ADU rules in San Diego County
What state law allows on any property in San Diego County, and which cities ADUCheck covers in full. Updated November 6, 2026.
State rules apply now. The City of San Diego comes first. Enter an address to see which rules apply to it.
What state law allows anywhere in San Diego County
Every city must allow at least this much. A city can allow more, never less. State rules current to November 6, 2026.
- Detached ADU
Up to 1,200 sq ft. At least 800 sq ft is always allowed.
- Height
16 ft; 18 ft within half a mile of transit, plus 2 ft for a roof that matches the home.
- Setbacks
4 ft from the side and back of the property.
- Parking
None needed within half a mile of transit, or for a conversion.
- Fees
No impact fees up to 750 sq ft. No school fees up to 500 sq ft.
- Timeline
The city must decide within 60 days of a complete application.
Cities in San Diego County
19 cities get the state rules today.
- CarlsbadState rules only
- Chula VistaState rules only
- CoronadoState rules only
- Del MarState rules only
- El CajonState rules only
- EncinitasState rules only
- EscondidoState rules only
- Imperial BeachState rules only
- La MesaState rules only
- Lemon GroveState rules only
- National CityState rules only
- OceansideState rules only
- PowayState rules only
- San DiegoState rules only
- San MarcosState rules only
- SanteeState rules only
- Solana BeachState rules only
- Unincorporated San Diego CountyState rules only
- VistaState rules only