ADUs & Additions in Santa Ana

City of Santa Ana Planning and Building Agency, Building Safety Division. Plan review, permits and inspections run through the Building Safety Division of the Planning and Building Agency. For single-family homes and duplexes, swimming pools and spas, patio covers and enclosures, one-story room additions up to 500 square feet, garage-to-ADU conversions and ADUs built from the city's pre-approved plans qualify for over-the-counter plan check, with plans reviewed the same day as the permit application, but only when the project is not subject to FEMA Flood Zone A or AE requirements and does not involve a historic property or district. Any improvement or alteration to a property on the Santa Ana Register of Historic Properties, or to a contributing property in a historic district, must meet the Secretary of the Interior's Standards for Rehabilitation and requires a Certificate of Appropriateness, and since July 2026 the Planning Commission has served as the city's hearing body for the historic preservation matters previously considered by the Historic Resources Commission. In Heninger Park, the SD-40 zoning district, the neighborhood's architectural design guidelines require Planning Commission approval for residential additions and new accessory structures. We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.

The Heninger Park design guidelines describe the common residential site configurations in Santa Ana as prominent entries facing the street, front porches, ample front yards and detached garages located toward the rear of the property. Heninger Park itself, bounded by First Street, Sycamore Street, McFadden Avenue and Flower Street, has little vacant land for new infill, and the guidelines call rear additions almost always appropriate when they meet the SD-40 development standards. New garages and accessory structures there should be detached, placed at the rear of the residence and kept out of view from the street, and the Hollywood driveway, two parallel paved strips separated by turf or gravel, is the preferred design. One local condition that shapes the work: No known active fault runs through Santa Ana, but the General Plan Safety Element warns that shaking from nearby faults could still cause significant damage and identifies the majority of the city as susceptible to liquefaction. The California Building Code's soils and foundation standards are how new construction answers that risk, which puts site soils near the front of any pool shell, addition or ADU scope.

All of it, including Floral Park, Historic French Park, Heninger Park and Park Santiago. Our crews run every job out of our Cahuenga Pass base in Los Angeles, with our own people on site.

Detached ADU: generally $150,000 to $400,000+ across Southern California. What moves it is square footage, finish level, utility runs, and site access; garage conversions typically run well below a ground-up detached build. We give line-item pricing after seeing the site rather than quoting a number over the phone.

Plan a realistic year. Design and engineering typically take one to three months, city plan check and corrections add several more, and construction usually runs four to eight months depending on size and site access.

Usually yes, and often substantially, because the foundation, walls and roof already exist. The trade-offs are that you lose the garage, and older slabs and framing sometimes need upgrading to meet current code.

California ADU law is designed to allow long-term rental, and an ADU is one of the few ways to add rentable square footage to a single-family lot. Short-term rental rules vary by city, so confirm your local ordinance before counting on that income.

Yes. Plans, engineering, Title 24 and the city submittal are all handled in-house, including responding to plan-check corrections. That is a service we sell on its own, so it is not something we hand off.