ADUs & Additions in Fountain Valley

City of Fountain Valley Building Division. In-ground pools and spas go through plan review with the Building Division at 10200 Slater Avenue, and the submittal includes two sets of stamped, wet-signed structural plans and a steel schedule prepared by a California licensed engineer. The Planning Department verifies setback distances to property lines, Public Works staff review the plans for utility easements, site grading, site drainage and encroachment permit requirements, and the shotcrete requires deputy inspection. The city's single-family standards set pools and spas back five feet from the house and from the side and rear property lines. ADUs are governed by FVMC 21.08.055, and an attached or detached unit must match the main house in exterior color and material, roof material and color, and window and door types, with clerestory or frosted glass on any ADU window within five feet of a property line. We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.

Level single-family lots where the city's development standards, rather than slope, set the limits: lot coverage tops out at 60 percent including accessory structures, or 50 percent on parcels of 10,000 square feet or more, and 1,000 square feet of open space must stay in the rear yard. Pool equipment and AC units need a three-foot setback in a side yard, or 18 inches behind the house in the rear yard. A detached ADU goes in the rear yard at least ten feet from the main house, and the city requires no more than four feet of side and rear setback for it. One local condition that shapes the work: The city's 2023 vulnerability assessment places groundwater less than ten feet below the surface, likely a legacy of the swampland that covered the area in the early 1900s, and shows all of Fountain Valley except an isolated area along Newland Street as susceptible to liquefaction, with especially high potential beside the Santa Ana River and south of the I-405.

All of it, including Mile Square Park area, North of the I-405, South of the I-405 and Santa Ana River edge. 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.