Everything homeowners need to know about building an accessory dwelling unit in San Diego - size limits, setbacks, permits, and how the city's own program builds on California's statewide by-right ADU law.
Last verified: August 2026
9/10 · Very ADU-friendly
1,200 sq ft
Max ADU size
16 ft*
Max height
Not required
Owner-occupancy
By-right
Permit type
This page summarizes San Diego Municipal Code Chapter 14, Article 1, Division 3 (Accessory Dwelling Units and Junior Accessory Dwelling Units) and California's statewide ADU law (Government Code Section 65852.2) for general reference - it is not legal advice. Regulations change; always confirm current requirements with the San Diego Development Services Department before designing or applying for permits. See sources below.
Zoning & size requirements
What you're allowed to build
ADU type
Max size
Max height
Notes
Detached (new build or garage conversion)
1,200 sq ft (150 sq ft minimum)
Follows the base zone; a 16 ft design generally qualifies for reduced setbacks, while taller designs (up to 2 stories in single-unit zones) use standard zone setbacks
Converting an existing structure is exempt from the 1,200 sq ft cap
1,200 sq ft or 50% of the primary dwelling's floor area, whichever is smaller
Matches the primary structure
Common approach for basement or above-garage conversions
Junior ADU (within existing walls)
150-500 sq ft
Same as primary structure
Must be within an existing/proposed single-unit home or attached garage; owner-occupancy generally required
Allowed zoning districts
Single-unit and multi-unit residential zones citywide under San Diego Municipal Code Chapter 14, Article 1, Division 3. The Coastal Overlay Zone has some provisions pending California Coastal Commission certification - confirm your parcel's zone and overlay with Development Services.
Additional standards
Setbacks, parking & other rules
Setbacks
Interior side and rear may extend to the property line for ADUs up to 16 ft tall outside fire hazard zones; a 4 ft minimum applies where the ADU abuts a residential zone and exceeds 16 ft, or in Very High Fire Hazard Severity Zones. Front and street-side setbacks generally follow the base zone
Parking
Not required outside the Coastal Zone. Inside the Coastal Zone's Beach Impact Area, 1 space is required unless the ADU is 500 sq ft or smaller, historically designated, attached, or car-share is available nearby
Units per lot
Single-unit zones: 1 primary home plus 1 attached/detached ADU, 1 converted ADU, and 1 JADU, with additional "bonus" ADUs available through the ADU Bonus Program (4-6 total ADUs/JADUs depending on lot size, capped or unavailable in the lowest-density RS-1 zones). Multi-unit zones: up to 8 detached ADUs
Owner-occupancy
Not required for standard ADUs. JADUs require an on-site owner unless the JADU has independent sanitation facilities or the owner is a government entity or nonprofit
Building code
Must meet California Residential Code / California Building Code dwelling-unit standards
Short-term rental
Prohibited for any ADU built after January 1, 2017. The city actively enforces this - 2025 reporting identified roughly 170 properties illegally listing an ADU as a short-term rental, resulting in delisted ads and civil penalties
Ordinance history
How San Diego's ADU rules got here
2017Statewide ADU law arrives. SB 1069 and AB 2299 take effect January 1, 2017, creating the first modern statewide ADU framework that local ordinances must align with.
2020State law strengthens ministerial review. AB 68, AB 881, AB 670, and SB 13 take effect January 1, 2020, mandating 60-day ministerial approval, cutting setbacks to 4 ft, and temporarily barring owner-occupancy requirements.
2022General Plan Maintenance Fee added. Effective August 9, 2022, the fee began applying to ADU permits along with other development.
2024Owner-occupancy ban made permanent; permits surge. AB 976 takes effect January 1, 2024, permanently prohibiting owner-occupancy requirements statewide. San Diego issued 538 ADU permits in 2024, up sharply from just 77 in 2023.
2025City Council adopts a sweeping ADU reform package. On July 22, 2025, the Council approved 25 changes (Ordinance O-21989) covering minimum and maximum sizes, conversions, rental terms, unit counts, fire-zone setbacks, owner-occupancy, and separate sale of ADUs, effective around August 22, 2025 outside the Coastal Zone. The city issued 1,122 ADU permits that year, more than double 2024's total, with January-February 2026 pace of 241 permits suggesting continued growth.
San Diego's permit growth has tracked its own local reforms closely: the city's ADU Bonus Program, which trades a deed-restricted affordable unit for extra floor area and faster review, has been repeatedly adjusted (including new caps in the lowest-density RS-1 zones) as the program has scaled up.
Permit process
How San Diego ADU permitting works
1
Pre-application check
Review Information Bulletin 400 and confirm your zone, lot size, and eligibility with Development Services before designing.
2
Choose your program
Decide between a standard ADU or the ADU Bonus Program, which adds a deed-restricted affordable unit, fire sprinklers, and parking in exchange for extra floor area and expedited review.
3
Prepare your plan set
Site plan, floor plans, and elevations, submitted through the city's e-PlanSD portal or in person.
4
Plan review
Qualifying projects get ministerial review, with a decision required within 60 days of a complete application under state law.
5
Pay fees & pull permit
Development impact, school, and General Plan Maintenance fees apply as applicable; Bonus Program projects also pay a Community Enhancement Fee.
6
Construction & inspections
Build to California Residential Code standards and schedule inspections through final sign-off.
Fees and timelines are approximate and vary by project type and zone - confirm current figures with Development Services.
Budgeting
What it costs to build an ADU in San Diego
Garage conversion
Roughly $100,000-$260,000, depending on existing condition, utility access, and finishes
Basement conversion
Uncommon in San Diego's mostly slab-on-grade housing stock. Where feasible, costs run comparable to or higher than a garage conversion - confirm with a local contractor
New detached ADU
Roughly $200,000-$450,000+ (about $375-$600+ per sq ft turnkey), with site conditions like slope and soil quality adding $20,000-$60,000 in some cases
Development impact & school fees
Vary by project size and valuation; ADUs 750 sq ft or smaller are exempt from school fees statewide
ADU Bonus Program Community Enhancement Fee
Applies to Bonus Program projects only; amount varies by project
These are general ranges from local contractor estimates and regional reporting, not quotes - soft costs like design, permits, and school fees typically add another $20,000-$40,000 on top of construction costs.
Before you apply
Tips for a smooth approval
Decide early whether the ADU Bonus Program is worth it. It unlocks extra floor area and faster review, but comes with a 15-year affordability deed restriction on at least one unit.
Check your fire hazard zone before finalizing setbacks. High and Very High Fire Hazard Severity Zones require 4 ft minimum setbacks and access to two evacuation routes.
Budget with the 2025 reforms in mind. The city's July 2025 package touched sizes, setbacks, and rental terms - confirm current standards rather than relying on older guides.
Check Coastal Zone status separately. A Coastal Development Permit may be required, and some ADU provisions await California Coastal Commission certification.
Don't plan on short-term rental income. ADUs built after 2017 can't legally be listed on Airbnb or VRBO, and the city has stepped up enforcement against violators.
FAQ
Common questions
Do I need to live on the property to build an ADU in San Diego?
No. California's AB 976 permanently eliminated owner-occupancy requirements for ADUs statewide as of January 1, 2024. JADUs generally still require an on-site owner unless specific exceptions apply.
How many ADUs can I build on one lot?
On a single-unit lot: 1 attached/detached ADU, 1 converted ADU, and 1 JADU, plus additional bonus ADUs through the ADU Bonus Program (up to 4-6 total ADUs/JADUs depending on lot size). Multi-unit zones allow up to 8 detached ADUs.
Do I need extra parking for an ADU?
Generally no, outside the Coastal Zone. Inside the Coastal Zone's Beach Impact Area, 1 space is required unless the ADU is 500 sq ft or smaller, historic, attached, or car-share is available.
How long does the permit process take?
State law requires a ministerial decision within 60 days of a complete application. Confirm current processing timelines with Development Services, since volume has grown substantially since 2023.
What's the maximum size for a detached ADU?
1,200 sq ft, with height following the base zone (16 ft typically qualifies for reduced setbacks; taller designs up to 2 stories use standard setbacks).
How much does an ADU cost to build in San Diego?
Garage conversions tend to run roughly $100,000-$260,000, and new detached units roughly $200,000-$450,000 or more, based on local contractor estimates and regional reporting - not counting development impact and school fees.
How many ADU permits has San Diego actually issued?
The city issued 1,122 ADU permits in 2025, up from 538 in 2024 and just 77 in 2023. Early 2026 activity, with 241 permits in January and February alone, suggests the pace is continuing to climb.
Can I rent my ADU out on Airbnb or a short-term rental platform?
No. Any ADU built after January 1, 2017 is prohibited from short-term rental use under the San Diego Municipal Code, and the city has actively enforced this against non-compliant listings.
