ADU Rules in Riverside, CA (2026)
ADU rules, permit requirements, size limits, and fees for Riverside, CA. Source-cited from official municipal code.
Yes, ADUs are allowed in Riverside, CA.
Riverside, CA permits accessory dwelling units (ADUs) on residential properties. ADUs — also called granny flats, in-law units, backyard cottages, or secondary suites — are secondary housing units on a single-family or multifamily lot. California state law actively preempts local restrictions, making ADU approval a streamlined ministerial process. In Riverside, the local building department handles ADU permit applications. Below you will find the current size limits, setbacks, fees, and timeline for building an ADU in Riverside.
ADU Size Limits
ADU Size Limits in Riverside: Detached ADU: up to 1200 sq ft (max height: 16 feet). Attached ADU: size varies by zoning — see official source. Junior ADU (JADU): up to 500 sq ft — must be within the existing primary dwelling or accessory structure. Detached ADU maximum 1,200 sqft per California Gov Code §66314(d)(5) (Stats. 2024 Ch. 7 §20). JADU maximum 500 sqft within existing space of primary structure per Gov Code §66333 (Stats. 2024 Ch. 7 §20). Riverside's Inland Empire housing market is more affordable than coastal LA but has appreciated significantly in the past decade — ADU rental income provides meaningful cash flow. Riverside's R-1 lots typically range from 7,000-12,000 sqft — larger than coastal LA, facilitating detached ADU placement. Riverside Municipal Code Chapter 19.060.
| Type | Max Size | Max Height |
|---|---|---|
| Detached ADU | 1200 sq ft · Verified June 7, 2026 · Source | 16 feet · Verified June 7, 2026 · Source |
| Attached ADU | See official source | See official source |
| JADU | 500 sq ft · Verified June 7, 2026 · Source | Within existing structure |
Permit Fees
ADU Permit Fees in Riverside: Plan check fee: Varies. Building permit fee: Varies. Impact fees: None. School fees: None or N/A. Total estimated permit cost: Varies.
| Fee Type | Amount |
|---|---|
| Plan Check | $350–$1,800 |
| Building Permit | $700–$3,500 depending on valuation |
| Impact Fees | None |
| School Fees | Exempt for ADUs under 500 sqft. Riverside Unified School District development fees apply for ADUs 500+ sqft. |
| Total Estimate | See official source |
Permit Timeline
Riverside ADU Permit Timeline: The permitting agency shall either approve or deny the application to create or serve an accessory dwelling unit within 60 days from the date the permitting agency receives a completed application if there is an existing single-family or multifamily dwelling on the lot. Apply through the local building department online permit portal. Contact them through their official website for current contact information.
Setback Requirements
ADU Setback Requirements in Riverside: Front setback: follows zone standard. Side setback: 4 feet. Rear setback: 4 feet.
Parking Requirements
Parking Requirements: Parking requirements have not been confirmed — see official source.
Restrictions & Requirements
- ADU must comply with Riverside Municipal Code Chapter 19.060 objective standards
- ADU cannot be sold separately from primary dwelling (unless Urban Lot Split per Gov Code §66411.7 applies)
- ADU must have permanent foundation
- Riverside's hillside areas (Box Springs Mountain, Lake Hills) may have additional grading requirements
- Santa Ana River floodplain properties require elevated construction per FEMA SFHA standards
How Many ADUs Are Allowed?
Number of ADUs Allowed in Riverside: Single-family lots: not confirmed — see official source. Multifamily properties: not confirmed — see official source.
- Single-Family Lots
- 1 ADU + 1 JADU per single-family lot
- Multifamily Properties
- Up to 25% of existing units (minimum 2) as detached ADUs; internal non-livable space conversions per unit
Statewide Preemption
ADU Preemption
California state law preempts local ADU rules — local governments cannot impose stricter standards.
View California preemption detailsState Law & Preemption
State Preemption: CA state law preempts local ADU restrictions. Riverside must approve compliant ADU applications by right.
Frequently Asked Questions
Can I build an ADU in Riverside?
Yes. Riverside, CA allows accessory dwelling units. On a single-family lot you can build 1 ADU + 1 JADU per single-family lot.
How big can an ADU be in Riverside?
The maximum size for a detached ADU in Riverside is 1,200 square feet. A Junior ADU (JADU) can be up to 500 square feet.
How long does it take to get an ADU permit in Riverside?
The typical ADU permit timeline in Riverside is The permitting agency shall either approve or deny the application to create or serve an accessory dwelling unit within 60 days from the date the permitting agency receives a completed application if there is an existing single-family or multifamily dwelling on the lot.. Total estimated permit fees are $1,500–$6,500 total permit fees — lower than LA metro but higher than Central Valley cities.
Do I need extra parking for an ADU in Riverside?
Riverside parking rules for ADUs: No additional parking required for ADUs within one-half mile of Metrolink Riverside stations or RTA bus rapid transit routes. No replacement parking when garage converted to ADU. Per California Gov Code §66322(a)(1) and §66314(d)(11) (Stats. 2024 Ch. 7 §20).
Do I have to live on-site to have an ADU in Riverside?
Owner-occupancy requirement in Riverside: No additional standards, other than those provided in Section 66314, shall be used or imposed, including an owner-occupant requirement.
Source: Riverside Municipal Code Chapter 19.060 (Zoning); California Government Code §§66314–66333 (Stats. 2024 Ch. 7 §20). Last verified April 6, 2026. View source