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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CityPaks is a minority & woman-owned ADU builder in the San Francisco Bay Area specializing in affordable, sustainable backyard cottages & detached ADUs using SIP panels. No crane needed, no sales tax, pre-approved in San Jose.
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Urban Building Workshop is a full-service architecture firm in the Bay Area specializing in custom homes, remodels, and ADUs. Experts in Marin County, San Francisco, and Sonoma County permitting, they deliver efficient, light-filled designs.
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Karl Kardel Company offers home remodeling, additions, and ADU construction in Oakland, Pasadena, and the Bay Area. Services include detached ADUs, garage conversions, granny flats, kitchen and bathroom renovations for residential properties.
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Custom ADU construction and remodeling services focused on creating functional, comfortable living spaces with quality craftsmanship and reliable workmanship.
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J&A Builders Inc serves San Jose & the Bay Area with residential construction, remodeling, ADUs, second floor additions & garage conversions. Services include kitchen, bathroom, whole-home remodels & granny flats.
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Diagram Architecture & Diagram Design Build completed a 871 sq ft detached ADU with 2 beds, 1.5 baths, open floor plan, stainless appliances, custom closets & natural light—maximizing compact living through integrated design-build expert... read more
Bao-Tran Builders Inc specializes in ADU construction, including detached ADUs, granny flats, JADUs, garage conversions & multi-unit properties. Expert ADU contractor delivering functional, high-quality housing solutions for property owners.read more
Eagle ADU is a licensed ADU builder in Northern California offering three signature models: Eagle Studio ($180K–$220K), Eagle One ($230K–$280K), and Eagle Two ($310K–$360K), with rental income potential up to $4,000/month.
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Loona Construction Inc. is a San Francisco ADU contractor specializing in detached ADUs, garage conversions, attached ADUs, and JADUs. They handle design, permitting, and construction, helping homeowners add rental income or family housing.
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Valley Boutique Builders is a licensed Bay Area ADU contractor offering full-service accessory dwelling unit construction, custom home additions, kitchen and bathroom remodeling, and new construction with free initial consultations.
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HDR Remodeling is a Bay Area Design Build firm since 1987, specializing in kitchen remodels, bathroom renovations, and home improvements across Oakland, Berkeley, Alameda, and the East Bay, backed by an experienced team of architects and designers... read more
9 Builders is a Bay Area ADU contractor offering full-service design, permits & construction. Specializing in detached ADUs, garage conversions & additions, costs range $150K–$350K, taking 8–14 months to complete.
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Decor Builders is a San Jose-based ADU contractor with 15+ years of Bay Area experience. They offer full-service ADU design and construction, including granny flats and in-law suites, handling permits, engineering, and project management.
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.