ADUs & Additions in Downey

City of Downey Community Development Department, Building and Safety Division. Residential permits, pools included, are issued by the Building and Safety Division of the Community Development Department, on the first floor of Downey City Hall. The division routes plans to each involved city department for concurrent review, and inspections are scheduled through the Accela Citizen Access portal. The zoning code keeps pool equipment, like other mechanical equipment, out of street setbacks and at least four feet from interior property lines, and requires it to be screened from neighboring properties and public streets and placed so noise and vibration do not carry to abutting lots. Detached ADUs beside a single-family home are generally limited to 16 feet in height with four-foot side and rear setbacks, under standards the city adopted in April 2025 and amended in June 2026. We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.

Predominantly flat single-family lots zoned R-1, in sub-zones whose minimum lot sizes run from 5,000 to 10,000 square feet with minimum widths of 50 to 70 feet. The floor area ratio tops out at 0.45, or 0.50 with the city's renewable energy bonus, and lot coverage at 45 percent, so the size of an addition is weighed against those limits from the start. A pool house or other accessory building may rise no higher than 12 feet and, garages and patio covers aside, is limited to 700 square feet in one open room without a kitchen or bedroom, designed to match the style, form, color and materials of the house. One local condition that shapes the work: Since the Army Corps of Engineers finished raising the channel levees in 2000, FEMA has placed no Downey property in a 100-year flood zone, and current flood maps show most of the city as Zone X, an area with reduced flood risk due to levee.

All of it, including Downtown Downey and Gallatin. 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.