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Granite Bay · Detached ADU
A standalone backyard unit, built for a Granite Bay estate lot.
Its own foundation, its own roof, real separation from the main house — a true detached ADU on the kind of acre-plus Granite Bay lot that was made for one.
Trusted by homeowners across Sacramento & surrounding areas.
Detached ADU in Granite Bay — fast facts
City
Granite Bay
ADU type
Detached ADU
Contractor license
CSLB #1119373
Free estimate
(916) 677-9774
Last updated
Freestanding, shares nothing
A detached unit is its own building
What makes a detached ADU worth the money is exactly what makes it the hardest build: it shares nothing with your house. Its own slab. Its own walls. Its own roof. Last year off Cavitt Ranch we set a 648 sq ft single-story unit on a lot that ran better than an acre, and because it stood completely free we could pull it 90 feet off the main house and orient the windows toward the oaks instead of the driveway. That separation is the whole point in Granite Bay — the lots have room most cities don't. The cost of it is a second foundation, a separate roof system, and a long materials path from the road to the back of the property. We map every foot of that before you sign.
Independent foundation, framing, roof and exterior envelope
Sited and rotated for the oaks, the slope and the main-house sightline
Real separation — these estate lots have the room detached needs
Placer County permitting
Granite Bay permits run through the County
Granite Bay is unincorporated, so there is no city counter. Your detached ADU permit goes through Placer County — not Roseville next door, not the City of anything. That catches people. They assume an address this nice sits inside a city, and it doesn't. We submit a full Placer County package: site plan, floor plan, elevations, structural, Title-24, the MEP sheets, and the PG&E service coordination. State law made the review ministerial, which means a complete, code-compliant set has to get issued — that's leverage we lean on. Clean first submissions on detached units have been coming back in roughly 4-6 weeks. Submit something thin and you'll burn correction cycles the County didn't force on you.
Reviewed by Placer County — Granite Bay has no city of its own
Complete plan set drawn in-house, fewer correction rounds
Ministerial review under state law: a clean set must be issued
Access, PG&E and the trench
Getting materials and power to the back
Everything that builds a detached unit has to physically reach the spot. On a Los Lagos or Treelake lot that's usually easy — long driveways, room to stage. The catch in Granite Bay isn't width, it's distance and rock. A utility trench from the main house to a unit 100 feet back is a real run, and the ground here is literally named for what's under it: granite outcrops and decomposed granite everywhere. Hit solid rock in that trench and you're into rock excavation, which is the single line that moves a Granite Bay budget the most. And power is PG&E here. Not SMUD, not Roseville Electric — PG&E, with its own service application and meter timeline. We measure access and probe the soil before we price anything.
Long utility runs from the main house planned and priced upfront
Rock excavation risk flagged before the trench, not after
PG&E service, panel and meter coordination — not SMUD, not Roseville
What the number actually is
What a detached ADU costs in Granite Bay
I'll give a range, then tell you why the range lies a little here. A 600-ish sq ft one-bed detached unit with the kind of finishes a Granite Bay owner expects generally lands around $268K to $340K all-in. Go bigger — 1,000-plus sq ft, two bedrooms, real cabinetry, fully separate utilities — and you're closer to $390K to $510K. Two honest caveats specific to this town. First, detached carries its own foundation and roof, so it never pencils cheaper than converting an existing structure — if budget alone is driving the call, that's a different conversation. Second, granite. A foundation or trench that hits rock can add real money, and we won't pretend we can quote that blind. We walk the lot, probe it, then hand you a fixed price.
Fixed-price proposal after a free in-person Granite Bay site visit
Detached runs above a conversion — second foundation and roof
Rock excavation is the wildcard, so we probe before we quote
Build Smart. Invest Wise.
Build Your ADU. Your Investment, Your Future.
From design to move-in, we handle everything. Transparent pricing, on-time delivery, and uncompromising quality.
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Years of Experience
120+
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Trusted by homeowners across Sacramento & surrounding areas.
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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.
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.
Placer County. Granite Bay is unincorporated — there is no City of Granite Bay and no city permit counter — so your detached ADU permit, plan check, and inspections all run through Placer County's building department. This trips up a lot of owners, because the addresses look like they belong to a city and they don't. Roseville is right next door and runs its own city process, but a parcel a mile away in Granite Bay is County jurisdiction with County standards and County fees. We confirm your parcel is unincorporated before we draw a sheet, because submitting to the wrong agency is a quiet way to lose two weeks.
PG&E. Not SMUD, and not Roseville Electric. This is the one that catches people moving over from Sacramento — SMUD stops well short of Granite Bay — and the ones coming from Roseville, where the city runs its own municipal utility. In Granite Bay the service drop, any panel upgrade, and the new meter for your detached ADU all go through PG&E's application process, which has its own forms and its own timeline. On a long lot the run from the main panel to a unit set well back can be substantial, and if your main service is near capacity you're often looking at a panel upgrade before the unit can be energized. We engage PG&E early so the meter isn't the last thing holding up your final sign-off.
It can, and it's the biggest budget wildcard in this town. The place is named for the granite — outcrops above grade, decomposed granite below — and a detached ADU carries its own new foundation plus a fresh utility trench, both of which dig into that ground. Hit solid rock and you're into rock excavation: hoe rams, sometimes rock saws, slower digging and haul-off. On a clean lot it's a non-issue. On a rocky one it can add real money to the foundation and the trench. We don't quote it blind — we probe the soil at the proposed pad and along the trench route during the site visit, so the number we hand you reflects what's actually under your dirt.
Yes, and it's a real Granite Bay step. A lot of these estate lots run on septic rather than sewer, and an ADU adds bedrooms, which adds wastewater load. Placer County's environmental health inspector has to sign off that your existing septic system can handle the additional bedroom load before the ADU goes forward — and if it can't, you're looking at expanding the leach field or upsizing the system. We check whether you're on septic or sewer on the first visit. If it's septic, we factor the County's load review into the timeline early, because finding out late that the system needs work is the kind of surprise that stalls a project for weeks.
Because you're pouring a brand-new foundation and framing a brand-new roof, plus all the exterior walls, siding, and weatherproofing of a standalone building. A garage or structure conversion reuses a slab and a roof that already exist. On a Granite Bay lot that structural difference alone is often $50K to $80K for a 600 sq ft unit — and if the foundation hits granite, the gap widens. Detached buys you a freestanding unit you can place and orient anywhere the setbacks allow, with genuine separation from the main house, which is exactly what these big lots are good for. But if the lowest possible price is the goal, a conversion almost always beats it.
Not always. State law lets a detached ADU under 750 sq ft keep shared utilities with the main house, which dodges thousands in separate-connection costs. Above 750 sq ft a separate water connection is more likely to be required. For a unit you plan to rent long-term, a separate PG&E meter is usually worth it so the tenant pays power directly. The Granite Bay wrinkle is the trench — separate meters and separate runs mean more digging across the lot, and on rocky ground every foot of that trench carries the rock-excavation risk. We design the utility plan around how you actually intend to use the unit and what the soil will allow.
Almost certainly — and fit is rarely the problem here. The state floor is 4-foot side and rear setbacks for a detached ADU, and Granite Bay lots tend to run an acre or more, so you usually have room to spare. That's the upside of building detached in this town: you can pull the unit well off the main house, set it among the oaks, and give it a private approach without crowding anything. The real constraints aren't square footage. They're the rural-residential zoning rules, any horse-property or well-setback requirements, the septic load, and where the granite sits. We measure all of it on the first visit and show you what genuinely works before you commit.
Yes, and Granite Bay is one of the best places around to do it. On a typical city lot a detached ADU ends up 10 or 15 feet off the main house because that's all the yard allows. Out here the lots are large enough that we can place the unit 80, 100, sometimes 150 feet back — its own approach, its own outdoor space, oaks or a slope between it and the main house. That's a genuinely separate dwelling, not a cottage tucked against the fence. It costs more to reach a pad that far out — longer driveway work, longer trench, more rock exposure — but the privacy you get on these estate lots is the reason people build detached in the first place.
For a complete, code-compliant set, Placer County has been returning first plan-check comments on detached units in about 4-6 weeks, usually with one correction cycle before issuance. Total pre-construction — signed contract through permit-in-hand — normally runs 8-12 weeks once you fold in design, structural engineering, any septic load review, and the soils work the granite tends to require. On-site construction then runs 18-28 weeks. The Granite-Bay-specific stretches are the trench and foundation if rock shows up, and the septic sign-off if you're not on sewer. Submittal quality is the lever you actually control — a thin set triggers extra correction rounds that eat more calendar than the County queue ever does.
Yes — the Folsom Lake and Beals Point side, along Douglas Blvd and Auburn-Folsom Road, Cavitt Ranch, Los Lagos, Quarry Ridge, Treelake, and the Eureka school neighborhoods. Each pocket has its own character: some lots are flat and clean, others run up against granite outcrops, plenty are on septic, and many are true horse properties with rural-residential zoning. Granite Bay is about 25 minutes northeast of our Sacramento home base, well within our core service area, and we know what Placer County flags on these lots before it flags it. We build detached units across all of it.
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 read1,841 words8 sections
Building a Detached ADU in Granite Bay — A Straight-Talk Guide for Placer County Estate Owners
A detached ADU is the version most Granite Bay owners actually want: a freestanding unit with its own foundation, its own roof, and its own front door, set well off the main house on a lot that has the room for it. It's also the version with the most moving parts. This guide is about building one in Granite Bay specifically — the Placer County permit path, the PG&E wrinkle that catches Sacramento and Roseville transplants, the septic load review, the granite under your dirt, and the real 2025-2026 numbers. We build these for a living, so most of what follows is what we'd tell a neighbor across the fence.
01Section
What "detached" actually means here
Detached means freestanding. The unit doesn't touch your house — its own slab or stem-wall foundation, its own roof structure, four of its own exterior walls. That's the line separating it from an attached ADU, which shares at least one wall with the main home, and from a conversion, which reuses an existing shell. All three are legitimate ADUs under California law. They just build, cost, and live differently.
The appeal of detached, and the reason it fits Granite Bay so well, is independence. Because it stands alone, we place it where the lot wants it and orient it for light, for the oaks, for privacy — not locked to the geometry of your house. A tenant or family member gets a genuinely separate dwelling: their own entrance, their own outdoor space, no footsteps overhead. And on an acre-plus lot, that separation can be real. The unit can sit a hundred feet back rather than crammed against a fence.
