OCA Builders offers ADU design & construction in Santa Cruz County, including detached, attached, garage conversion, internal & junior ADUs. They use county-approved floor plans to streamline permitting and reduce timelines.
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E&E General Construction Inc (License #1067263) specializes in ADU construction and garage conversions in Richmond, CA. Services include detached ADUs, attached units, and garage conversions across the Bay Area. Free estimates available.
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Realty Builders Inc. is a licensed ADU contractor specializing in custom accessory dwelling units, including in-law suites, granny flats, garage conversions & rental units, offering streamlined permitting & guaranteed workmanship.
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Gordon Reese Design Build is a licensed ADU contractor in Walnut Creek, CA, with 41+ years of experience. They offer custom ADU design and construction, 3D renderings, transparent pricing, serving the Bay Area including Danville, Lafayette & Concord.
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Alon Design & Remodeling is a leading ADU contractor offering detached, attached, garage conversion, basement, and JADU options. ADUs boost property value, generate rental income, and provide independent living spaces with full amenities.
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Manzanita Design Build is an East Bay ADU contractor specializing in accessory dwelling units. Serving Berkeley, Oakland, Alameda & more. New ADU construction starts ~$300K, 5–8 month build time. Licensed (#1034108) & insured.
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Urban Shore Builders offers full-service ADU design & construction, including garage conversions, detached units & additions. As a turnkey ADU contractor, they handle permits, design & build. Services include plumbing, electrical, HVAC & retaining walls.
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ADU Premium builds eco-friendly, RVIA-certified tiny homes and ADA-accessible ADUs. Models range from 90–360 sq ft, starting at $49,200. Includes permits, delivery, and installation. Financing available via RV loans, HELOC, and more.
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Jeff Martinez Construction Inc. builds ADUs in Oakley, CA with 27+ years of experience. Services include detached ADUs, garage conversions, permits, finishing, and landscape integration across Contra Costa County.
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Home by Tom is a Bay Area ADU contractor with 21+ years of experience serving Walnut Creek. They build detached ADUs, attached ADUs, and garage conversions, managing design, permits, and construction for rental income or multi-generational living.
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Optivest Build is a licensed general contractor offering ADU construction, garage conversions, home additions, renovations, and new builds. They manage permits, design, and inspections, delivering residential and commercial projects on time and within budget.
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AKD Homes is a Bay Area ADU contractor with 20+ years of experience. They offer full-service ADU design and build, including detached ADUs, custom designs, and conversions from Berkeley to San Jose.
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Collins Remodeling is a licensed ADU contractor in Alameda, CA, specializing in detached ADUs, garage conversions, JADUs, and granny flats. They manage permitting, design, and construction, helping homeowners add value and rental income.
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DNM Architecture is a California-based firm specializing in ADU design and permitting. Their ADUxDNM program covers site analysis, design, permitting, and construction management, offering detached ADUs, garage conversions, and more.
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WS Builders offers expert ADU construction in Santa Cruz with 20 years of experience. Services include permit management, design collaboration, and full project oversight. Serving Santa Cruz, Scotts Valley & Soquel.
read moreSan Mateo, California, sits at the heart of the San Francisco Peninsula, making it one of the most desirable — and expensive — housing markets in the nation. With median home prices consistently among the highest in the country, homeowners in San Mateo are increasingly turning to Accessory Dwelling Units (ADUs) as a smart way to add rental income, house family members, or increase property value. Finding experienced ADU contractors in San Mateo is the critical first step toward making this investment a reality.
San Mateo operates under both California state ADU law and its own local municipal code. The City of San Mateo has worked to align with state mandates that streamline ADU approvals, but there are still important local considerations every homeowner must understand before breaking ground:
Working with a licensed ADU contractor familiar with San Mateo's building department is essential. The city's permitting process involves plan checks, inspections, and compliance with the California Building Code, Title 24 energy standards, and local zoning ordinances. An experienced local contractor will know how to navigate the San Mateo Community Development Department, helping to avoid costly delays and revisions.
Given the variety of lot sizes and home styles across San Mateo neighborhoods — from the flat streets near downtown to hillside properties in areas like Sugarloaf — ADU contractors in San Mateo commonly build several types of units:
When selecting an ADU contractor in San Mateo, CA, look for professionals who are licensed by the California Contractors State License Board (CSLB), carry proper insurance, and have a proven portfolio of completed ADU projects in the Bay Area. Request detailed bids, check references, and confirm familiarity with San Mateo's specific permitting timelines. A qualified contractor will guide you from design and permitting through construction and final inspection, ensuring your ADU is built safely, legally, and on budget.