Attached ADU near Costa Mesa, CA

Oceanside ADU Design is an Oceanside, CA firm specializing in detached, attached, garage conversion, and junior ADUs. Founded by structural engineer Devin, they handle architecture, engineering, and permitting in-house for efficient, budget-consci... read more

Stephens Brothers Construction is Temecula & Murrieta's top ADU builder since 2011, offering detached ADUs, JADUs, garage conversions & casitas. Costs from $300–$350/sq ft. Licensed, hands-on, and serving all of Riverside County.

Cornejos Builders offers ADU construction, garage conversions & home additions in LA & Orange County. 24 ADUs completed in 4 years. Costs range $80K–$250K. Licensed, insured, bonded. 1-year warranty included.

Arrowhead Remodeling & Design is a licensed California ADU contractor specializing in detached ADUs, garage conversions, and in-law suites. They offer free in-home consultations and manage projects from planning to completion.

ADU Resource Center is a Glendale, CA-based ADU contractor with 600+ completed units. They offer full-service ADU building, including design, permitting, financing, and construction of detached, attached, and garage conversion ADUs across Southern... read more

Silver Hammer Builders is a licensed ADU contractor in Los Angeles with 15+ years of experience. Services include garage conversions, detached ADUs, JADUs & in-law suites. Full project management, permits, and free consultations offered.

Oasis Builders is a trusted ADU contractor serving Greater Los Angeles, specializing in detached ADUs, attached ADUs, and garage conversions. Costs range from $100K–$300K, with timelines of 6–12 months. Full-service: permits, blueprints & ... read more

Vertebrae is an LA-based, woman-owned architecture studio founded in 2012, specializing in ADU design and small-space living. Award-winning projects include the 2025 Architizer A+ Award and 2023 AIA LA Honor Award winners.

TNT Design & Build specializes in ADUs, garage conversions & room additions in San Diego's North County. 15 years experience, in-house management, free architectural design, prices from $325/sqft with guaranteed budget & timeline.

L Square Construction is an ADU contractor serving Los Angeles & Orange County, CA. They offer full-service design-build ADU solutions including detached units, in-law suites, garage conversions, and energy-efficient builds with solar integrat... read more

Custom Home Builders Malibu specializes in ADU construction, backyard Casitas & granny flats. They offer turnkey design-build services, handling permits & compliance with California ADU laws for legal, independent living spaces.

R Remodeling is a trusted ADU contractor in Whittier, specializing in accessory dwelling units for added living space or rental income. Experienced in detached ADUs, they manage projects from consultation to completion with minimal property disrup... read more

Full-service ADU contractor offering design, permitting, and construction of detached ADUs, attached ADUs, JADUs, and garage conversions. Most builds complete in 3–5 months. Includes quartz countertops, tile showers, and luxury vinyl flooring. R... read more

Construction Masters™ is a trusted ADU contractor offering full-service design, engineering, and construction of accessory dwelling units. They build granny flats, in-law suites, and detached ADUs, boosting property value with a free consultatio... read more