Basement Conversion near Castro Valley, CA

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.

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.

Intelligent Choice Builders is a licensed Bay Area ADU contractor serving Palo Alto, Cupertino, San Jose & Sunnyvale. They build detached ADUs, garage conversions, granny flats & more, managing permits, design & construction end-to-end.

ADU Builders Group is a Bay Area family-owned ADU contractor with 21+ years of experience. They build attached, detached, converted, and junior ADUs, offering full design-build services, permitting support, a 3-year warranty, and a 10-year structural guarantee.

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.

Leon's Construction Inc. offers ADU construction services in Escondido, Encinitas, and San Marcos, CA. They build backyard cottages, basement apartments, tiny homes, and more using durable, energy-efficient materials.

BuildZig ADU Services is a Bay Area ADU contractor specializing in design, permitting, and construction. They handle garage conversions, detached ADUs, basement/attic conversions, and more, offering transparent pricing throughout.

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.

E&E General Construction Inc (License #1067263) specializes in ADU construction and garage conversions in Richmond, CA. Services include detached ADUs, attached units, and garage conversions across the Bay Area. Free estimates available.

ADU Builders Bay Area specializes in detached ADUs, garage conversions, in-law suites & more. Expert ADU contractors offering transparent pricing, full permitting & quality construction throughout the Bay Area.

Alon Design & Remodeling is a leading ADU contractor offering detached, attached, garage conversion, basement, and JADU options. ADUs boost property value, generate rental income, and provide independent living spaces with full amenities.

Dream Build Services is a full-service ADU contractor in Fremont, CA, offering detached ADUs, garage conversions, basement conversions, and JADUs. Services include design, permits, electrical, plumbing, HVAC, and solar integration across the East Bay.

ADUs add rental income & property value. Services include garage conversions, detached ADUs, JADUs & granny flats. ADU Feasibility Studies cover code, utilities & ROI. Architectural services via Adapt Dwellings ensure smooth approval to construction.

American Builders is a San Francisco ADU contractor specializing in garage conversions, detached units, in-law suites & basement conversions. They handle permits, zoning, and deliver code-compliant accessory dwelling units on time and on budget.

ELS Home Builders specializes in ADU design and construction across San Jose, Palo Alto & the SF Bay Area. Services include granny flats, in-law suites, garage conversions & detached ADUs for multigenerational living.