San Diego has its own ADU rules in the Municipal Code, explained in Information Bulletin 400, plus an ADU Bonus Program for deed-restricted affordable units.[1]
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 | 150 to 1,200 sq ft gross floor area. One ADU up to 800 sq ft is allowed even when it pushes the lot over its floor area ratio. Conversions of existing space are not held to the 1,200 sq ft cap.[1] 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).[4] |
|---|---|
| Height | On single-family-only lots, detached ADUs may not exceed two stories, and all ADUs follow the base zone and overlay zone height limits.[1] 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).[4] |
| Setbacks | Converted or rebuilt structures may keep their existing setbacks. Other cases follow IB 400; Coastal Overlay projects follow Housing Action Package 1.0 setbacks.[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).[4] |
| Parking | No parking required outside the Coastal Overlay Zone. Inside it, one space can be required only in the Beach Impact Area outside a transit priority area, with exceptions.[1][2] 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).[4] |
| Owner occupancy | A JADU or the main home must be owner occupied if the JADU shares a bathroom. A JADU agreement is recorded before the permit.[2] 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).[4] |
| Permit steps and timeline | A building permit is required for every ADU or JADU, with no exemptions. Coastal Overlay projects may also need a Coastal Development Permit. The city accepts County of San Diego and Encinitas permit-ready plans if they meet city submittal rules.[1][2] 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).[4] |
| Fees | ADUs pay school fees and the General Plan Maintenance Fee, and are subject to Development Impact Fees per city rules. Full list: Information Bulletin 501.[1] 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.[4] |
Also worth knowing: Bonus program: ADUs deed restricted as affordable for 15 years can earn bonus ADUs; inside Transit Priority Areas there is no cap on the total.[1]
We connect you with builders who serve your area. Free, no obligation.
Sources
Every fact above links to an official city or state page. Rules change; check the source before you build.
- [1] City of San Diego: Information Bulletin 400 (Jan 2026) checked Oct 2026
- [2] City of San Diego: ADU/JADU program checked Oct 2026
- [3] City of San Diego Planning: Accessory Dwelling Units checked Oct 2026
- [4] HCD ADU Handbook (March 2026) checked Oct 2026