ADUs & Additions in Orange

City of Orange Community Development Department, Building Division. Inside city limits, the Building Division accepts permit applications only through the city's Civic Portal, and an ADU or JADU needs an approved Planning Division application before plans can go to building plan check. Pockets of El Modena and Orange Park Acres remain unincorporated county land, where OC Public Works Building and Safety handles permits instead. Exterior changes in Old Towne must meet the Historic Preservation Design Standards for Old Towne, the Fairhaven, Fairhills and Fairmeadow Eichler tracts follow the Orange Eichler Design Standards, and additions, infill and ADUs in any of the city's four historic districts also require a historic resource assessment prepared by a qualified preservation professional. The Orange City Wildland-Urban Interface Code, adopted in November 2025, applies to new homes in any Fire Hazard Severity Zone and to structures accessory to them, with exceptions that include detached utility buildings at least 50 feet from the house; for new buildings in a Very High zone, the final fuel modification plan must be approved by the fire code official before a grading permit is issued. We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.

Single-family zoning runs from 6,000-square-foot minimum lots in R1-6 up to one acre in R1-40 and two and a half acres in the rural R1-R district, whose stated purpose is to minimize changes to riparian habitat, oak woodlands and prominent landforms; the 5,000-square-foot R1-5 district is intended for limited use in large-scale developments that keep at least 40 percent of their planning area as open space. Old Towne's residential quadrants sit on the flat plain around the Plaza. Serrano Heights and Santiago Hills II are governed by their own specific plans, and Orange Park Acres, in east Orange, by a neighborhood plan, where the General Plan's Estate Low Density designation provides for estate homes on large lots and can allow private equestrian use. One local condition that shapes the work: The central and western city sits on an alluvial plain underlain by many thousands of feet of river and floodplain sediment, and ground beside the Santa Ana River and Santiago Creek is susceptible to flooding and seismically induced liquefaction. The Building Division requires a geotechnical report for residential foundation work except one-story additions and one-story detached ADUs or accessory structures of up to 1,200 square feet outside liquefaction areas.

All of it, including Old Towne, El Modena, Fairhaven and Orange Park Acres. 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.