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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Edri Construction, Inc. is a San Francisco-based ADU contractor offering full-service accessory dwelling unit construction across the Bay Area, including garage conversions, detached ADUs, granny flats, and energy-efficient home additions with in-house project management.
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Todd Jersey Architecture (TJA) is a Berkeley-based sustainable design firm serving the SF Bay Area. Specializing in ADUs, remodels, new homes & historic preservation, TJA combines 30+ years of experience with a performance-driven, eco-conscious approach.
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Shefer Builder Inc. offers full-service ADU construction, managing design, permits, and building. Specializing in detached ADUs, granny flats, and in-law suites, they deliver custom accessory dwelling units that boost property value and rental income.
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Deharo Construction is a trusted ADU builder serving Livermore, Pleasanton, and Dublin. Specializing in accessory dwelling units, new construction, and home additions, they deliver custom granny flats, detached ADUs, and in-law suites across the Tri-Valley area.
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S.D White Construction Inc, a licensed Bay Area ADU contractor with 20+ years experience, builds detached, attached, garage conversion & above-garage ADUs in Richmond, CA. Full-service from design & permits to final inspection, completed in 3–5 months.
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We guide you through design options and material choices, taking precise measurements to create a custom plan that perfectly fits your property. This careful planning ensures that your new ADU will seamlessly blend with your existing space and meet all your functional needs.
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Epic Modulars delivers fast, flexible, and customizable solutions for homes and ADUs. Their manufactured homes and ADUs are built in controlled factory environments, ensuring superior quality, faster timelines, and predictable costs.
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ADUs (accessory dwelling units) are self-contained homes on existing properties. California's 2020 laws simplified ADU permits statewide. Alpha ADU Solutions, a San Francisco-based ADU builder with 100+ team members, specializes in granny flats, garage conversions & in-law suites.
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Clever Design & Remodeling builds ADUs across the San Francisco Bay Area, including garage conversions, attached, detached, and junior ADUs. Services cover permits, construction, interior design, and landscaping. Average ADU cost is ~$145,000.
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Burton Builders LLC is a trusted construction company specializing in ADU construction, single-family, multifamily, and commercial builds. Known for quality workmanship and client-focused service, they deliver expert results on every project.
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Quality Choice Construction & Painting offers ADU construction services including studio, 1-bedroom, and 2-bedroom units. Options include garage conversions, backyard cottages, and detached ADUs for rental income or multi-generational living.
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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.
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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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prefabADU is a Bay Area ADU builder with 16+ years of experience offering affordable kits and plans from under $45K. With 12 state-approved plans valid across California, they simplify permits, design, and installation for homeowners.
read moreCastro Valley is a unique location for ADU construction because it is an unincorporated community governed by Alameda County rather than an independent city. This means that homeowners looking to build an Accessory Dwelling Unit must work with the Alameda County Planning Department and follow Alameda County's specific zoning codes and building regulations. Experienced ADU contractors in Castro Valley understand this distinction and are well-versed in navigating county-level permitting processes, which differ significantly from those of neighboring incorporated cities like San Leandro or Hayward.
Because Castro Valley falls under Alameda County jurisdiction, ADU contractors must comply with the county's ADU ordinance, which aligns with California state law but includes local nuances. Some important regulatory considerations include:
Hiring a contractor with direct experience in Castro Valley and Alameda County is essential for a smooth ADU project. Local ADU contractors are familiar with the Alameda County Building Services Agency, which handles permit applications, inspections, and plan checks. They understand the typical timelines, required documentation, and how to address common issues that arise during the approval process. Castro Valley's hillside terrain in many neighborhoods also presents unique grading and foundation challenges that experienced local contractors are equipped to handle.
Castro Valley homeowners are increasingly choosing ADUs to address the Bay Area's housing demand and to generate rental income. The most popular ADU types in the area include:
Working with a qualified ADU contractor in Castro Valley ensures your project meets all Alameda County requirements while maximizing your property's potential. From initial design and permitting through final inspection, the right contractor will guide you every step of the way, helping you add value to your home in one of the East Bay's most desirable communities.