At ADU San Mateo, we combine architectural insight, construction experience, and deep knowledge of Bay Area zoning laws to deliver high quality accessory dwelling units from design through move in. Our mission is simple: to make building your ADU clear, fast, and stress free.
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Sustainable Building & Design (SB&D) is a licensed general contractor in Humboldt County, CA, specializing in ADU construction, remodeling, and new builds using sustainable materials at affordable prices.
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EcoSmart Builders is a licensed Southern California ADU contractor specializing in accessory dwelling units, home expansions, and fire rebuilds. Serving Los Angeles County, they manage design, permitting, and construction of detached, attached, garage conversion, and junior ADUs.
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At Gadi Construction, they design and build Accessory Dwelling Units (ADUs) that maximize your property’s potential. Whether you want extra income through rental space, a private guest suite, or a comfortable home office, their ADU construction services make it possible.
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iHome Design & Remodel specializes in custom ADU and casita construction, offering full-service builds from design to completion. Services include garage conversions, detached ADUs, permit handling, and free 3D consultations for homeowners.
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ADU Custom Home Source, based in Riverside, CA, specializes in custom manufactured homes and ADUs. Serving Southern California, they handle design, permitting, financing, and installation, offering granny flats, casitas, and detached ADUs.
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Mills Builders Inc is a Sacramento-based residential construction firm founded in 1999. Specializing in ADU construction, home renovation, in-fill development, and whole-house builds, they serve Sacramento's historic neighborhoods with decades of hands-on expertise.
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Prefab vs. stick-built ADUs explained. Homeplex offers the Clever ADU, an HCD-certified modular unit built all-electric in a factory, saving 5–6 months vs. traditional construction. Costs vary based on site conditions.
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K&S Design Build specializes in ADU construction and garage conversions, offering full design-build services from concept to completion. They handle permits, city regulations, and create granny flats, in-law suites, backyard cottages, and rental units.
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ADU1 helps multifamily property owners add ADUs to boost income. Add up to 25% more units plus 2 detached ADUs. Services include a $250 feasibility report, full design-build, and free weekly Q&A sessions every Wednesday.
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Better Place Design & Build is a San Diego ADU contractor specializing in detached ADUs, garage conversions, and room additions. Their feasibility-first process verifies zoning, utilities, and site conditions before pricing, reducing costly surprises.
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EG Construction is a trusted San Diego ADU builder offering full-service design, permits & construction. They provide a Price Guarantee & 60-Day Completion Guarantee. Serving all of San Diego County. License #864642.
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Regency Construction & Remodeling BA is a San Francisco ADU contractor offering new builds, space conversions, and prefab ADU solutions. They handle design to completion, manage permits, and ensure compliance with local zoning laws.
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WM Construction is a licensed ADU contractor in Los Angeles offering full-service builds, from site assessment and design to permitting and post-construction support, helping homeowners add granny flats, garage conversions, and in-law suites compliantly.
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DB Construction is a full-service ADU contractor in Greater Los Angeles, building detached ADUs, garage conversions, JADUs, in-law suites, and room additions. They manage permits in-house, offering transparent costs and turn-key project completion.
read moreCalifornia 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.
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.
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:
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.
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.