ADU Construction in Los Angeles in Brentwood
Serving 90049 and Bel Air, Pacific Palisades, Santa Monica
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 Brentwood
Every neighborhood has its own architectural character, permit jurisdiction, and finish-level expectations. Here's how we approach adu construction in los angeles in Brentwood specifically.
Brentwood permitting
LADBS handles Brentwood. Hillside-zone properties (most of north of Sunset) trigger additional grading and slope-stability review. Plan check timelines: 6–10 weeks for kitchens, 8–14 weeks for hillside structural work.
Lot constraints
Brentwood Village lots run 50'×130' typical, while hillside lots are larger but constrained by slope. ADU additions are feasible in both but the design approach is very different. We assess feasibility before promising scope.
Finish expectations
Brentwood clients typically expect upper-mid to high-end finishes — slab counters, custom cabinetry, Bosch/Wolf-tier appliances. We source through trade channels to keep finish quality high without unnecessary markup.
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 Brentwood
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 permits. Hillside-zone properties require additional review. Plan check typically 6–10 weeks for kitchens, longer for structural or hillside 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 do projects in Brentwood Village (90049 flats)? +
Yes. The flat-lot homes are some of our favorite to work on — older bones, charming proportions, room to upgrade systems while preserving character.
Hillside foundation surprises — how do you handle them? +
Older hillside Brentwood homes occasionally have settled or stepped foundations that affect remodel plans. We bring in licensed structural engineers during design to assess before scope is locked.
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 Brentwood?
Onn personally reviews every inquiry. Tell us about your project — Onn will be in touch within one business day.