Adu permit — Costa Mesa, CA
Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total investment. The final figure depends heavily on whether you choose a prefab unit or a custom build from the ground up. Site conditions are another major factor; if your property requires extensive grading, utility trenching, or foundation work, costs will climb. You also have to consider your choice of finishes, like high-end appliances or custom cabinetry. Navigating local permit fees and impact assessments also adds to the total.
About this service
Obtaining an ADU permit is the legal process of getting city approval for your secondary structure. You need this documentation before any construction begins to ensure your build meets local safety and zoning codes. The permitting phase can involve architectural plans and engineering reviews. Fees and design costs for this stage typically add several thousand dollars to your project. Exact pricing confirmed free on the call.
Frequently asked in Costa Mesa
What's the permit cost for an ADU in Costa Mesa?
What's involved in ADU building in Costa Mesa?
What are the local ADU regulations in Costa Mesa?
What ADU services are available in Costa Mesa?
Are prefabricated ADUs a good option in Costa Mesa?
What's the cost of an accessory dwelling unit in Costa Mesa?
What are affordable ADU options?
Also serving nearby: Santa Ana · Huntington Beach · Westminster · Irvine · Garden Grove
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Costa Mesa — population 108,354; about 6,855 residents per square mile across 15.8 sq mi. ZIP codes covered include 92626, 92627, 92628.
Neighborhoods served in Costa Mesa: Mesa North, Mesa South, Westside Costa Mesa, Eastside Costa Mesa, Downtown Costa Mesa — and every surrounding area.
Areas we serve
Browse by state, then city.
California (3)
All of California · Costa Mesa · Jurupa Valley · Santa Maria