Two Detached ADUs in San Ramon (AB 956, 2027)
Plan Two ADUs in San Ramon: Free Site Assessment
San Ramon ADU rules today (2026)
From January 1, 2027, state law (AB 956) requires the City of San Ramon to approve up to two detached ADUs on a lot with a single-family home. San Ramon already offers nine free permit-ready ADU plans, all one-bedroom units under 800 sq ft, which makes it one of the easier places in the valley to plan a two-unit project.
- Code: San Ramon Zoning Ordinance § D4-39, explained in the city’s ADU Handout dated December 2024.
- Units allowed now: the handout lists one ADU (detached or attached) plus one JADU on a single-family lot. State law also allows a converted ADU with a detached ADU and a JADU.
- Detached ADU size: 150 to 850 sq ft for a studio or one bedroom, and up to 1,200 sq ft with more than one bedroom. JADUs are 150 to 500 sq ft.
- Height: 16 ft for a detached ADU (18 ft on a lot with a multistory multifamily building). Attached ADUs: the lower of 25 ft or the zoning limit.
- Setbacks: 4 ft side and rear and a 20 ft front setback. An ADU of up to 800 sq ft, 16 ft high, with 4 ft side and rear setbacks qualifies under the state-exempt path; planning staff decide eligibility.
- Parking: one space, exempt within half a mile of transit, including a bus stop.
- Permit-ready plans: nine city plans (three floor plans in Craftsman, Mediterranean and Suburban Ranch styles), all 1 bed / 1 bath and 560 to 708 sq ft. They cannot be revised.
State review of San Ramon's ADU rules
On February 24, 2023, the state housing department (HCD) found 12 problems with the version of the ordinance it reviewed (Ordinance No. 496). They included limits on unit combinations, setbacks and heights stricter than state law, and subjective design standards. Where local rules are stricter than state law, state law applies.
Recent Axiom work
Professional photos from a recent Axiom Renovation full remodel and addition in Los Gatos.
What changes on January 1, 2027
AB 956 raises the number of detached, new-construction ADUs the city must approve from one to two. The city may cap each at 800 sq ft of living space and apply height limits; side and rear setbacks can be no more than 4 ft. Where two are built, the city need not approve a JADU. HOA protections also apply.
San Ramon’s handout allows only one ADU plus a JADU on a single-family lot today, so AB 956 is a large step for San Ramon owners. All nine permit-ready plans are under 800 sq ft and fit the new size cap, and the city’s 16 ft detached height already matches the state limit. The city will need to update its ADU ordinance, and we confirm the current rules with planning staff as it does.
Planning two detached ADUs on a San Ramon lot
- Easements: detached ADUs in the permit-ready programs may not sit in any easement. Units over or near an easement go to the city’s engineering staff.
- Fire: San Ramon Valley Fire Protection District requires sprinklers in an ADU only if the main house is sprinklered, and does the final inspection.
- Sewer: Central San lists San Ramon as a service community. Two units need a sewer layout that works for both, and approval from your water provider.
- Electrical: two new units usually call for a load calculation and often a service upgrade.
Building ADUs in San Ramon with Axiom
Axiom Renovation designs, permits and builds ADUs. For two units we start with a site study of fit, utilities and review path. See our San Ramon ADU builder page, our San Ramon service area page, the AB 956 overview, and guides for nearby Danville and Dublin.
Process
Our ADU Process
Step 1
Initial Consultation
We begin with a thorough initial consultation to understand your needs, assess your space, and discuss your vision, budget, and timeline.
Step 2
Planning and Design
At Axiom Renovation, we understand that the planning and design phase of an ADU project is crucial to its success. Our dedicated project managers will work closely with you to understand your goals, design ideas and budget for the project.
Step 3
Material Selection
We guide you through selecting high-quality materials that fit your design and budget, ensuring durability and aesthetic appeal.
Step 4
Demolition and Preparation
Careful demolition and preparation work are performed to ready the space for construction, minimizing disruptions and ensuring a clean work environment.
Step 5
Construction and Installation
Our skilled craftsmen handle the construction phase, including obtaining permits, scheduling appointments, and the actual construction and installation with precision, building the new space according to the approved design.
Step 6
Electrical and Plumbing Work
Licensed professionals conduct all electrical and plumbing work, ensuring everything is up to code and seamlessly integrated into the new ADU.
Step 7
Painting and Finishing
We pay close attention to detail during the painting and finishing stage, ensuring all surfaces are properly prepared and beautifully finished.
Step 8
Fixture and Appliance Installation
We expertly install all fixtures and appliances, ensuring they function correctly and fit perfectly with the overall design.
Step 9
Final Touches and Clean-Up
Final touches are added, and a thorough clean-up is performed, leaving your new space pristine and ready for use.
Step 10
Final Walkthrough and Client Satisfaction
We conduct a final walkthrough with you to ensure every detail meets your expectations and address any remaining concerns, ensuring your complete satisfaction.
San Ramon Two-ADU FAQ
Can I build two detached ADUs in San Ramon?
From January 1, 2027, AB 956 requires the city to approve up to two detached, new-construction ADUs on a lot with a single-family home, if the project meets objective standards. Until then, the city handout lists one ADU plus one JADU.
How large can each ADU be in San Ramon?
Today a detached ADU can be 150 to 850 sq ft with one bedroom or up to 1,200 sq ft with more. Under AB 956, the city may limit each of two detached ADUs to 800 sq ft of living space.
How tall can a detached ADU be in San Ramon?
16 ft, or 18 ft on a lot with a multistory multifamily building. San Ramon does not state a two-story allowance for detached ADUs.
Does San Ramon have pre-approved ADU plans?
Yes. The city offers nine permit-ready plans, all one bedroom and one bath, from 560 to 708 sq ft. They cannot be changed, and you still need fire district and utility approvals.
Do San Ramon ADUs need fire sprinklers?
Only if the main house is sprinklered. San Ramon Valley Fire Protection District follows that rule and does the final inspection on ADUs.
Who builds two-ADU projects in San Ramon?
Axiom Renovation designs, permits and builds ADUs in San Ramon and is planning two-unit projects for 2027. Call 408-702-2022, Monday to Friday, 9 am to 5 pm.
Sources: AB 956 (Quirk-Silva), signed September 29, 2026, effective January 1, 2027, as summarized by Brownstein Hyatt Farber Schreck and California YIMBY. This page is general information, not legal advice. Local rules change; we confirm current requirements with the city for every project.