Backyard accessory dwelling unit — 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
This is a detached unit built on your property, separate from your main home. It is a practical solution if you have extra yard space and want to add living quarters for family, guests, or tenants. These structures offer privacy while keeping you close to your primary residence.
Frequently asked in Costa Mesa
What are some good options for homes with in-law suites in Costa Mesa?
Can I get an ADU estimate for my Costa Mesa property?
How do I find the best accessory dwelling unit builders near me in Costa Mesa?
Where can I find an accessory dwelling unit for rent in Costa Mesa?
What ADU quotes are available in Costa Mesa?
What is the permit cost for an accessory dwelling unit in Costa Mesa?
What are the requirements for ADU building 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 North, Mesa South, The Villages, College Park, Fairview Shores — and every surrounding area.
Areas we serve
Browse by state, then city.
California (3)
All of California · Costa Mesa · Jurupa Valley · Santa Maria