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.
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New Avenue, Inc is a full-service design-build company serving the San Francisco Bay Area and Portland, OR since 2011. They specialize in ADUs, custom homes, renovations, additions, and Enclaves, managing design, permitting, and construction under one roof.
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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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Geico Builders offers ADU services including detached ADUs, attached ADUs, Junior ADUs, garage conversions, and home additions. Ideal for rental income, family housing, or maximizing space on your existing property.
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Bay Star Garage transforms garages into functional spaces in Santa Clara & Livermore, CA. Services include remodeling, flooring, EV charging, lighting, conversions & cabinets. Licensed, bonded & insured contractor specializing in ADUs and garage upgrades.
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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.
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BUILD 33 (CSLB #1051529) is a licensed general contractor based in Cupertino, CA, serving California, Arizona, Nevada, and Louisiana. They offer home additions, flooring, painting, plumbing, electrical, and more. Free quotes available.
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Vitalize Build is a Bay Area ADU contractor offering design and construction services for detached ADUs, garage conversions, and in-law suites. They provide preapproved, predesigned, and custom layouts ranging from 238 to 1,200 sq ft.
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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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ON Design & Remodeling is a Bay Area ADU builder offering home additions, garage conversions, granny flats, and in-law suites. They help homeowners expand living space, boost property value, and generate rental income.
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SFBay ADU is a Bay Area ADU contractor offering full-service design, permitting, and construction. Specializing in 600–1,200 sq ft units, they offer studio, 2-bed, garden cottage, and in-law suite options, with projects completed in as little as 6 months.
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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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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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RWB Construction is a Lafayette, CA-based ADU contractor serving the Bay Area. They build detached ADUs, garage conversions, granny flats & in-law suites, managing design, permitting, and construction from start to finish.
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.