ADU Contractors in California - Find & Compare Local Builders

A1 ADU Contractor

13701 Riverside Drive #200, Sherman Oaks, CA 91423

A1 ADU Contractor specializes in garage conversions and custom ADU construction throughout Los Angeles and the San Fernando Valley. With over 15 years of experience, our team provides complete design, permitting, and construction services to transform underutilized spaces into beautiful, functional living areas. Whether you're creating a rental unit, guest house, home office, or multi-family dwelling, we deliver high-quality craftsmanship and personalized solutions tailored to your needs.

Modulart

11300 Sorrento Valley Road, San Diego, CA 92121

ADU Company San Diego County specializes in off-site ADU construction, offering efficient, affordable accessory dwelling units. From granny flats to detached ADUs, their expert team guides clients from concept to Certificate of Occupancy.

OT Bay Builders

1580 Oakland Road, San Jose, CA 95131

OT Bay Builders is a complete remodeling company with over 40 years of combined experience amongst our team. We’re expert Bay Area ADU builders in San Jose with a customer-first mindset. As a full-service ADU builder, you can trust us to remain by your side from the first consultation to the final walkthrough.

Ruiz 805 Builders

1820 San Ramon Road, Paso Robles, CA 93422

Free Consultation

Ruiz 805 Builders is a Paso Robles, CA construction company serving the Central Coast. They specialize in concrete work, retaining walls, stamped concrete, and full-scope ADU construction, collaborating with architects for quality results.

ASL Remodeling

690 Saratoga Avenue, San Jose, CA 95129

Licensed 11 years in business Eco-Friendly

ASL Remodeling is a California licensed ADU contractor (CSLB #1060310) with 20+ years experience and 300+ completed projects. Services include detached ADUs, garage conversions, granny flats, JADUs, and in-law suites with full design-build support.

SJB Construction Inc

9739 Deer Hollow Court, Santee, CA 92071

Building a granny flat (ADU) in San Diego can boost property value and ease housing needs. Detached ADUs up to 1,200 sq ft start at $250/sq ft. Fee waivers may save homeowners $14,000+. Rules apply regarding zoning, lot use, and size limits.

Level House Construction Inc

17332 Keaton Ave, Sonoma, CA 95476

Level House Construction Inc. builds ADUs in Marin & Sonoma County, CA. Specializing in granny flats, in-law units & backyard cottages, they help homeowners add rental income, family housing & extra living space while boosting property value.

IND Construction

16430 Ventura Boulevard, Encino, CA 91436

At IND, we have a talented team of contractors, project leads, designers, and installers dedicated to creating your perfect home remodel or updating any interior or exterior project. We begin by scheduling a meeting with one of our exceptional IND project leads to assess your needs and develop several design and furnishing options.

Herbertson OG

6306 DOWNEY St, Riverside, CA 92509

Eco-Friendly

Herbertson OG is a construction and solar company offering ADU building, remodeling, new construction, roofing, HVAC, and solar panel installation. They serve homeowners, investors, and designers across residential and commercial projects.

UDA ADU

Palm Avenue, Los Altos, CA 94022

UDA ADU is a California ADU contractor specializing in detached ADUs, garage conversions, JADUs, and in-law suites. They handle design, permitting, and construction, offering homeowners a streamlined, full-service ADU building experience.

Nucave Construction Inc.

440 South Melrose Drive, Vista, CA 92081

Free Consultation Free Site Assessment

Experienced ADU contractor offering a structured process: site assessment, custom design options, transparent cost estimates, permit guidance, and financing support. Specializing in detached ADUs, garage conversions, and in-law suites.

Hamilton Exteriors

21634 Redwood Road, Castro Valley, CA 94546

Licensed

Hamilton Exteriors builds detached ADUs, garage conversions, and JADUs across 6 Bay Area counties. Licensed (CSLB #1078806), insured, and bonded. Projects run 5–9 months with fixed-price contracts. CalHFA grants and $0-down financing available.

ADU Hotline

5301 Laurel Canyon Blvd, Los Angeles, CA 91607

7 years in business

ADU Hotline offers affordable ADU design and permitting in Southern California. From granny flats to garage conversions, they handle the full process in 3–4 weeks, helping homeowners add rental income or family housing efficiently.

Motif Architecture

30211 Avenida De Los Banderas #200, Rancho Santa Margarita, CA 92688

Luxury Builds

Motif Architecture offers ADU, JADU, and garage conversion design services in Orange County, CA. Their five-phase process covers space planning, permitting, and construction. Projects include backyard cottages and garage-to-ADU conversions in Costa Mesa and Irvine.

Integrity Home Improvements

7343 Ronson Road, San Diego, CA 92111

Licensed 20 years in business Free Consultation

Integrity Home Improvements is a San Diego remodeling company founded in 2003 by Ryan Parkinson. Specializing in kitchen & bathroom remodels, home additions, and outdoor living, they serve communities across the greater San Diego area.

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What you need to know

ADU Contractors in California: Navigating the Golden State's Unique Landscape

California is at the forefront of the Accessory Dwelling Unit (ADU) movement in the United States. With one of the most severe housing shortages in the nation, the state has enacted sweeping legislation to make ADU construction more accessible. Since 2020, California laws such as AB 68, AB 881, and SB 13 have significantly reduced barriers, eliminating minimum lot size requirements, reducing setback rules, and streamlining the permitting process. For homeowners looking to add value to their property or create additional rental income, working with experienced ADU contractors in California has never been more important.

What California ADU Contractors Must Know About State Regulations

Professional ADU contractors operating in California must stay current with a constantly evolving regulatory environment. Under California law, local agencies are required to approve or deny ADU permit applications within 60 days. Additionally, ADUs under 800 square feet cannot be denied solely based on floor area ratio limits. Contractors must also be familiar with owner-occupancy rules, utility connection requirements, and fire safety standards that vary by county and municipality. Cities like Los Angeles, San Diego, and San Jose each have their own local ordinances layered on top of state law, making local expertise a critical asset.

Types of ADUs Built by California Contractors

Experienced California ADU contractors are skilled in building a wide variety of ADU types to suit different property configurations and homeowner needs. The most common types include:

How to Choose the Right ADU Contractor in California

Selecting the right contractor is one of the most critical decisions in any ADU project. Homeowners should look for contractors who hold a valid California Contractors State License Board (CSLB) license, ideally a Class B General Building Contractor license. It is also important to verify that the contractor carries proper liability insurance and workers' compensation coverage. Look for professionals with a proven track record of successfully permitted ADU projects in your specific city or county.

The Benefits of Building an ADU in California

Building an ADU in California offers significant financial and lifestyle benefits. Homeowners can generate rental income to offset mortgage costs, house family members, or increase overall property value. In high-cost markets like the San Francisco Bay Area or Los Angeles, a well-built ADU can add hundreds of thousands of dollars in property value. With the right California ADU contractor by your side, the process can be smooth, compliant, and highly rewarding.