Adu estimate — 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
An estimate is a preliminary assessment of what your ADU project might cost before the final design is locked in. It helps you decide if your budget aligns with the size of the unit you want. Costs vary based on whether you choose a detached structure or a garage conversion. It is a starting point for planning. Exact pricing confirmed free on the call.
Frequently asked in Costa Mesa
What does an accessory dwelling unit mean in Costa Mesa?
Where can I find accessory dwelling unit builders in Costa Mesa?
What are accessory dwelling unit companies in Costa Mesa?
Are there accessory dwelling unit grants available in Costa Mesa?
Where can I find local ADU services in Costa Mesa?
Where can I find accessory dwelling unit builders near me in Costa Mesa?
What permits are needed for an ADU in Costa Mesa?
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 del Mar, South Coast Metro, Fairview Shores, Lido Village, College Park — and every surrounding area.
Areas we serve
Browse by state, then city.
California (3)
All of California · Costa Mesa · Jurupa Valley · Santa Maria