What is the maximum size for an ADU in Arcadia?

A detached or attached ADU may be up to 850 square feet for a studio or one-bedroom unit, and up to 1,000 square feet for units with two or more bedrooms.

Does an ADU require its own parking space?

Generally, one off-street parking space is required. However, exemptions apply if the ADU is within a half-mile of public transit, located in a historic district, or part of the existing primary residence.

Are short-term rentals allowed in Arcadia ADUs?

No, ADUs and JADUs in Arcadia may not be rented for a term shorter than 28 days.

Can I build an ADU if I have a multifamily property?

Yes. Multiple ADUs are permitted on multifamily lots, including those converted from non-livable spaces (up to 25% of unit count) and up to two detached ADUs.

Arcadia, CA Accessory Dwelling Unit (ADU) Regulations

The City of Arcadia allows for the creation of Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs) in residential and mixed-use zones. These units are intended to provide independent living facilities on lots with existing or proposed primary residences while remaining subordinate to the main dwelling in size and appearance [§ 9109.01.020, § 9102.01.080].

Definitions of Units

Arcadia distinguishes between two types of accessory units:

Accessory Dwelling Unit (ADU): An attached or detached residential unit providing complete independent living facilities (including permanent provisions for living, sleeping, eating, cooking, and sanitation) located on a lot with a primary residence [§ 9102.01.080].
Junior Accessory Dwelling Unit (JADU): A unit no more than 500 square feet in size contained entirely within a single-family structure. It must include an efficiency kitchen and may have separate or shared sanitation facilities with the primary home [§ 9109.01.020].

Permitted Zones and Locations

ADUs are permitted in the following areas:

Residential Zones: Any lot zoned for single-family or multifamily use [§ 9102.01.080].
Mixed-Use/Downtown Zones: CBD (Central Business District), MU (Mixed-Use), and DMU (Downtown Mixed-Use) zones allow ADUs as accessory uses provided the site currently has a single-family or multifamily dwelling [§ 9102.05.020].
JADU Specifics: JADUs are only permitted on lots zoned for single-family residences [§ 9102.01.080].

Development Standards

ADUs must adhere to specific physical requirements regarding size, height, and setbacks.

Unit Size Limits

Detached or Attached ADU: Maximum of 850 square feet for studio or one-bedroom units; 1,000 square feet for units with two or more bedrooms [§ 9102.01.080].
Attached ADU Percentage: Attached units are further limited to 50% of the floor area of the existing primary dwelling. However, the City must allow at least an 800-square-foot ADU regardless of floor area ratio (FAR) or lot coverage limits [§ 9102.01.080].

Height Requirements

Detached ADUs: Generally limited to 16 feet. This may increase to 18 feet if the lot is within one-half mile of a major transit stop, or up to 20 feet to match the roof pitch of the primary dwelling [§ 9102.01.080].
Attached ADUs: Maximum height of 25 feet or the height limit of the underlying zone, whichever is lower. Attached ADUs cannot exceed two stories [§ 9102.01.080].

Setbacks

Side and Rear: Minimum of 4 feet [§ 9102.01.080].
Front: Minimum of 25 feet, though this may be reduced if it prevents the construction of an 800-square-foot unit [§ 9102.01.080].
Existing Structures: No setback is required for an ADU constructed within the same location and dimensions of an existing structure [§ 9102.01.080].

Parking Requirements

One off-street parking space is required per ADU, which may be provided as tandem parking or within setback areas [§ 9102.01.080]. No parking is required if the ADU meets any of the following criteria:

Located within one-half mile walking distance of public transit.
Located within an architecturally and historically significant district.
Part of the proposed or existing primary residence or an accessory structure.
When on-street parking permits are required but not offered to the ADU occupant.
When a car-share vehicle stop is located within one block [§ 9102.01.080].

Operational and Legal Requirements

Rental Term: ADUs and JADUs cannot be rented for terms shorter than 28 days [§ 9102.01.080].
Owner Occupancy: ADUs created after January 1, 2020, do not require the owner to live on-site. JADUs do require owner occupancy in either the primary dwelling or the JADU [§ 9102.01.080].
Separate Sale: ADUs and JADUs cannot be sold or conveyed separately from the primary dwelling and the lot [§ 9102.01.080].
Deed Restriction: For JADUs, a deed restriction must be recorded against the title of the property to ensure compliance with size and occupancy rules [§ 9102.01.080].

Approval Process

The City reviews ADU and JADU applications ministerially, meaning no public hearing or discretionary review is required. The City must approve or deny a completed application within 60 days of receipt [§ 9102.01.080].

Accessory Dwelling Unit (ADU) Regulations in Arcadia, CA