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
Brentwood homeowners adding an ADU or home addition face a specific set of conditions: large lots from the 1990s and 2000s, hot Delta summers, expansive clay soil, and a city that has genuinely streamlined ADU permitting. The work here is rarely a one-size-fits-all prefab drop. Most Brentwood jobs involve foundation engineering for clay soil, electrical panel upgrades on older central-core homes, and navigating block-by-block setback rules. If you’re looking for an ADU builder in Brentwood who puts the price in writing before any work starts, call (559) 282-2291.
Why Brentwood Homes Are Different
Brentwood’s ADU boom is fueled by its high-growth single-family subdivisions from the 1990s and 2000s, where generous lot sizes and a recent city push to streamline ADU permitting (including pre-approved plans) make it one of the easier East Bay cities for homeowners to add a backyard unit. But the rapid expansion means contractors must navigate a patchwork of older septic-to-sewer conversions and newer zero-lot-line setbacks that differ block by block. A house on one side of Balfour Road can have a completely different setback envelope than a house two streets over, and the permit path shifts with it.
Most Brentwood homes are two-story stucco or wood-frame builds from the last 25 years. The central core is different: ranch-style homes from the 1970s and 80s that often still run a 100-amp electrical panel. We frequently have to upgrade the panel before framing even starts. Add in the climate, and the job changes again. Brentwood’s hot, dry summers regularly pass 100°F, which means we size the HVAC and insulation for real heat loads, not the mild Bay Area averages. Winter fog and rain can push concrete pours and drywall finishing by days, so our schedules build that in from the start.
The terrain matters too. Much of Brentwood sits on former agricultural land with deep, rich topsoil and legacy irrigation lines. We hit old pipes during excavation more often than homeowners expect, and the expansive clay underneath needs proper foundation design. Skip that step and you get slab cracks within a few seasons. We compact the soil, engineer the foundation for clay movement, and document every step, because a cracked ADU foundation in Brentwood is a known failure mode, not a rare surprise.
Our Main Brentwood Services
Brentwood homeowners call on us most for two types of projects: standalone backyard ADUs and attached home or room additions. Each has its own dedicated Brentwood page with local pricing and job specifics.
ADU Builders in Brentwood
Brentwood lot sizes make detached ADUs the most common request we see. A typical project involves a prefab panel system from Abodu or Dvele, or a site-built frame, set on an engineered foundation sized for the clay-heavy soil. We handle the electrical panel upgrade if the home needs it, run new sewer or septic connections, and coordinate the city’s pre-approved plan path where it applies. See ADU Builders in Brentwood for local pricing and full scope details.
Home Addition Contractor in Brentwood
A Brentwood home addition means tying a new structure into a 1990s or 2000s frame without creating a roofline that looks bolted on. We match stucco texture and roof pitch, and we account for the fact that many central-core Brentwood homes need a panel upgrade before an addition can pass inspection. On larger lots, we’ll also map legacy irrigation lines before excavation so the dig doesn’t turn into an unplanned plumbing job. See Home Addition Contractor in Brentwood for full details.
Room Addition Contractor in Brentwood
Room additions in Brentwood are usually about function: a home office, a fourth bedroom, or a space for an aging parent. These are smaller projects, but they follow the same rules as full additions, namely matching the existing stucco, meeting current setback limits, and passing the same structural review. Many Brentwood room additions also trigger a panel upgrade in older homes. See Room Addition Contractor in Brentwood for what a room addition costs and how we price it.
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.
Why Brentwood Homeowners Choose Benson ADU Builders
Benson ADU Builders, part of the Relay Home Co. family founded in 2006, works differently in Brentwood. Every project starts with a written price before any work begins, no verbal estimate that drifts once the slab is poured. That price is backed by our 365-Day Done Right Promise: if the work isn’t right within a full year, we make it right. Every job also comes with a written guarantee and a free second visit if any covered repair fails. Our technicians are background-checked and arrive in uniform, so you always know exactly who is on your property. And a live person answers our phone around the clock, every day of the year.
We’re one of the few contractors in the Brentwood market authorized to build with leading prefab brands including Abodu, Cover, Dvele, and Mighty Buildings. That gives you curated options instead of a single take-it-or-leave-it product. Lead times vary by brand, but we walk you through each option with real prices attached, so you can compare before you commit. Whether you choose prefab panels or a site-built frame, the process stays the same: written price first, real-time tracking during the build, and before-and-after photos at every milestone.
Brentwood’s mix of older central-core homes and newer subdivisions means no two projects follow the same script. We plan for panel upgrades, clay soil, legacy irrigation lines, and the city’s permit paths from the first site visit. The goal is that the price you see on day one is the price you pay at the end, and that the unit we build actually works through a Brentwood summer.
Brands We Build With in Brentwood
We’re authorized to build with Abodu, Cover, Dvele, and Mighty Buildings. Each brand brings a different speed, finish level, and price point. See our brands page for a side-by-side look at what we can source for your Brentwood project.
Pricing for ADU Company in Brentwood, CA
| Service | Typical Range in Brentwood |
|---|---|
| Detached ADU (prefab, turnkey) | $200,000 – $350,000 |
| Detached ADU (site-built, turnkey) | $250,000 – $400,000 |
| Garage conversion ADU | $120,000 – $200,000 |
| JADU (attached junior unit) | $80,000 – $130,000 |
| Home addition (ground floor) | $180,000 – $300,000 |
| Home addition (second story) | $220,000 – $350,000 |
| Room addition (single room) | $60,000 – $120,000 |
| Foundation-only work | $20,000 – $45,000 |
| Electrical panel upgrade (100A to 200A) | $3,500 – $6,000 |
| Site prep and soil compaction | $5,000 – $15,000 |
What pushes Brentwood prices up is usually below grade: clay soil that needs extra compaction, legacy irrigation lines that have to be removed or relocated, and older panels in central-core homes. The price we give you before work starts is the price you pay, in writing, no change orders from surprises we should have caught.
Neighborhoods We Serve in Brentwood
We cover the full Brentwood area, from the 1990s subdivisions to the older ranch-style streets near the central core. Typical scheduling puts us on-site within a week of the written estimate for planning and site review, with full construction start dates confirmed in writing once permits clear.
- Central Brentwood (1970s-80s ranch homes)
- North Brentwood (newer subdivisions)
- East Brentwood (larger lots, former agricultural land)
- South Brentwood (mix of 1990s-2000s builds)
- Streetsville and surrounding communities
Service Area – Cities Near Brentwood
Brentwood sits in a network of East Bay communities where we regularly work. If you’re nearby, we also serve Chatsworth, CA, West Hills, CA, Northridge, CA, and Canoga Park, CA. Scheduling is coordinated from our San Francisco Bay Area office, with crews serving Brentwood locally.
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
Timelines vary by project type and permit path. A prefab ADU using a pre-approved plan can go from permit to occupancy in roughly 6 to 10 months, while site-built units and homes needing panel upgrades or sewer work take longer. Call (559) 282-2291 for a written timeline tied to your specific property.
Some Brentwood subdivisions have HOAs with design review rules, while others do not. We review your property’s deed restrictions and HOA covenants during the site visit and flag any approval steps before you commit. Call (559) 282-2291 and we’ll walk you through what applies.
No. Our written price before any work starts is the price you pay. The 365-Day Done Right Promise covers the workmanship for a full year, and if a covered repair fails, we return at no charge. Call (559) 282-2291 for a free estimate in writing.
If you’re planning an ADU or home addition in Brentwood, start with a real number, not a guess. Call (559) 282-2291 to schedule your free estimate, and we’ll put the price, the scope, and the timeline in writing before you decide 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
"Room addition off the kitchen. Framing, drywall, and paint all done well."
- Wade L."Fixed quote and clear change orders approved by text."
- Trina M."Communication was the best part. I always knew what was happening that week without having to ask."
- Dolly N.
