The ADU Permit Process in San Diego, Step by Step

Ask five neighbors how hard it is to permit an ADU in San Diego and you'll get five different answers, usually ranging from "impossible" to "they basically approve everything now." The truth is closer to the second answer than the first — state law has made ADU approval largely ministerial, meaning if your plans comply, the city must approve them. But "ministerial" doesn't mean "instant," and the process rewards people who do it in the right order.

Here's the path we walk with clients, step by step.

Step 1: Feasibility before anything else

Before a single line gets drawn, someone needs to confirm what your lot actually allows: zoning, setbacks, height limits, whether you're in a coastal, historic, or fire-hazard overlay, and where your sewer and utilities run. This is a few hours of research that prevents months of pain. It's also when the big-picture questions get answered — detached ADU or garage conversion, one unit or more, and how the unit will sit relative to the main house. (On that last point, our post on designing privacy between your home and your ADU covers what the site plan should protect.)

Step 2: Design and drawings

ADU plan sets are real construction documents: floor plans, elevations, structural details, Title 24 energy compliance, and site plans showing setbacks and utility connections. The city also offers pre-approved standard plans that can shorten review — worth a look if one happens to fit your lot and taste, though most of our clients want a design that responds to their specific yard, slope, and sightlines.

Step 3: Submittal and review cycles

Plans go in through the city's online portal, and reviewers from several disciplines — zoning, structural, and utilities among them — take their passes. State law caps ADU review timelines, but the clock resets with each correction cycle, and corrections are where inexperienced applicants lose months. A clean, complete first submittal is the single biggest schedule lever there is. Expect at least one round of comments even on good plans; the goal is to make round one small and round two unnecessary.

Step 4: Permit, construction, and inspections

Once corrections clear and fees are paid — and note that impact fees are waived by state law for ADUs under 750 square feet — you have a permit and construction can start. From there, the project runs like any well-managed build: foundation, framing, rough utilities, insulation, drywall, finishes, with city inspections at each milestone and a final inspection that makes the unit legally occupiable. June's gloomy mornings are actually a gentle season for foundation and framing work — cool crews are efficient crews.

The honest timeline

Add it up — feasibility, design, review cycles, construction — and a realistic ADU journey runs on the order of a year, sometimes faster for a simple conversion, sometimes longer for a hillside lot or coastal review. That surprises people who've only heard the "streamlined approval" headlines. The streamlining is real; it just applies to one stage of a multi-stage process.

If the numbers side is what's holding you back, we covered how homeowners actually finance ADUs back in December. And if you're ready to find out what your lot can do, our ADU design-build process starts with that feasibility work. Tell us what you're planning or give us a call — we'll map your lot's real possibilities before you spend a dollar on drawings.