ADU Construction in Los Angeles in Bel Air
Serving 90077 and Beverly Hills, Brentwood, Holmby Hills
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.
ADU Construction in Los Angeles specifically for Bel Air
Every neighborhood has its own architectural character, permit jurisdiction, and finish-level expectations. Here's how we approach adu construction in los angeles in Bel Air specifically.
Hillside foundation realities
Many Bel Air homes sit on caissons or stepped foundations on slopes. Structural changes require careful engineering review. We bring in licensed structural engineers early — never as an afterthought.
Site logistics
Narrow private roads, gated entrances, and limited staging area mean material deliveries get scheduled around access windows. We plan logistics into the timeline, not bolted on.
Working with existing teams
Many Bel Air clients have long-standing relationships with architects, landscape designers, AV integrators, and security firms. We integrate with whoever you have — we don't insist on bringing our own team if yours is in place.
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.
Pricing in Bel Air
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.
LA Department of Building and Safety (LADBS) handles Bel Air permits. Hillside-zone properties trigger additional grading review and slope-stability requirements. Plan check timelines: 6–12 weeks for kitchens, longer for hillside structural work.
Frequently asked
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 you handle estates over 10,000 sq ft? +
Yes. We've done full-home projects in that range and approach them with project management appropriate to the scale — multiple subs running parallel, weekly milestone reporting, and a single accountable PM (Onn).
Will you work with my existing architect? +
Absolutely. Many clients come to us with plans already drawn. We pick up at construction documents, run the build phase, and coordinate inspections.
From the blog
ADU vs Garage Conversion: Which Makes Sense for Your LA Property?
A clear-eyed comparison of detached ADUs, attached ADUs, JADUs, and garage conversions for LA homeowners — costs, timelines, ROI, and which one fits your lot.
LA County Kitchen Permits Explained (2026 Edition)
When you actually need a permit for a kitchen remodel in Los Angeles, how the plan-check process works, typical timelines for LADBS and surrounding cities, and how to avoid the common mistakes.
ADU Construction in Los Angeles in other neighborhoods
Live in Bel Air?
Onn personally reviews every inquiry. Tell us about your project — Onn will be in touch within one business day.