ADU Builder & Home Additions in Brentwood, CA
Source: https://www.remodelyourvibe.com/services/adus-additions/brentwood
Last modified: 2026-09-24T00:00:00.000Z
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Image: Detached backyard ADU with wood siding and black-framed glass doors at dusk
- Brentwood
Design · Permit · Build
ADUs & Additions in Brentwood
Detached ADUs, garage conversions and additions, from plans to move-in.
Book a Consultation Call 818-300-2393
Built for Brentwood Homes
There are really two build conditions here. On the flat park-district streets we work around mature protected sycamores and oaks whose root zones decide where a pool shell can land. Up in Mandeville, Kenter and Sullivan canyons, single-lane roads and fire-zone construction requirements drive the schedule, and exporting more than 1,000 cubic yards of soil from a hillside grading area requires a haul route approved at a public hearing. We price both realities separately.
Broad, level, deeply landscaped lots in the flat park district, transitioning to long, narrow canyon parcels with steep side slopes and single-lane frontage.
We are a design-build team, which means the people who draw your project are the people who build it. Design, engineering, permits and construction run through one project manager and our own crews, so nothing gets lost in a handoff between a salesperson and a subcontractor. We are licensed, bonded and insured, CSLB license #1119054 .
Permits in Brentwood: Permits are issued by LADBS, since this is part of the City of Los Angeles rather than a separate city. Hillside lots north of Sunset fall under the Baseline Hillside Ordinance (No. 184,802) for height, floor area and grading limits, and import or export of more than 1,000 cubic yards in a hillside grading area triggers a haul route hearing before the Board of Building and Safety Commissioners.
The canyons are mapped Very High Fire Hazard Severity Zone, which brings Chapter 7A ignition-resistant construction and brush clearance obligations. The city's protected tree and shrub ordinance (No. 186,873) covers oak, western sycamore, Southern California black walnut and California bay laurel, plus toyon and Mexican elderberry.
Permit details checked September 2026 against LADBS , LA City Clerk , LAFD and City of Los Angeles . Rules change, so we confirm them again for your parcel.
What We Build
- Protected tree root-zone planning
- Canyon access, staging and haul route logistics
- Detached ADUs, ground-up
- Garage conversions to living space
- Junior ADUs within the main house
- Room additions and bump-outs
- Second-story additions
- Full kitchens and bathrooms in the ADU
- Separate utility metering where required
- Private entries, patios and landscaping
- Plans, engineering and city submittals
- Title 24 energy compliance
Local Conditions
What to Know in Brentwood
These local conditions change the scope, the schedule and the budget.
01
Flat park-district lots carry mature sycamores, oaks and walnuts whose protected root zones frequently dictate where a pool shell, footings and utility trenching can go.
02
Canyon properties north of Sunset sit on single-lane roads with limited turnarounds, so concrete, crane and soil-export days have to be reserved well in advance.
03
Soils shift from expansive clay to shallow bedrock within a few hundred feet, which changes excavation cost and foundation design substantially between neighboring lots.
04
Mid-century canyon homes often retain original service panels and galvanized water lines that need upgrading before pool equipment, spa heaters and outdoor kitchens are added.
Areas we serve in Brentwood:Brentwood ParkMandeville CanyonKenter CanyonSullivan CanyonBrentwood GlenCrestwood Hills
Investment
What It Costs in Brentwood
Real Southern California price ranges, not teaser numbers.
Detached ADU
$150,000 to $400,000+
What moves it: square footage, finish level, utility runs, and site access; garage conversions typically run well below a ground-up detached build
Garage conversion ADU
$80,000 to $180,000
What moves it: whether the existing slab and framing meet current code, how far utilities have to run, and the finish level of the kitchen and bathroom
Plans, drawings and permit management
$4,500 to $25,000+
What moves it: project type and size, whether structural engineering, Title 24 or a soils report is required, and how many jurisdictions or review bodies are involved
Your lot, access and finishes set the price. We walk the site, then show you where every dollar goes.
Get a line-item price for your Brentwood property
The Process
How We Work in Brentwood
01
Feasibility
We check lot size, setbacks, utilities and access to confirm what your property will actually support.
02
Design & 3D
Layout, elevations and finishes, modeled in 3D so you approve the unit before submittal.
03
Plans & Permits
We prepare the full drawing set, handle engineering and Title 24, and manage the city submittal and corrections. In Brentwood that submittal goes to Los Angeles Department of Building and Safety (LADBS).
04
Foundation & Framing
Site prep, foundation, framing and dry-in by our own crews.
05
Systems & Finishes
Electrical, plumbing, HVAC, insulation, then kitchen, bath and interior finishes.
06
Final Inspection
We pass final inspection, walk the unit with you and hand over the keys.
Questions
What Brentwood Homeowners Ask
Who issues the permits for this work in Brentwood?
Los Angeles Department of Building and Safety (LADBS). Permits are issued by LADBS, since this is part of the City of Los Angeles rather than a separate city. Hillside lots north of Sunset fall under the Baseline Hillside Ordinance (No. 184,802) for height, floor area and grading limits, and import or export of more than 1,000 cubic yards in a hillside grading area triggers a haul route hearing before the Board of Building and Safety Commissioners.
The canyons are mapped Very High Fire Hazard Severity Zone, which brings Chapter 7A ignition-resistant construction and brush clearance obligations. The city's protected tree and shrub ordinance (No. 186,873) covers oak, western sycamore, Southern California black walnut and California bay laurel, plus toyon and Mexican elderberry.
We prepare the drawings, make the submittal and handle plan-check corrections ourselves, so you are not the one chasing plan check.
What makes building in Brentwood different?
Broad, level, deeply landscaped lots in the flat park district, transitioning to long, narrow canyon parcels with steep side slopes and single-lane frontage. One local condition that shapes the work: Flat park-district lots carry mature sycamores, oaks and walnuts whose protected root zones frequently dictate where a pool shell, footings and utility trenching can go.
Which parts of Brentwood do you work in?
All of it, including Brentwood Park, Mandeville Canyon, Kenter Canyon and Sullivan Canyon. Our crews run every job out of our Cahuenga Pass base in Los Angeles, with our own people on site.
What does an ADU or addition cost in Brentwood?
Detached ADU: generally $150,000 to $400,000+ across Southern California. What moves it is square footage, finish level, utility runs, and site access; garage conversions typically run well below a ground-up detached build. We give line-item pricing after seeing the site rather than quoting a number over the phone.
How long does an ADU take start to finish?
Plan a realistic year. Design and engineering typically take one to three months, city plan check and corrections add several more, and construction usually runs four to eight months depending on size and site access.
Is a garage conversion cheaper than a detached ADU?
Usually yes, and often substantially, because the foundation, walls and roof already exist. The trade-offs are that you lose the garage, and older slabs and framing sometimes need upgrading to meet current code.
Can I rent the ADU out?
California ADU law is designed to allow long-term rental, and an ADU is one of the few ways to add rentable square footage to a single-family lot. Short-term rental rules vary by city, so confirm your local ordinance before counting on that income.
Do you handle the permits?
Yes. Plans, engineering, Title 24 and the city submittal are all handled in-house, including responding to plan-check corrections. That is a service we sell on its own, so it is not something we hand off.
More Services in Brentwood
Pool & Spa Remodeling in Brentwood Backyard & Outdoor Living in Brentwood Kitchen, Bath & Interior Remodeling in Brentwood Plans, Permits & Design in Brentwood Everything we build in Brentwood
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Planning Guides
Before You Build in Brentwood
Costs, materials and process notes from our own projects.
ADU Cost Breakdown by Size in Los Angeles A detached ADU in Los Angeles runs $150,000 to $400,000-plus. Here is the real cost broken down by unit size, with the soft costs, utility work and finish decisions that move the number. Read guide Garage Conversion to ADU: The Step-by-Step Build A garage conversion runs $80,000 to $180,000 in Southern California. Here is the real sequence, from slab testing and plan check to the raised floor, the mini-split and final sign-off. Read guide ADU Rental Income Math in the San Fernando Valley A one-bedroom ADU in the San Fernando Valley rents for roughly $2,100 to $2,900 a month. Here is the honest arithmetic on payback, carrying costs and what the unit adds to the property. Read guide Second Story Addition vs Building Out: Which Costs Less Building out runs $350 to $500 per square foot. Going up runs $450 to $700. Here is when the cheaper option is actually the wrong one, and what drives each number. Read guide
Planning an ADU in Brentwood?
Sit down with your project manager and get an accurate estimate. We call you back within one business day.
Book a Consultation 818-300-2393
Licensed, bonded & insured · CSLB license #1119054
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