Accessory Structures in Riverside County, CA (2026)

6 county-level rules, plus city-specific rules for 8 cities in Riverside County, California.

Verified from official government sources

Note: These county rules apply to unincorporated areas of Riverside County. If you live within an incorporated city, that city's own rules apply: see the city list below.

ADU Rules

Riverside County caps non-ministerial ADUs at 1,000 square feet with a 16-foot height limit and 4-foot side/rear setbacks in the unincorporated area, applying to ADUs that don't qualify for the state's ministerial approval track.

Riverside County ADU Size and Height Limits

Some Restrictions

Riverside County Code § 17.294.080(D)(1)(a)

One-family dwelling: The maximum floor area shall not exceed fifty (50) percent of the primary dwelling's floor area. If fifty (50) percent of the primary dwelling's floor area is less than eight hundred (800) square feet than the maximum floor area shall be eight hundred (800) square feet. In no event shall the maximum floor area exceed one thousand (1,000) square feet.

Full ordinance details →Official source ↗

ADU Impact Fees

Riverside County calculates accessory dwelling unit impact and connection fees under County Code Section 17.294.070, tied to Government Code Sections 65852.2 and 65852.22 and County Ordinance No. 659. Attached and interior ADUs skip a new utility hookup, while detached ADUs, second units and MOG units can be required to add one. Section 4.62.100 exempts ADUs from the county's MSHCP mitigation fee, but only to the extent state law requires it.

Riverside County ADU Impact and Connection Fees

Some Restrictions

Riverside County Code § 17.294.070; § 4.62.100(C)

17.294.070 - Fees and utility connections. A. Impact and connection fees shall be calculated in accordance with applicable state and local laws and regulations including, but not limited to, Government Code Sections 65852.2 and 65852.22, and Riverside County Ordinance No 659. B. An attached/interior ADU or junior ADU shall not be required to install a new or separate utility connection directly...

Full ordinance details →Official source ↗

ADU Owner Occupancy

Riverside County's owner-occupancy rule for accessory dwelling units turns on the permit date. Under County Code Section 17.294.090(A)(1), owners of an ADU permitted between January 1, 2020 and June 1, 2025 do not have to live on the property, but owners of any ADU permitted after June 1, 2025 must occupy either the primary dwelling or the ADU, proven with utility bills, ID or official mail.

Riverside County ADU Owner-Occupancy Rule

Some Restrictions

Riverside County Code § 17.294.090(A)(1)

17.294.090 - Occupancy and fire protection. A.Occupancy.1.Accessory dwelling unit. Property owners shall not be required to occupy, or live within, the primary dwelling or ADU located on the same lot, if the ADU is permitted between January 1, 2020 and June 1, 2025. If an ADU is permitted after June 1, 2025, property owners must occupy, or live within, the primary dwelling or ADU located on the...

Full ordinance details →Official source ↗

ADU Rental Restrictions

Riverside County bars renting an accessory dwelling unit, junior ADU, second unit, or ranchet for 30 days or less, so any lease on these additional residential accommodations must run at least 31 days in the unincorporated county.

Riverside County ADU 31-Day Rental Minimum

Some Restrictions

Riverside County Code § 17.294.090(A)(6)

5.Except for guest quarters and MOG units, additional residential accommodations may be rented to and occupied by any person(s) in accordance with occupancy requirements provided in this chapter... 6.Additional residential accommodations shall not be rented for a period less than or equal to thirty (30) days.

Full ordinance details →Official source ↗

Shed & Carport Rules

In unincorporated Riverside County, a shed or other non-habitable detached accessory building must sit no closer to the front lot line than the house, cannot exceed two stories or 40 feet, and needs a plot plan once it tops 5,000 square feet.

Riverside County Shed and Accessory Building Rules

Some Restrictions

Riverside County Code § 17.172.130

Detached accessory buildings and structures are allowed on lots where the principal use of the lot is a one family dwelling...Detached accessory buildings or structures shall not be located closer to the front lot line than the principal dwelling on the same lot, except the planning director may...allow detached accessory buildings or structures to be setback a minimum of twenty-five (25) feet ...

Full ordinance details →Official source ↗

Tiny Homes

Riverside County allows tiny homes and residential shipping containers as a use by right in the R-7 and MU zones and in any zone that permits one-family dwellings or ADUs, under County Code Chapter 17.314. A tiny home cannot exceed 500 square feet, must sit on a concrete slab, and is capped at 25 feet in height with 5-foot side and rear setbacks on a lot of at least 1,500 square feet.

Riverside County Tiny Home Zoning Rules

Some Restrictions

Riverside County Code §§ 17.314.030(A), 17.314.070

17.314.030 - Location and permit processing. A.Except as otherwise provided in this chapter, tiny homes and residential shipping containers are allowed as a use by right in the R-7 and MU zone classifications as well as in all zoning classifications that permit one-family dwellings or accessory dwelling units. ... 17.314.070 - Development standards. A.Lot size. The minimum lot size shall be one...

Full ordinance details →Official source ↗