Check your property's zoning, browse designs & get contractor estimates for your ADU project:
Last Updated 09/16/21
City Hint: The City of Santa Ana permitted a total of 173 ADU projects in the past year of 2020.
Number of ADUs allowed:
According to state law, all single-family homes are allowed at least one Accessory Dwelling Unit (ADU). Additionally, single-family lots which are owner-occupied may create one Accessory Dwelling Unit (ADU) and one Junior Accessory Dwelling Unit (JADU).
Sites developed with a multi-family building may convert existing nonhabitable square footage within the building to a minimum of one (1) ADU and a maximum that shall not exceed twenty-five (25) percent of the number of units on the site. Sites developed with a multi-family building are also permitted to construct two (2) ADUs or to convert existing detached accessory buildings, garages, carports, or covered parking structures to a maximum of two (2) ADUs
Types of ADUs allowed:
Detached ADU, Attached ADU, Junior ADU are permitted. ADUs may be new construction or converted from existing space. JADUs must be converted from existing space.
Single family and multi-family residential parcels will not be subject to the minimum lot size of the underlying zoning district or by ordinance for Accessory Dwelling Unit projects. ~ AB-68
Detached ADU: max 1,000 sq. ft.
Attached ADU: Max 1,000 sq. ft.
JADU: Max 500 sq. ft.
-Attached ADUs may be fifty (50) percent of the size of the habitable space of the primary dwelling on the site, not to exceed 1,000 square feet in size.
-ADUs may not exceed 800 square feet in size in cases where both an ADU and JADU are developed or proposed on a site.
-Existing accessory structures may be converted into an ADU and may be expanded by up to 150 square feet of the existing footprint to accommodate ingress and egress only.
Side and Rear Setback requirement: 4 feet
No minimum setback shall be required for an ADU constructed in the same location and to the same dimensions as an existing structure that encroached into a required setback that was demolished to construct the proposed unit. This provision shall not apply to conversions of existing buildings.
One Parking space is required for attached or detached ADUs. No parking is required for JADUs.
No parking for the ADU is required if one or more of the following applies:
1. The ADU is located within one-half (1/2) mile walking distance of public transit.
2. The ADU is located within an architecturally and historically significant historic district.
3. The ADU is part of the proposed or existing primary dwelling or an existing accessory structure.
4. When on-street parking permits are required but not offered to the occupant of the ADU.
5. When there is a car share vehicle located within one (1) block of the ADU.
6. The ADU is constructed as a studio, without bedrooms.
When an existing garage, carport, or other covered parking structure is demolished in conjunction with the construction of an accessory dwelling unit, or converted to an accessory dwelling unit, replacement of those offstreet parking spaces shall not be required.
Fire sprinklers are not required for the ADU unless they are required for the primary dwelling.
Shape, materials and style:
The design and materials of the ADU shall be consistent with the primary dwelling.
Maximum height for attached and detached ADUs will be subject to the requirements of the underlying zone.
A local agency shall approve an application for a building permit to create within a single-family residential zone one accessory dwelling unit per single-family lot if the unit is contained within the existing space of a single-family residence or accessory structure, has independent exterior access from the existing residence, and the side and REAR setbacks are sufficient for fire safety. Accessory dwelling units shall not be required to provide fire sprinklers if they are not required for the primary dwelling.
Number of Bedrooms:
Not specified by State Standards.
Owner-occupancy will not be required for new Accessory Dwelling Units (conversion and new construction) built between 2020 and 2025. ~ SB-13
Approval by the local health officer where a private sewage disposal system is being used, if required.
ADUs and JADUs shall conform to the United States Secretary of Interior's Official Standards for the Treatment of Historic Properties.
Notwithstanding any other law, a local agency shall not impose parking
standards for an accessory dwelling unit in any of the following instances:
(1) The accessory dwelling unit is located within one-half mile of public
(2) The accessory dwelling unit is located within an architecturally and
historically significant historic district.
(3) The accessory dwelling unit is part of the existing primary residence
or an existing accessory structure.
(4) When on-street parking permits are required but not offered to the
occupant of the accessory dwelling unit.
(5) When there is a car share vehicle located within one block of the
accessory dwelling unit.
Entry & Access
No passageway shall be required in conjunction with the construction of an accessory dwelling unit.
*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***
The lot is zoned for single-family or multifamily use and contains an existing, single-family dwelling.
Local building code requirements that apply to detached dwellings, as appropriate.
Residential Building Code:
The California Building Code (CBC) 2019 is adopted.
ADU Design Library
Browse hundreds of models to find the right fit for your property.
ADU Model 375 sqft
25 ft x 15 ft
ADU Model 1120 sqft
35 ft x 32 ft
ADU Model 875 sqft
35 ft x 25 ft
This estimate is based on recently completed projects in the area and is inclusive of all typical soft costs such as permitting, design and engineering fees.