Do I need a permit to build an ADU in San Diego?

Yes. As of October 2026, every ADU and junior ADU in the City of San Diego needs a building permit, garage conversions included, and the city's Development Services Department issues it. A qualifying ADU is approved ministerially, with no public hearing, and state law gives the city 60 days to act once the application is complete.

Which office issues my permit?

It depends on where the lot sits, not on the mailing address. Inside City of San Diego limits, Development Services handles ADU permits. Chula Vista, La Mesa, El Cajon and Escondido each run their own permit counters, and unincorporated communities are permitted by the County of San Diego. A "San Diego" mailing address can belong to the county or to a neighboring city, so we confirm the jurisdiction from the parcel before anything else.

What does the city look at during review?

• Zoning. Whether the lot is single-family or multifamily, and any overlay zones such as the coastal zone or fire hazard areas.
• Placement. Side and rear setbacks (capped at 4 feet by state law for an ADU, as of October 2026), front setback, height and spacing from other buildings.
• Building code. Structure, fire separation, egress windows, plumbing, electrical and mechanical systems.
• Energy. Title 24 compliance, including solar on a new detached unit where required.
• Utilities. How water, sewer and power reach the unit.

How fast does the city have to review an ADU?

As of October 2026, state law gives a permitting agency 15 business days to decide whether an ADU application is complete, or it is treated as complete. From there, the agency has 60 days to approve or deny it when a home already exists on the lot. Since 2026 the same 60-day period applies inside the coastal zone. Correction rounds pause the clock in practice, which is why clean, complete plans matter more than anything else for speed.

What is Information Bulletin 400?

It is the City of San Diego's main written guide for ADUs and junior ADUs. Development Services announced an updated version on August 27, 2025, covering state-allowed ADUs and JADUs, the revised ADU Home Density Bonus Program, and the new option to sell most ADUs separately as condominiums. We work from the current edition and the municipal code section it references (SDMC §141.0302).

Is a permit different in the coastal zone?

Coastal lots can carry an extra layer of review under the California Coastal Act. As of the most recent reporting we found (December 2025), the city's 2025 Bonus ADU limits took effect outside the coastal zone in August 2025, while inside the coastal zone they still needed California Coastal Commission certification. If your lot is near the shore, we check its coastal status and the current Bonus ADU rules before design.

What if I already have an unpermitted unit?

As of October 2026, state law says a city generally cannot deny a permit to legalize an ADU built before January 1, 2020 just because it breaks building standards or ADU rules, with exceptions that include health and safety hazards. Expect to open some walls so inspectors can see framing, wiring and plumbing. We can review what you have and tell you what legalization would likely involve.