ADU rules in San Diego
The key facts first, then what we've learned building there.
The snapshot
Checked October 2026. We re-check every lot against the current code.
San Diego
| Rule | Answer |
|---|---|
| Detached ADU size | Up to 1,200 sq ft |
| Setbacks | 4 ft side and rear |
| Height | 16 ft; 18 ft near transit; 25 ft attached |
| Selling an ADU separately | Allowed: San Diego opted in to AB 1033, so an ADU can be sold as a condo, with conditions |
| Coastal zone | Ocean Beach, Pacific Beach, La Jolla and other coastal areas may need a coastal permit; the Coastal Height Limit applies near the beach |
| Fire hazard map | The city's updated fire map took effect August 30, 2025 |
| Legalizing an existing unit | Yes, under the city's guidance for unpermitted ADUs |
| SB 1211 apartment ADUs | Yes |
| Utilities | SDG&E |
| Building department | Development Services Department (DSD) |
What's different here
San Diego is one of the few cities that opted in to AB 1033, so an ADU can be split off and sold as a condo, with conditions. It changes how we lay out the lot from the start.
In Ocean Beach, Pacific Beach, La Jolla and other coastal areas, an ADU may need a coastal permit, and the Coastal Height Limit applies near the beach.
The city adopted its updated fire hazard map in 2025. In a mapped zone, the ADU gets ember-resistant construction and access checks.
The city has guidance for bringing unpermitted ADUs up to code. We inspect, draw what's needed and take it through DSD.
What applies here
Turn an older unpermitted unit into a legal, rentable home.
Learn moreSince January 2025, California lets an existing apartment property add detached ADUs, one for every existing unit up to eight, plus conversions of garages and storage.
Learn moreSB 9 lets a single-family lot be split in two, with up to two homes on each.
Learn moreCities must now keep a set of pre-approved ADU plans.
Learn morePlans that fit
Ready-drawn plans we adapt to your lot and your city.
Ask about your address
We check the lot against these rules and tell you what fits.