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Redwood City · Custom ADU
A Redwood City ADU drawn for your lot, your house, and the family it's for.
From the flat bungalow streets to the slopes of Emerald Hills, Redwood City hands you a tight Peninsula lot and strict permitting — we draw a bespoke unit around all of it and build it.
Trusted by homeowners across Sacramento & surrounding areas.
Custom ADU in Redwood City — fast facts
City
Redwood City
ADU type
Custom ADU
Contractor license
CSLB #1119373
Free estimate
(916) 677-9774
Last updated
Why custom in Redwood City
When the lot won't take a stock plan
A stock detached plan wants a flat, empty rectangle on quiet dirt. Redwood City rarely hands you that. Land value out here is brutal, lots run tight, and the city splits between flat bungalow neighborhoods near the bay and the hill areas — Emerald Hills, Farm Hills — where the parcels steepen and a slab is off the table. Add active faults across the region and a permit counter that moves slower than the Sacramento suburbs we usually work, 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 worth matching — then we build it.
Foundations engineered to the slope and the region's faults, not a generic slab
Drawn to fit a tight, high-value Peninsula lot from the first line
The answer when no off-the-shelf footprint lands on your 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 Redwood City 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 on a Friendly Acres bungalow lot. That first visit reshapes the plan, and up in Emerald 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 Redwood City. 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 in Emerald Hills from day one
Full construction documents drawn in-house, then filed with the city
Matching the main house
Matching your Redwood City home
A custom unit should look like it grew out of your house, not like it got parked behind it. Redwood City makes that real work, because the housing stock shifts block to block — older bungalows and ranch homes through Mount Carmel and Centennial, modest cottages in Friendly Acres, then the larger custom homes stepping down the slopes of Emerald Hills and the newer waterfront builds out at Redwood Shores. Drop a blank stucco box behind any of them and it reads wrong from the street. We pull roof pitch off your actual house, match the eave depth, copy the trim and the window proportions, and source siding that reads the same from the curb. A copied stock elevation rarely belongs on a Mount Carmel lot. A drawn one does.
Bungalow and ranch detailing for Mount Carmel, Centennial, Friendly Acres
Larger hillside vocabulary for Emerald Hills and Farm Hills
Roof pitch, eave depth and trim drawn to your specific home
Multi-gen + finishes
Multi-generational layouts done right
A lot of our Redwood City custom work is families solving one exact problem — aging parents who want their own front door, or adult kids priced out of the Peninsula 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 Peninsula 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 Redwood City land roughly $427K to $750K-plus depending on size, finish level, and how rough the site is. The big variable here is the ground. A hill lot in Emerald Hills 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 region requires near its active faults, plus high city permit fees and tight-lot access. The flip side is why owners build here anyway: Redwood City rents run far above Sacramento, with durable Peninsula demand underneath them. 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 two hours from Redwood City. 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 bungalow lot, a Peninsula-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 Redwood City 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 Emerald Hills lot that needs a pier foundation, a mature oak or a pool you won't tear out, an odd-shaped Friendly Acres parcel, an accessible suite for parents — 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. On the Peninsula, that's rarer than you'd think.
Longer than stock — that's the honest answer, and Redwood City's permitting is slower than the Sacramento suburbs we usually work. Design and construction documents run six to ten weeks. City of Redwood City review on a clean set often runs ten to sixteen weeks, longer on a hill lot that pulls in geotechnical 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 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. I'd rather quote you a real range than a hopeful one.
That's exactly where custom earns its keep here. A flat-pad stock plan has nothing to offer a 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 region's faults demand. 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 Redwood City hillside, custom isn't an upgrade — it's the path that works.
Heavily, and it should. Redwood City sits in a part of the Bay Area threaded by active faults, and building here means building for real ground motion. 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 bungalow lot that's a well-detailed slab on grade; up in Emerald Hills 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 Redwood City parcel builds it into the structural drawings from the start.
The permit goes through the City of Redwood City — its own incorporated city, so plan check and inspections run through the city's building and planning departments, not San Mateo 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 the city 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 Redwood City lot has room to site a unit that size depends on the parcel. A flat backyard in Centennial or Friendly Acres takes it more easily than a steep, narrow Emerald Hills 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 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 plan-check comments come back. One team owns the design and owns the result — which matters even more on a Redwood City 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.
Yes, and honestly that's half the reason custom exists. A stock plan assumes a clean rectangle of open dirt. Real Redwood City backyards rarely cooperate — there's a pool you're not filling in, a mature oak the city would rather you keep, a lot that pinches to a wedge after the setbacks, or a side-yard access too tight for a truck. We site the unit around what's actually there. The footprint bends to clear the tree's drip line, the building turns to keep the pool usable, the materials path gets mapped on the first visit so nobody's surprised at framing. A repeated plan can't do any of that. A drawn one is built for exactly your yard, the way it sits today.
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 read1,996 words8 sections
Custom ADU design and construction in Redwood City
Some Redwood City backyards just won't take a stock plan. An Emerald Hills lot that climbs away behind the house, a tight bungalow parcel where the buildable strip is barely wide enough, a mature oak or a pool you won't tear out, 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 Peninsula for owners who want our craftsmanship and value, draws a bespoke ADU for your exact Redwood City lot, and builds it design through final inspection, one team the whole way. Call (916) 677-9774.
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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 Redwood City 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 Redwood City 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 faults, the roofline answers your house. Nobody else has this plan.
