A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Brentwood, CA
Most Brentwood homeowners ask us the same question first: what will an ADU actually cost on my lot, and who exactly will show up to build it. On the cost side, a detached ADU in Brentwood typically runs $180,000 – $320,000 before site work, depending on whether you choose a prefab line like Cover or Dvele or a custom stick-built plan. On the who-shows-up side, every Sutton technician is background-checked, identity-verified, and photo-badged through the Threshold Standard, and we send you their name and photo before they arrive. Call (472) 248-8213 for a free estimate and a written price.
Why Brentwood Homes Are Different
Brentwood sits in the East Contra Costa County corridor where the Sacramento-San Joaquin Delta meets the foothills of Mount Diablo. That geography shapes ADU and addition work in ways that don’t apply in the inner Bay Area. Summers here routinely pass 100 degrees, which means we plan foundation pours and exterior cladding work around the heat and specify materials, including James Hardie siding, that hold up to intense UV and dry-summer expansion. Winters bring Delta fog and occasional freeze mornings near Deer Ridge and Marsh Creek, so roof flashing and moisture barriers get more attention than they might in a milder coastal climate.
The housing stock matters too. Brentwood grew fast between the late 1990s and the late 2000s, so many lots in communities like Summerset, Garin Ranch, and Apple Hill were platted with generous side and rear yards. That’s good news for a detached ADU, but it also means HOA design-review timelines and city setback rules (the required gap between your new structure and the property line) can vary by subdivision. We check setback, height, and parking requirements specific to your parcel before we quote, so the written price reflects what Brentwood’s planning department will actually sign off on.
Our Main Brentwood Services
Brentwood homeowners come to us most often for home additions, detached ADUs, and room additions. Each has its own dedicated Brentwood page with pricing and specifics; start with whichever fits your lot and budget.
Home Addition Contractor in Brentwood
A home addition in Brentwood means extending your existing footprint, whether that’s a ground-floor primary suite, a family room bump-out, or a second-story build over a single-level ranch. Lots in older Brentwood neighborhoods along Balfour Road and Fairview Avenue tend to be wide enough for side-yard additions, while newer subdivisions often push additions toward the rear of the lot. Foundation and roofline integration with the existing structure is where we spend most of our planning time, since Brentwood’s clay-heavy soils expand and contract with seasonal moisture. Read the full breakdown on our Home Addition Contractor in Brentwood page, including line-item price ranges and permit notes.
ADU Builders in Brentwood
Detached ADUs are the most common project we build in Brentwood, and most homeowners choose a prefab or modular shell from Cover, Dvele, or Boxabl to shorten on-site time, then have us handle site work, utilities, foundation, and finish. Your lot’s side-yard width and rear-yard depth determine whether a 480-square-foot one-bedroom ADU or a 1,000-square-foot two-bedroom fits, and Brentwood’s HOA-governed communities often have their own architectural-review step on top of city permits. We manage both. Full pricing and a walk-through of the process are on our ADU Builders in Brentwood page.
Room Addition Contractor in Brentwood
A room addition is the smallest-scope project we handle, usually a single bedroom, a home office, or an expanded kitchen/family space. In Brentwood this often means capturing underused side yards, converting a covered patio, or pushing out a rear wall on homes where the lot slopes toward Marsh Creek or the Delta. The key variables are foundation type (slab versus raised), electrical panel capacity, and whether the existing HVAC can handle the new square footage. Our Room Addition Contractor in Brentwood page covers cost ranges for each scenario and what to expect during design review.
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
We work with the ADU and exterior brands Brentwood homeowners ask about most: Cover, Dvele, Mighty Buildings, and Boxabl, plus Tuff Shed conversions and James Hardie cladding systems. We know which prefab lines clear Brentwood’s planning checks fastest and which need extra foundation prep. See the full list on our brands page.
Pricing for ADU Company in Brentwood, CA
| Service | Typical range in Brentwood |
|---|---|
| Detached ADU (prefab shell with local site work) | $180,000 – $320,000 |
| Detached ADU (custom stick-built, 480 – 750 sq ft) | $220,000 – $380,000 |
| Detached ADU (custom stick-built, 750 – 1,000 sq ft) | $300,000 – $460,000 |
| Garage conversion to ADU | $120,000 – $220,000 |
| Home addition (ground-floor primary suite) | $180,000 – $310,000 |
| Home addition (large family room, 300 – 450 sq ft) | $130,000 – $240,000 |
| Second-story addition (includes stairwell) | $280,000 – $430,000 |
| Room addition (single bedroom, 120 – 200 sq ft) | $70,000 – $145,000 |
| Room addition (home office or studio) | $55,000 – $110,000 |
| Combined addition + ADU (full site package) | $320,000 – $520,000 |
In Brentwood, the biggest price movers are soil work (clay-heavy lots may need deeper footings), electrical panel upgrades on older homes, and HOA design-review fees in managed communities. Whatever the final scope, you get a written price before any work starts, and that price is what you pay; the 365-Day Done Right Promise backs the workmanship for a full calendar year after completion.
Neighborhoods We Serve in Brentwood
We build ADUs, additions, and room additions throughout Brentwood, from the established ranch-home streets south of Balfour Road to newer master-planned communities and the semi-rural parcels east toward Byron and Discovery Bay. Our field teams are locally scheduled, and our San Francisco Bay Area office coordinates dispatch for Brentwood jobs.
- Garin Ranch
- Apple Hill
- Summerset
- Deer Ridge
- Downtown Brentwood and Balfour Road corridor
Service Area – Cities Near Brentwood
While this page focuses on Brentwood, CA, our ADU and addition teams also take on projects in surrounding communities across Contra Costa and neighboring counties. If your property sits outside Brentwood proper, reach out and we’ll confirm coverage. Nearby pages include 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
Most Brentwood ADU projects get through city design review and HOA approval in three to six months, then site work and construction run four to eight months depending on whether you choose a prefab shell or custom build. We schedule a site visit within about a week of your first call. Call (472) 248-8213 to get on the schedule.
Yes. Many Brentwood communities such as Garin Ranch and Summerset have architectural-review committees that layer additional approval steps and design rules (materials, rooflines, paint palettes) on top of city permitting. We pull the HOA’s design guidelines before quoting and include their review timelines in the project schedule.
Yes. You receive a written price before any work starts in Brentwood, and that figure doesn’t drift upward unless you request a scope change in writing. Change orders, when they happen, are priced and approved separately before any extra work is done. The 365-Day Done Right Promise covers workmanship defects for one full calendar year from completion, and a second visit is free if an element fails.
Call (472) 248-8213 for a free estimate. We’ll walk your Brentwood lot, talk through what fits, and hand you a written price before you commit to anything.
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
"Backyard ADU for my mother. The project manager showed ID and walked me through the permit steps, the foundation plan, and the schedule. Moved her in on time."
- Margaret C."Insulated the walls and ceiling properly. It stays comfortable even in July."
- Tamika W."They handled the drawings and the permit paperwork for us. All I had to do was pick the finishes."
- Rosa M.
