San Ramon ADU Zoning and Building Standards

With recent changes to California’s ADU policies, San Ramon offers a great opportunity for ADU construction, potentially adding value to your property. However, it’s important to understand the specific regulations governing accessory dwelling units in San Ramon before starting your project.

The zoning and building standards in San Ramon were designed to meet the community’s unique needs, ensuring your ADU blends well with the neighborhood. This section provides a comprehensive guide to help you navigate these local regulations.

San Ramon ADU Zoning and Building Standards

Property Requirements

Building Size

  • Single Family Zone Lots: You can build one detached ADU up to 850 sq. ft. for one bedroom or 1,000 sq. ft. for two or more. Think cozy guest suites or spacious family retreats. You can add one “Junior ADU” (think converted garage or basement) up to 500 sq. ft. for a bonus workspace or studio.
  • Duplex Zone Lots: You can build two detached ADUs on duplex lots, each following the same size limits as in the Single-Family Zone. Think rental income potential or convenient multi-generational living.
  • Multi Family Zone Lots: Multi-family lots offer more flexibility. The total ADU floor area can be at most 25% of the existing square footage of all the buildings on the property. So, if you have a big apartment complex, you have more room to play with different ADU sizes and configurations.


In San Ramon, owner-occupancy is not required for ADUs built between January 2020 and January 2025, offering flexibility for rentals. However, after January 2025, living in your ADU for some period will become mandatory, so plan accordingly.

Number of Units Allowed

Single-family lots in San Ramon can have one detached ADU and one “Junior ADU.” In contrast, duplex lots can have two detached ADUs, maximizing the potential for additional living space or rental income.

San Ramon Building Height

  • Single-Family: Your detached ADU can stretch up to 16 feet tall, like a two-story cottage with plenty of headroom.
  • Duplex Family: Also allow for a 16-foot height limit for each detached ADU.
  • Multi-Family: In this zone, the height regulations are slightly more flexible. While there’s no specific limit, the ADU’s height can’t exceed the existing buildings on the property.

San Ramon Building Size

  • Single-Family: You can build one detached ADU, ranging from 850 sq. ft. for a cozy one-bedroom haven to 1,000 sq. ft. for a spacious family retreat. Bonus: Add a “Junior ADU” (like a converted garage) up to 500 sq. ft. for a dedicated workspace or studio.
  • Duplex Family: Duplex lots allow two detached ADUs, each following the Single-Family size limits. Think rental potential or convenient multi-generational living.
  • Multi-Family: Your total ADU floor area can be at most 25% of the property’s existing buildings’ square footage. So, imagine a bigger playground for ADU configurations depending on your complex’s size.

Fire Safety Regulations

All units require smoke detectors, fire extinguishers, and sprinkler systems meeting specific standards. Ensure your dream ADU complies by consulting the San Ramon Valley Fire Protection District guidelines.


Detached and attached ADUs typically need one parking space unless exempted by being close to public transit or part of an existing structure. Smaller ADUs, like conversion ADUs and junior ADUs, usually don’t require dedicated parking.

Utility Connections

In San Ramon, connecting your ADU to the utility grid involves splitting lines from your existing home for water, sewer, and gas. While you won’t need separate meters for small ADUs, you may need them for larger units.


San Ramon sets minimum distances for your ADU: 4 feet from side and rear property lines for most, with 20 feet from the front for detached units. Think buffer zones for privacy and ensuring harmony with your neighbors’ space.

Zoning Regulations

San Ramon ADU Zoning Regulations

Single Family

Offer spacious canvases for detached ADUs (up to 1,000 sq ft) and cozy havens in “Junior ADUs” (500 sq ft). Think family retreats, rental income, or dedicated workspaces within your backyard.

Duplex Family

Build two detached units, each mirroring the Single-Family zone’s size limits (850 sq. ft. for one bedroom, 1,000 sq. ft. for two or more).


The total floor area can be less than 25% of existing buildings, so consider flexible configurations. Imagine spacious studios or charming one-bedrooms, all adding to the vibrant apartment life.

RF Zone Minimum Lot Area in San Ramon

  • Single-family: 5,000 sq. ft. – spacious comfort for your family.
  • Two-family: 7,500 sq. ft. – ideal for duplex living or rental possibilities.
  • Three-family: 10,000 sq. ft. – perfect for multi-generational living or larger rentals.
  • Four-family: 12,500 sq. ft. – spacious option for larger families or multiple rental units.
  • Five+ family: 15,000 sq. ft. – ample space for extended families or co-living arrangements.

Room Specifications

San Ramon ADU Room Specifications

Room TypeSpecifications
Bathroom– Minimum size: 50 sq. ft. (including toilet, sink, and shower/tub)

– Shower or tub required, whirlpool tubs not allowed – Grab bars and towel bars required

– Ventilation required

Kitchen– Minimum size: 40 sq. ft. (including sink, countertop, and cooking space)

– Refrigerator, range, and sink required

– Adequate countertop space and storage  -Ventilation required

Sleeping Areas– Minimum floor area per occupant: 70 sq. ft.

– Minimum ceiling height: 7 ft.

– Natural light and ventilation encouraged

– Adequate closet space (minimum 10 sq. ft.)

– Smoke detectors are required in each bedroom

Storage– Built-in or designated storage space required for each room

– Minimum 5% of ADU floor area dedicated to storage

– Consider maximizing vertical space with shelves and cabinets

Location Requirements

  • Detached ADU: Build a separate unit, up to 850 sq. ft. for one bedroom or 1,000 sq. ft. for two, perfect for guests, rentals, or independent living. Think privacy, flexibility, and potential rental income.
  • Attached ADU: Add an attached unit, respecting the main building’s height, for extra bedrooms, a dedicated workspace, or even an entertainment haven. Think convenience, shared amenities, and potential for increased overall property value.
  • Junior ADU: Convert a garage, attic, or basement into a cozy haven under 500 sq. ft. Think home office, studio apartment, or guest room. Compact and efficient, JADUs offer added functionality without major construction.

Rental Requirements

  • Owner-occupancy: Not required between January 2020 and January 2025, but mandatory after that.
  • Permits: Obtain all necessary permits from the City of San Ramon, including building, electrical, and plumbing permits.
  • Zoning: Ensure your ADU complies with zoning regulations for your specific lot (Single-Family, Duplex, Multi-Family).
  • Size: Detached ADUs can be up to 850 sq. ft. for one bedroom or 1,000 sq. ft. for two or more. Attached ADUs can be larger but must not exceed the height of the main structure.
  • Utilities: Split lines from your existing home for water, sewer, and gas. Consult with utility providers for connection fees and potential meter requirements.
  • Parking: One parking space is generally required for detached and attached ADUs, unless within walking distance of public transit or part of an existing structure. Smaller ADUs (conversion or junior) may not require dedicated parking.
  • Fire Safety: Install smoke detectors, fire extinguishers, and sprinkler systems meeting San Ramon Valley Fire Protection District standards.
  • Health and Safety: Ensure the ADU meets all building codes and health and safety regulations, including ventilation, electrical safety, and accessibility.
  • Business License: If you intend to operate your ADU as a short-term rental (less than 30 days), you will need a business license from the City of San Ramon. Fees vary depending on the length of stay and number of occupants.

Development Standards for San Ramon ADU

ADU TypesDevelopment Standards Specifications
Single-family – Max size: 850 sq. ft. (1 bedroom) or 1,000 sq. ft. (2+ bedrooms)

– 4 ft. setbacks from side & rear property lines, 20 ft. from front (detached)

– Must comply with Single-Family Zone regulations

Duplex– Two detached units, each following Single-family size and setback requirements

– Shared driveway and utilities possible

Multi-family– Floor area can’t exceed 25% of existing buildings on site

– Height restrictions based on existing structures

– Specific regulations for each multi-family subzone

Junior ADUs (JADUs)– Max size: 500 sq. ft.

– Often exempt from dedicated parking – Conversion ADUs (garages, attics) common

San Ramon Property Designations for ADU

  • Flood Zones: Check FEMA flood maps to know your risk of being in a flood zone. Building in this area may require special permits and techniques. Consider an elevated foundation for your ADU to protect it from potential flooding.
  • Geohazard Zones: San Ramon has areas prone to landslides and other geohazards. Consult a qualified geotechnical engineer to assess your site’s stability before construction.
  • Easements: Underground utility lines on your property may restrict construction in certain areas. Check with local utility providers for easement maps, as public access easements could impact where you can build, including ADU placement.

ADU Permit Requirements and Fees

Elegant ADU In San Ramon

  • Building permit: This applies to all ADU construction, including detached, attached, and conversions. Costs vary based on size and complexity but expect $1,000-$5,000+.
  • Electrical and plumbing permits: Ensures safe installations. Fees typically range from $50-$200 each.
  • Fire sprinkler permit: Most ADUs require fees depending on size and system complexity (usually $500-$1,500+).
  • Plan review fees: The city reviews your ADU plans for compliance, with fees starting around $500.
  • Impact fees: May apply to offset infrastructure costs, ranging from $0-$10,000+ depending on ADU size and location.

Design Your Dream ADU Today!

Designing and building your dream Accessory Dwelling Unit (ADU) requires creativity and vision amid city regulations and permit requirements. Whether for family, work, or rental, the potential is limitless. Contact our expert team at +1-669-293-1126 for seamless guidance in making your dream ADU a reality. The journey begins with a single step. Take it today!



San Ramon allows home-based childcare in ADUs, but specific regulations apply regarding the number of children, play areas, and licensing requirements.

San Ramon welcomes furry friends! Ensure your ADU has adequate designated outdoor space and proper waste disposal facilities, and consider soundproofing if pets might bark or meow frequently.

Adding an ADU may boost property value and increase property taxes. San Ramon provides programs to lessen the impact, so consult the assessor's office for details.