Building an ADU in San Diego

What you can build in San Diego

ADUs are generally allowed in zones that permit homes. Look up your zone in the city's Zoning and Parcel Information Portal (ZAPP). The city's rules are in San Diego Municipal Code Chapter 14, Article 1, Division 3, and DSD summarizes them in Information Bulletin 400 (January 2026).

Single-family zones. Besides the main house you can have one attached or detached ADU, one ADU converted from space in the house or an existing accessory building, and one junior ADU (JADU).

Multifamily zones. You can convert non-living space (storage rooms, garages, basements and similar) in an existing apartment building into ADUs, up to 25% of the existing units (at least one). You can also build up to eight detached ADUs on a lot with an existing apartment building, but no more than the number of existing units, or two on a lot with a proposed one. Attached ADUs are not allowed on multifamily lots. If a multifamily-zoned lot has a single house on it, the single-family rules apply.

Coastal Overlay Zone. Several recent rule changes, including the 2025 ADU and JADU amendments (O-21989), won't apply in the coastal zone until the Coastal Commission certifies them. Coastal ADUs follow the setback and landscape rules of Housing Action Package 1.0. Check the Coastal Overlay Zone map. Statewide rules are on our California page. [1][3]

Size, height and setbacks

Size. An ADU must be between 150 and 1,200 sq ft. Converting part of the house or an existing accessory building has no 1,200 sq ft cap, and you can add up to 150 sq ft only for entry and exit. A garage or carport under an ADU doesn't count toward its 1,200 sq ft.

Floor area ratio. ADU floor area counts toward the zone's floor area ratio (FAR), with an exception: one ADU of up to 800 sq ft is allowed even if it pushes the lot over the FAR limit.

Height. ADUs follow the height limit of the base zone and any overlay zone. On lots that allow only single-family homes, a detached ADU (or one attached to an accessory building) can't exceed two stories.

Setbacks for new ADUs.

• Front: the zone's front setback, but one ADU of 800 sq ft or less may encroach into it.
• Street side: the zone's setback or 4 feet, whichever is less.
• Interior side and rear: the ADU may go up to the property line, unless building code rules (fire separation, openings) require more.
• If the ADU is taller than 16 feet and the neighbor is residential, 4 feet (or the zone's setback if less).
• In a Very High Fire Hazard Severity Zone, 4 feet regardless of height. Brush management areas may need more.

Decks, balconies and exterior stairs must meet the zone's normal setbacks. Converting a building, or rebuilding it in the same spot and size, keeps its existing setbacks. The city's FAQ also says ADUs must conform to the front setback, so if you want to build in the front yard, confirm with DSD. [1][3]

Parking

No parking is required for ADUs outside the Coastal Overlay Zone. Inside it, parking is required only in the Beach Impact Area and outside a transit priority area; even there, no space is needed if the ADU is 500 sq ft or less, attached to the house or an accessory building, in a designated historic district, in a residential permit parking district, or within one block of a car-share vehicle. JADUs never need parking.

Converting or tearing down a garage or carport doesn't require replacing the parking (except in that same beach area). If the ADU leaves your driveway too short to meet city standards (for example, less than 18 feet from the back of the sidewalk), the driveway must be closed. Bonus ADUs outside a transit priority area need one space each. [1][3]

Fees

Development impact fees. The municipal code exempts ADUs under 750 sq ft and all JADUs. In addition, the first two ADUs on a lot are exempt at any size (the two smallest, if you build more), except for certain ADUs built with SB 9 projects. ADUs of any size are also exempt if the owner signs a recorded affidavit to live in one of the homes for at least three years after the permit is issued. Any impact fees that do apply are due before final inspection. State law separately bars impact fees on an ADU with 750 sq ft of interior livable space or less and requires proportional fees above that.

Other fees DSD lists. ADUs and JADUs pay school fees and the General Plan Maintenance Fee. Projects with more than one ADU pay Regional Transportation Congestion Improvement Program fees. If your ADUs bring the lot to 10 or more homes (5 in the coastal zone), inclusionary housing rules apply. Bonus ADUs pay a Community Enhancement Fee. Under state law, ADUs and JADUs under 500 sq ft of interior livable space are not subject to school impact fees.

Water and sewer. State law says utilities can't treat an ADU or JADU as a new residential use when calculating connection fees or capacity charges, unless it is built at the same time as a new single-family home. DSD's application forms include a Water Meter Data Card (DS-16); confirm any water or sewer charges with DSD.

For the full fee schedule see Information Bulletin 501 and the DSD fees page. For typical costs see our ADU cost guide. [1][2][4]

How long it takes

Under state law, the city must tell you within 15 business days whether your ADU application is complete, and approve or deny a complete application within 60 days when there is an existing home on the lot. Applications that use a preapproved plan get a 30-day review.

DSD first screens your documents and sets your fees. Once plan-check fees are paid, your project goes into review queues for each discipline. DSD posts current average intake, review and issuance times on its permit timeline page. See our ADU permit process guide. [3][4][5]

ADU Home Density Bonus Program

The bonus program lets you build extra ADUs if you deed-restrict some of them as affordable. The City Council changed it in 2025 (ordinance O-21989), and those changes aren't yet in effect in the coastal zone.

• Where. Bonus ADUs aren't allowed in the RS-1-1 to RS-1-4 and RS-1-8 to RS-1-11 zones, unless the lot is in a state-designated High or Highest Resource opportunity area and planned for residential use. In a Very High Fire Hazard Severity Zone, the lot must front an improved street with at least two evacuation routes.
• How many. In a Sustainable Development Area, you get one market-rate bonus ADU for each deed-restricted affordable ADU. Elsewhere, you can have at most one affordable and one bonus ADU. On single-family lots, total ADUs and JADUs are capped at 4 (lots of 8,000 sq ft or less), 5 (8,001 to 10,000 sq ft) or 6 (larger).
• Requirements. Affordable ADUs are deed-restricted to very low, low or moderate income households for 15 years, through an agreement with the San Diego Housing Commission signed before the first permit. All affordable and bonus ADUs need fire sprinklers, and you must plant at least one tree (two per 5,000 sq ft of lot).
• Accessible bonus. If you build at least two affordable ADUs, you can add one more market-rate ADU that meets accessibility standards.

Check whether you're in a Sustainable Development Area with ZAPP. [1][3]

Garage conversions and junior ADUs

Garage conversions. A converted garage keeps its existing setbacks, has no 1,200 sq ft cap, and can add 150 sq ft for entry and exit. You don't have to replace the parking outside the beach impact area, but the driveway may need to be closed. An ADU needs fire sprinklers only if the main house has them. New detached ADUs need solar panels under the state energy code; conversions don't. More in our garage conversion guide.

Junior ADUs. A JADU is 150 to 500 sq ft inside an existing or proposed house or attached garage, on a single-family lot. It needs a separate outside entrance and a kitchen or efficiency kitchen, and it can share a bathroom with the house. It may add up to 150 sq ft for entry and exit, and its floor area doesn't count toward the lot's FAR. The owner must live on site only if the JADU shares a bathroom; the owner may live in any unit. You must sign a Junior Unit Agreement before the permit is issued. See our junior ADU guide. [1]

Renting it out or selling it

You don't have to live on the property to have an ADU. An ADU can't be leased for less than 31 consecutive days, so vacation rentals aren't allowed. A JADU must be rented for more than 30 days and can't be a short-term rental.

ADU condos. San Diego lets you turn new or existing ADUs into condominiums and sell them separately from the house. This isn't allowed for bonus program ADUs, or, while their restrictions last, for ADUs financed by the San Diego Housing Commission or rent-restricted for lower-income households. You need a condo subdivision, every lienholder's written consent, and final inspections on the ADU. For the first 30 days of listing, you must offer it to buyers who will live in it.

SB 9. ADUs built with an SB 9 two-unit project or lot split follow SDMC Chapter 14, Article 3, Division 13, and a lot split needs a signed owner affidavit. See our SB 9 guide. [1][3]

Permit steps in San Diego

1. Check your zone and overlays

   Look up your zone, coastal status and Sustainable Development Area in ZAPP and read Information Bulletin 400. [1][3]

2. Prepare plans and forms

   You need a site plan, floor and roof plans, elevations, structural plans and calculations, and Title 24 energy calculations, plus the General Application, Water Meter Data Card (DS-16) and Storm Water checklist. You can use an accepted preapproved plan instead of custom drawings. [1][3]

3. Get a Coastal Development Permit if needed

   In the Coastal Overlay Zone, a Coastal Development Permit is required for an ADU or JADU that isn't fully inside the existing house, adds habitable area, or converts non-habitable space (some JADUs qualify for an exemption). In the non-appealable area it can be issued as a building permit if findings are met. [1]

4. Apply online

   Submit through the Development Services Application Portal under Building Applications, "Building Construction." After you get a PRJ number you can book a virtual appointment for project setup. [1][5]

5. Pay fees and go through review

   DSD screens your documents and sets fees. After plan-check fees are paid, reviewers in each discipline check the plans and issue corrections. [5]

6. Sign agreements and get the permit

   Sign any required agreements before issuance, such as the Junior Unit Agreement for a JADU, the three-year owner affidavit for the impact fee exemption, or the Housing Commission agreement for bonus ADUs. [1][2]

7. Build, pay impact fees and pass final inspection

   Any development impact fees that apply must be paid before you request final inspection. [2]

Pre-approved and sample plans

• Accepted preapproved ADU plans

  San Diego accepts preapproved plans from the County of San Diego, Chula Vista and Encinitas, with a 30-day review; you license the plan from its provider. [3]

• County of San Diego Standard ADU Plans

  One of the plan sets the City of San Diego accepts for a 30-day review. [3]

Who to call

• City of San Diego Development Services Department

  ADU and JADU permits, plan review and inspections (customer service line Monday-Friday, 8 a.m.-3 p.m.)

  619-446-5000

  [6]

Questions people ask