ADU builders and rules in City of San Diego

This page covers addresses inside City of San Diego limits. Lakeside, Ramona, Spring Valley and other unincorporated areas follow the County's ADU rules, and other cities such as Poway and Coronado run their own. For the permit process in depth, read our San Diego ADU permit guide.

City of San Diego ADU rules

The city's ADU regulations sit in San Diego Municipal Code § 141.0302. An ADU permit is ministerial: if your plans meet the objective rules, the city must approve them without a public hearing.

Two points make San Diego unusual. First, the city lets you build a 1,200 sq ft ADU with no interior side or rear setback as long as it stays at 16 feet or under, which suits narrow lots. Second, the city opted into the state law that lets an ADU be sold separately as a condominium, so an ADU can become its own property. For the state rules behind these numbers, see California ADU laws.

On a single-family lot, state law guarantees at least a conversion ADU, a detached ADU and a junior ADU. Starting January 1, 2027, AB 956 adds the right to two detached ADUs on single-family lots statewide. Deciding between a backyard unit and an addition? Compare attached vs. detached ADUs and two-story ADUs.

The ADU Home Density Bonus

San Diego went beyond state law with a bonus program that let owners add extra ADUs in exchange for deed-restricted affordable units. In 2025 the city restricted the bonus on single-family lots: the total number of homes allowed now steps up with lot size, from 4 to 5 to 6 units in all. If a builder pitches a multi-unit backyard project, ask which lot-size tier applies to your parcel before you pay for design.

City of San Diego ADU fees

Fees depend mostly on size. A builder's published table gives a sense of the range; these are not the city's own schedule, so confirm your project with Development Services.

• Impact fees. State law bars impact fees on an ADU of 750 sq ft or less. San Diego's code goes further and exempts the first two ADUs on a property from development impact fees, whatever their size.
• School fees. None for an ADU under 500 sq ft. Above that, San Diego Unified charges $5.38 per sq ft. Confirm which school district serves your address, since the fee follows the district.
• Construction. Fees are a small share of the total. See what an ADU costs in San Diego or try the ADU cost calculator.

City of San Diego pre-approved ADU plans

A detached ADU built from a pre-approved plan must be reviewed within 30 days. The City of San Diego accepts permit-ready plans from the County of San Diego and other agencies, including Chula Vista and Encinitas, though the plan set still has to meet the city's submittal rules and fit your lot. The County's free plans come in 600, 800, 1,000 and 1,200 sq ft versions and are about 85% complete. Our guide to pre-approved ADU plans in San Diego compares the options, and ADU floor plans covers layouts.

Getting an ADU permit in the City of San Diego

1. Check your lot. Zone, fire hazard zone, Coastal Overlay Zone and transit distance decide setbacks and parking.
2. Prepare plans. Information Bulletin 400 lists what an ADU submittal needs, including the general application and a Water Meter Data Card.
3. Apply online through the Development Services application portal.
4. Plan review. State law gives the city 15 business days to confirm the application is complete and 60 days to approve or deny it. The city posts current review times on its permit timeline page.
5. Inspections. Passing the final inspection is your approval to occupy the ADU.

Garage conversions follow the same path; see our garage conversion ADU guide. Before you sign with anyone, read how to hire an ADU contractor and check a contractor's license.

Coastal zone ADUs

Most ADUs in the city's Coastal Overlay Zone also need a Coastal Development Permit. According to the city's ADU bulletin, the Coastal Commission certified the city's 2024 ADU rules for the coastal zone, but some later amendments were still awaiting certification, so a coastal lot can fall under an older version of the rules. Ask which version applies before you design.

Fire hazard zones

In high and very high fire hazard severity zones, even a low ADU needs a 4-foot side and rear setback. An ADU needs fire sprinklers only if the main house is required to have them, but if the house has sprinklers, the ADU must too.

Legalizing an unpermitted unit

If an ADU was built without permits before January 1, 2020, the city can't deny a permit to legalize it unless a fix is needed for health and safety, and it can't charge impact fees for it. San Diego's process is in Information Bulletin 242.

Financing and taxes

The San Diego Housing Commission's ADU Finance Program has offered loans of up to $250,000 to owners who rent the ADU at an affordable rent for seven years. Confirm with the Housing Commission whether funding is open before you plan around it. Other options are in our ADU financing guide and ADU grants in California.

Building an ADU doesn't reassess your whole property: the County Assessor adds only the new construction. For what an ADU can earn, see ADU rental income in San Diego.

Common questions