City ADU planning guide

Riverside ADU regulations and next steps

Start with the most important planning decisions, then review the detailed city rules below before choosing a detached ADU plan or requesting a property-specific feasibility review.

Riverside ADU rules overview

Detailed local requirements vary by property. Use this section as a starting point for setbacks, parking, height, utilities, and approval considerations.

Lot fit

Setbacks and buildable area

Start with rear and side setbacks, lot coverage, access, and where a detached ADU can realistically sit on the property.

Design limits

Size, height, and unit type

Check whether the property is better suited for a detached ADU, attached ADU, garage conversion, or junior ADU.

Approvals

Parking, utilities, and permits

Confirm parking exemptions, utility connection requirements, impact fees, and city review steps before finalizing plans.

Types of ADUs Allowed:

  • Riverside permits several types of ADUs
    • Detached ADUs: These are standalone units that are separate from the main house, often built in the backyard or another area of the property.
    • Attached ADUs: These units are physically connected to the primary residence, such as converting a garage or adding a unit above the existing home.
    • Junior ADUs (JADUs): These are smaller units, typically up to 500 square feet, created by converting a portion of the primary dwelling, such as a bedroom, basement, or garage.

Zoning and Location Requirements:

  • Permitted Zones ADUs are allowed in most residential zones in Riverside, including single-family (R-1) and multi-family (R-2, R-3, etc.) zones, subject to meeting specific zoning and development standards.
  • Lot Size Riverside does not impose a minimum lot size for the construction of an ADU. However, the ADU must meet other zoning requirements like setbacks, height limits, and lot coverage.

Size Limits for ADUs:

  • Detached ADUs
    • The maximum size for a detached ADU is generally 1,200 square feet.
    • Larger ADUs may be allowed if specific conditions are met, depending on the property's size and configuration.
  • Attached ADUs
    • An attached ADU can be up to 50% of the existing living space of the primary dwelling, with a maximum size of 1,200 square feet.
  • Junior ADUs (JADUs)
    • JADUs are smaller, with a maximum size of 500 square feet.

Setbacks and Lot Coverage:

  • Setbacks
    • Rear Setback: A detached ADU typically requires a 4-foot setback from the rear property line.
    • Side Setback: ADUs must generally have a 4-foot setback from the side property lines as well.
    • Front Setback: The front setback for ADUs typically follows the setback requirements of the primary dwelling, although exceptions may apply in some cases (e.g., second-story units).
  • Lot Coverage Riverside’s zoning code limits the total coverage of a property, including both the primary home and the ADU. The total lot coverage depends on the zoning district but is typically between 40% and 50%.

Parking Requirements:

  • Parking Exemptions: Riverside follows state law that exempts parking requirements for ADUs in certain circumstances
    • No additional parking is required for ADUs that are located within ½ mile of a public transit stop.
    • Junior ADUs (JADUs) do not require additional parking.
    • No parking is required for ADUs created by converting an existing garage or carport.
  • Standard Parking Requirements If no parking exemptions apply, one off-street parking space is generally required for each ADU. This space can be located in a garage, a driveway, or in tandem with other vehicles.

Height Limits:

  • Detached ADUs The maximum height for a detached ADU is typically 16 feet.
  • Attached ADUs The height limit for attached ADUs is generally the same as the height limit for the primary residence, though this may vary depending on the zoning district and the specific design.

Design and Aesthetic Requirements:

  • Architectural Compatibility ADUs must be designed to be compatible with the primary dwelling in terms of materials, colors, and architectural style. This ensures that the ADU blends in with the neighborhood and complements the overall look of the property.
  • Privacy Considerations New ADUs must be designed to respect the privacy of neighboring properties. For example, window placements may be adjusted, or screening may be used to prevent overlooking adjacent homes.
  • Building Materials ADUs should use similar or complementary building materials to the primary dwelling to maintain architectural consistency.

Permit and Approval Process:

  • Ministerial Approval Riverside’s ADU approval process is typically ministerial, meaning that as long as the project complies with zoning and building codes, it is approved without the need for discretionary review, public hearings, or complex approvals.
  • Expedited Review California law requires that ADU applications be reviewed and either approved or denied within 60 days of submission for most standard applications.
  • Building Permits ADUs in Riverside must comply with all applicable building codes, including electrical, plumbing, and safety standards, as well as any additional health and safety codes.

State Laws Affecting ADUs in Riverside:

  • SB 9 (2021) This California law allows for the development of up to two residential units on single-family lots. This can include ADUs in addition to the primary dwelling. SB 9 provides a streamlined approval process for small lot splits and can be combined with ADU construction to increase the number of units on a property.
  • SB 13 (2019) and AB 68 (2019)
    • These state laws have simplified the process of constructing ADUs by reducing restrictions on parking, setbacks, and fees for smaller units. Riverside follows these state mandates, meaning that ADUs are subject to more flexible zoning rules than in the past.

Impact Fees:

  • Impact Fees Riverside charges impact fees for ADUs larger than 750 square feet. These fees are used to support infrastructure needs such as parks, schools, and roads. The exact fee amount depends on the size of the ADU and the property's location.
  • Affordable Housing Fees Riverside may also charge an affordable housing fee for ADUs, depending on the size of the unit. ADUs under 750 square feet are typically exempt from impact fees, but larger units may be subject to these fees.

Utilities and Services:

  • Utility Connections ADUs must be connected to the same utilities as the primary residence (water, sewer, electricity, etc.). If the existing utility infrastructure is insufficient, homeowners may need to upgrade or install new utility lines.
  • Water Conservation ADUs must comply with California’s water conservation requirements, including the installation of low-flow fixtures and water-efficient appliances to reduce water consumption.

Incentives and Financing:

  • Financing Options Homeowners may be able to access financing programs, such as California Housing Finance Agency (CalHFA) ADU financing or other local programs, to help fund the construction of an ADU.
  • Fee Reductions Riverside may offer reduced or waived fees for ADUs that provide affordable housing or for projects located near transit hubs or major transportation corridors.
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