Riverside permits ADUs, junior ADUs (JADUs) and movable ADUs (MADUs) under Municipal Code Chapter 19.442. Any residential property can add at least one ADU under state law, and single-family lots can also add a JADU or MADU.[1]
What is an ADU? An accessory dwelling unit is a small second home on the same lot as the main house: a backyard unit, garage conversion, attached addition or guest house with its own kitchen and bath.
California cities can set their own ADU rules, but never stricter than state law. Grey lines show the state floor from the HCD ADU Handbook.
| Size limits | Detached ADU: up to 1,200 sq ft of livable space. Attached ADU: up to 1,200 sq ft or 50% of the primary dwelling, whichever is less, with a floor of at least 850 sq ft (one bedroom or less) or 1,000 sq ft (two or more bedrooms). JADU: up to 500 sq ft. MADU: 150 to 430 sq ft measured within the exterior faces of the exterior walls.[1][2] State law: a city's maximum size must allow at least 850 sq ft, or 1,000 sq ft for more than one bedroom, and local rules cannot block an 800 sq ft ADU with 4 ft side and rear setbacks (Gov. Code 66321).[3] |
|---|---|
| Height | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: detached ADUs get at least 16 ft; 18 ft within a half mile walk of a major transit stop or high-quality transit corridor (plus 2 ft to match roof pitch) or on a lot with a multistory multifamily building; attached ADUs up to 25 ft or the main home's limit if lower (Gov. Code 66321).[3] |
| Setbacks | ADUs are allowed in side and rear yards, not in front yards. A second story cannot sit in the side or rear setback.[1] State law: side and rear setbacks can be no more than 4 ft for new ADUs; converted existing space needs no new setback (Gov. Code 66314, 66323).[3] |
| Parking | No parking required for an ADU, per the city FAQ.[1] State law: at most 1 space per ADU or per bedroom, whichever is less, and none within a half mile walk of public transit, in a historic district, within one block of a car share, or for ADUs inside the house (Gov. Code 66314, 66322).[3] |
| Owner occupancy | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: no owner occupancy requirement for ADUs (Gov. Code 66315). A JADU requires the owner to live on site if it shares a bathroom with the main home (Gov. Code 66333).[3] |
| Permit steps and timeline | A building permit is required. Plans must be prepared by a licensed design professional and submitted to Building and Safety for plan check.[1] State law: the city must approve or deny a complete application within 60 days when there is an existing home on the lot (Gov. Code 66317).[3] |
| Fees | No city-specific figure verified. The state minimum below applies; confirm local details with the city. State law: no impact fees on ADUs of 750 sq ft or less; above that, impact fees must be proportional to the size of the main home. Plan check, permit and school fees can still apply.[3] |
Also worth knowing: On a single-family lot the city allows the primary dwelling, one attached ADU, one detached ADU or MADU, and one JADU.[1]
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Sources
Every fact above links to an official city or state page. Rules change; check the source before you build.
- [1] City of Riverside: ADU, JADU and MADU FAQs (2022) checked Oct 2026
- [2] Riverside Municipal Code Ch. 19.442 (Accessory Dwelling Units) checked Oct 2026
- [3] HCD ADU Handbook (March 2026) checked Oct 2026