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San Jose · Custom ADU
A San Jose ADU drawn for your lot, your house, and the family in it.
Willow Glen bungalows, Almaden hillside lots, tight Naglee Park parcels — none of them fit a catalog plan. Our designer draws a bespoke unit around your exact San Jose lot, then we build it.
Trusted by homeowners across Sacramento & surrounding areas.
Custom ADU in San Jose — fast facts
City
San Jose
ADU type
Custom ADU
Contractor license
CSLB #1119373
Free estimate
(916) 677-9774
Last updated
Why custom in San Jose
When the lot decides, not the plan
A stock detached plan assumes a generic family on a flat, cooperative rectangle. San Jose hands you neither. We get the calls from Willow Glen, where a 1920s bungalow sits on a deep narrow lot with a mature oak the owner refuses to lose, and from Almaden Valley and Evergreen, where lots run up toward the foothills on a real slope. This is the largest Bay Area city, the capital of Silicon Valley, and the land is worth a fortune — which means every square foot has to earn its place. Our designer starts from your actual parcel: the survey, the setbacks, the slope, the tree, how three generations will share the back of the lot. Stock makes the family fit the plan. Custom makes the plan fit the lot.
Drawn around a tight Naglee Park or deep Willow Glen lot where every foot counts
Designed around a mature tree, a pool, or an Almaden hillside slope
The answer when the lot or the family need is too specific for a shelf plan
The design phase
Design phase, site walk to permit
Custom is won in the drawings, so that's where the hours go. It opens with a site walk and a measure-up. In San Jose the first things I'm reading are the slope and the trees — on an Evergreen or Almaden lot the grade alone can move the whole footprint, and a protected oak can decide where the unit can't go before a single line gets drawn. Then concept sketches. You react, we revise. Most clients run two or three rounds before a floor plan feels right; some push past five. Once the layout locks we move to construction documents: structural sized for seismic design near the Calaveras and Hayward faults, Title-24, mechanical, plumbing, the PG&E load calc. The honest part — this front end runs six to ten weeks before a permit lands at the City of San Jose. Longer than any stock plan. That's the trade.
Site walk reads slope and protected trees first on hillside and bungalow lots
Two to five revision rounds until the floor plan is genuinely right
Construction documents drawn in-house, seismic-engineered, then filed with the City of San Jose
Matching the main house
From Willow Glen to the Rose Garden
A custom unit should look like it grew out of your house, not like it got parked behind it. San Jose makes that real work, because the housing swings hard from block to block. Willow Glen and the Rose Garden run charming older bungalows and period revivals where trim profiles, porch detailing and roof pitch actually matter. Naglee Park is grand early-century homes near downtown. Cambrian and Santa Teresa are postwar ranch. Berryessa, Almaden and Evergreen mix ranch with newer stucco, some on slopes. We match roof pitch, pull eave depth, copy the trim, and source siding that reads the same from the curb — whether that's a low Craftsman gable in Willow Glen or a stucco hip in Evergreen. A copied stock elevation almost never belongs to the property. A drawn one does.
Period-correct trim and pitch for Willow Glen and Rose Garden bungalows
Postwar ranch detailing for Cambrian and Santa Teresa
Stucco and hillside siting for Almaden, Evergreen and Berryessa lots
Multi-gen + finishes
Multi-generational layouts done right
A lot of our San Jose custom work is families solving one exact problem — aging parents who want their own front door, or an adult kid who, in a market this expensive, would rather build in the backyard than sign another lease at Silicon Valley rents. Demand here is intense because home prices and rents are so high, and that reshapes the plan. We draw zero-step entries, 36-inch doorways, curbless showers with grab-bar blocking already in the walls, and a second primary suite so two generations each keep privacy. The detached state ceiling is 1,200 sq ft, and custom clients tend to push right up against it — at that size you fit two real bedrooms, a full kitchen, a proper living room. Then there's finish level. Quartz, real oak floors, a tiled shower instead of a fiberglass insert. Custom is where the premium package is designed in from day one rather than bolted on.
“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.
Bay Area ADU economics are a different planet, and I won't soft-pedal it — this is the priciest path in the priciest market we serve. For 2025-2026, finished custom detached units in San Jose commonly run $400K to $700K or more, depending on size, finish level, the slope of the lot, and the seismic engineering. Call it roughly $420 to $620 a square foot. A 1,150 sq ft premium multi-gen unit on a hillside Almaden lot can climb well past $650K once you add the foundation the grade demands. So why does anyone build? Because rents and home prices here are so high that the rental math still pencils, and because a custom unit solves a one-off lot or family need a stock plan can't reach.
Honest answer: we're a Sacramento-based design-build crew, and San Jose is about two hours from our home base. We don't pretend otherwise. We extend down here for homeowners who want our craftsmanship and our value, or for larger custom projects worth the drive. Bay Area pricing has a lot of slack in it, and a Sacramento crew that builds to a high standard can deliver real quality without the local markup. The two-hour distance is the real trade-off, so we're straight about it up front: for a small stock unit it rarely makes sense, but for a larger custom build worth doing right, the math and the result both work.
A stock plan is pre-drawn and repeated — faster and cheaper, because the design work is already finished and it drops onto a pad. Custom starts at zero for your parcel: our designer sizes and shapes the unit around your San Jose lot, the look of your 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 tight downtown lot, a hillside slope in Evergreen, a Willow Glen bungalow to match, a protected oak to design around, or an accessible multi-gen suite for parents — that a rectangle off the shelf simply can't reach. If a stock plan solves it, we'll tell you to take the stock plan.
Longer than stock, and longer than most other cities we work in — that's the honest answer. Design and construction documents run six to ten weeks. City of San Jose permitting is strict and slower than a small Sacramento-area town, so plan on eight to sixteen weeks at the counter, sometimes more on a hillside or historic lot. The build itself is usually seven to ten months for a custom detached unit, with a stepped or engineered foundation on a slope adding a couple weeks. Door to door you're looking at roughly twelve to twenty months. The design front end, the seismic engineering, and the slow City permitting are what stretch it past a stock plan.
It does, and it's not optional. San Jose sits near the Calaveras and Hayward fault systems, so the structural engineering on any custom unit is sized to ride out real ground movement — heavier shear walls, hold-downs tying the framing to the foundation, and a foundation engineered for the soil and the slope. On a flat lot that's mostly detailing baked into the construction documents. On a hillside lot in Almaden or Evergreen it's bigger: stepped footings or piers that have to resist both gravity and lateral shaking. A stock plan ships with a generic foundation detail that may not match your soil or your fault exposure. Custom draws the structure to the ground actually under your lot, which on a slope near a fault is exactly where you want it.
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 for a multi-gen household. Smaller is allowed; we just rarely see custom clients want it, especially in a market where every square foot of finished space carries this much value. Attached ADUs follow a different size rule tied to the main house, so if you're attaching to a Cambrian ranch or a Naglee Park home, we'll run those numbers for your specific parcel.
Yes — this is one of the strongest reasons to go custom in San Jose. Older neighborhoods like Willow Glen and the Rose Garden have heritage trees the City protects, and plenty of lots have an existing pool the owner isn't tearing out. A stock rectangle pretends those don't exist. Our designer works the unit around them: we site the footprint clear of a protected oak's root zone and drip line, bend the plan to keep the pool and its deck usable, and orient windows and doors to the parts of the yard you actually want to see. On a tight, high-value lot that kind of fit is the difference between a unit that works and one that crowds everything it sits next to.
Usually, yes, and a slope is exactly where custom earns its cost. Lots toward the foothills in Almaden Valley and Evergreen can carry real grade, and a flat-pad stock plan simply won't sit on them. We start with a survey that captures the actual contours, then the engineer designs a foundation to the slope — typically stepped footings or piers that hold the unit level while resisting both gravity and seismic movement near the fault. The drainage gets drawn deliberately too, so water runs away from the structure and the main house. It adds cost and a couple weeks to the build. But it's the only way to put a solid, code-legal unit on a hillside lot, and we've done it.
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 engineer and a separate builder who all point fingers when the geotech report comes back and someone has to redraw the foundation. One team owns the design and owns the result — which matters a lot on a San Jose hillside lot near a fault, where the seismic call, the slope, and the build decision really should be made by the same people.
For the right reasons, yes — even from two hours away. San Jose has some of the most intense ADU demand in the state, because home prices and rents are so high that an extra unit has real value the day it's finished, whether that's housing parents, an adult kid, or rental income that pencils far better than it would in Sacramento. The honest caveats are the price, the slow strict City permitting, and the seismic engineering on hillside lots — none of which make custom cheap or fast. But if you've got a tight lot, a slope, a tree to save, or a specific family need, custom is the only path that actually solves it, and this market rewards doing it right.
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
8 min read1,741 words7 sections
Custom ADU design and construction in San Jose
Some San Jose backyards just won't take a stock plan. A Willow Glen bungalow on a deep narrow lot with a heritage oak the owner won't lose, an Almaden hillside parcel running up toward the foothills, a family with parents moving in who need a unit drawn around them — that's when you build custom. We're a Sacramento design-build crew about two hours north (CA license #1119373) that draws a bespoke ADU for your exact San Jose lot and builds it, design through final inspection. Call (916) 677-9774.
01Section
What actually makes an ADU custom
People throw "custom" around loosely, so let me draw the line. A stock ADU is a plan we've already drawn — pick a size, swap a finish, and it drops onto a pad. Quickest, cheapest route, and on a flat San Jose lot with a one-bedroom ask it can be the right one. But it isn't custom.
Custom means the design starts at zero, on your parcel. Our designer takes the survey, the City of San Jose setbacks, the geotech report, the slope, the protected tree, and how your family actually plans to live — then draws a unit that didn't exist until your lot called for it. The footprint bends to the constraints. The foundation answers the soil and the grade. The roofline answers your house.
