Prefab / Modular ADU in California

Econstruct Inc is a Los Angeles ADU contractor offering full-service construction of accessory dwelling units. With 40+ pre-approved designs and 3D/AR tools via Ohana Dwellings, costs range from $200K–$450K+.

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.

US Modular Inc. is a trusted ADU builder in Riverside County, CA, with 35+ years of experience. They offer prefab ADUs, garage conversions & casitas starting at $150,000, completed in 6–9 months.

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.

Dan Boyle Construction offers expert ADU construction in Santa Rosa & Sonoma County. With 30+ years experience, they handle site evaluation, permits, design & full builds for detached ADUs, granny flats & backyard cottages.

Bay Area Home Remodelers builds ADUs in Daly City, San Francisco & San Jose. Services include garage conversions, granny flats, JADUs & detached units. Full project support from permits to completion.

Wellmade is a California prefab ADU builder specializing in panelized accessory dwelling units. Founded in 2020, they've completed 200+ projects, reducing construction waste by 85%. Serving CA, OR, and WA with all-inclusive pricing.

Bastion Structures offers modular concrete masonry homes, ADUs, and tiny houses that are fire-, mold-, and termite-resistant. Models range from 305 SF studios to 3,955 SF homes, ideal for California properties seeking durable, weatherproof living solutions.

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.

EHD Builders offers ADU construction services in Los Angeles, CA, including garage conversions, detached units & additions. Costs range from $150K–$350K+. Services cover permits, framing, plumbing, electrical & more.

The Springfield by Superior ADUs is a 2-bed, 2-bath detached ADU with open-concept living, vaulted ceilings, mini-split HVAC, kitchen island, ample storage, and optional ethanol fireplace—ideal as a granny flat or in-law suite.

Elite Construction builds ADUs in Santa Cruz County, offering detached units, garage conversions & addition ADUs. Projects range 250–1,200 sq ft, cost $115K–$450K, and take 6–9 months. Free estimates available.

West Coast ADU is a California-based ADU builder offering prefab & manufactured accessory dwelling units. They help homeowners add rental income, house family members & boost property value with streamlined permitting & construction.

SnapADU is San Diego's largest detached ADU design-build company, completing 100+ builds with a 4.9+ rating. They offer in-house design, permitting, and construction with fixed pricing across San Diego County.

ADUs are secondary units built on existing lots. ORR Construction builds detached ADUs, garage conversions, JADUs & in-law suites in California. Costs range $50–$300/sq ft. California laws like SB 897 simplify the permitting process.