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Daly City · Attached ADU
One shared wall, a whole second home above the fog.
An attached ADU grows off your Daly City house — its own door, its own kitchen and bath — detailed for the coast, the slope and the San Andreas Fault running along the west edge of town.
Trusted by homeowners across Sacramento & surrounding areas.
Attached ADU in Daly City — fast facts
City
Daly City
ADU type
Attached ADU
Contractor license
CSLB #1119373
Free estimate
(916) 677-9774
Last updated
Joined, not freestanding
What an attached ADU really is
An attached ADU shares exactly one wall with your existing Daly City house. That single wall is the whole difference between this and a detached cottage in the yard. Past it, the unit is a full home — a private entrance off the side or rear, a working kitchen, a real bath, a bedroom a tenant reaches without crossing your living room. The new build ties into your roofline, your foundation and your wall line. On a Westlake lot stepping up a hillside, with the San Andreas Fault sitting in the lake valley just west, that tie-in is structural, not decorative. We carry the new roof into the old, match the stucco, hold the elevation lines. Done right, the seam disappears.
Shares one wall; everything past it stands fully independent
Private entrance, working kitchen, full bath, real bedroom
Ties into the existing roof, foundation and wall line
The wall between two homes
The shared-wall fire and sound assembly
Your shared wall stops being an ordinary interior wall the moment two separate dwellings sit on either side of it. Code wants a rated separation. Usually that means a one-hour fire assembly running floor to roof — correct gypsum layers, fireblocking at every penetration, and a sound-rated cavity so your tenant isn't living inside your TV. This is the part that surprises Westlake owners. Open the wall on one of those uniform "little boxes" tract homes from the 1950s and you'll often find thin insulation and dated wiring that won't carry the rating as it sits. So the existing wall usually needs work too, not just the new side. We draw the assembly on the plans, build it to the listed spec, and the inspector signs off on a wall that actually performs.
One-hour rated separation between the two dwellings
Sound-rated cavity so neither household hears the other
Existing wall often needs upgrading to hit the rating
City of Daly City permits
Permitting an attached ADU in Daly City
Your permit files with the City of Daly City — its own counter, its own pace, its own fee schedule. Set expectations early: Bay Area review runs slower and pricier than what we see back in Sacramento. Attached units draw an extra look, because reviewers study how the addition connects to your existing house, so your home's as-built condition matters more here than on a detached build. And there's a wrinkle most of the coast doesn't have: the San Andreas Fault runs right along the west edge of town, so Alquist-Priolo fault-zone setbacks and a geotechnical layer can land on top of everything else. State law keeps ADU review ministerial — but a thin submittal buys correction cycles you'll feel in months, not weeks.
City of Daly City review — slower and pricier than Sacramento
Alquist-Priolo fault-zone setbacks are a real design input
A complete, code-compliant set keeps review ministerial
Shared utilities, real savings
Why the shared wall costs you less
The reason an attached ADU usually pencils cheaper than a detached one is right there in the name. You tap the foundation, the PG&E service and the water line already running to your Daly City house, instead of trenching across a steep, narrow lot to a freestanding cottage. That matters out here, where detached units commonly land between $400K and $750K and up. The shared wall is how you knock a real chunk off that number. One honest caveat: cross 750 square feet and the City can require a separate water meter, and PG&E may want a panel upgrade before a second all-electric kitchen's load goes live. An attached unit also fits a tighter side yard than a detached cottage needs — handy on those repetitive Westlake parcels where there's no open ground to spare.
Taps the existing foundation, PG&E service and water line
Cross 750 sq ft and a separate water meter can apply
Fits a tighter side yard than a detached build needs
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“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.
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$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.
An attached ADU shares one wall with your existing house. A detached unit stands alone in the yard. That shared wall is the whole difference — it lets the new unit borrow your foundation, your PG&E service and your water line, which usually makes it cheaper than a freestanding cottage on the same Daly City lot. In a market where detached units commonly run $400K to $750K and up, that gap is not small. An attached unit also fits a narrower side yard, which helps a lot in Westlake and Crocker, where the tract lots are tight and repetitive and there's rarely open ground on all four sides. On a steep, stepped parcel, building off the house you already have usually beats carving a second pad out of the slope. We'll look at your lot and tell you straight which one it actually wants.
With the City of Daly City. The City handles ADU permits directly, and we file the full set: site plan, floor plan, elevations, the structural tie-in and foundation details, Title-24, MEP, seismic design and PG&E coordination. Bay Area permitting is slower and the fees run higher than inland counties, so we budget for both going in. If your lot falls inside the Alquist-Priolo fault zone along the west side of town, there's a geotechnical layer on top of that. State law keeps ADU review ministerial, which means a complete, code-compliant set has to get issued. The whole game in Daly City is turning in a clean, complete set so you're not stuck in correction cycles that drag on for months.
It does, and in Daly City it's not theoretical. The San Andreas runs right along the west edge of town — the lake sits in the fault valley — and there's an Alquist-Priolo earthquake fault zone mapped through that stretch. Seismic design shapes the structure from the first framing decision. Your new unit gets engineered shear walls, hold-downs and a foundation detailed for ground shaking, and the tie-in to your existing house has to move with the main home in a quake instead of tearing away from it. On an attached unit that connection point is exactly where the seismic detailing earns its keep. If your lot sits in or near the fault zone, expect a geotechnical report and fault-zone setbacks to drive the design.
Once two separate dwellings sit on either side of a wall, code wants it rated — typically a one-hour fire assembly running floor to roof, with the correct gypsum layering and fireblocking at every penetration. We also build a sound-rated cavity into it so your tenant isn't listening to your living room. On the 1950s Westlake tract homes we open up — the famous "little boxes" — the existing wall often needs upgrading to carry the rating, since thin insulation and dated wiring won't do it as-is. We catch that on the plans rather than mid-build.
At and above 750 square feet the City can require a separate water meter for the ADU instead of letting it ride on your existing service. Below that line, you usually share. PG&E may also want a panel upgrade before you add a second all-electric kitchen's load. We size the unit knowing exactly where both lines sit, so you're not tripping a meter requirement to gain a handful of square feet you didn't actually need. On Daly City's higher Bay Area fee schedule, every avoidable trigger is worth dodging.
That's the honest question, and the answer is usually yes — because of the rents. Bay Area ADU construction is a different planet from Sacramento; detached units commonly land $400K to $750K and up. But Daly City rents are far higher too, and the demand is real. You're one BART stop and a quick drive from San Francisco, so a quiet unit with its own entrance fills fast with people who can't pay city rents but want to stay close. An attached unit cuts the build cost by sharing your wall and utilities, so you're paying less in and collecting the same high rent out. Run that income against the build over the years you'll hold the property and the unit often carries itself.
Straight answer: we're based in Sacramento, about two hours from Daly City, and we extend out here for homeowners who want our craftsmanship and value, or for larger projects worth the drive. We're not pretending to be the corner outfit who's framed a hundred jobs in Serramonte. What we bring is design-build discipline, real seismic and shared-wall experience, and a Sacramento pricing sensibility applied to a market where local quotes can run wild. For the right Daly City project, that drive pays for itself. For a small one with a great contractor a block away, hire them — we'll tell you so.
Longer than Sacramento, and I won't dress that up. Bay Area permitting is slower in practice, and a fault-zone or geotechnical question on a sloped St. Francis Heights lot can add weeks. A clean, complete attached set keeps you out of correction loops, which is the single biggest schedule lever here. Construction depends on the tie-in, the terrain — a stepped hillside foundation behaves differently than a flat pad — and the seismic work. We give you a real schedule after we see the lot, the soil and how your house sits on the slope, not a generic number off a brochure.
That's the point of doing it right. We match the stucco or siding, carry the elevation lines across and tie the new roofline into your existing roof so the addition reads as part of the original home. Westlake is famous for its uniform rows of tract houses marching up the hillsides, so matching that repetitive elevation cleanly is its own discipline — a sloppy addition stands out badly on a street where every house is the same. Someone walking past shouldn't be able to find the seam between the old house and the new unit. On an attached build, that match is most of the craft.
It does, more than people expect. Daly City sits in the marine layer, and that constant coastal moisture is hard on a building that isn't detailed for it. So we put real care into flashing and ventilation — proper weather-resistive barriers, flashing at every window and roof-to-wall junction, and ventilation paths that let the assembly dry instead of trapping damp inside the walls. On an attached unit, the connection between the new roof and the old is exactly where water wants to get in, so that junction gets detailed deliberately. Skip this and you're looking at rot and mold a few foggy winters down the line. We'd rather spend the time on flashing now.
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
10 min read2,182 words8 sections
Building an Attached ADU in Daly City, San Mateo County
An attached ADU in Daly City borrows one wall from your existing house and turns the rest into a separate, legal home — its own entrance, kitchen and bath. We're a Sacramento design-build contractor, license #1119373, about two hours east. That distance is the first honest thing on this page. We extend out to Daly City for owners who want our craftsmanship and value, or for projects big enough to earn the drive. What follows is how we think about attached units here — where the San Andreas Fault, the fog and the City's permitting change the math, and where it gets harder than the brochure admits.
01Section
What "attached" actually buys you
The word attached carries the whole concept. Your new unit shares precisely one wall with your existing Daly City house and is otherwise a complete, independent home — a private door off the side or rear, a working kitchen with its own range and sink, a full bath, and a bedroom a tenant reaches without stepping into your space. That single shared wall is the only thing tethering the two homes. Everything else stands on its own.
That one connection is why people pick attached over detached. You're not setting a freestanding cottage at the back of a high-value lot and trenching utilities the length of the parcel to reach it. You grow off the house already standing, leaning on the foundation, the panel and the water line already there. On a Daly City lot — valuable, usually tight, often stepping up or down a hillside — that sidesteps a fair amount of the site's difficulty before you've poured anything.
