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ADU construction in San Francisco typically costs $106,200 to $259,600 for a complete accessory dwelling unit, with most homeowners landing between $150,000 and $210,000 for a standard one-bedroom unit of roughly 500 to 600 square feet. The spread is wide because San Francisco carries some of the steepest labor rates, permit fees, and site constraints in the country. A detached unit on a flat Sunset District lot costs less than a garage conversion on a steep Bernal Heights slope, but both fall inside that range once engineering, utility connections, and finishes are accounted for.
This guide breaks down where the money goes, what the city itself adds to your bill, and how Bradford Remodeling Co San Francisco puts every number in writing before the first shovel hits the ground.
Key Takeaways
- San Francisco ADU construction runs $106,200 to $259,600 all-in for 2026.
- Per-square-foot costs land between $210 and $460 depending on scope, site access, and finish level.
- San Francisco permit fees and Department of Building Inspection compliance add $8,000 to $20,000 on top of construction costs.
- Detached ADUs cost more than garage conversions or attached additions, but add more resale value per square foot.
- Bradford Remodeling Co San Francisco provides a written price before any work starts, with a 365-Day Done Right Promise on every completed project.
If you’re considering an ADU on your property, start with our ADU Construction in San Francisco service page to see what a full build includes. For a faster read on pricing, keep going.
ADU Construction Cost Breakdown (2026)
Here is the itemized range for a standard one-bedroom, one-bath ADU of 500 to 600 square feet in San Francisco, based on current market pricing and what Bradford Remodeling Co San Francisco sees on bids across the city.
| Line Item | Cost Range (San Francisco) |
|---|---|
| Design and architectural drawings | $8,000 – $18,000 |
| Structural engineering | $3,500 – $8,500 |
| Permit fees (SFDBI, planning, school fees) | $8,000 – $20,000 |
| Site preparation and demolition | $5,000 – $15,000 |
| Foundation | $12,000 – $30,000 |
| Framing and structural | $18,000 – $45,000 |
| Roofing | $6,000 – $18,000 |
| Plumbing rough-in and fixtures | $10,000 – $25,000 |
| Electrical rough-in and panel | $8,000 – $22,000 |
| HVAC / heating | $6,000 – $16,000 |
| Insulation and drywall | $7,000 – $18,000 |
| Flooring | $4,000 – $10,000 |
| Kitchenette | $8,000 – $22,000 |
| Bathroom | $10,000 – $25,000 |
| Windows and doors | $5,000 – $14,000 |
| Paint and finish work | $4,000 – $10,000 |
| Landscaping and exterior | $3,000 – $12,000 |
Total: $106,200 to $259,600.
That spread is real, and it is driven by three things: whether you build detached or convert existing space, how much site work your lot demands, and what level of finish you choose. A garage conversion where the foundation and roof already exist removes two expensive line items. A detached unit on a Noe Valley hillside where crews need to hand-carry materials and shore up a slope adds tens of thousands before a single cabinet arrives.
What Bradford does not do is hand you a range with no commitment. Our home office runs on The Garrison Standard: a written price before any work starts, every time. The number we give you is the number on the contract. It does not move at the door.
What Affects ADU Construction Pricing in San Francisco
- Detached versus conversion. A detached ADU starts with a new foundation, new utility trenching, and full exterior enclosure. That is why detached units run $260 to $460 per square foot. Converting an existing garage or basement space drops that to $210 to $330 per square foot because you are working inside an existing envelope.
- Lot slope and site access. San Francisco is built on hills. In neighborhoods like Portola, Diamond Heights, and the roads above Glen Park, steep lots mean retaining walls, pier drilling, and sometimes crane work. Flat lots in the Outer Richmond and Sunset trim $15,000 to $40,000 off site costs.
- PG&E utility connections. A detached ADU needs a separate electrical service or a panel upgrade on the main house. In San Francisco, upgrading from a 100-amp to a 200-amp panel runs $4,000 to $8,000, and trenching for gas and water lines adds another $5,000 to $15,000 depending on distance and concrete cutting.
- Finish level. Builder-grade cabinets, laminate counters, and a fiberglass shower keep the interior under $40 per square foot of fixture area. KraftMaid or Wellborn cabinetry, Cambria or Caesarstone counters, and Kohler fixtures push that closer to $80 per square foot. Bradford installs documented brands like these so every specification is traceable, but the spec level is a homeowner decision, not a hidden markup.
- Permit and impact fees. San Francisco charges school impact fees, inclusionary housing fees for some ADU categories, and DBI plan-check fees that combined run $8,000 to $20,000. These are non-negotiable and vary by project scope. A good contractor lists them as line items, not buried surprises.
- Fire and seismic requirements. San Francisco’s soft-story and seismic retrofit requirements can affect ADU scope if the main house shares a wall or foundation. Adding shear wall, hold-downs, and Simpson ties typically adds $4,000 to $12,000. It is not optional, and it is not something to cut corners on.
Detached vs. Garage Conversion vs. Attached ADU: What Each Costs
San Francisco homeowners choose among three ADU types, and the price difference between them is larger than most people expect.
- Detached ADU (new freestanding unit): $150,000 to $259,600. Full foundation, full utility runs, full exterior. Highest cost, highest rental value, most privacy for both households. Best for lots over 3,000 square feet with usable rear yard space.
- Attached ADU (addition or interior conversion attached to the main house): $106,200 to $190,000. Builds off existing walls and sometimes existing plumbing and electrical. Lower cost because one or two walls and the roof are shared. Common in single-family Victorians and Edwardians where a lower floor or side yard can be enclosed.
- Garage conversion ADU: $106,200 to $177,000. The existing structure gives you a head start, but you give up parking and often need to raise the floor, add insulation, install a proper foundation retrofit, and rework the roofline for headroom. In neighborhoods like the Mission and Noe Valley where garages are small, expect the lower end; in the Sunset where garages run deeper, expect the mid-range.
The city waived many ADU permit fees through 2024, but in 2026 you should budget the full fee schedule. Do not let a low initial bid omit permit line items. A written scope that lists every fee is the only way to compare bids honestly.
How Much Does an ADU Cost Per Square Foot in San Francisco?
A realistic 2026 figure for ADU construction in San Francisco is $210 to $460 per square foot, fully finished. That includes design, permits, site work, materials, labor, and fixtures. Here is what that looks like:
- 400-square-foot studio ADU: $84,000 to $184,000. Compact, efficient, and the most common starter unit for rental income. Single bath, kitchenette, open sleeping area.
- 500-square-foot one-bedroom ADU: $105,000 to $230,000. The sweet spot for most homeowners. Full bedroom separation, full bath, standard kitchen.
- 750-square-foot two-bedroom ADU: $157,500 to $345,000. A full two-bedroom unit that exceeds the lead range because of additional framing, HVAC zones, and a second bedroom’s worth of drywall, flooring, and electrical.
If a bid comes in below $210 per square foot in San Francisco, ask what is missing. Often it is permit fees, utility trenching, or finish allowances that get added later. Bradford’s written price includes everything in the scope document. If it is not in writing, it is not in the bid.
What the City of San Francisco Adds to Your ADU Bill
San Francisco has its own rules, and they cost money. The San Francisco Department of Building Inspection (DBI) plus the Planning Department, Public Works, and PG&E all touch an ADU project. Here is what to expect:
- DBI plan check and permit fees: $3,000 to $8,000 depending on valuation.
- Planning Department ADU review: $1,500 to $4,000 for standard ADU applications.
- School impact fees: $2 to $4 per square foot of new residential space. On a 600-square-foot ADU, that is $1,200 to $2,400.
- PG&E connection fees: $2,000 to $6,000 for new service or panel upgrades, before trenching costs.
- Waste diversion and debris hauling: $800 to $2,500 depending on demolition scope. San Francisco’s construction waste rules require high recycling rates.
Total: $8,000 to $20,000 before a single framing nail goes in. That is why any bid without a written fee schedule should stop the conversation. Bradford lists every city fee as a line item in the written price. We do not ask you to trust a verbal estimate on fees that we cannot control. We put them in the contract so you see exactly what the city charges and exactly what our work costs.
How to Save on ADU Construction
The biggest savings come from three decisions, in order: location on your lot, size, and finish spec.
- Convert instead of building detached. A garage or basement conversion saves $30,000 to $60,000 in foundation, roof, and exterior work. It also avoids variance and setback complications that delay detached units on tight San Francisco lots.
- Keep the footprint modest. A 400-square-foot studio rents for roughly 70 to 80 percent of what a 600-square-foot one-bedroom commands in most San Francisco neighborhoods, but costs 35 percent less to build. The math favors smaller units.
- Choose fixtures from a documented standard line. Kohler and Moen offer solid mid-range product lines that hold up well and do not carry designer pricing. Cambria and Caesarstone have quartz options in the $60 to $90 per square foot range installed, compared to $120-plus for exotic slabs. You do not need to sacrifice the written guarantee to save on materials that meet the spec.
- Bundle the ADU with a main-house project. If your home needs a panel upgrade, roof work, or foundation work anyway, doing it alongside the ADU project saves on mobilization, permits, and crew scheduling versus two separate jobs. Bradford’s whole-home remodeling background means we can scope both jobs in one written price.
- Do not wait for permit fees to rise. San Francisco adjusts its fee schedule annually. Waiting a year can add $500 to $2,000 in city costs alone. A free estimate today locks in a number that reflects current fees.
Bradford Remodeling Co San Francisco gives free estimates on ADU construction. Call (831) 610-5598 and a live person answers, 24/7. We will schedule a walkthrough, put a written price in your hands, and let you decide on your schedule, not ours.
What Does Bradford Remodeling Do Differently on ADU Projects?
Curtis Lane runs Bradford Remodeling Co San Francisco as part of the Garrison Partners family, established in 2004 and held to The Garrison Standard. What that means for your ADU project is specific, not promotional.
Written price before work starts. The Garrison Standard requires a line-item price in writing before any contract is signed. That price includes materials, labor, permits, city fees, and the finish level you chose. If a change order comes up mid-project, it is also in writing, with the cost stated before the work is approved. No numbers move at the door.
Background-checked, uniformed technicians. The crew that shows up at your home has been vetted and uniformed. You know who is walking through your gate before they arrive. The identity and conduct standards are set at the Garrison Partners level and apply to every job, not left to individual job sites.
365-Day Done Right Promise. Every finished ADU carries a full-year written guarantee. If something fails inside that year because the work was not done right, Bradford returns and corrects it at no charge. The promise is written into your contract, and you have a signed copy in your hand when the job closes.
Documented material roster. Bradford installs brands with published specifications and manufacturer warranties: KraftMaid and Wellborn cabinetry, Cambria and Caesarstone surfaces, Kohler and Moen fixtures, GAF and James Hardie exterior products, Therma-Tru doors. No generic substitutions. If the spec sheet says a brand, that brand is what gets installed.
Clean site at job close. “Squared away” means the debris is hauled, the site is swept, the scope is documented, and the signed written guarantee is in your hand before we leave. That is what closing a project looks like under The Garrison Code.
For a broader view of what we build, see our ADU Construction in San Francisco service page, where the scope and process are documented in detail.
FAQs – ADU Construction Cost
How much does a 500-square-foot ADU cost in San Francisco?
A 500-square-foot one-bedroom ADU in San Francisco costs $105,000 to $230,000 fully finished in 2026. That includes design, permits, site work, utilities, materials, and labor. If the unit is a garage conversion, expect the lower half of that range. If it is a detached unit on a sloping lot, expect the upper half. Call (831) 610-5598 and Bradford Remodeling Co San Francisco will give you a written price for your specific lot.
Is it cheaper to convert a garage or build a detached ADU in San Francisco?
A garage conversion costs $106,200 to $177,000, versus $150,000 to $259,600 for a detached unit. The conversion saves money because the foundation, roof, and three of four walls already exist. But you lose parking, and San Francisco’s seismic retrofit and floor height requirements can erase $15,000 to $30,000 of those savings. Bradford will scope both options and price them in writing so you can compare honestly. Call (831) 610-5598 for a free estimate on both approaches.
Can you build an ADU in San Francisco for under $100,000?
In 2026, the realistic floor for a legal, permitted ADU in San Francisco is $106,200, and that assumes a small garage conversion with modest finishes and no surprises in the site work. A new detached unit under $100,000 is not possible with current labor, permit, and material rates. If a bid comes in below that number, ask what is excluded. It will be permit fees, utility connections, or foundation work. Bradford’s written price includes everything in the scope, so you know the real number up front.
How long does ADU construction take in San Francisco?
A typical ADU takes 6 to 12 months from design through final inspection, with permits alone taking 2 to 4 months at the San Francisco DBI. Garage conversions run faster, usually 4 to 8 months. Detached units on site-constrained lots run longer. At project close, Bradford hands you the signed 365-Day Done Right Promise, so what gets finished stays finished for a full year at no charge if anything fails.
What is the return on investment for an ADU in San Francisco?
A San Francisco ADU typically adds $200,000 to $400,000 to resale value, depending on neighborhood and unit quality, while generating $2,200 to $3,800 per month in rent at current market rates. The return is stronger for detached units in neighborhoods like the Richmond, Sunset, and Bernal Heights where lot sizes accommodate them and buyer demand is high. Bradford Remodeling Co San Francisco can walk you through the financial picture in a free consultation. Call (831) 610-5598 any time, day or night. A live person answers.
Get a Free ADU Construction Estimate in San Francisco
A written price from Bradford Remodeling Co San Francisco is the fastest way to know what your ADU actually costs. We walk your lot, review your scope, and put every line item in writing: city fees, utility connections, materials, labor, and finish level. That price is yours to keep, whether or not you move forward. No pressure, no countdowns. Just a straight number.
Call (831) 610-5598 to schedule your free estimate. A live person answers 24/7. Curtis Lane and the Bradford team serve homeowners across San Francisco.
Pricing reflects the San Francisco market as of 2026. Bradford Remodeling Co San Francisco offers free estimates – call (831) 610-5598.
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