ADU Construction in Los Angeles
California's ADU laws have made backyard units one of the highest-leverage property improvements an LA homeowner can make. We design and build all three types — detached new builds, attached additions, and JADUs (Junior ADUs converted from existing space). End to end. Permits, plans, foundations, framing, finishes, and final inspections, all under one roof. You work directly with Onn from feasibility study through certificate of occupancy.
What we handle
Feasibility & site planning
Lot review, setbacks, height limits, utility access, soil assessment. We tell you up front whether your project pencils — square footage, code constraints, expected timeline.
Architectural design
Floor plans, elevations, 3D renderings. We design to maximize functional space within California's ADU size limits (up to 1,200 sq ft detached, 850 sq ft for studios/1-bedroom).
Permits & utilities
Plan check submission, energy compliance (Title 24), structural engineering, separate or shared utility service. We deal with LADBS or your municipal building department.
Foundation, framing, finish
New foundations or attached construction, framing, MEP rough-in, exterior, and full interior finishes — kitchen, bath, flooring, HVAC, electrical.
Final inspection & C of O
Final inspections, Certificate of Occupancy, and walkthrough. We hand you a unit you can live in, rent, or use as a guest house.
Typical price range
Typical detached ADU build cost in Los Angeles, all-in (design, permits, construction, finishes, utility hookups). Attached ADUs typically run lower; JADUs converting existing space lower still.
Need help spreading payments? We work with Enhancify financing — prequalification doesn't affect your credit.
Frequently asked questions
How big can my ADU be in Los Angeles? +
California state law allows detached ADUs up to 1,200 sq ft (or larger if your local jurisdiction permits). Attached ADUs are limited to 50% of the primary home's square footage or 1,200 sq ft, whichever is less. Junior ADUs (JADUs) are capped at 500 sq ft and must be inside the existing primary structure.
How long does an ADU project take? +
Plan to design and build a detached ADU in 9–14 months total: 2–3 months for design and permits, 6–10 months for construction. Attached ADUs and JADU conversions can run shorter.
Do I need separate utilities? +
Not always. California allows ADUs to share utilities with the primary residence in many cases — especially helpful for cost. We assess your existing service and make a recommendation based on cost, code, and your plans for the unit (rental vs. family).
Can I rent out my ADU? +
Yes — California state law specifically protects ADU rentals. Most LA jurisdictions allow standard long-term rentals. Short-term rental (Airbnb-style) rules vary by city — verify with your municipality before banking on it.
What's the ROI on an ADU in LA? +
Highly variable. Rental income alone can cover the financed cost in 8–14 years in many LA neighborhoods. Property value typically increases by 20–30% of the build cost. The bigger benefit for many clients is flexibility — multi-generational housing, home office, or a future downsizing option.
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Learn more »Ready to start?
Onn personally reviews every inquiry. We'll set up an in-home consultation to walk through your vision, scope, and a realistic budget — no obligation.