8 ADU Builders to Consider in San Francisco (2026)

Accessory dwelling units give Bay Area property owners a way to add living space or create rental-income potential on land they already hold. San Francisco remains one of the country’s highest-rent major markets, though whether an ADU pencils out depends heavily on project cost, financing, achievable rent, vacancy, taxes, insurance, and maintenance.

For those interested in residential real estate exposure without a construction project, Ark7 offers fractional exposure to rental-property investments through securities tied to individual property series, with shares starting as low as $20 per share, subject to offering availability and eligibility. These are speculative securities involving substantial risk, including illiquidity and complete loss of capital.

This guide profiles eight ADU builders serving San Francisco and the greater Bay Area, compiled from publicly available company information. Pricing, contact details, ratings, and license status change quickly, so verify current information directly before hiring.

Key Takeaways

• San Francisco requires a building permit for all ADU construction, and many projects can proceed under state-law or ministerial pathways subject to applicable requirements.
• San Francisco building permits may require review by multiple departments, including DBI, Planning, Fire, Public Utilities, and Public Works, depending on the project. Not every ADU receives identical review by all five.
• Permitting time varies substantially based on the ADU program, scope, and required reviews, so treat any single figure as indicative rather than standard.
• The City’s own guidance notes ADUs typically cost at least $125,000 in labor and materials, with architects and engineers commonly around 10% of construction cost and city fees around 6% to 9%, while emphasizing wide variability.
• Construction cost and rent figures circulating for Bay Area ADUs are planning estimates or general apartment-market context rather than verified ADU-specific datasets.
• Gross rental yield varies substantially by construction cost and attainable rent, and any yield figure excludes vacancy, operating expenses, financing, and taxes.
• Ark7 offers fractional shares tied to individual rental-property series starting as low as $20 per share, subject to offering availability and eligibility.

How This List Was Compiled

This list was assembled from publicly available company information rather than a reproducible scoring model, and no ranking is implied by the order below. The companies below are among the Bay Area ADU builders reviewed for this guide.

License numbers appear where they could be independently identified; verify current status at cslb.ca.gov before contracting. Addresses, phone numbers, project counts, product pricing, and review ratings change and in several cases conflict across sources, so confirm all of it directly with the company. Company-published pricing, timelines, and completion figures are labeled as such throughout.

San Francisco ADU Rules to Understand First

• Permits required: All ADU construction in San Francisco requires a building permit.
• Review path: Building permits may require review by DBI, Planning, Fire, Public Utilities, and Public Works, depending on the project. The city routes applications to the agencies a given project requires rather than applying one fixed workflow.
• Program tracks: San Francisco maintains distinct State and Local ADU processes, and many projects can proceed under state-law or ministerial pathways subject to applicable requirements.
• Timelines: Permitting duration varies substantially by program, scope, and required reviews. Project characteristics can lengthen the process considerably.
• Cost guidance: The City indicates ADUs typically cost at least $125,000 in labor and materials, with architect and engineer fees commonly around 10% of construction cost and city fees around 6% to 9%, while noting wide variability.

8 ADU Companies Serving San Francisco and the Bay Area

1. Type Five

Location: Channing Way, Berkeley, CA 94702. Directory listings conflict on the suite number, so confirm the current address directly.

Phone: (510) 380-7500

License: CSLB #1086540, associated with general building activity

Type: Combined Architecture and General Contracting

Timeline: The company advertises roughly eight to 14 months

Service Area: Berkeley, Oakland, San Francisco, San Jose, Peninsula cities, and the wider Bay Area

Type Five operates as both an architecture firm and a general contractor, which removes the coordination gap between separate designers and builders. Its standardized designs carry fixed pricing set before construction begins.

What Sets Type Five Apart:

• Fixed pricing locked before construction starts
• Architect and general contractor under one contract
• Process built around ministerial, by-right permit review
• Standardized designs that reduce iteration time

2. Nestadu

Location: 100 Shoreline Hwy, Suite 386B, Mill Valley, CA 94941

Phone: Published sales numbers differ from the business phone shown in the current CSLB record, so confirm the correct contact directly

License: CSLB #1117837, Class B General Building, current and active

Company-Published Pricing: Product names and prices vary across current listings, with figures reported from roughly $115,000 for the entry model up to about $317,000 for a two-bedroom unit. Reconfirm exact current model names and prices with the company.

Custom Build Pricing: Roughly $400 to $600 per square foot depending on style selection

Service Area: Mill Valley, the San Francisco Bay Area, Los Angeles, San Diego, and Sacramento

Nestadu offers both prefabricated and custom site-built ADUs in modern, traditional, farmhouse, and Spanish styles. Prefab construction may reduce onsite construction time, although overall delivery depends on permitting, manufacturing lead time, and site work. One current company page lists an eight to 10 month lead time for its two-bedroom model, so establish what any quoted window actually covers.

What Sets It Apart:

• Both prefab and custom site-built pathways
• Multiple exterior style options
• Factory production that shortens the onsite phase
• Coverage across several California markets

3. Apex Homes ADU

Location: Cupertino, CA 95014. Contractor profiles list a different street address than the company has previously published, so confirm before visiting.

Phone: (408) 877-8080

Type: Full-Service Design-Build

Timeline: The company advertises roughly six to 12 months

Service Area: San Jose, Palo Alto, Cupertino, Santa Clara, Mountain View, Los Gatos, the wider Bay Area, and Southern California

Apex Homes handles design, permitting, and construction, and says it has completed more than 40 ADUs across the Bay Area and Southern California. It promotes pre-approved design options in select jurisdictions; ask which specific cities apply to your parcel, since pre-approval is city-by-city.

What Sets It Apart:

• Design, permitting, and construction under one contract
• Pre-approved plan options in select jurisdictions
• Solar included for Title 24 compliance
• Licensing covering both Northern and Southern California markets

4. Valley Home Builders

Location: 3466 Edward Avenue, Santa Clara, CA 95054

Phone: Listings conflict between the company’s current contact page and third-party directories, so confirm directly

Credentials: BBB accredited with an A+ rating, and a NARI member per the company

Type: Full-Service Design-Build

Service Area: San Francisco Bay Area with a Silicon Valley focus

Operating since 2005, Valley Home Builders keeps architects, designers, and project managers in house, and runs a customer portal that lets owners track progress remotely, which helps if you are not local.

What Sets It Apart:

• Customer portal for remote project tracking
• One-year labor guarantee on work performed
• In-house design team alongside construction
• Backyard cottages, guest houses, in-law suites, and garage conversions

5. We Do Construction

Phone: (415) 416-5494

License: CSLB #1096552

Type: San Francisco Design-Build

Company-Advertised Pricing: Garage conversions roughly $120,000 to $250,000

Timeline: The company advertises roughly seven to nine months for garage conversions

Service Area: San Francisco citywide

We Do Construction focuses on the San Francisco market with particular emphasis on garage conversions, managing SF Planning and DBI permitting in house. Its familiarity with San Francisco’s multi-agency permitting process may be useful given how much of the schedule sits with review rather than construction.

What Sets It Apart:

• San Francisco garage conversion specialization
• In-house permit management
• Fixed design-build contracts
• Title 24 energy compliance handled directly

6. SFBayADU

Location: 111 North Market Street, San Jose, CA 95113

Phone: (408) 514-5087 in San Jose, (415) 306-8549 in San Francisco

Type: Design-Build

Service Area: San Francisco, Oakland, San Jose, and the Peninsula

SFBayADU has plans pre-approved by San José, which can expedite the permitting stage, though site-specific submission is still required. It builds units from roughly 600 to 1,200 square feet in studio, two-bedroom, garden cottage, and in-law configurations.

What Sets It Apart:

• San José pre-approved plans
• Working relationships across regional building departments
• Range of unit sizes and configurations
• Regional permitting experience

7. Hamilton Exteriors

License: CSLB #1078806

Company-Advertised Pricing: Garage conversions from $80,000, with the company’s published typical range of $80,000 to $150,000 including permits. Actual cost varies by scope and site.

Certifications: GAF Master Elite, Owens Corning Preferred, CertainTeed ShingleMaster, and James Hardie Elite Preferred

Service Area: Bay Area and Northern California

Hamilton Exteriors offers one of the lower published entry points for garage conversions. Note that its certifications are roofing and exterior-product manufacturer credentials, so they do not by themselves validate ADU design, foundation, plumbing, electrical, or project management quality.

What Sets It Apart:

• Garage conversion specialization
• Published entry pricing with permits included
• Several roofing and exterior-product manufacturer certifications
• Northern California coverage

8. Gannon Construction Company

License: #544989, with Class A Engineering and Class B Building classifications

Type: Engineering-Capable General Contractor

Service Area: Marin, Sonoma, Napa, and San Francisco counties

Founder Brian Gannon had more than 25 years of construction experience before starting the company. The Class A Engineering license lets the firm handle grading, retaining walls, and utility installation, which matters on hillside and difficult North Bay sites where site preparation can rival the cost of the unit itself.

What Sets It Apart:

• Dual Class A and Class B licensing
• Complex site work, grading, and retaining walls
• Utility installation on challenging terrain
• North Bay hillside experience

Bay Area ADU Construction Costs

The figures below are rough estimates compiled from builder quotes rather than market averages, and they exclude soft costs unless noted. The City of San Francisco emphasizes that ADU costs vary widely by foundation, utilities, site access, finishes, and whether design and fees are included:

• Garage conversion: roughly $80,000 to $250,000, commonly four to eight months
• Attached ADU: roughly $150,000 to $350,000, commonly six to 10 months
• Detached custom ADU: roughly $250,000 to $500,000 and above, commonly eight to 16 months
• Prefab ADU: roughly $115,000 to $350,000, with a shorter onsite phase but permitting, manufacturing, and site work on top
• Junior ADU: roughly $50,000 to $100,000

Per-square-foot quotes across the region commonly fall between roughly $350 and $600, with San Francisco at the upper end and the South Bay generally lower. These are builder-quote bands rather than a sourced regional dataset.

Soft costs: Rather than assuming a fixed dollar range, use San Francisco’s percentage-based guidance. The City indicates architect and engineer fees commonly run around 10% of construction cost and city fees around 6% to 9%, on top of at least $125,000 in typical labor and materials. Utility connections, structural engineering, and Title 24 compliance are separate line items worth pricing individually.

Rental Income and Return Considerations

San Francisco remains one of the country’s highest-rent major markets. For context, current citywide apartment-market averages run roughly $2,700 for studios, $3,568 for one-bedroom units, and $4,985 for two-bedroom units. Those figures cover the broader rental stock rather than ADUs specifically, so treat them as market context and pull current comparables for your own neighborhood and unit type.

An illustrative gross-yield example, using round numbers rather than observed outcomes: a $350,000 detached ADU renting at $2,800 per month produces $33,600 in annual gross rent, a 9.6% gross yield before expenses. Simple gross-rent payback on that example is approximately 10.4 years before vacancy, operating expenses, taxes, financing costs, and maintenance, all of which extend it. This is one constructed scenario and does not establish typical Bay Area results.

An ADU may affect property value, but the amount varies significantly by property, location, ADU characteristics, and market conditions. Confirm any expected value contribution with a local appraiser rather than assuming a dollar figure or percentage.

How to Choose the Right ADU Builder

• Match specialty to project type: Garage conversions, prefab delivery, fixed-price standardized designs, and complex hillside sites each call for different experience.
• Verify the license: Check status and complaint history at cslb.ca.gov, and confirm the classification covers your scope.
• Confirm insurance: Request certificates of liability and workers’ compensation coverage.
• Review portfolio and references: Ask for addresses of completed projects and speak with at least two recent clients.
• Pin down contract terms: Confirm fixed pricing, payment schedule, timeline commitments, and who carries permitting responsibility.
• Get multiple bids: Three or more bids reveal market pricing, and large variations usually signal different scope assumptions worth clarifying.

Questions to Ask Any San Francisco ADU Builder

• Which review agencies will my specific project require?
• Does my project qualify for a state-law or ministerial pathway?
• Does your quote include design, engineering, permits, utility connections, and site work?
• Does your timeline start at contract signing, permit issuance, or the start of construction?
• For prefab, what does the quoted window cover: factory lead time, delivery, installation, or all of it?
• What is your CSLB number, and can you supply recent local references?

Financing an ADU

• Home equity options: A HELOC allows flexible draw-down during construction; a cash-out refinance provides a lump sum at a fixed rate.
• Construction loans: Staged funding that converts to a mortgage at completion.
• FHA 203(k): May finance eligible rehabilitation projects, subject to FHA property, borrower, appraisal, and loan-limit requirements.
• Fannie Mae HomeStyle Renovation: Eligible borrowers may finance qualifying ADU construction as part of a purchase or refinance, subject to program requirements.
• ADU-specific lenders: Some lenders offer products tailored to accessory dwelling unit projects; compare total borrowing cost rather than monthly payment alone.

Comparing ADUs and Fractional Real Estate

ADU construction can be economically attractive in some cases, but returns depend heavily on project cost, financing, achievable rent, vacancy, taxes, insurance, maintenance, and permitting time. It also requires substantial upfront capital and ongoing landlord responsibilities.

ADU considerations:

• Any yield figure quoted before expenses is a gross calculation, not an investor return.
• Rent estimates drawn from general apartment-market data are context, not ADU-specific evidence. Use current comparables near your property.
• Property-value effects vary by property, location, unit characteristics, and market conditions.
• Total duration depends on permitting, manufacturing where applicable, site work, utilities, and inspections rather than construction alone.

How fractional investing compares:

For those who prefer fractional exposure to rental-property investments rather than developing and managing an ADU directly, Ark7 is another model to consider:

• Entry point as low as $20 per share, subject to offering availability, eligibility, and property-specific minimums
• Shares represent an investment in a particular property series rather than direct ownership of the underlying real estate
• Cash distributions when available, subject to property performance, expenses, reserves, and offering terms
• Professional property selection and management
• No construction timelines or permitting to manage
• Securities are issued electronically and are not listed or quoted on a public securities exchange. Potential access to secondary trading is subject to holding periods, legal and state restrictions, platform availability, and market liquidity. Liquidity is not guaranteed, and investors should be prepared to hold shares indefinitely.
• Ark7 IRA options support Traditional and Roth accounts used to purchase eligible Ark7 property shares, subject to IRA rules, individual tax circumstances, and custodian fees

These are speculative securities involving substantial risk, including illiquidity, lack of diversification, and complete loss of capital.

Conclusion

The Bay Area’s ADU builder market spans architecture-led design-build firms, prefab manufacturers, San Francisco garage conversion specialists, and engineering-capable contractors for difficult terrain. The harder part is separating verified facts from marketing: several builder addresses, phone numbers, product prices, and review ratings currently conflict across sources, and widely circulated cost, rent, and return figures are estimates rather than datasets.

Why San Francisco Stands Out for ADU Projects

• Ministerial pathways: Many projects can proceed under state-law or ministerial review subject to applicable requirements.
• Published city guidance: San Francisco provides percentage-based cost guidance and identifies the departments that may review a permit.
• High-rent market: San Francisco remains one of the country’s highest-rent major markets.
• Pre-approved plans regionally: San José operates a pre-approved plan program that some builders here design around.
• Varied delivery models: Prefab, standardized fixed-price design-build, garage conversion specialists, and engineering-capable contractors all serve the region.

Investor Tips for Bay Area ADU Projects

Verify every contractor’s CSLB license, address, and phone number yourself, since several listings in circulation conflict with current records. Ask which review agencies your specific project triggers rather than assuming a fixed five-agency process, and confirm whether a state or local program pathway applies. For prefab, establish exactly what a quoted window covers, since factory lead times of eight to 10 months have appeared alongside much shorter installation figures. Budget soft costs using the City’s percentage guidance rather than a fixed dollar range. Finally, treat any yield or payback figure as a gross calculation with its assumptions disclosed, and confirm expected value contribution with a local appraiser instead of a published estimate.

For those who prefer residential real estate exposure without a construction project, Ark7 offers fractional exposure to rental-property investments starting as low as $20 per share, subject to offering availability and eligibility. Cash distributions are made when available and are subject to property performance, expenses, reserves, and offering terms.

Frequently Asked Questions

How long does it take to build an ADU in San Francisco?

Timelines vary substantially by builder, program pathway, and scope. Builders in this guide advertise roughly four to eight months for garage conversions and eight to 16 months for custom detached units. Prefab shortens the onsite phase, but factory lead times, permitting, foundation and site work, utilities, and inspections still control when a unit can be occupied. Permitting duration varies with the ADU program, scope, and required reviews, so ask each builder for a current estimate rather than assuming a fixed window.

How much does an ADU cost to build in the Bay Area in 2026?

Builder quotes commonly run from around $80,000 for garage conversions to $500,000 and above for custom detached units, with per-square-foot figures generally between $350 and $600 across the region. San Francisco’s own guidance indicates ADUs typically cost at least $125,000 in labor and materials, with architect and engineer fees around 10% of construction cost and city fees around 6% to 9%. Treat all figures as planning estimates rather than quotes.

What rental income can I expect from a Bay Area ADU?

Current citywide apartment averages in San Francisco run roughly $2,700 for studios, $3,568 for one-bedroom units, and $4,985 for two-bedroom units, but those cover the broader rental stock rather than ADUs specifically. Achievable ADU rent varies by neighborhood, size, finishes, and configuration, so pull current comparables near your property rather than relying on citywide figures.

Do I need a permit to build an ADU in San Francisco?

Yes, all ADU construction requires a building permit. Many projects can proceed under state-law or ministerial pathways subject to applicable requirements, and the city maintains distinct State and Local ADU processes. Permits may require review by multiple departments including DBI, Planning, Fire, Public Utilities, and Public Works, depending on the project, so confirm which reviews apply to yours.

Is building an ADU a good investment in 2026?

It depends entirely on the numbers for your specific project. Gross rental yield varies substantially with construction cost and attainable rent, and any yield figure quoted before vacancy, operating expenses, taxes, and financing is a gross calculation rather than an investor return. As an illustration, a $350,000 build renting at $2,800 monthly produces a 9.6% gross yield and roughly 10.4 years of simple gross-rent payback before expenses. ADU construction also requires substantial upfront capital, construction management, and ongoing landlord responsibilities, so build your own model from local comparables and actual quotes.

Neither Ark7 nor Ark7 Properties is a broker-dealer or an investment adviser. Dalmore Group LLC, a registered broker-dealer and member FINRA/SIPC, located at 525 Green Place, Woodmere, NY 11598, is the broker-dealer of record for Ark7, an issuer direct offering. Neither Ark7 nor Dalmore makes recommendations or provides advice about investments, and nothing here should be construed as a recommendation for any security. An investment constitutes an investment in a particular series and not in Ark7 or the underlying assets. Investments on the Ark7 platform are speculative and involve substantial risks, including illiquidity, lack of diversification, and complete loss of capital. Securities are issued electronically and are not listed or quoted on a public securities exchange. Cash distributions are not guaranteed and are subject to property performance, expenses, reserves, and offering terms. Past performance is no guarantee of future results. This article is for informational purposes only.