A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in San Francisco, CA
Adding an ADU or home addition in San Francisco means working with wood-frame Victorians and Edwardians, fog-damp west-side lots, and hillside setbacks that shift from block to block. Sutton ADU Builders handles those conditions every week. We write your price before any work starts, send you the name and photo of every technician before they arrive, and back the finished build with a 365-day written promise. If you’re planning a detached unit, garage conversion, or room addition, call (831) 272-7212 for a free estimate.
Why San Francisco Homes Are Different
San Francisco’s housing stock runs heavily to timber-frame Victorians and Edwardians built between roughly 1880 and 1915. Most sit on raised foundations, and a lot of them have ground-floor garages or storage rooms that are frankly underused. That’s the ADU opportunity here, and it’s bigger than in almost any California city. The state’s ADU statutes are permissive, and San Francisco’s housing shortage means the city processes a steady stream of garage and basement conversions each year.
But the buildings fight back a little. The fog that rolls through the Sunset and Richmond keeps summer temperatures low, so most San Francisco ADUs don’t need air conditioning. What they do need is insulation that handles damp air and a good vapor-control strategy, especially on west-facing walls. On the hills, things get steeper. In Noe Valley, a garage conversion can run into slope setbacks and neighbors’ view easements. In the Sunset, digging for a legal basement ADU sometimes means hitting sand and a high water table. A contractor who only builds on flat suburban lots will find San Francisco humbling quickly.
Our Main San Francisco Services
San Francisco homeowners typically call us for one of three things: adding square footage to the main house, building a separate ADU in the yard or garage, or converting an existing room into something more useful. Each service has its own page with local pricing and specifics.
Home Addition Contractor in San Francisco
A home addition in San Francisco usually means working within a tight lot, matching the existing Victorian or Edwardian roofline, and getting buy-in from Planning on setbacks and neighborhood character. We handle the structural engineering, the permit package, and the build, and we’re comfortable with the city’s historic-district review process. Home Addition Contractor in San Francisco
ADU Builders in San Francisco
San Francisco is one of the best cities in the state for ADUs right now. The combination of high rents and state preemption of local restrictions means detached units and garage conversions pencil out quickly. We build site-built units and we also work with prefab and modular lines where the lot suits them. ADU Builders in San Francisco
Room Addition Contractor in San Francisco
A room addition renovates interior space rather than adding a separate structure. In San Francisco, that often means reclaiming a ground-floor storage room, finishing an attic under existing rooflines, or converting a garage bay into a legal bedroom with proper egress and insulation. Room Addition Contractor in San Francisco
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Brands We Service in San Francisco
We handle Tuff Shed conversions, Plant Prefab and Boxabl modular units, and James Hardie exterior cladding systems. In most cases we can quote parts and labor the same week you call. See our brands for the full list.
Pricing for ADU Company in San Francisco, CA
These ranges reflect typical San Francisco project scopes before site-specific work like seismic upgrades or foundation repair. Every project starts with a written price, so you’ll know your exact number before anything gets built.
| Service | Typical range in San Francisco |
|---|---|
| Detached ADU (400 – 800 sq ft) | $180,000 – $320,000 |
| Garage conversion ADU | $120,000 – $220,000 |
| Basement ADU conversion | $160,000 – $280,000 |
| Prefab/modular ADU (installed) | $150,000 – $300,000 |
| Room addition (200 – 400 sq ft) | $90,000 – $180,000 |
| Home addition (400 – 800 sq ft) | $160,000 – $320,000 |
| Seismic retrofit (per project) | $15,000 – $45,000 |
| Foundation repair before build | $10,000 – $40,000 |
| Kitchen addition | $120,000 – $250,000 |
| Bath addition | $40,000 – $90,000 |
What pushes a San Francisco ADU toward the top of that range? Almost always the site: hillside engineering, a failing foundation on a 1910 building, or a water table issue in a Sunset basement dig. We quote those costs before work starts, not after. That’s the whole point of a written price.
Neighborhoods We Serve in San Francisco
We work across the city, from the fog belt to the bay side. Every neighborhood has its own feel, and the crew we send knows the difference between a Noe Valley hillside and a Richmond flat block. We’ll give you a straight answer on schedule when we quote.
- Sunset District
- Richmond District
- Noe Valley
- Bernal Heights
- Mission District
Service Area – Cities Near San Francisco
Our San Francisco Bay Area office also coordinates work in a few nearby communities. If you’re in Brisbane, CA, South San Francisco, CA, Alameda, CA, or Pacifica, CA, we can help with ADUs and additions there too.
Serving San Francisco, CA - Our Local Coverage Area
We’re based in the San Francisco 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 About ADU Company in San Francisco
Most San Francisco ADUs run four to eight months from permit submission to final inspection. Permit review at the Department of Building Inspection is the biggest variable, and hillside projects can add structural review time. We’ll give you a written schedule with your quote. Call (831) 272-7212 for specifics on your lot.
Yes. We pull the permits and manage every required inspection through the Department of Building Inspection. San Francisco has its own energy and seismic standards, and our build plans are drawn to pass the first time. You’ll see the permit status at every stage. Call (831) 272-7212 to talk through your project.
Yes. Every technician is background-checked, identity-verified, uniformed, and photo-badged under the Threshold Standard. Before any visit, you’ll get the person’s name and photo. It’s a simple system, and in San Francisco, where you don’t always know your neighbors, it matters. Call (831) 272-7212 for a free estimate.
Call (831) 272-7212 to schedule your free estimate. We’ll send a real person, a written price, and a plan for your San Francisco ADU or addition.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What San Francisco Customers Say
"They handled the drawings and the permit paperwork for us. All I had to do was pick the finishes."
- Rosa M."Itemized estimate with allowances laid out. Final cost was within a hair of the quote."
- Naomi R."Backyard ADU for my mother. The project manager showed ID and walked me through the permit steps, the foundation plan, and the schedule. Moved her in on time."
- Margaret C.
