Detached ADU Design — Custom, Permit-Ready Plans for Your Backyard
A detached accessory dwelling unit is a completely independent structure built on your existing lot, separate from your primary residence. It comes with its own entrance, kitchen, bathroom, and living area — essentially a small, self-contained home in your backyard.
At Uni Construction, we’ve completed over 800 ADU designs across Los Angeles County, with deep experience in Diamond Bar, West Covina, Hacienda Heights, Rosemead, and the surrounding San Gabriel Valley. Every detached ADU we design is built from scratch around your specific lot conditions, goals, and budget.
Why Homeowners Choose Detached ADUs
Maximum privacy for both the main home and the ADU occupant
Separate utility connections reduce long-term operating costs
Highest rental income potential among all ADU types
No structural modifications to your existing home
Adds significant property value — studies show up to 20–30% in Los Angeles County
What We Design
Our detached ADU design service covers everything you need to get from concept to city-approved permit:
Site plan: Property survey integration, setback compliance, and building placement optimization
Architectural plans: Floor plans, elevations, roof plans, and sections
Structural engineering: Foundation design, framing plans, and calculations stamped by a licensed engineer
MEP design: Mechanical, electrical, and plumbing layouts
Title 24 energy compliance: California energy code documentation required for permit
Green building: CALGreen compliance reports
Size & Zoning Quick Reference
Under current California ADU law, detached ADUs can be up to 1,200 square feet of interior livable space regardless of lot size. Height is limited to 16 feet in most single-family zones, with 18 feet allowed within half a mile of a major transit stop. Side and rear setbacks are 4 feet. No additional parking is required if your property is within half a mile of a bus stop or public transit.
ADUs under 750 square feet are exempt from development impact fees, making smaller units especially cost-effective to build.
Our Process
Free feasibility report — We evaluate your property’s zoning, setbacks, lot coverage, and utility access at no cost.
Concept design — We develop a preliminary layout based on your goals (rental income, family housing, home office).
Full construction documents — Architecture, structural, MEP, Title 24, and CALGreen — everything the city needs.
Permit submission support — We coordinate with the city and respond to plan check corrections until your permit is approved.
Serving the San Gabriel Valley and Beyond
We design detached ADUs throughout Los Angeles County with particular expertise in Diamond Bar, West Covina, Hacienda Heights, Rosemead, Walnut, Rowland Heights, La Puente, Covina, Pomona, and Arcadia. Each city has its own overlay requirements, and we know them well.
Ready to see if a detached ADU works on your property? Contact us for a free feasibility report — no obligation, no cost.
