Adu 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
An ADU unit is simply a secondary dwelling located on the same lot as a primary residence. You might look into an ADU if you need more space for a home office, a gym, or housing for extended family. Exact pricing confirmed free on the call.
Frequently asked in Costa Mesa
What are the rules for accessory dwelling units in New Hampshire?
While we focus on Costa Mesa, California, accessory dwelling unit regulations vary significantly by state and locality. For New Hampshire, you'd need to consult their specific state laws and local municipal ordinances. These rules often cover things like size, placement, and permitting. For accurate information relevant to New Hampshire, it's best to consult local authorities there. We focus on California ADU regulations.
What are the financing options for an ADU in Costa Mesa?
Financing an ADU in Costa Mesa can be achieved through various avenues. Many homeowners leverage home equity lines of credit (HELOCs) or home equity loans. Personal loans or specialized construction loans are also options. It's advisable to speak with local banks or credit unions about their offerings. We can provide you with a quote to help with your loan applications. Let's get you that estimate.
Who is a good ADU builder in Costa Mesa?
Are homes with in-law suites common in Costa Mesa?
What ADU services are offered in Costa Mesa?
What is an emergency ADU in Costa Mesa?
What ADU company should I choose 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, Westside Costa Mesa, Eastside Costa Mesa, South Coast Metro, The Heights — and every surrounding area.
Areas we serve
Browse by state, then city.
California (3)
All of California · Costa Mesa · Jurupa Valley · Santa Maria