ADU Builders in Brentwood - Design, Permits and Build Under One Contract

Fast, Reliable ADU Builders Across Brentwood

An ADU in Brentwood typically costs between $180,000 and $320,000 for a detached unit, or $90,000 to $160,000 for a garage conversion, with HOA architectural review adding 30 to 60 days to the calendar. We’re Lodgewick ADU Builders, the ADU company of the Kingswell family, and we’ve walked Brentwood homeowners through the city permit and HOA review process in Ayers Ranch, Deer Ridge, and Loma Vista more times than we can count. Call (254) 602-5618 for a free estimate, and you’ll get a written price before any work starts.

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Why Lodgewick ADU Builders Is Brentwood’s Preferred ADU Builders Company

Brentwood homeowners come to us after being burned, usually by a contractor who gave a verbal number and changed it at the door, or who filed the city permit and forgot the HOA architectural review packet until framing had already started. We don’t work that way. Russ Delmar leads our team, and every project operates under The Kingswell Guarantee: a written price before work begins, a defined arrival window, a clean job site, and a written guarantee on every job. A live person answers the phone 24/7, not a voicemail loop.

We know Brentwood’s subdivisions block by block. The D.R. Horton and Shea Homes tracts on the east side share nearly identical lot geometry, garage dimensions, and stucco-and-tile exterior packages. That means we can walk into a Deer Ridge or Loma Vista home, measure the garage, and tell the homeowner within a week exactly what the HOA committee will ask for, what the city will flag, and what the total budget should look like. That’s local knowledge you can’t get from a general contractor in Concord or Walnut Creek.

ADU Construction in Brentwood

ADU construction in Brentwood means building a second living unit on a lot that already has a primary home, and here it almost always means navigating two approval tracks at once: the city building permit and the HOA architectural review committee. The good news is Brentwood’s housing stock, built largely between 1998 and 2010 as large stucco-and-tile tract homes with modern 200-amp electrical panels and gas infrastructure already in place, is mechanically simpler for ADU work than older Bay Area housing. The bad news is that these homes were never roughed-in for secondary units, so plumbing runs to a backyard detached ADU can be long and costly on these deep 7,000 to 10,000 sq ft lots.

Two-Track Approval, One Schedule

We file the city permit and the HOA architectural review packet together, on the same day. Most Brentwood homeowners don’t realize these are separate tracks until the design committee sends them back for color, roof pitch, or height revisions after framing has already started. Filing both at once means the review windows overlap instead of stacking, and the job isn’t sitting half-finished waiting on a committee.

What a Brentwood ADU Build Typically Includes

Every ADU construction project we run in Brentwood includes site assessment against your specific tract’s HOA guidelines, architectural drawings that match the subdivision’s stucco-and-tile language, permit filing, foundation or garage conversion work, mini-split HVAC, plumbing and electrical, and final inspections. We schedule around the approval calendar so crews start framing the week the last signature lands, not months later.

Detached ADU in Brentwood

A detached ADU in Brentwood is a freestanding unit built in the backyard of a tract home, and on these deep 7,000 to 10,000 sq ft lots, the distance from the main house to the ADU pad is the single biggest budget variable most homeowners never see coming. Plumbing and electrical runs across a 70-foot yard can add $15,000 to $30,000 to a project that looked simple on paper. We flag those distances at inquiry, not after demolition, so the written price you get is the price you pay.

What Brentwood’s Climate Demands

Brentwood sits deep in the inland Diablo Valley and regularly hits 105 to 112°F in summer. The Delta Breeze arrives too late in the evening to condition a small detached structure through the day, which means dedicated mini-split HVAC is essentially non-negotiable for a habitable ADU here. Budget an extra $5,000 to $10,000 for that system compared to what a coastal Bay Area build would cost. Skipping it leaves a 600 sq ft unit unlivable through the afternoon heat, and no HOA committee will save you from that mistake.

The 600-Square-Foot Sweet Spot

Brentwood’s signature 3-car attached garages, built by D.R. Horton and Shea Homes across the east side, measure almost precisely 600 sq ft. That’s the minimum threshold California state law requires cities to allow as a converted ADU without additional square footage. A contractor who knows this dimension cold can take a Brentwood homeowner from inquiry to permit-ready plans faster than anywhere else in Contra Costa County. We know it cold.

Trusted Brands We Service in Brentwood

We work hands-on with the leading prefab ADU manufacturers, including Abodu, Cover, and Mighty Buildings, and we match each brand to the homeowner’s lot, budget, and timeline rather than pushing one product. For Brentwood customers, we keep local inventory and parts on hand for the systems these units use, which means service calls and warranty work don’t wait on a shipment from the Bay Area. If you already own a prefab unit or are comparing options, we can walk you through which brand’s panel system handles the Diablo Valley heat best.

Common ADU Builders Problems We See in Brentwood Homes

• City permit filed, HOA packet forgotten. The tract’s design committee then sends the homeowner back for color, roof, and height revisions after framing has already started. This is the most common and most expensive mistake we see in Ayers Ranch and Loma Vista.
• Garage conversions without dedicated mini-split HVAC. A 600 sq ft attached unit in Brentwood hits 100°F by noon in July, and a single window unit can’t keep up. The late Delta Breeze never catches a garage with a closed door.
• Plumbing runs underestimated. A detached ADU on a 10,000 sq ft lot can require a 70-foot plumbing run from the main house. Contractors who price it like a coastal Bay Area backyard get the number wrong by thousands.
• HOA color and material mismatches. Brentwood’s tract design committees expect the ADU to match the subdivision’s stucco-and-tile language. A contractor who doesn’t submit the right color palette gets sent back, and the calendar stretches by months.

Pricing for ADU Builders in Brentwood, CA

We Also Serve Cities Near Brentwood

Lodgewick ADU Builders serves homeowners across the East Bay, including Brentwood and nearby communities. If you’re in Oakley, Antioch, Discovery Bay, or further out toward the Delta, the same team, same written guarantee, and same live-answer phone line apply. We know the tract-home geography of this whole corridor.

FAQs About ADU Builders in Brentwood