Prefab / Modular ADU near Diamond Bar, CA

Prefab vs. stick-built ADUs explained. Homeplex offers the Clever ADU, an HCD-certified modular unit built all-electric in a factory, saving 5–6 months vs. traditional construction. Costs vary based on site conditions.

Level Up Contractor is an ADU builder in Los Angeles offering garage conversions, detached ADUs, and JADUs. Services include full permitting, design-build, and LADBS coordination. Costs range from $100K to $450K depending on project type.

A1 ADU Contractor specializes in garage conversions and custom ADU construction throughout Los Angeles and the San Fernando Valley. With over 15 years of experience, our team provides complete design, permitting, and construction services to transform underutilized spaces into beautiful, functional living areas. Whether you're creating a rental unit, guest house, home office, or multi-family dwelling, we deliver high-quality craftsmanship and personalized solutions tailored to your needs.

ABODU offers factory-built, fire-resistant ADUs installed in a single day. HCD-approved and AB 462-compliant, their prefab units help wildfire rebuild families return home faster, with Certificates of Occupancy issued before primary dwelling completion.

USModular Inc. is a Temecula, CA ADU builder specializing in modular, prefabricated construction. Units are up to 90% factory-built, completed in ~120 days, and comply with IRC and local codes. Services include feasibility studies, design, engineering, permitting, and installation.

BSPK Design is a Venice, CA residential studio founded by Chris Faulhammer & Roman Reiterer, with 50+ years combined experience. Services include custom homes, fire rebuilds & prefab NextGen Building. Multiple Houzz Best of Design award winners.

Addition Builders LA is a full-service ADU contractor in Los Angeles offering custom ADUs, prefab units, and garage conversions. Licensed, bonded, and insured, they manage design to construction, completing projects in as little as nine months with transparent pricing.

California Backyard Homes Inc specializes in prefab ADUs, tiny houses, and modular homes across California. Starting from $44,500, they offer turnkey installation including permits and utility connections, with financing available up to 23 years.

Paramount Manufactured Sales in Riverside offers Skyline Homes-built ADUs for Southern California homeowners in LA, Orange, Riverside, San Bernardino & San Diego Counties. Models range from 479–849 sq ft. California law now allows detached ADUs up to 1,200 sq ft.

Ultra-Unit Architectural Studio, based in Long Beach, CA, offers architecture and construction services for ADUs, residential, multifamily, and commercial projects. Led by Cameron Crockett AIA, LEED, with 25+ years experience. Free initial consultations available.

Full Circle Builders offers custom ADU construction in Riverside County & the Inland Empire. Detached ADUs start at $185,000 (590 sq ft, 1BD/1BA). Container homes also available. Turn-key builds, permitting assistance included.

Nagar Builders Inc. is a Los Angeles construction company offering ADU construction, garage conversions, kitchen and bathroom remodeling, room additions, roofing, electrical work, and commercial remodeling since 2019.

ADU Los Angeles (ADLA) is a specialized ADU contractor serving LA County. They offer consulting, custom design, construction, garage conversions, basement ADUs, attached and detached units, helping homeowners maximize property value.

Revival Homes is a California ADU project manager handling planning, financing, design, permitting, and construction. They build detached ADUs, garage conversions, JADUs, and more, with costs ranging from $100K to $300K.