Check your property's zoning, browse designs & get contractor estimates for your ADU project:
Last Updated 09/16/21
City Hint: The City of Riverside permitted a total of 61 ADU projects in the past year of 2020.
Number of ADUs allowed:
1.Single-family: The number of dwellings permitted on a single lot in any single-family residential zone shall be limited to the primary dwelling, one ADU and one JADU.
A. Existing Structures
- At least one ADU, but no more than 25 percent of the existing number of multi-family dwellings, shall be permitted within existing structures on lots with multi-family dwelling structures.
- ADUs can include conversion of storage rooms, boiler rooms, passageways, attics, basements or garages provided the ADU complies with building standards for dwellings
- No more than two new detached ADUs shall be permitted on a lot that has an existing multi-family dwelling.
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). Also, multi-family lots may now add one ADU per every four existing residential units, so long as they were legally established.
Types of ADUs allowed:
Detached ADU, Attached ADU, Junior ADU are approved. ADUs may be new construction or converted from existing space. JADUs must be converted from existing space.
Residential properties will not be subject to any minimum lot size for Accessory Dwelling Unit (ADU)s by ordinance or of the underlying zoning district. ~ Updated: State Law AB-68
The floor area of an ADU or JADU shall not be counted when calculating lot coverage.
1.The total floor space of an attached ADU shall not exceed 50 percent of the existing primary dwelling living area or 1,200 square feet, whichever is less.
2.The total floor space of any detached ADU shall not exceed 1,200 square feet.
3.JADUs shall be no more than 500 square feet in size.
ADUs are allowed in the side and rear yards but are not allowed in front yards. In the side and rear yards, ADUs must be set back at least four feet from all property lines and from other buildings
1.No parking shall be required for an ADU or JADU.
2.No replacement parking shall be required for the primary dwelling if a garage, carport or covered parking is converted to an ADU.
Fire sprinklers are not required for the ADU unless they are also required for the primary unit.
Shape, materials and style:
ADU Design: No exterior stairways may be located on the side of the structure facing a public right-of way, except for alleyways.
ADUs are subject to the same height and story limits set by the Zoning Code for the primary dwelling. In most areas of the City, the maximum height is 35 feet and two stories. ADUs may also be constructed above existing structures such as garages or as second-story additions to the primary dwelling.
ADUs will be reviewed in a Ministerial process, without discretion, and will be approved or denied within 120 days of application, according to state law.
Number of Bedrooms:
Not specified by State Standards.
An ADU can be rented separately from the primary dwelling. The property owner does not have to occupy one of the homes on the property to rent either home to other occupants. An ADU cannot be sold or conveyed separately from the primary dwelling except in limited circumstances by nonprofit affordable housing organizations
1. ADUs shall not be considered a new residential use for the purposes of calculating connection fees or capacity charges for utilities, including water and sewer service unless the ADU is constructed with a new single-family dwelling.
2.A new or separate utility connection, connection fee, or capacity charge shall not be required by the utility provider for an ADU located within the existing primary dwelling unit.
3.A new or separate utility connection, connection fee, or capacity charge shall not be required by the utility provider for an ADU unless the ADU is constructed with a new single-family dwelling.
4.For new ADUs on a lot with an existing primary dwelling unit, the connection may be subject to a connection fee or capacity charge that shall be proportionate to the burden of the proposed ADU, based upon either its size or the number of its plumbing fixtures, upon the water or sewer system.
5.ADUs served by a private sewage system shall comply with County Health Department requirements, as applicable.
*** Beginning in 2020, according to state law, all residential zoning districts, including single-family and multi-family, are allowed to build Accessory Dwelling Units. ***
Accessory dwelling units are allowed in all single family residential zones.
Lot Coverage: Maximum lot coverage shall comply with that of the underlying zone.
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 797 sqft
54 ft x 19 ft
ADU Model 1000 sqft
50 ft x 20 ft
ADU Model 240 sqft
20 ft x 12 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.