ADU Company in Brentwood, CA
Brentwood is one of the most ADU-ready cities in Contra Costa County, thanks to a housing stock built almost entirely between 1998 and 2010. Those large stucco tract homes come with 3-car garages that run 600 to 700 square feet, 200-amp panels already in place, and lots big enough to add a detached unit without eating the backyard. What makes Brentwood different from Antioch or Oakley is the HOA layer: nearly every subdivision here has an architectural review committee, so a Brentwood ADU or garage conversion means working two approval tracks at once. If you’re weighing an accessory dwelling unit, a garage conversion, or a home addition, call Russ Delmar and the Lodgewick team at (254) 602-5618 for a written estimate before any work begins.
Why Brentwood Homes Are Different
Brentwood sits deep in the inland Diablo Valley, which shapes every build decision we make here. Summer temperatures regularly run 105 to 112 degrees, and the Delta Breeze doesn’t arrive until evening, when it’s too late to cool a small detached structure that’s been baking all day. A habitable ADU in Brentwood needs dedicated mini-split HVAC, period. That single line item adds $5,000 to $10,000 to a project budget compared to a coastal Bay Area build, and any bid that doesn’t include it is lowballing you into a unit that won’t be livable from June through September.
The housing stock itself is an advantage. Brentwood’s Ayers Ranch, Deer Ridge, and Loma Vista subdivisions were built by production builders like D.R. Horton and Shea Homes. Those homes have modern electrical service and gas lines already installed, which simplifies a garage conversion mechanically. What they don’t have is plumbing roughed in for a secondary unit, so a detached backyard ADU in Brentwood often requires a long sewer and water run from the main house. That distance is one of the biggest variables in a Brentwood ADU quote. The homes were never designed for it, and pretending otherwise leads to surprise change orders mid-dig.
Our Main Brentwood Services
Most Brentwood homeowners call us about one of three projects: expanding the existing footprint, converting an oversized garage into living space, or adding a detached unit in the backyard. Each has its own Brentwood page with full pricing and process detail.
Home Addition Contractor in Brentwood
A Brentwood home addition usually means extending into a backyard that’s already generous by Bay Area standards, typically 7,000 to 10,000 square feet. The work here is slower and more involved than in older cities because Brentwood homes were built tight and fast during the 2000s boom; tying a new roofline into stucco and tile requires careful waterproofing, especially where summer heat has already stressed the original envelope. We handle the full permit package. Home Addition Contractor in Brentwood has the full breakdown.
Garage Conversion Contractor in Brentwood
Brentwood’s standard attached 3-car garage is almost exactly 600 square feet, which matters more than most homeowners realize. That’s the minimum threshold California law requires cities to allow as a converted ADU without additional square footage. A contractor who knows that dimension cold can move a Brentwood homeowner from first inquiry to permit-ready plans faster than anywhere else in the county. We know which Brentwood HOAs require architectural review for garage conversions and which forms to submit. Garage Conversion Contractor in Brentwood covers the process.
ADU Builders in Brentwood
A detached ADU in Brentwood means choosing between a site-built unit and a prefab from a manufacturer like Cover or Dvele, then dealing with the plumbing run we mentioned earlier. Lots here are flat, which helps with site prep, but the HOA piece is real. Under California AB 670, an HOA cannot prohibit an ADU, but it can make you fight through an architectural review committee that moves on its own timeline. We’ve worked that two-track process enough to know what gets flagged and what sails through. ADU Builders in Brentwood has Brentwood-specific pricing and timelines.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Brands We Service in Brentwood
For Brentwood prefab and panelized builds, we work most often with Cover, Dvele, and Boxabl, depending on lot width, setback requirements, and budget. We coordinate directly with the manufacturer on delivery and crane placement, then handle the site work, utility connections, and finish. See our brands for the full list of what we install and service.
Pricing for ADU Company in Brentwood, CA
| Service | Typical range in Brentwood |
|---|---|
| Garage conversion (attached, 600 – 700 sq ft) | $120,000 – $180,000 |
| Detached ADU (site-built, 600 – 800 sq ft) | $250,000 – $400,000 |
| Detached ADU (prefab, 400 – 600 sq ft) | $180,000 – $280,000 |
| Prefab ADU + site work and utility connections | $220,000 – $320,000 |
| JADU (conversion within existing home footprint) | $80,000 – $140,000 |
| Home addition (primary residence, 400 – 600 sq ft) | $200,000 – $350,000 |
| Mini-split HVAC for a detached ADU | $5,000 – $10,000 |
| Plumbing run from main house to detached ADU | $8,000 – $20,000 |
Brentwood pricing gets pushed upward by two things: the long utility runs to detached units we mentioned, and the mini-split HVAC that inland summer heat makes unavoidable. Everything we quote is a written price before work starts, so those costs are on paper from day one, not discovered mid-project.
Neighborhoods We Serve in Brentwood
We work throughout Brentwood, from the older streets near downtown to the master-planned subdivisions on the east side. HOA requirements vary by tract, and we’ll flag the specific architectural review process for your neighborhood before you commit to anything.
- Ayers Ranch
- Deer Ridge
- Loma Vista
- Garaventa Ranch
- Shadow Lakes
We schedule Brentwood estimates within a few days of your call, and our crews come from the San Francisco Bay Area office to work locally.
Service Area – Cities Near Brentwood
While this page is focused on Brentwood, Lodgewick also serves nearby communities in the broader region. If you’re outside Brentwood proper, check the page for your city: Ojai, CA, Oak View, CA, Ventura, CA, and Santa Paula, CA.
Serving Brentwood, CA - Our Local Coverage Area
We’re based in the Brentwood area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About ADU Company in Brentwood
We can typically get a Brentwood homeowner from first call to a written estimate within a few days. The timeline from there depends on permit processing speed and, if you have one, your HOA’s architectural review committee. Some Brentwood HOAs turn applications around in two weeks; others take longer. We’ll map that out at the first meeting. Call (254) 602-5618 to schedule your free estimate.
Yes. California AB 670 prohibits HOAs from banning ADUs outright. What they can do is require architectural review, and nearly every Brentwood subdivision with an HOA does. We prepare the submittal package to match your HOA’s specific guidelines, which reduces the back-and-forth. Call (254) 602-5618 and we’ll tell you exactly what your HOA will ask for.
We handle the full permit package with the City of Brentwood, not just the HOA side. The two approvals run on separate tracks, and we coordinate both so one isn’t silently holding up the other. Your written estimate lays out the entire permit path before any work begins. Call (254) 602-5618 for a free estimate.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Brentwood Customers Say
"Garage conversion into an office and guest room. Fair written price, finished close to on schedule, and they fixed a small drywall crack under warranty months later without any hassle."
- Diana Cho"The ADU came out beautiful and the permitting, which terrified me, was handled start to finish. They kept me updated every week so I was never wondering what was happening."
- Shauna Mills"A whole backyard ADU from scratch. Terrified me going in, but they kept me updated weekly and there were no nasty surprises. Quality work and a fair price."
- Noreen Fletcher