Accessory dwelling unit builders — 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

These are the professionals responsible for the design, permitting, and physical build of your project. Choosing the right builders means finding a team that manages the entire lifecycle of the project, including the complex approval phase with your city. You need specialized builders when you want a turnkey experience that minimizes your stress and ensures quality craftsmanship. We oversee every phase. Exact pricing confirmed free on the call.

Frequently asked in Costa Mesa

Also serving nearby: Santa Ana · Huntington Beach · Westminster · Irvine · Garden Grove

All cities in California →

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 Verde, South Coast Metro, Westside Costa Mesa, Downtown Costa Mesa, College Park — and every surrounding area.