Detached ADU near Castro Valley, CA

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.

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.

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 ... read more

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.

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 T... read more

Quartz Construction builds ADUs in San Jose, including detached units, garage conversions, and in-law suites. ADUs offer extra space, passive rental income, and multigenerational living solutions for Bay Area homeowners.

Edrington and Associates helps property owners add ADUs—garage conversions, detached units, or Junior ADUs. They offer ADU Feasibility Studies in three packages and a free 15-minute consultation to explore options.

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 fir... read more

C.J. Skeeles General Contractor specializes in ADU construction in Hayward, Oakland & San Francisco, CA. Services include detached ADUs, garage conversions & interior conversions, all built to California zoning & permitting requirement... read more

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.

Eco Scale Construction builds ADUs in Sunnyvale, Los Altos & Palo Alto, CA. Services include detached ADUs, garage conversions & JADUs. Costs range from $80K–$400K+. Fully compliant with California ADU regulations.

JS Design & Build is a full-service ADU builder with the experience to navigate local codes, streamline approvals, and deliver exceptional results. Their in-house team of designers, builders, and project managers ensures seamless communication... read more

Bayside Builders Group is a licensed Bay Area ADU contractor with 25+ years of experience. Services include detached ADUs, garage conversions, and in-law suites. Serving Oakland, San Jose, San Francisco, and surrounding counties.

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.