Fast, Reliable New Detached ADU Across San Rafael
A new detached ADU in San Rafael typically runs $285,000-$385,000 all-in for a two-bedroom unit, and $190,000-$265,000 for a studio, drawings through final inspection. The single biggest variable in this city is not square footage. It’s whether your parcel sits in a Very High Fire Hazard Severity Zone, which triggers Chapter 7A construction requirements on hillside lots in Dominican, Sun Valley, and the slopes above Terra Linda. Flat parcels in Terra Linda and Glenwood build under standard code. Same city, two very different price bands. Call (971) 497-2402 for a written quote on your specific parcel.
Ellery ADU Studio has designed and built detached ADUs across San Rafael since 2015, from the flat ranch lots of Terra Linda to the steeper parcels off Lucas Valley Road. We know where the fire-hardening line falls, which older panels show up in 1960s tract homes, and how Marin County’s septic and well setbacks change a project on acreage. That local knowledge goes into every written price before you sign anything.
Why Ellery ADU Studio Is San Rafael’s Preferred New Detached ADU Company
We operate as a design-build studio, not a contractor. That distinction matters on a six-figure project. The drawings, the permit set, and the construction are a single contract at a single written price. When a designer and a builder are two separate companies, each can point at the other when something goes wrong. That blame gap is where most ADU projects stall. We removed it.
Every San Rafael project is governed by The Haven Standard. Clause 1: a written price before any work begins. No exceptions, no verbal ranges that drift once the foundation is poured. Clause 5: the scope is locked at signing. No door-side upsells, no surprise change orders when the electrical panel turns out to be undersized. Nadia Ellery founded the studio in 2015, the year California’s ADU permitting landscape shifted, and the permit set has been our core product ever since.
We’ve completed 900+ ADUs since then, every one with a documented photo record when work was complete. If the finished ADU is not built to the permitted drawings, the 365-Day Done Right Promise applies, in writing, before the project starts. A live person answers calls 24/7 at (971) 497-2402. No voicemail queue.
Our New Detached ADU Services in San Rafael
Custom Built ADU
A custom detached ADU on a flat Terra Linda lot is the most straightforward build we do in San Rafael. Those 6,000-9,000 sq ft parcels were platted with generous setbacks, and the city’s standard plan check moves without the fire-hardening review that hillside properties trigger. We handle the full permit set, including the site plan, structural drawings, and Title 24 energy compliance. Design through final inspection is one contract, one written price.
Prefab ADU Installation
Prefab systems make sense on San Rafael hillside parcels where we want to limit the number of days crews are working on a sloped site. We specify and coordinate Abodu, Cover, and Mighty Buildings units within the same single contract. Chapter 7A requirements still apply on VHFHSZ lots, which means we verify the manufacturer’s fire-rated assemblies against Marin County’s specific checklist before we quote. Not every prefab model passes on a Dominican hillside without modification.
Modular ADU
Modular construction changes the site work math, not the permitting math. On open lots around San Rafael with septic and well systems, we survey setbacks before design, because a foundation that encroaches on the required 100-foot separation from a well is a redesign at your expense. We’ve caught this early on parcels off Lucas Valley Road and saved clients the cost of moving a foundation after the fact.
Studio ADU
A studio ADU in San Rafael runs $190,000-$265,000 all-in, which makes it the most popular entry point for homeowners who want rental income without the footprint of a full two-bedroom. Studio builds on flat parcels in the Canal district and Glenwood clear plan check fastest. The older downtown flats, with their pre-WWII electrical panels and cast-iron sewer laterals, usually need utility upgrades before the city signs off. We scope those line items in the written quote, not as a surprise at final inspection.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in San Rafael
When a San Rafael homeowner wants a prefab or modular ADU, we specify and coordinate the system within our single contract. We work regularly with Abodu, Cover, Dvele, and Mighty Buildings, and we know which models clear Marin County’s Chapter 7A checklist on hillside parcels. That coordination is part of the written price. You’re not buying a kit and then finding a separate contractor to handle foundation, utilities, and the permit set. We handle the entire scope, drawings through occupancy.
Common New Detached ADU Problems We See in San Rafael Homes
- VHFHSZ parcels quoted without Chapter 7A upgrades. Ember-resistant vents, ignition-resistant siding, and Class A roofing can add $15,000-$40,000 after a contract is signed if the original quote ignored the fire zone. On a hillside ADU in Dominican, this is a hard cost, not an optional upgrade.
- Terra Linda garage conversions with 60-amp sub-panels. The 1960s-era sub-panels feeding those detached garages are almost universally 60A or less. Current load requirements demand a replacement panel before the city signs off. A near-universal line item on Terra Linda bids.
- Detached ADUs on open lots with unsurveyed septic and well setbacks. If the foundation encroaches on the required 100-foot separation from a well, you’re looking at a redesign. We survey before we design, which keeps the foundation where it belongs the first time.
- Older downtown flats with 100A or less incoming service. Pre-WWII Craftsman and Victorian cottages in the Canal district and downtown flats frequently need a main panel upgrade before an ADU can receive a certificate of occupancy. We scope that in writing before you sign.
Pricing for New Detached ADU in San Rafael, CA
Here are real ranges for New Detached ADU in San Rafael projects, drawings through final inspection:
| ADU Type | Typical Range (All-In) |
|---|---|
| Studio ADU (flat parcel, standard code) | $190,000-$265,000 |
| Studio ADU (VHFHSZ hillside, Chapter 7A) | $225,000-$305,000 |
| 1-Bedroom ADU (flat parcel) | $240,000-$325,000 |
| 1-Bedroom ADU (VHFHSZ hillside) | $275,000-$365,000 |
| 2-Bedroom ADU (flat parcel) | $285,000-$385,000 |
| 2-Bedroom ADU (VHFHSZ hillside) | $320,000-$425,000 |
San Rafael sits in an inland Marin valley, and that geography drives cost. Summer runs noticeably hotter and drier here than in Sausalito or Stinson Beach, and fall Diablo wind events extend the fire season. That’s why so many hillside parcels carry the VHFHSZ designation, and why the same floor plan can differ by $15,000-$40,000 depending on which side of the fire zone your lot falls on. We price your parcel, not a generic San Rafael average. Call (971) 497-2402 for a written quote on your specific address.
We Also Serve Cities Near San Rafael
Our New Detached ADU team serves San Rafael and the surrounding Marin and East Bay communities, including Richmond, San Pablo, Novato, and Hercules. The same written-price guarantee and 365-Day Done Right Promise apply on every project, in every city.
Serving San Rafael, CA - Our Local Coverage Area
We’re based in the San Rafael area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - New Detached ADU in San Rafael
Yes, if your parcel falls within a Very High Fire Hazard Severity Zone, which includes most of Dominican, Sun Valley, and the slopes above Terra Linda. Chapter 7A requires ember-resistant vents, Class A roofing, ignition-resistant siding, and tempered glass on any new detached ADU built there. This typically adds $15,000-$40,000 to the project. Flat parcels in Terra Linda and Glenwood are exempt. We verify your parcel’s VHFHSZ status before quoting, so the number on your written price reflects what Marin County will actually require. Call (971) 497-2402 and we’ll pull the designation for your address.
Because the 1960s-era sub-panels feeding those oversized detached garages are almost universally 60A or less, and the city will not sign off on an ADU fed by a 60-amp panel. Electrical panel replacement is a near-universal line item on Terra Linda garage conversions, typically running $4,000-$8,000 depending on the service upgrade required. A written quote from Ellery ADU Studio includes this line item before you sign, not as a discovery during construction. Estimates are free at (971) 497-2402.
Marin County requires a 100-foot separation between any new foundation and an existing well, and specific setbacks from septic tanks, leach fields, and drain lines that vary by parcel. We survey those setbacks before design begins. On a 1.2-acre parcel off Lucas Valley Road, we flagged a failing septic lateral that had to be rerouted 40 feet from the well and scoped the drain field replacement before quoting. Getting these surveyed early is the difference between a clean build and a foundation that has to move. Call (971) 497-2402 to start with a site review.
Most flat parcels in Terra Linda and Glenwood do not require a grading plan for a standard detached ADU, though we still document existing drainage patterns in the permit set. Hillside parcels, and any lot where the city or county requires drainage review, will need a grading and drainage plan. Chapter 7A fire-hardening and slope stability often trigger this requirement together. We’ll tell you during the initial site review whether your parcel needs one, and the fee is in the written price.
Yes. We specify and coordinate Abodu, Cover, and Mighty Buildings units on VHFHSZ parcels, but the manufacturer’s standard details have to be verified against Marin County’s Chapter 7A checklist before we quote. This includes ember-resistant venting, ignition-resistant siding, and Class A roofing on the factory-built shell. When we quote a prefab ADU in Dominican or Sun Valley, the fire-hardening upgrades are already in the written price. Call (971) 497-2402 and we’ll run your parcel’s requirements against the model you’re considering.
Get Your Written San Rafael ADU Quote
No verbal ranges. No ballpark numbers that shift once the plans are drawn. We survey your parcel, check the VHFHSZ designation, pull the panel and sewer history where relevant, and give you a written price for the entire scope of work before any contract is signed. That’s Clause 1 of The Haven Standard, and it applies on every project in San Rafael.
Call (971) 497-2402 for your free estimate on a new detached ADU in San Rafael. A live person answers.
Written by Nadia Ellery, Owner at Ellery ADU Studio.
New Detached ADU in Nearby Areas
