San Francisco ADU / Accessory Dwelling Unit Guide

San Francisco property owners can add an ADU to create additional housing on residential lots. The Department of Building Inspection (DBI) requires specific permits for these projects, particularly for units exceeding 150 square feet or involving structural modifications to existing properties.

Need help navigating San Francisco permits? Connect with licensed contractors who handle permits for you →

What Requires a ADU / Accessory Dwelling Unit in San Francisco

San Francisco has unique ADU regulations that differ from other California municipalities. Any residential property seeking to construct an ADU must obtain a permit from the Department of Building Inspection, regardless of the unit's size or location on the property. Specific triggers include converting existing spaces like garages or basements, constructing new detached units, or adding living quarters above existing structures.

The DBI mandates comprehensive documentation for ADU projects, including detailed architectural plans, site surveys, and proof of zoning compliance. Property owners must demonstrate that the proposed ADU meets San Francisco's strict building codes, which include requirements for ceiling heights, egress windows, and minimum living space dimensions.

Zoning restrictions in San Francisco can be particularly complex. Most residential districts allow ADUs, but height limitations, setback requirements, and neighborhood-specific design guidelines must be carefully navigated. Property owners should consult the DBI's zoning maps and consult with a permit specialist to ensure full compliance.

What Doesn't Require a Permit

Not all property modifications in San Francisco require a full ADU permit. Minor interior renovations that do not alter structural elements, electrical systems, or plumbing typically fall under minor work exemptions. These might include painting, replacing floor coverings, or installing non-load-bearing shelving.

San Francisco provides limited exemptions for temporary structures under 120 square feet that do not include permanent utility connections. However, any structure intended for continuous habitation will require comprehensive permitting through the Department of Building Inspection.

ADU / Accessory Dwelling Unit Costs and Fees in San Francisco

San Francisco's ADU permit fees are structured through a complex, tiered system based on project valuation. For a $100,000 ADU project, applicants can expect base permit fees around $5,638, with additional costs for plan review, environmental assessment, and site inspections.

The Department of Building Inspection charges a Building Permit Base fee that escalates with project complexity. For projects between $50,000 and $99,999, the base fee starts at $1,314 plus $13.15 per additional $1,000 of project value. Environmental review fees, such as the Community Plan Evaluation at $10,855, represent significant additional expenses.

Other potential costs include a $2,317 demolition permit if existing structures must be removed, and consultation fees at $283 per hour. Applicants should budget for multiple inspections and potential revision fees of $366 per modification.

How Long Does ADU / Accessory Dwelling Unit Approval Take

San Francisco's ADU permit process typically ranges from 4-8 months, depending on project complexity and current DBI workload. Initial plan review can consume 6-10 weeks, with additional time required for zoning compliance and environmental assessments.

The Department of Building Inspection recommends early consultation to streamline the process. Projects involving minimal structural changes may move faster, while comprehensive renovations or new constructions require more extensive review.

Required Documents for San Francisco ADU / Accessory Dwelling Unit

San Francisco requires comprehensive documentation for ADU permits. Applicants must submit detailed architectural plans drawn to scale, showing existing and proposed structures. These plans should include precise measurements, proposed utility connections, and compliance with local building codes.

Additional required documents include a current property survey, proof of ownership, detailed project scope narrative, and comprehensive site plans. The Department of Building Inspection mandates high-resolution digital submissions through their online portal, with minimum 300 DPI resolution for all graphical documents.

Step-by-Step Application Process

The San Francisco ADU permit process demands methodical preparation and precise documentation. Successful applicants follow a structured approach that minimizes potential delays and complications.

1. 1

   Initial Consultation

   Schedule a consultation with DBI permit specialists to review project feasibility and preliminary requirements.

2. 2

   Document Preparation

   Compile comprehensive architectural plans, property surveys, and required supporting documentation.

3. 3

   Online Submission

   Submit complete application package through SFDBI online portal with all required digital documents.

4. 4

   Plan Review

   DBI conducts thorough review of submitted plans, assessing zoning, structural, and environmental compliance.

5. 5

   Permit Issuance

   Upon approval, receive official permit with specific conditions and inspection requirements.

Required Inspections

San Francisco mandates multiple inspection stages for ADU projects. Initial site inspections verify existing conditions and confirm proposed modifications match submitted plans. Subsequent inspections occur at critical construction stages, including foundation, framing, electrical, and plumbing rough-ins.

The Department of Building Inspection requires a final comprehensive inspection before issuing occupancy clearance. Contractors must schedule these inspections through the DBI portal, providing minimum 48-hour advance notice for each required assessment.

Common Adu Permit Mistakes in San Francisco

One of the most common mistakes homeowners make when pursuing an Adu permit in San Francisco is underestimating the complexity of the process. Many fail to account for the lengthy timeline, which can stretch 6-12 months from initial application to final permit issuance. Another pitfall is not budgeting for the various fees, which can add up quickly - the base permit alone costs $833 in San Francisco. Homeowners also often overlook the strict zoning and building code requirements, leading to delays or even permit denials. To avoid these issues, it's crucial to work closely with the Department of Building Inspection (DBI) and hire experienced architects or contractors who understand the unique challenges of Adu projects in the city.

Sample Adu Permit Cost Calculation

Let's look at a typical Adu project in San Francisco to estimate the total permit costs. Assume a 1,500 square foot home with an 800 square foot Adu addition. The base permit fee would be $833, plus $7 per square foot for the first 80 square feet of additional street space ($560) and $18 per square foot for any additional space ($12,960), totaling $14,353. The building permit fee would be $6,391, based on the $100,000 construction valuation. Other required fees include $10,855 for a Community Plan Evaluation, $2,317 for a Demolition Permit, and $98 for a Medium-sized Excavation Inspection. Add in a $366 Permit Revision fee and the total could reach over $34,000 just in permit costs for this 800 square foot Adu in San Francisco.

How San Francisco Compares to Other California Cities

Compared to other major California cities, San Francisco's Adu permit process is more complex and costly. In Los Angeles, the base permit fee is only $368, significantly lower than San Francisco's $833. The timeline is also typically faster in LA, with permits issued in 3-6 months versus 6-12 months in San Francisco. San Diego has a more streamlined online portal for Adu applications, while San Francisco still relies on a paper-based system. However, San Francisco does offer more flexibility, allowing Adu's up to 1,000 square feet, compared to LA's 850 square foot limit. Overall, San Francisco's stringent requirements and higher fees create more barriers for homeowners looking to add an Adu, though the city aims to balance housing needs with safety and zoning concerns.

Recent Adu Permit Changes in San Francisco

In 2024, the San Francisco Department of Building Inspection (DBI) launched a new online portal for Adu permit applications, streamlining the previously paper-based process. This change has reduced processing times and improved transparency for homeowners. Additionally, the city updated its building code in 2025 to align with the latest California Title 24 energy efficiency standards, requiring Adu's to meet stricter insulation, ventilation, and renewable energy requirements. While these updates add more complexity, they also ensure new Adu's meet modern sustainability goals. Finally, DBI is currently evaluating fee structures, with the potential to adjust Adu permit costs in 2026 to better reflect the city's actual administrative and review expenses. Homeowners should check the DBI website for the most up-to-date information on Adu permit requirements and fees.

Tips for Faster Approval in San Francisco

San Francisco's complex permitting landscape demands meticulous preparation. Successful applicants invest time in comprehensive initial documentation, ensuring all submitted materials precisely match DBI requirements. Professional architectural drawings that clearly demonstrate code compliance can significantly expedite the review process.

Engaging a permit expediter familiar with San Francisco's specific regulations can reduce potential delays. These specialists understand DBI's nuanced requirements and can help identify and resolve potential issues before formal submission.

Frequently asked questions about San Francisco adu permits

Related Permits in San Francisco