ADU housing laws and regulations in Santa Ana, CA

Zoe Harper

Finance Author

April 18, 2024

Santa Ana allows homeowners and landlords to build accessory dwelling units across its residential zoning districts, making it one of the more ADU-friendly cities in Orange County. An accessory dwelling unit (ADU) is a secondary housing unit on the same lot as a primary residence. These units go by many names: granny flat, in-law suite, backyard cottage, or carriage house. Landlords build them to generate rental income, house family members, or add long-term value to their property. If you're planning a project in Santa Ana, here's what you need to know before breaking ground.

Where ADUs are allowed in Santa Ana

ADUs are permitted in all of Santa Ana's residential zoning districts, covering both single-family and multifamily lots. On a single-family lot, you can build one ADU and one Junior Accessory Dwelling Unit (JADU). Multifamily properties follow a different set of rules, so check the city's ADU development standards for details specific to your property type.

Santa Ana recognizes four main ADU types:

Detached ADUs: standalone structures built on the same lot as the primary home
Attached ADUs: additions connected directly to the primary residence
Conversion ADUs: existing spaces, such as garages or basements, converted into living quarters
JADUs: units up to 500 square feet carved out of the existing primary dwelling

Size limits, setbacks, and height

Detached ADUs can be up to 1,200 square feet. Attached ADUs are capped at 50% of the primary residence's living area. JADUs max out at 500 square feet and must stay within the walls of the existing home.

Standard setbacks for detached ADUs require at least 4 feet from the rear and side property lines. Height limits generally align with those of the primary dwelling. Total lot coverage, meaning all structures combined, must stay within the percentage allowed by the applicable zoning district.

If your property sits in one of Santa Ana's historic districts, design, materials, and placement face an additional layer of review under Section 41-194 of the zoning code. The historic preservation review checks whether new construction fits the character of the surrounding area, so plan extra lead time into your schedule if this applies to you.

The permitting process

All ADU projects in Santa Ana require a building permit from the Planning Division. The process starts with submitting plans for review against local zoning and building codes. One way to reduce review time and upfront design costs is the city's Pre-Approved ADU Plans Program, which gives homeowners ready-to-use building plans at no custom architectural fee. Using a pre-approved design can move your project through review faster than submitting custom drawings.

Development and impact fees apply to most projects, calculated based on the ADU's scope. These fees fund water, sewer, and public services. Smaller ADUs may qualify for reductions or exemptions. Because fee schedules change, contact the Planning Division or the relevant utility agencies directly for current figures. A full permitting walkthrough, including required forms, is on the city's ADU FAQs and Helpful Links page.

Parking requirements

Most ADUs require one parking space per unit or per bedroom, whichever is less. That requirement is waived if the ADU is within half a mile of a public transit stop. If you're converting an attached garage to living space, you may be able to satisfy the parking obligation through alternative means, but verify this with the Planning Division before proceeding. Assumptions here can create complications later in the approval process.

Utilities and habitability standards

Every ADU needs its own potable water connection and sanitation facilities. For detached units, that typically means extending existing water and sewer lines from the main home. Kitchens must include a sink with hot and cold running water, a cooking appliance, and proper ventilation. Bathrooms need a toilet, sink, and shower or bathtub.

Beyond plumbing, building and safety standards require that ADU materials match or complement the primary residence. A stucco exterior on the main home calls for a compatible finish on the ADU. Garage conversions require a structural inspection to confirm the existing frame meets current safety codes before work begins. Kitchen and bathroom surfaces must be non-porous and cleanable; bathroom walls and floors need moisture-resistant materials to prevent mold. Every fixture must meet Santa Ana's residential occupancy standards.

Rental rules and owner-occupancy

ADUs can be rented as long-term housing. Santa Ana does not permit ADUs to be used as short-term vacation rentals on platforms like Airbnb. The one ADU plus one JADU limit per single-family lot keeps density controlled while still allowing owners to generate rental income.

On owner-occupancy: California state law suspended the requirement that property owners live on-site for units permitted between 2020 and 2025. That window has closed. If you're starting a new project, confirm the current occupancy rules directly with the Santa Ana Planning Division, since state and local rules can shift.

Selling an ADU separately from the primary dwelling is only permitted under narrow conditions, typically when a qualified nonprofit develops both units under specific state guidelines. For most private owners, the ADU and primary residence remain on the same title.

HOA considerations

California state law limits what homeowners associations can do to block ADU construction. Under state law, HOA rules that effectively prohibit ADUs are unenforceable. That said, HOAs may still apply design and aesthetic standards, such as exterior color, materials, or landscaping requirements, as long as those rules don't prevent construction altogether. If your property is in an HOA, review the governing documents before you finalize your plans, and check with the HOA board early. Surprises during design review can delay your project.

Landlord insurance for ADU rentals

Renting out an ADU creates real financial exposure: a tenant injury, property damage, or a liability claim can be costly without proper coverage. Standard homeowner's insurance typically does not cover rental activity. Before you start collecting rent, it's worth reviewing your policy and adding landlord coverage if needed. You can compare coverage options for California rental properties at Steadily's California landlord insurance page.

Financial help and cost considerations

Construction costs vary widely based on size, materials, and whether you're building new or converting an existing structure. Predevelopment expenses, covering design, permits, and site work, can add up before a single wall goes up. The CalHFA ADU Grant Program offers grants to offset predevelopment costs for qualifying homeowners. Funding levels and eligibility requirements change, so check directly with CalHFA for current details. Santa Ana residents may also qualify for other city or county programs tied to affordable housing development. The city's pre-approved plans program is itself a meaningful cost-saving tool, since it removes the need to pay for custom architectural work on standard designs.

Frequently asked questions

What is the maximum size for a detached ADU in Santa Ana?

Detached ADUs can be up to 1,200 square feet. Attached ADUs are limited to 50% of the primary home's living area. JADUs top out at 500 square feet. See the city's development standards for full details.

Do I need to live on the property to rent out an ADU?

The owner-occupancy requirement was waived for units permitted between 2020 and 2025. Whether it applies to new projects depends on current local and state law. Confirm the current rules with the Santa Ana Planning Division before starting your project.

Can I convert my garage into an ADU?

Yes. Garage conversions are allowed, provided the structure passes a safety inspection and meets all ADU development standards, including setbacks, habitability requirements, and parking provisions. More details are on the city's FAQs page.

How close to the property line can a detached ADU be built?

The standard minimum setback is 4 feet from the rear and side property lines. Lot size, ADU type, and other circumstances can affect this. Check the ADU development standards page for your specific situation.

Is parking always required for an ADU in Santa Ana?

No. If the ADU is within half a mile of a public transit stop, the parking requirement is waived. Otherwise, one space per unit or bedroom, whichever is less, is required.