What the City of San Diego's own companion and junior unit page says — sizes, setbacks, parking, preapproved plans, and the details that surprise people.
Summarized from the City of San Diego's official ADU page (Development Services — Companion & Junior Units) — nothing here comes from aggregators or other cities' rules. Rules change; confirm the current standards with the city before relying on them.
| What counts | An ADU is an attached or detached unit with complete independent living facilities — kitchen, sleeping, sanitation, living — on a lot with a proposed or existing primary residence. A JADU is a smaller unit contained entirely within a single-family residence (150–500 sq ft), with a kitchen or efficiency kitchen; it may share sanitation with the main home. |
| Where allowed | ADUs in single, multiple, and mixed-use zones. JADUs in single residential zones. |
| How many | Per the city's comparison table: 2 ADUs in single-dwelling zones; one JADU. |
| Size | ADU: 150–1,200 sq ft. JADU: 150–500 sq ft. |
| Setbacks | A new detached structure must meet the zone's front setback. An ADU may encroach into side, street-side, and rear setbacks — in some cases up to the property line. If the side or rear line adjoins residential premises and the ADU is over 16 ft tall, a 4-ft side and rear setback applies. In a Very High Fire Hazard Severity Zone, a minimum 4-ft side and rear setback applies regardless of height. Under 16 ft and outside the fire zone, no rear or side setback is needed. Exterior stairs, balconies, and decks may not encroach. |
| Parking | No parking required for an ADU, except in the Beach Impact Area. When a garage converts, replacement parking is not required — except in the Beach Impact Area outside a Transit Priority Area (one space, with exceptions, including units of 500 sq ft or less). |
| Owner occupancy | If a JADU shares sanitation with the main home, the JADU or the single-family residence must be owner-occupied. A recorded JADU Agreement is required. |
| Permits | A building permit is required to create an ADU or JADU — there are no exemptions. |
Published ranges by type, the educational estimator, cost drivers, and fee notes.
Read the guide →Eight quick questions and a plain-language likely / maybe / talk-to-the-city result.
Read the guide →Next door, different details — La Mesa's pre-approved PADU plans and how to use them.
Read the guide →That feasibility conversation — your lot, your city's current rules, your utilities, your budget — is the real answer to every cost and rules question. It is exactly what a match request starts: one licensed local builder, matched to your project, and nobody else.
The intake form lives on our main page — that page states whether intake is currently open.
San Diego ADU Match is a matching service, not a contractor. We never quote or estimate a price for your property, and we do not give feasibility or legal opinions — those calls belong to licensed builders and your city. Guides on this site are general information, not advice about your property.