Does Your Property Qualify for an ADU? Here's What San Diego Homeowners Need to Know

If you own a home in San Diego, chances are you've heard the buzz around ADUs — Accessory Dwelling Units. Also known as granny flats, backyard cottages, or in-law suites, ADUs have exploded in popularity across Southern California, and for good reason. They add living space, generate rental income, and can significantly boost your property value.

But before you start dreaming about that backyard studio or detached guest house, there are real requirements to understand. The good news? San Diego is one of the most ADU-friendly cities in California. Here's a straightforward breakdown of what it takes to qualify and build.

What Is an ADU, Exactly?

An ADU is a secondary residential unit on a property that already has a primary home. It can be:

• Detached — a standalone structure in your backyard
• Attached — connected to your main home
• A garage conversion — transforming your existing garage into livable space
• A Junior ADU (JADU) — created within the walls of your existing home (typically up to 500 sq ft)

Each type comes with its own set of rules, but all follow a consistent framework under California state law and San Diego's local code.

Does Your Property Qualify?

Most San Diego residential properties can accommodate at least one type of ADU. Under current California state law, there is no longer a minimum lot size requirement — even smaller lots can qualify. The key criteria are:

• Your property must be zoned residential (single-family or multifamily)
• A primary dwelling unit must already exist or be proposed on the lot
• The ADU must meet applicable setback, height, and size requirements for your zone

Properties in special overlay zones — such as the Coastal Overlay Zone or areas near steep slopes — may require additional review, but that doesn't mean an ADU is off the table. It just means placement and design need extra attention.

Size Limits: How Big Can You Build?

San Diego allows detached ADUs up to 1,200 square feet, regardless of your overall lot size. Attached ADUs and garage conversions generally follow similar size guidelines, while JADUs are capped at 500 square feet and must be created from within the existing home's walls.

Two-story ADUs are permitted in San Diego, with a maximum height of up to 24 feet on single-family lots (subject to base zone regulations). As of August 2025, the city limits ADUs on single-family lots to two stories maximum.

Setback Requirements

Setbacks — the required distances between a structure and the property lines — are one of the most important factors in determining where on your lot an ADU can be built:

• Side and rear setbacks: A minimum of 4 feet from the property line for new detached ADUs
• Front yard setback: Must match your zone's existing requirements (typically 15–20 feet)
• Distance from main house: At least 6 feet of separation between a detached ADU and the primary dwelling
• ADUs under 800 sq ft may encroach into front setbacks if lot constraints don't allow rear placement — San Diego has fully adopted this California provision

If you're converting an existing structure like a garage or storage room, setback rules may not apply at all — conversions can often use the setbacks of the existing structure, even if they don't meet today's minimums.

Parking Requirements

One of the most homeowner-friendly aspects of San Diego's ADU regulations: in most cases, ADUs do not require additional parking spaces. And under California's SB 1211 (effective January 2025), if a garage or carport is demolished or converted to build an ADU, you don't have to replace those parking spaces either.

The Permitting Process

In San Diego, ADU permits typically take 4 to 10 weeks (up to 60 days) to process. The timeline can vary based on your zone, project complexity, and whether your property falls in the Coastal Overlay Zone.

The general permitting steps include:

1. Determine your zoning and lot eligibility
2. Design your ADU in compliance with local and state code
3. Submit plans to the City of San Diego Development Services Department
4. Receive permits and begin construction
5. Pass inspections and receive certificate of occupancy

Working with an experienced contractor who knows San Diego's ADU regulations can make this process significantly smoother and help you avoid costly revisions.

Why Build an ADU with Unike?

At Unike General Contracting, we specialize in thoughtfully designed ADUs that add real value to your property — not just square footage. From the initial eligibility check through final inspection, our team handles every phase of your ADU project with the craftsmanship and communication you deserve.

We know every lot is different, and we'll work with your specific property to design an ADU that maximizes your space within San Diego's guidelines.