Detached ADU near Castro Valley, CA

Harmony Design & Development builds custom ADUs across the San Francisco Bay Area, including detached units, garage conversions, and in-law suites. They manage permits, design, and construction from start to finish.

Acton ADU is a Bay Area ADU contractor founded by Stan Acton with 30+ years of experience. They offer full-service ADU design, construction, garage conversions, and permitting across San Jose and the broader Bay Area.

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.

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.

ADBC Architecture completed an 800 SF detached ADU in East Bay, CA in 2025, designed for multigenerational living. Built with thermally modified wood and steel, the backyard cottage features high ceilings and large windows for a spacious feel.

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.

Shed Shop offers ADUs (Accessory Dwelling Units) via their Mini Cottage program. Sizes range from 192 to 480 sq. ft. Services include foundation, plumbing, electrical, permits & more. Available in select cities.

CDU Inc. offers expert ADU construction & remodeling in the Greater Bay Area. Services include new builds, garage conversions, electrical, plumbing & custom design to boost property value & functionality.

ENE Smarthome, Inc. is a Bay Area contractor offering home remodeling, ADU construction, smart home upgrades, and accessibility improvements. Services include garage conversions, granny flats, aging-in-place remodels, and SB9-compliant ADU projects.

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.

King David Construction is a Palo Alto ADU contractor offering full-service design, permitting & construction across the Bay Area. Specializing in detached ADUs, garage conversions & in-law suites.

Anura Design specializes in ADU design, offering styles from modern farmhouse and contemporary steel to Mediterranean stucco. Their interiors feature open-concept layouts, natural wood tones, and refined finishes tailored to compact, functional living spaces.