Prefab / Modular ADU in California

Backyard Unlimited, founded 2009 in Rocklin, CA, specializes in Amish-crafted sheds, gazebos, pergolas, and ADUs for Greater Sacramento homeowners. They handle full ADU design, permitting, and installation in-house, with no subcontractors.

prefabADU is a Bay Area ADU builder with 16+ years of experience offering affordable kits and plans from under $45K. With 12 state-approved plans valid across California, they simplify permits, design, and installation for homeowners.

ADU Premium builds eco-friendly, RVIA-certified tiny homes and ADA-accessible ADUs. Models range from 90–360 sq ft, starting at $49,200. Includes permits, delivery, and installation. Financing available via RV loans, HELOC, and more.

Victory Home Remodeling builds detached, attached, garage conversion, Junior, and above-garage ADUs in Los Angeles. Benefits include added property value, rental income, and multi-generational living. Timelines range from 2–10 months depending on ADU type.

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.

Avica Construction & Development Inc is a licensed LA-based ADU contractor building detached ADUs, garage conversions, attached ADUs & JADUs across Los Angeles, Orange County & San Bernardino County, managing design, permits & construction.

Type Five is a Berkeley, CA-based ADU builder offering custom backyard cottages, granny flats & in-law suites. They combine modular design, transparent pricing & streamlined construction for stress-free, high-quality detached ADUs built to last.

Pro-built Homes builds factory-constructed Accessory Dwelling Units (ADUs) delivered 99% complete. Ideal as in-law suites, rental units, or backyard cottages, their ADUs offer quality, speed, and long-term value with minimal on-site disruption.

Samara's Backyard ADU offers prefab accessory dwelling units for California homeowners. Five sizes available, including the 950 sq ft XL 10. Factory-built, fire-resistant, energy-efficient, with full-service permitting, installation & flexible financing.

Zume Builders, based in San Mateo, CA, specializes in custom homes, ADUs, and prefab construction across the Peninsula, serving Atherton, Palo Alto, Hillsborough & more.

Roof and Realm is a California-based steel-framed modular home and ADU builder offering fire, earthquake, and wind-resistant structures. Their eco-friendly builds use 98% recyclable materials, generate minimal waste, and support solar-ready, Net Positive energy designs.

Cousin Gary Homes, serving Chico since 1972, offers a wide range of ADU models—from 439 to 1,177 sq ft—including granny flats and backyard cottages. Visit their showroom at 13468 Highway 99 North to explore options.

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.

Ghousetechnologies is a California ADU contractor offering steel frame accessory dwelling units. Models range from 360–1,200 sq ft. Builds are fire, flood, earthquake, and hurricane-resistant, eco-friendly, and completed faster than traditional construction.

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.