must be sufficient for fire and safety. |
| Height — Detached | Up to 16 feet. |
| Height — Detached within ½ mile of a major transit stop or high-quality transit corridor | Up to 18 feet, plus 2 feet to accommodate a roof pitch. |
| Height — Detached on a lot with a multi-family, multi-story dwelling | Up to 18 feet. |
| Parking — ADUs | No parking may be required. |
| Parking — JADUs | No new parking may be required; replacement parking may be required if the JADU converts space in an attached garage. |
| Access — Conversion ADU / JADU | Must have exterior access separate from the main entrance of the single-family home. |
| Access — JADU | If the JADU does not include a separate bathroom, it must include a separate entrance and an internal connection to the main living area. |
Source: Cal. Gov. Code §66323. State-exempt ADUs cannot be used as short-term rentals (<30 days) and are not subject to historic-resource standards.
Number and combination of state-exempt ADUs/JADUs that must be allowed on a property. An ADU application may not be denied due to maximum density. Jurisdictions may allow more. Source: Cal. Gov. Code §66323 via ABAG (2025-07-01).
| Property Type | Number and Combination of Units Allowed |
|---|---|
| Single-family | Up to three accessory units: one detached ADU (up to 800 sf), one conversion ADU, and one JADU. (HCD interprets state law to allow a detached and/or conversion ADU together with a JADU.) |
| Multi-family — Detached ADUs | Up to eight on a property with an existing multi-family dwelling (not exceeding the number of existing primary units; must be detached); up to two on a property with a proposed multi-family dwelling. |
| Multi-family — Conversion ADUs | At least one, up to a number equal to 25% of the existing multi-family units, created from portions not used as living space (e.g., parking, storage). JADUs are not allowed on multi-family properties. |
Source: Cal. Gov. Code §66323.
Minimum standards a local ADU ordinance must allow for ADUs that are not state-exempt. Local ordinances may be less restrictive but may not prohibit an attached or detached ADU of up to 800 sf with 4-foot side/rear setbacks. Source: Cal. Gov. Code §§66314–66322 via ABAG State ADU Law Summary (2025-07-01).
| Standard | State Minimum Requirement |
|---|---|
| Zones allowed | All residential and mixed-use zones, with limited exceptions based on traffic flow, water, sewer, or public safety (no exceptions for §66323 ADUs). |
| Size — minimum | Must allow an ADU as small as 150 square feet (efficiency unit). |
| Size — detached maximum | Must allow at least 850 sf (studio/1-bedroom) and 1,000 sf (2+ bedroom); up to 1,200 sf for jurisdictions without a local ADU ordinance. |
| Size — attached maximum | At least 850 sf (studio/1-BR) and 1,000 sf (2+ BR). May be capped at the greater of a percentage of the primary dwelling or those minimums; without an ordinance, must allow up to 50% of the primary dwelling and cannot restrict an ADU of 800 sf or less. |
| Size — conversion | Within the converted space of a proposed/existing single-family home or accessory structure, or non-livable space of an existing multi-family dwelling; accessory structure may expand up to 150 sf for ingress/egress. |
| Setbacks — side & rear | No more than 4 feet for new construction (may be reduced below 4 feet). |
| Setbacks — front | Front setbacks may apply but cannot preclude an ADU of at least 800 sf. |
| Setbacks — conversions / rebuilds | No additional setbacks required; may use the existing building footprint if sufficient for fire and safety. |
| Height — attached | Up to 25 feet, or the maximum allowed by the underlying zoning, whichever is lower. |
| Height — detached | Up to 16 feet. |
| Height — detached within ½ mile of major transit / high-quality transit corridor | Up to 18 feet, plus 2 feet for a roof pitch. |
| Height — detached on a multi-family, multi-story lot | Up to 18 feet. |
| Parking | Up to one space per ADU may be required (jurisdiction may waive). No parking may be required if the ADU is state-exempt, a studio, a conversion, within ½ mile of transit, in a historic district, within one block of car share, not provided a required on-street parking permit, or submitted with a permit for a new primary dwelling per §66322(a)(1)–(5). |
| Replacement parking | None required for ADUs. Tandem parking and parking in setbacks are allowed. |
| Local standard limits | A jurisdiction may not impose FAR, lot coverage, size, front setback, or open-space requirements that do not allow at least an 800 sf ADU with 4-foot side and rear setbacks. |
| Density | An ADU application may not be denied due to the lot's maximum density. |
Source: Cal. Gov. Code §§66314–66322. Processing: ADU applications must be approved or denied ministerially within 60 days of a complete application (else deemed approved); a completeness letter is due within 30 days.
Statewide rules that jurisdictions must follow for ADUs and JADUs. Source: Cal. Gov. Code §§66314, 66315, 66323, 66324, 66329, 66332, 66333, 66341, 66342 and Civil Code §§714.3, 4751, via ABAG State ADU Law Summary (2025-07-01).
| Rule | Requirement |
|---|---|
| Occupancy — ADU | Owner occupancy cannot be required. |
| Occupancy — JADU | Owner must live in the JADU or the primary home, unless the owner is a government agency, land trust, or housing organization. |
| Sale — ADU | Must be allowed where a qualified nonprofit corporation built/developed the primary home and/or ADU and it would be sold to a qualified buyer (conditions apply). Jurisdictions may adopt an ordinance allowing separate sale of ADUs (AB 1033 condominium conveyance). |
| Sale — JADU | Separate sale is not allowed (a deed restriction prohibiting separate sale is required). |
| Impact fees — ADU | No impact fees for ADUs under 750 sf. For ADUs 750 sf or larger, fees must be proportional to the primary home. |
| Impact fees — JADU | No impact fees allowed. |
| Utility fees | ADUs/JADUs are not a new residential use for utility connection fees or capacity charges (unless built with a new single-family home). Converted ADUs/JADUs cannot be required to provide new or separate utility connections; charges must be proportionate to the primary home. |
| Amnesty (pre-2020 units) | A permit to legalize a pre-2020 ADU/JADU must be approved even if it violates building standards or local/state ADU codes, unless the unit is deemed substandard (Health & Safety Code §17920.3). |
| Rentals | State-exempt ADUs cannot be used as short-term rentals (<30 days). Jurisdictions may allow or prohibit short-term rental of non-exempt ADUs by ordinance. |
| Historic resources | ADUs/JADUs are allowed in historic districts and on lots with a historically significant main home; agencies may impose standards preventing adverse impacts to California Register properties. State-exempt ADUs are not subject to historic standards. |
| Coastal & hazard zones | Additional state regulations may apply in coastal zones, fire-hazard zones, and other hazard zones. |
| Homeowners association (HOA) | HOAs may set reasonable objective design guidelines but may not prohibit or unreasonably restrict ADUs/JADUs, and may not prohibit renting an ADU/JADU (Civil Code §§714.3, 4751). |
Sources: Cal. Gov. Code §§66314, 66315, 66323, 66324, 66329, 66332, 66333, 66341, 66342; Civil Code §§714.3, 4751.
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