San Diego ADU

Permitting FAQ.

Yes. ADUs and JADUs require a building permit. There are no casual exemptions for turning a garage, room, or backyard structure into a legal dwelling unit.

Depending on your lot, the permit path can also involve planning review, utility coordination, grading review, or coastal review. That is why the real first step is verifying the property conditions, not just sketching a floor plan.

The City of San Diego's Information Bulletin 400 is the best official starting point for city properties.

State law generally requires ministerial action on a complete ADU application within 60 days. That is the benchmark most people hear about, but it is not the whole story.

The full timeline usually depends on surveys, soils or drainage issues, structural coordination, corrections after first review, and whether the lot is coastal or has utility complications.

In practice, the fastest projects are the ones that solve zoning, site, and utility questions before submittal instead of during plan check.

For a compliant detached ADU, 4-foot side and rear setbacks are the baseline homeowners ask about most. That is often the starting point for feasibility.

• Side and rear: 4 feet is the common state-law baseline for detached ADUs.
• Front yards: These can still vary by jurisdiction and lot conditions.
• Garage conversions: Existing structures can often keep their current setback position rather than moving the walls back.

The catch is that overlays, easements, fire access, and coastal conditions can still complicate what looks straightforward on paper.

The exact cap depends on your jurisdiction and the type of ADU you are proposing, but detached ADUs in the San Diego area commonly top out at up to 1,200 square feet.

• State-law baseline: A local agency generally cannot deny at least an 800 square foot ADU that meets key baseline standards.
• Detached ADUs: Often allowed up to 1,200 square feet.
• JADUs: Limited to 150 to 500 square feet and treated under a different code path.

Bedrooms, lot layout, height limits, and local zoning can still affect what version of that size is actually practical to build.

Often no. Parking is one of the most misunderstood parts of ADU permitting because many projects qualify for exemptions.

• ADUs near public transit often do not need new parking.
• Conversions within an existing home or accessory structure often avoid new parking requirements.
• Garage conversions often do not require replacement parking.

Beach-area and coastal conditions can still create exceptions, so this is one of the first things worth confirming at the property level.

A JADU is not just a smaller ADU. It is a different unit type with its own rules.

• Size: 150 to 500 square feet.
• Location: Usually created within or attached to the primary dwelling, often including an attached garage conversion.
• Rules: JADUs can involve recorded agreements and owner-occupancy requirements depending on the jurisdiction.

JADUs are attractive when budget and speed matter more than getting a large detached backyard unit.

Yes. Coastal properties deserve their own review because they can trigger extra requirements that inland lots do not.

Within the Coastal Overlay Zone, your ADU may need additional permit review depending on whether the work expands habitable area, converts non-habitable space, or falls within a city or county coastal process.

If the property is coastal, it is safer to verify the coastal path before design decisions are locked in.

Most delays are not caused by one dramatic code issue. They come from normal project information being incomplete or wrong.

• Survey or site plan inaccuracies
• Drainage, slope, or grading complications
• Utility or sewer conflicts
• Fire access or driveway issues
• Plans built around assumptions that do not match the parcel's zone or overlays

The cheapest time to discover these issues is before drawings are finalized, not after plan check comments come back.