Two Detached ADUs on One Lot: AB 956 Explained
Plan Two ADUs on Your Lot: Free Site Assessment
What AB 956 allows
Starting January 1, 2027, California law lets homeowners build two detached ADUs on a lot with a single-family home. Today the limit is one detached ADU. AB 956 was signed on September 29, 2026, and Axiom Renovation is already helping Bay Area owners plan for it.
- Up to two detached, new-construction ADUs on a lot with an existing or proposed single-family home, in residential and mixed-use zones.
- Ministerial approval: cities must approve a compliant application without a public hearing.
- Size: a city may limit each of the two ADUs to 800 square feet of living space and may apply its height limits.
- Setbacks: side and rear setbacks can be no more than 4 feet.
- JADU trade-off: if two detached ADUs are built, the city no longer has to also approve a junior ADU (JADU) on that lot.
- HOAs: the law widens the ban on HOA rules and deed restrictions that block or unreasonably restrict ADUs.
What is not settled yet
The law takes effect January 1, 2027. Until then, current rules apply: one detached ADU plus one JADU on most single-family lots. Cities will need to update their ADU ordinances, forms and plan-check checklists, and some will move faster than others. Each lot still has to meet fire access, utility, tree, slope, septic or sewer and building code requirements, so not every property can fit two detached units.
Recent Axiom work
Professional photos from a recent Axiom Renovation full remodel and addition in Los Gatos.
How we plan two ADUs on your lot
- Site assessment: we check setbacks, trees, slope, access, sewer or septic, water and fire-flow, and whether your electrical service can support two more units.
- Layout options: we show where two detached units fit, how they share utilities, and what each can be sized at under your city’s rules.
- Design and permits: we prepare plans to your city’s current standards and track its AB 956 updates, so your application is ready.
- Construction: one licensed general contractor (CA Lic. #1105006) builds both units, including utility upgrades and the final inspection.
Two detached ADUs: city guides
Rules on size, height, trees, fire and utilities still come from your city. Each guide below covers that city’s current ADU rules and what AB 956 changes there:
Peninsula: San Bruno · Millbrae · Burlingame · Hillsborough · San Mateo · Belmont · San Carlos · Redwood City · Atherton · Menlo Park
Silicon Valley: Palo Alto · Los Altos · Los Altos Hills · Mountain View · Sunnyvale · Cupertino · Saratoga · Los Gatos · Campbell · Santa Clara · San Jose · Milpitas
South County: Morgan Hill · San Martin · Gilroy
East Bay and Tri-Valley: Fremont · Newark · Union City · Hayward · Castro Valley · Dublin · Pleasanton · Livermore
Contra Costa: San Ramon · Danville · Alamo · Walnut Creek · Lafayette · Moraga · Orinda
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.
Two Detached ADUs: FAQ
When can I build two detached ADUs in California?
AB 956 takes effect January 1, 2027. Before that date, most single-family lots are limited to one detached ADU plus one junior ADU. You can plan and design now so your project is ready when cities begin accepting applications under the new law.
How big can each ADU be under AB 956?
The law lets a city limit each of the two detached ADUs to 800 square feet of living space and apply its height limits. Some cities allow larger ADUs under their own ordinance.
Can I still build a junior ADU if I build two detached ADUs?
If two detached ADUs are built on the lot, the city is no longer required to also approve a JADU. A city may still choose to allow one.
Can my HOA stop me from building two ADUs?
AB 956 widens the existing ban on HOA rules and deed restrictions that prohibit or unreasonably restrict ADUs and JADUs, including on lots zoned to allow single-family use.
Does every lot qualify for two detached ADUs?
No. Each unit still has to meet setbacks, fire access and fire-flow, utility, tree, slope and building code requirements. A site assessment shows what fits on your property.
Does Axiom build two-ADU projects?
Yes. We design, permit and build detached ADUs across the Bay Area and can plan two units on one lot, including the electrical, sewer and water work they need. 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.