# ADU permits in the City of San Diego

> San Diego goes further than state law in several places, most visibly on setbacks. It also has more conditions attached than its reputation suggests, and a different rulebook near the coast.

Source: https://www.lotlinepermits.com/california/san-diego/
Publisher: Lotline
Last reviewed: 2026-11-10

## Key points

- A new ADU can be built up to the side and rear property line, unless the building code requires separation. [1]
- Over 16 feet tall next to residential property, a 4-foot setback returns. [1]
- In a Very High Fire Hazard Severity Zone, 4 feet applies at any height. [1]
- Parts of the bulletin don't yet apply in the Coastal Overlay Zone. [1]

## State rule and San Diego practice

| Topic | California statute | San Diego |
|---|---|---|
| Side and rear setback | For a new ADU that is not a conversion, the side and rear setback a city requires can be no more than four feet. [2] | A new detached ADU may encroach into the zone's side and rear setbacks, up to the property line, unless the California Building Standards Code requires otherwise. [1] Note: The city allows less than the four feet state law permits a city to require. Fire separation rules in the building code still decide how close a wall with windows can sit. |
| Fire sprinklers | An ADU does not need fire sprinklers if they are not required for the primary residence. [2] | An ADU must have automatic fire sprinklers if the primary dwelling on the premises is protected by a sprinkler system. [1] |
| Replacement parking | When a garage, carport or parking space is demolished for or converted to an ADU, the local agency cannot require replacement off-street parking. [2] | No parking spaces are required for ADUs outside the Coastal Overlay Zone. [1] |

## The document to read

San Diego publishes its ADU building permit guidance as Information Bulletin 400, and the version in force when we read it is dated January 2026. [1] A building permit is required for every ADU and JADU, with no exemptions. [1]

## How many, and how big

On a lot in a single dwelling unit zone, the city allows one attached or detached ADU, one more converted from existing space, and one JADU. [1]

An attached or detached ADU can be up to 1,200 square feet of gross floor area. [1] Conversions of an existing accessory structure or part of the house aren't held to that cap. [1] And where the existing house has already used up the zone's floor area ratio, one ADU of up to 800 square feet can still be built. [1]

## Setbacks, with the conditions that matter

The headline is that a new ADU may encroach into the side and rear setbacks all the way to the property line. [1] Three conditions narrow it:

1. **Height.** Beside a residential neighbor, a structure over 16 feet has to keep a minimum of 4 feet at the interior side and rear, or the zone's own setback if smaller. [1]
2. **Fire hazard zone.** In a Very High Fire Hazard Severity Zone, the 4 feet applies whatever the height. [1]
3. **Fire official.** The Fire Code Official can require more, and so can a Brush Management Zone. [1]

At the front, the ADU observes the zone's setback, though one ADU of 800 square feet or less may encroach into it. [1]

> **Tip:** Check the fire hazard map for your address before sketching a unit on the lot line. It changes the answer.

## Near the coast

The bulletin opens with a warning that some of its rules aren't effective in the Coastal Overlay Zone, because later ordinances are still awaiting Coastal Commission certification. [1] A Coastal Development Permit is required there for ADUs and JADUs that aren't wholly inside the existing primary structure, that add habitable area, or that convert non-habitable space. [1]

## Living in it, renting it, selling it

- The owner doesn't have to live on site. [1]
- An ADU can't be leased for less than 31 consecutive days. [1]
- ADUs may be subdivided into condominiums and sold separately, under conditions set out in the Municipal Code. [1]
- A JADU needs a recorded Junior Unit Agreement before its permit is issued. [1]

## What to submit

Applications are made digitally through an Online Permitting Account. [1] Besides the plans and calculations, three forms are listed: the General Application (DS-3032), the Water Meter Data Card (DS-16) and the Storm Water Applicability Checklist (DS-560). [1]

A newly built detached ADU that isn't a manufactured unit falls under the Energy Code's solar requirement, and the panels can be placed on the ADU or on the main house. [1]

If you use a preapproved plan, the application is subject to a 30-day review. [1]

## Fees to expect

School fees apply to ADUs and JADUs. [1] So does the city's General Plan Maintenance Fee. [1] The bulletin points to a separate fee bulletin for the full list, which we haven't summarized here.

## Our read

San Diego rewards a careful first hour of site research. Whether your lot is in the Coastal Overlay Zone or a Very High Fire Hazard Severity Zone decides which version of the rules you are reading, and both can be checked on the city's zoning portal before you pay for drawings.

## Frequently asked questions

### Can I build an ADU right on the property line in San Diego?

The city allows a new ADU to encroach into the side and rear setbacks up to the property line, unless the building code requires separation. [1] A 4-foot setback applies above 16 feet next to residential property [1] and in a Very High Fire Hazard Severity Zone. [1] For how openings near a lot line are treated elsewhere, see [Oakland's fire separation rules](https://www.lotlinepermits.com/california/oakland/#fire-separation).

### Can I use my San Diego ADU as a short-term rental?

An ADU may not be leased for a term of less than 31 consecutive days. [1]

### Does an ADU in San Diego need solar panels?

A newly built detached ADU that is not a manufactured unit is subject to the Energy Code's solar requirement, and the panels can go on the ADU or the main house. [1]

## References

1. Information Bulletin 400: Accessory Dwelling Unit/Junior Accessory Dwelling Unit (January 2026). City of San Diego, Development Services Department. https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400 (read 2026-11-10)
2. California Government Code, Title 7, Division 1, Chapter 13, Article 2 (Sections 66314 to 66331). California Legislative Information. https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=GOV&division=1.&title=7.&part=&chapter=13.&article=2. (read 2026-11-10)

General information only, not legal advice. See https://www.lotlinepermits.com/disclaimer/