The short answer: Under San Diego ADU rules, an ADU can be 150 to 1,200 sq ft, a Junior ADU (JADU) 150 to 500 sq ft, and a conversion of an existing structure is exempt from the maximum. Outside the coastal overlay no parking is required, and you don’t have to live on the property for an ADU. But the city’s own bulletin says ADUs are subject to development impact fees, so budget for them.
Last verified: October 5, 2026 · Written by the ADU Scope editorial team
This guide covers the City of San Diego. The core size, height and parking numbers come from Information Bulletin 400 (November 2024 edition). The permit-process, fee, fire, multifamily and rental sections below come from the January 2026 edition, the current one at the time we checked. Confirm any figure against the latest edition. The City Council’s 2025 ADU/JADU amendments (Ordinance O-21989) took effect August 22, 2025 outside the Coastal Overlay Zone, and the coastal-zone provisions await California Coastal Commission certification. Confirm current numbers with the Development Services Department.
San Diego ADU rules: size limits
| Type | Size |
|---|---|
| ADU | 150 to 1,200 sq ft; conversions of existing structures are exempt from the maximum |
| Junior ADU (JADU) | 150 to 500 sq ft |
Both must meet the California Building Standards Code minimum room dimensions.
San Diego ADU rules: height and setbacks
- Outside High and Very High Fire Hazard Severity Zones, a detached ADU of 16 feet or less has no minimum side or rear setback.
- A taller ADU, or a multi-story ADU next to residential uses, needs at least 4 feet of side and rear setback. In Very High (and, according to the city’s announcement, High) Fire Hazard Severity Zones, a 4-foot side and rear setback applies. Verify the current height threshold in Information Bulletin 400.
- Front and street-side yards follow the base zone’s requirements.
San Diego ADU rules on parking
Outside the Coastal Overlay Zone, the bulletin says no parking is required. In the Beach Impact Area of the coastal zone, one space is generally required unless the ADU is 500 sq ft or less, is attached to the main home, is in a historic district, or is near car-sharing.
San Diego ADU rules on fees
The bulletin states that ADUs are subject to development impact fee requirements under San Diego Municipal Code § 142.0640(b)(1). School district fees are collected separately; ask the city about other per-permit fees. State law exempts ADUs of 750 sq ft or less from impact fees, so ask the city which exemption applies to your design before you budget. For how fees work statewide, see ADU Impact Fees: When You Pay Them.
Owner occupancy
An ADU does not require the owner to live on the property. If a JADU exists on the premises, the owner must live on site.
San Diego ADU rules: permit process
- All ADUs and JADUs need a building permit. There are no exemptions.
- Applications are submitted digitally through the city’s Online Permitting Account.
- Standard plans go through regular review. Pre-approved plans get a 30-day review period.
See How Long Does It Take to Get an ADU Permit? for how this compares with other California cities.
How the San Diego permit process works step by step
The January 2026 edition of Information Bulletin 400 says a building permit is required to create an ADU or JADU, with no exemptions. You apply through the city’s Online Permitting Account (the Development Services Application Portal) and choose “Building Construction.”
The minimum submittal listed in the bulletin includes:
- A site plan and vicinity map (Information Bulletin 122).
- Floor and roof plans, elevations and sections.
- Structural plans and details, with structural or truss calculations.
- Title 24 energy calculations.
- Forms DS-3032 (General Application), DS-16 (Water Meter Data Card) and DS-560 (Storm Water Applicability Checklist).
The city’s page for new housing projects describes four steps: you submit plans and forms; you pay plan review fees once the submittal is complete; you provide additional forms after engineering approval; and you pay final inspection and issuance fees before you receive stamped plans. Later changes to an issued permit go through a “Construction Change to a Building Permit.”
Fees beyond the development impact fee
Several other charges can appear on a San Diego ADU project. According to the bulletin:
- The General Plan Maintenance Fee applies to all ADUs and JADUs, and has since August 9, 2022.
- Projects with more than one ADU pay the Regional Transportation Congestion Improvement Program fee.
- Inclusionary housing requirements apply once a project reaches 10 or more total units (5 or more in the Coastal Overlay Zone).
- School district fees are collected separately. The city’s school-fee bulletin says one new ADU or JADU with under 500 sq ft of assessable space is exempt under state law.
On development impact fees, the bulletin says ADUs are subject to them under San Diego Municipal Code section 142.0640(b)(1). The municipal code division it cites states that ADUs under 750 sq ft of gross floor area and JADUs are exempt. Because the bulletin phrases it more broadly, ask the city to confirm in writing which fees apply to your design before you budget. For the statewide rules, see ADU impact fees, and for how cities compare, ADU permit cost by city.
Fire sprinklers, solar panels and coastal permits
- Sprinklers: an ADU does not need automatic fire sprinklers unless the primary dwelling has them. If the primary home is sprinklered, the ADU must be too. A JADU follows the same logic and may need a fire-rated shared wall.
- Solar: a newly built detached ADU (not a manufactured one) needs a photovoltaic system, which can be installed on the primary dwelling. Conversions and additions are exempt.
- Coastal permit: inside the Coastal Overlay Zone, a coastal development permit is required for an ADU or JADU that is not entirely within the existing primary structure, adds habitable area or converts non-habitable space. In areas where the city’s decision is not appealable, the city issues the permit with administrative findings.
Multifamily lots and the 800 sq ft exceptions
The January 2026 bulletin also covers lots with more than one home. On an existing multifamily lot you can add up to eight detached ADUs, but not more than the number of existing units. Converting non-habitable space on such a lot is allowed up to 25% of the existing units, with a minimum of one. A lot with a proposed multifamily building can have two detached ADUs.
On any lot, one ADU of up to 800 sq ft may exceed the floor-area ratio and may encroach into the front setback. A conversion can add up to 150 sq ft for ingress and egress.
Renting, selling and pre-approved plans
An ADU may not be leased for less than 31 consecutive days, and the owner does not have to live on the property. A JADU must be rented for longer than 30 days with no short-term occupancy, and the owner must live on site unless the JADU has separate sanitation or the owner is a government agency, land trust or qualified housing organization.
The city’s August 2025 public notice says most new and existing ADUs may now be sold separately as condominiums. That is a local option layered on state law, so read the notice and our guide to selling an ADU separately before you plan around it.
Pre-approved plans follow state law (AB 1332): the city’s review is 30 days, the plans still have to comply with the San Diego Municipal Code, and you contact the plan provider directly for the license cost. The city’s ADU page lists available plans. It also accepts permit-ready plans from San Diego County and Encinitas if they meet its submittal guidelines.
FAQ
Can I convert my garage?
Yes. Conversions of existing structures are exempt from the 1,200 sq ft maximum. See Garage Conversion to ADU.
Do I need a separate meter?
Utility rules depend on the unit type. See Do ADUs Need Separate Utility Meters?.
I’m near the coast. What changes?
Parking rules differ in the Coastal Overlay Zone, and a coastal development permit may apply. Ask the city before you design.
Next steps
- California ADU Laws 2026: What Changed and What You Can Build
- ADU Cost in San Diego: Construction Prices, City Fees and Pre-Approved Plans
- ADU Setback Requirements Explained: California, Washington, Colorado and Portland
- ADU Impact Fees: When You Pay Them and How to Avoid Them
- ADU Permit Cost by City: California Fees Compared
General information, not legal advice. Local rules vary and change; confirm with your planning department.
Sources: City of San Diego, Information Bulletin 400: ADU/JADU (November 2024) · City of San Diego, Information Bulletin 400 page · HCD ADU Handbook · City of San Diego, Information Bulletin 400 (January 2026 edition) · City of San Diego, How to Apply for New Housing Projects · City of San Diego, Information Bulletin 146 (school fees)