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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Custom Home is a Bay Area ADU contractor (CSLB #986048) with 160+ projects since 2005. They build detached, attached, junior ADUs & garage conversions across South Bay & Peninsula, with costs from $120K–$500K+.
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We are a family-first, boutique residential design & build firm serving the Orinda and East Bay community. We’re not just service providers — we’re your neighbors. We understand the local permitting process, the hillside terrain, the fire-hazard restrictions, and the thoughtful planning needed to create homes that truly work for East Bay families.
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Atlas General Construction delivers complete ADU construction for detached, attached, and converted structures. Our team manages every phase of development including zoning research, architectural coordination, structural engineering, Title 24 compliance, permit processing, foundation work, framing, roofing, plumbing, electrical systems, HVAC installation, interior finishes, and final inspections.
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ADU Home Addition is a leading Bay Area ADU contractor with 12+ years of experience. They specialize in custom ADU construction, in-law suites, garage conversions, home additions, and rental-optimized ADUs, handling design, permits, and full construction.
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Haus+ is a Bay Area ADU builder offering turnkey accessory dwelling units for California homeowners. They handle design, permitting, and construction using a panelized hybrid method, with all-inclusive upfront pricing and in-house financing available.
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Step-up Construction is a San Jose ADU contractor specializing in garage conversions, attached additions, and detached backyard ADUs. Costs range from $80K to $475K. They guide homeowners through permits, zoning, and San Jose's ADU regulations.
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Licensed ADU contractor Full Steam Ahead Construction serves East Bay homeowners with custom accessory dwelling units, including garage conversions, backyard cottages & in-law suites. Serving Concord, Oakland, Berkeley & more.
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At Smith and Son Construction, they specialize in designing and building high-quality ADUs in San Leandro, CA. Whether you envision a private guest house, a rental unit, or a home office, they deliver innovative designs, expert craftsmanship, and a stress-free construction experience.
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Sightline Construction is a Santa Cruz general contractor specializing in ADUs, new home builds, renovations, remodels, and custom additions. They manage projects from planning to completion, ensuring code compliance and quality craftsmanship.
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Done Right Builders & Remodeling is a licensed Bay Area ADU contractor (Lic#1002689) with 20+ years experience. Services include detached/attached ADUs, JADUs & garage conversions in Union City, Hayward, San Jose & Santa Clara.
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Apex ADU Builders is a Los Angeles-based contractor specializing in accessory dwelling unit construction. Services include new builds, garage conversions, permitting, and design. Costs range from $80K–$400K, with potential ROI 35% higher than homes without ADUs.
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ExpandADU is a California-based prefab ADU builder offering full-service accessory dwelling unit construction, including consultation, design, planning, and build. Serving the Bay Area and beyond, they specialize in detached ADUs, granny flats, and JADUs.
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California Building and Remodeling offers ADU construction, kitchen & bathroom remodeling, roofing, and concrete services in Albany, CA and the Bay Area. Experienced ADU contractor serving Albany, Berkeley, Richmond & more.
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.