ADUs & Additions in Placentia

City of Placentia Development Services Department, Building and Safety Division. Building permit applications go to the Building Division of the Development Services Department at 401 East Chapman Avenue only after planning and zoning clearance is obtained. Pools and spas require a full plan submittal, with a pre-site required on both new construction and remodels, and Municipal Code Section 20.40.090 waives a separate grading permit for a pool authorized by a valid building permit. Elevated decks in the R-1, RPC, PUD and SP-7 zones need a special use permit from the Director of Development Services, with the decision date set at least 21 days after a complete application and notice mailed to owners within 100 feet. After the State Fire Marshal added Placentia to its 2025 Local Responsibility Area fire hazard maps, the City Council adopted Ordinance No. O-2025-04 designating those zones on June 17, 2025, so a parcel's zone status is confirmed before design. We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.

The subdivision code sets R-1 minimum lots at 7,000 square feet, 7,500 on corners, and R-A lots at 20,000 square feet. In R-1, buildings may cover no more than half the net lot, a new house keeps a 20-foot rear yard and additions and accessory structures a 10-foot one, patio covers may reach within five feet of the side and rear lines, and slopes steeper than five percent are not allowed within 17 feet of the rear of the house. Planned areas such as East Placentia (Specific Plan 7) and Specific Plan 8, where most lots are clustered and many of the remaining row lots look onto a golf course, follow their own specific plan standards, and some parcels carry an O or O-1 combining oil district overlay. One local condition that shapes the work: Oil wells and pipelines operate within the city, and the Municipal Code bars a new habitable building within 100 feet of any well that has not been abandoned unless the Planning Commission or City Council waives or modifies the distance. Old pits and wells backfilled with undocumented fill can also settle unevenly, so well locations are checked before an ADU or pool is sited.

All of it, including Old Town Placentia, Atwood, La Jolla and East Placentia. 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.