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Berkeley · Custom ADU
A Berkeley ADU drawn for the fault, the slope, and the family it's for.
Berkeley hands you a tight lot, a brown-shingle house under design review, and the Hayward Fault underneath — we draw a bespoke unit around all of it and build it.
Trusted by homeowners across Sacramento & surrounding areas.
Custom ADU in Berkeley — fast facts
City
Berkeley
ADU type
Custom ADU
Contractor license
CSLB #1119373
Free estimate
(916) 677-9774
Last updated
Why custom in Berkeley
When the lot won't take a stock plan
A stock detached plan wants a flat, empty rectangle on quiet dirt. Berkeley almost never hands you that. The lots are narrow, land value is brutal, and the city splits in two — flat west-side parcels down by the bay, then steep hill lots climbing toward Claremont and the upper streets. Add the Hayward Fault running straight under town and a design-review counter that protects every brown-shingle Craftsman in sight, and a catalog footprint gets bounced before it's printed. Custom answers what a pre-drawn plan can't see. We draw the unit to the buildable strip you actually have, to the slope, to the seismic engineering, and to a main house the city won't let you ignore — then we build it.
Foundations engineered to the slope and the Hayward Fault, not a generic slab
Drawn to fit a tight, high-value Berkeley lot from the first line
The answer when no off-the-shelf footprint lands on the parcel
The design phase
Site walk to permit, drawn in-house
Custom is won in the drawings, so we spend real hours there — and on a Berkeley lot, before anyone knows how the slope or the side-yard access behaves. It opens with a site walk and a measure-up. A survey leaves things out. It won't tell you how tight the only buildable strip really is, or how the materials path squeezes down a four-foot side yard. That first visit reshapes the plan, and up in the hills it points the foundation engineer at a soil report early. Then concept sketches. You react, we revise. Most clients run two or three rounds; a few push past five. When the layout locks we draw full construction documents and file with the City of Berkeley. Honest part: this front end runs six to ten weeks before the counter even sees it.
Site walk and access study before a single line gets drawn
Soil report drives a hill foundation from day one
Full construction documents drawn in-house, then filed with the city
Matching the main house
Matching a brown-shingle Berkeley home
A custom unit should look like it grew out of your house, not like it got parked behind it. Berkeley makes that real work, because the city is built on brown-shingle Craftsman and First Bay Tradition homes — and the design-review counter cares deeply how a new structure reads against them. Elmwood and North Berkeley run to shingle-clad Craftsman with deep eaves and exposed rafter tails. Claremont and the hills step woodsy houses down their slopes. Drop a blank stucco box behind any of them and you've earned yourself a stalled review. We pull roof pitch off your actual house, match the eave depth, copy the shingle coursing and the trim, and source siding that reads the same from the street. A copied stock elevation rarely belongs on an Elmwood lot. A drawn one does.
Shingle and Craftsman detailing for Elmwood and North Berkeley
Woodsy hillside vocabulary for Claremont and the upper streets
Roof pitch, eave depth and trim drawn to your specific home
Multi-gen + finishes
Multi-generational layouts done right
A lot of our Berkeley custom work is families solving one exact problem — aging parents who want their own front door, or adult kids priced out of the East Bay market who'd rather pay into the family than a landlord. The rent math out here is a different planet from Sacramento, which is why these units pencil. That reshapes the plan. We draw zero-step entries, 36-inch doorways, curbless showers with grab-bar blocking in the walls, and a second primary suite so two generations each keep their privacy. The detached ceiling is 1,200 sq ft, and custom clients push right up against it — at that size you fit two real bedrooms, a full kitchen, and a proper living room. Then finish level: quartz, real oak floors, a tiled shower instead of a fiberglass insert.
“Every ADU we build is designed to add long-term value and open new possibilities for your property. Let's build something great together.”
— Tim, ADU Specialist
Custom Designs
Built to fit your property & needs
Turnkey Process
We handle permits, plans & everything
Built to Last
Quality craftsmanship that stands the test
Financing Made Simple
$0 Down Options. Build Now, Pay Over Time.
You shouldn't have to drain your savings to build wealth. We partner with trusted ADU lenders to find financing that fits — many homeowners build with little to nothing out of pocket.
Home Equity (HELOC)
Tap your existing equity at competitive rates — the most popular way to fund an ADU.
Renovation Loans
Finance the build against your home's projected after-completion value.
ADU-Specific Financing
Specialized lenders who underwrite based on the rental income your ADU will produce.
Cash-Out Refinance
Roll the project into a new mortgage and keep one simple monthly payment.
Estimate Your Monthly Payment
See what financing your ADU could look like — and how rental income can help cover it.
$180,000Loan amount
Credit Score
Very good · 700–739
Estimated Monthly Payment
$1,320/mo
At 7.99% APR over 30 years (illustrative)
Often offset by $2,000–$3,500/mo in rental income
No prepayment penalties with most partners
Pre-qualification with no impact to your credit
Illustrative only — not a loan offer. Actual rates and terms are set by third-party lenders based on your qualifications.
Service areas
Where we build
Headquartered in the Greater Sacramento Area and serving homeowners from the Sierra foothills down through the Bay Area. Don't see your city? We probably still get there — just ask.
The most common things Sacramento homeowners ask before starting an ADU project.
Custom is the priciest path, and the Bay Area pushes it higher than almost anywhere we work — I won't soft-pedal it. For 2025-2026 we're seeing finished custom detached units in Berkeley land roughly $427K to $740K-plus depending on size, finish level, and how rough the site is. The big variable here is the ground. A hill lot toward Claremont needs a stepped or pier-and-grade-beam foundation cut into the slope — not a cheap generic pour — and that's real money before you've framed a wall. Then there's the seismic engineering the whole town requires near the Hayward Fault, plus Berkeley's high permit fees and tight-lot access. The flip side is why owners build here anyway: Berkeley rents, driven by a university that never stops needing housing, run far above Sacramento. Even a $600K-plus unit pencils out in a way it never would back home.
Fair question, and I'll be straight: we're based in Sacramento, about 90 minutes from Berkeley over the Causeway and the bridge. We're not the closest crew you can hire. We extend out here for homeowners who want our craftsmanship and our pricing over a Bay Area outfit's quote, or for a larger custom project that's worth the drive — and custom usually is, because the value sits in the design and the build quality, not in being five minutes away. I'll be on your lot for the site walk and for the foundation pour, the framing, and the key inspections. If your job is a small, simple unit on a flat west-side lot, a Berkeley-local crew may serve you better, and I'll say so. For a complex hill build, the right team beats the close one.
A stock plan is pre-drawn and repeated — faster and cheaper, because the design work is done and it drops onto a flat pad. Custom starts at zero for your parcel: our designer sizes and shapes the unit around the slope, the tight buildable strip, the seismic engineering, the look of your brown-shingle Berkeley home, and exactly how the family plans to live in it. Custom costs more and takes longer up front. The reason to choose it is a one-off problem — a steep Claremont lot that needs a pier foundation, a landmarked main house under design review, a pool or mature trees in the way, an accessible suite — that a rectangle off the shelf can't reach. If your lot were flat and clear and your house ordinary, we'd happily steer you to stock and save you money. In Berkeley, that's rarer than you'd think.
Longer than stock — that's the honest answer, and Berkeley's permitting is slower than the Sacramento suburbs we usually work in. Design and construction documents run six to ten weeks. City of Berkeley review on a clean set often runs ten to sixteen weeks, longer if the property carries a landmark flag or sits near a historic context that pulls in extra design review. The build itself is usually seven to ten months for a custom detached unit, with a hillside foundation stretching it. Door to door you're looking at roughly thirteen to nineteen months. The slow city counter, the design review, and the hill engineering are what stretch it past a flat-lot Sacramento job — plan for it from the start rather than getting surprised at month four.
It can, and on a custom job it's worth getting ahead of. Berkeley is ADU-friendly in written policy but strict and slow at the counter, and it runs a landmarks and historic-preservation process built to protect the brown-shingle Craftsman and First Bay Tradition homes the town is known for. If your main house falls into that world, a custom unit in the backyard brings the historic context into the review whether you expected it or not. The upside of custom here is real: because we're drawing from scratch, we can design the unit to complement your specific house — matching the shingle, the eave depth, the massing — so it reads as sympathetic rather than tone-deaf. We check for any landmark designation on the first visit and draw the set to clear review instead of fight it.
That's exactly where custom earns its keep here. A flat-pad stock plan has nothing to offer a Claremont or upper-hills lot that drops away behind the house. We start with a grade analysis and a soil report, then design a hillside foundation — often a stepped foundation or pier-and-grade-beam, where drilled piers reach down to stable material and grade beams tie them together so the unit sits level on a slope that doesn't. The structure gets engineered for the lateral loads a hill imposes on top of the seismic loads the Hayward Fault demands. It costs more than a flat slab; no way around that. It's also the only thing that puts a real, safe, level unit on a lot a catalog rectangle can't touch. On a Berkeley hillside, custom isn't an upgrade — it's the path that works.
Heavily, and it should. The Hayward Fault runs straight through the UC Berkeley campus and up into the hills, and it's considered one of the likeliest faults in the state to produce a major quake. Building here means building for that. On every custom unit we draw the shear walls, hold-downs, anchor bolting, and a foundation tied together so the structure rides a shake instead of coming apart in one. On a flat west-side lot that's a well-detailed slab on grade; up the hill it compounds with the slope loads, which is part of why those foundations are engineered the way they are. A stock plan drawn for a calm, flat site elsewhere doesn't carry this detailing. A custom set drawn for a Berkeley parcel builds it into the structural drawings from the start.
The permit goes through the City of Berkeley — it's its own incorporated city, so plan check and inspections run through the city's building and planning departments, not Alameda County. One counter, strict review, high fees. Power is PG&E. A custom unit's electrical service, any main-panel upgrade, the load calc, and the meter set all coordinate through PG&E, which in the Bay Area can be slow. An all-electric unit with a heat pump, an induction range, and maybe an EV charger pulls real load, so we size the service and line up PG&E early in design rather than at the end, where it stalls a final inspection. With Berkeley's counter already slow, getting the utility piece moving early is half of keeping a custom build on schedule.
State law caps a detached ADU at 1,200 sq ft, and most of our custom clients build right up near that ceiling — at 1,100 to 1,200 sq ft you fit two genuine bedrooms, a full kitchen, and a real living room, which is usually the whole point of going custom. Whether your Berkeley lot has room to site a unit that size depends on the parcel. A flat west-side backyard takes it more easily than a steep, narrow hill lot where the buildable area gets carved out of a slope and the setbacks bite hard. Smaller is allowed; we just rarely see custom clients want it. Attached ADUs follow a different size rule tied to the main house, so if you're attaching to a Craftsman we'll run those numbers for your specific lot.
In-house. Our designer does concept, floor plans, elevations, and the full construction document set, and that same drawing carries straight into the build with no handoff gap. You're not coordinating a separate architect, a separate geotechnical engineer, and a separate builder who all point fingers when the slope shifts or the design-review comments come back. One team owns the design and owns the result — which matters even more on a Berkeley custom job, where the field decisions on a hill foundation and the back-and-forth with a strict city counter are constant, and someone needs to own them end to end.
Other services
Not quite the right fit?
Every Sacramento ADU project is different. Here are the other paths we build under one roof — and we're happy to talk through which one fits your lot best.
We treat every home like it's our own — quality work, clear communication, and happy homeowners.
PaulOwner · Future Generation
9 min read1,930 words8 sections
Custom ADU design and construction in Berkeley
Some Berkeley backyards just won't take a stock plan. A Claremont lot that climbs away behind the house, a tight west-side parcel where the buildable strip is barely wide enough, a brown-shingle Craftsman that drags the design-review counter into the conversation, or parents moving in who need a unit drawn around them — that's when you build custom. We're a Sacramento design-build crew (CA license #1119373) that extends to the East Bay for owners who want our craftsmanship and value, draws a bespoke ADU for your exact Berkeley lot, and builds it design through final inspection, one team the whole way. Call (916) 677-9774.
01Section
What actually makes an ADU custom
People throw "custom" around loosely, so let me draw the line. A stock or model ADU is a plan we've already drawn and built before — pick a size, maybe swap a finish, and it drops onto a flat pad. Quickest, cheapest, and for a clean flat Berkeley backyard with an ordinary main house, often the right one. We build those gladly. But it isn't custom.
Custom means the design starts at zero, on your parcel. Our designer takes the survey, the City of Berkeley setbacks, the soil report, the grade, the seismic requirements, and how your family plans to live. Then a unit gets drawn that didn't exist until your lot called for it. The footprint bends to the buildable strip, the foundation answers the slope and the fault, the roofline answers your house. Nobody else has this plan.
