ADUs are popular in San Diego for good reason. They add space, flexibility, and potential rental income. At the same time, the ADU process is not one-size-fits-all. The same 600 square foot ADU can be straightforward on one property and complex on another.
This guide focuses on what actually drives feasibility, timeline, and cost in San Diego.
Step 1: Confirm the Basics Before Design
Before investing heavily in design, it helps to confirm:
- Where an ADU can sit on your lot
- Construction access
- Utility connection realities
Local placement rules and state code requirements both apply. Front-yard and street-side-yard conditions can limit placement, while side and rear placement may still trigger fire separation or building code requirements.
Step 2: Know Which ADU Type You Are Building
Common ADU paths include:
- Detached ADU
- Attached ADU
- Garage conversion
- JADU
Each option affects structural scope, utilities, and permitting complexity. A garage conversion may appear simple but often requires insulation, plumbing, electrical, and sometimes structural upgrades.
Step 3: Permits and Timelines Matter
Permitting is not just paperwork. It affects schedule and sequencing.
City permit processing timelines provide useful guidance for setting expectations, even though each project still varies.
Step 4: Parking and Setback Realities
Parking and setback rules depend on zoning, location, and overlays. Street-side yard conditions and minimum setbacks can still apply even when parking requirements are reduced.
Step 5: State Law Changes People Still Get Wrong
Many homeowners still believe they must live on the property to build an ADU. State law has changed over time, and owner-occupancy is not broadly required.
The practical takeaway is simple. Do not rely on outdated advice. Verify your specific situation early.
Step 6: Plan for Utilities Early
Utilities are often a major cost driver, including:
- Trenching distance
- Electrical panel capacity
- Sewer connection approach
- Metering decisions
You do not need every detail finalized, but you do need a realistic plan early so the budget reflects reality.
FAQ
How long does an ADU take in San Diego?
Design, permits, and construction each have their own timelines. City review timing varies.
Can every property build an ADU?
Many can, but feasibility depends on zoning, access, and site conditions.
Is a garage conversion always cheaper?
Often, but not always. Code upgrades can reduce the difference.
Do I need separate utilities?
Not always. It depends on design and practical constraints.