Number 1: Two Story ADU Builders
on GoogleOrange County
A general contractor in Orange County, California, working on home additions, ADUs and design-build projects.
ADU builders in Orange County
The 10 ADU builders from Google's results for Orange County, California, ordered by Google rating weighted by review count. No firm pays to be listed or ranked.
Last updated
- Garage conversion ADU
- $69,000 – $172,500existing structure
- Detached ADU
- $172,500 – $460,000new build, utilities
- Prefab ADU
- $138,000 – $345,000unit, foundation, install
- Orange County vs US
- +15%well above the US median
Licensing in California. California contractors need a CSLB license for most remodeling work. Check the license number and its bond on the CSLB site before you sign.
Number 2: DYM Builders
on GoogleIrvine, CA
DYM Builders Group builds custom homes and handles remodeling, ADUs and garage conversions in Orange County, Los Angeles and Dallas, Texas. Based in Irvine, it works on home additions and design-build projects alongside its other construction services.
(800) 396-6773 2372 Morse Ave #987, Irvine, CA 92614
Number 3: Builder Well
on GoogleNewport Beach, CA
Builderwell is a Newport Beach design-build contractor specializing in large ADU construction across Orange County. It builds guest houses, multi-generational suites and rental units, and also takes on fire rebuild work in Los Angeles.
(949) 232-0555 220 Newport Center Dr #22, Newport Beach, CA 92660
Number 4: ADU West Coast
on GoogleSeal Beach, CA
ADU West Coast is listed among ADU builders in the Seal Beach, California area.
(714) 253-7369 13001 Seal Beach Blvd #210, Seal Beach, CA 90740
Number 5: Superior Adus
on GoogleIrvine, CA
Superior Adus is listed among ADU builders serving Irvine, California.
(949) 216-0686 6 Venture, Irvine, CA 92618
Number 6: Orange County Construction
on GoogleAnaheim, CA
Orange County Construction is an Anaheim, California contractor listed for home additions and ADU construction.
(714) 231-9773 1173 N Red Gum St, Anaheim, CA 92806
Number 7: SoCal Casitas
on GoogleIrvine, CA
Working across Orange County from Irvine, SoCal Casitas builds custom accessory dwelling units and also handles room additions, home remodels and custom home builds. Its projects add separate living space to existing properties for family members, guests or rental use.
(949) 677-9757 16372 Construction Cir E, Irvine, CA 92606
Number 8: Gettler Construction
on GoogleOrange County
Gettler Construction builds accessory dwelling units across Orange County, California, and also converts garages into living space. Room additions are part of its work as well, and the firm prepares individual estimates for each ADU or conversion project.
Number 9: Usmodular Inc
on GoogleCalimesa, CA
From its base in Calimesa, USModular builds prefabricated accessory dwelling units for properties across Southern California. Its prebuilt units serve as extra living space or as rental homes, and projects start with an on-site evaluation of the property.
(888) 987-6638 579 W County Line Rd, Calimesa, CA 92320
Number 10: Orange County Custom Home Builder
Orange County
Avorino is an Orange County builder of custom homes, accessory dwelling units and commercial projects. The firm runs each job from planning to final handoff, coordinating the trades itself so the client deals with one point of contact through construction.
What ADU builders charge in Orange County
In Orange County, a garage conversion ADU typically costs $69,000 – $172,500. Remodeling labor in Orange County runs about 15% above the US median, which accounts for most of the difference from the same project elsewhere.
How to choose between them
- Check the license yourself. Where California or Orange County licenses this work, the licensing board's own lookup confirms a license number in a minute. Do it before you sign, not after.
- Get three bids on the same scope. Written down, split into labor, materials, allowances and anything structural. Most people compare a total against a total and end up choosing between two different projects.
- Ask what is not included. Permits, debris removal, fixture and finish allowances, and repairs after demolition are the four that turn a cheap bid into an average one.
- Never pay a large deposit up front. A deposit to order materials and hold a start date is normal. Half the total before anyone shows up is not.
How this list is ordered
These are the firms from Google's results for "adu builders orange county ca", with directories, chains and suppliers removed. They are ordered by Google rating weighted by review count, and the ratings shown are Google's. No firm pays to be listed or ranked. The list was last updated in October 2026.
ADU builders in Orange County: common questions
Can I build an ADU on my lot?
It depends on your city and state. California, Oregon and Washington have state laws that make ADUs allowed on most single-family lots. Elsewhere it is set by local zoning, so check lot size, setback and owner-occupancy rules with your city first.