Types of ADUs
TYPES OF ADUS
There are two types of ADUs: standard ADUs and Junior ADUs [also known as JADUs].
Standard ADUs
Standard ADUs involve the creation of a new independent living unit with a separate exterior entrance from a primary single- or multifamily dwelling. There are three ways that standard ADUs can be created on a property:
1. Conversion: Convert part of the existing home, garage, or accessory structure; or
2. New Construction – Attached: Build a new addition to the existing home or attached garage; or
3. New Construction – Detached: Build a new, free-standing dwelling unit on the property or build an addition to an existing detached garage or accessory structure.
Junior ADUs
JADUs involve the creation of a new living unit, a maximum 500 square feet, converted from within the walls of a single-family dwelling, including attached garages and other nonliving spaces. JADUs have an efficiency kitchen and a separate exterior entrance. A JADU may have interior access to the primary dwelling but this is not required. Bathrooms can be separate or shared with the primary dwelling.
Compare ADU Types
The summary table below can help you decide which ADU is right for you. As noted in the table footnote, one standard ADU of 800 square feet is always allowed on residential parcels, regardless of other size maximums or site standards. See County Code Section 20.00.010.L.3.a for full details.
| ADU Type | Minimum Size | Maximum Size* | Maximum Height** | Setbacks | Parking |
| Junior ADU | 150 sq. ft. | 500 sq. ft. | Varies by Zone District - no less than 25' high | Minimum required for fire safety*** | Not Required |
| Standard ADU: Conversion of Space in Residence | 150 sq. ft. | 1,200 sq. ft. | Varies by Zone District - no less than 25' high | Minimum required for fire safety*** | Not Required |
| Standard ADU: Attached New Construction | 150 sq. ft. | 1,200 sq. ft. | Varies by Zone District - no less than 25' high | Front setback: Zone District standard. Side setback: 4 feet. Rear setback: 4 feet Exceptions may apply on corner lots. | 1 space per ADU |
| Standard ADU: Detached New Construction | 150 sq. ft. | 1,200 sq. ft. | 16 ft. but may be higher under certain conditions. | Front setback: Zone District standard. Side setback: 4 feet. Rear setback: 4 feet Exceptions may apply on corner lots. | 1 space per ADU |
* Regardless of other ADU size requirements or Floor-to-Area (FAR) or lot coverage, one ADU of 800 sq. ft. may be considered.
** If a detached accessory dwelling is located on a parcel with a multistory, multi-unit dwelling structure, the unit is limited to a maximum of 18 ft.
An accessory dwelling located above a detached garage is limited to a maximum height of 25 feet.
An accessory dwelling attached to the primary dwelling is limited to the height allowed in the underlying zone district.
*** Conversion ADUs and JADUs can include up to 150 square feet of new construction. Any new construction portions of conversion ADUs and JADUs must meet applicable ADU height and setback standards.
