Two Detached ADUs in Lafayette (AB 956, 2027)
Plan Two ADUs in Lafayette: Free Site Assessment
Lafayette ADU rules today (2026)
From January 1, 2027, state law (AB 956) requires the City of Lafayette to approve up to two detached ADUs on a lot with a single-family home. Lafayette’s Class A ADU, a detached unit of 800 sq ft or less approved with a building permit alone, already matches the size the new law lets cities set.
- Code: Lafayette Municipal Code §§ 6-563 and 6-566, updated by Ordinance 695 (adopted December 9, 2024).
- Class A: one detached new-construction ADU of 800 sq ft or less, 16 ft or lower, with 4 ft side and rear setbacks, plus a JADU. Building permit only.
- Class B: conversions of the house or an accessory structure and a JADU. Building permit only.
- Class C: everything else, with an ADU Permit and a building permit. Attached or detached ADUs up to 1,200 sq ft; attached ADUs limited to 50% of the main home. Height 17 ft, or 18 ft within half a mile of transit.
- Setbacks (Class C): 4 ft side and rear; front setbacks by zoning district.
- Parking (Class C): one space for an ADU with a bedroom, unless exempt.
- Process: all classes are ministerial with no hearing. Staff review plans within 30 days and the Zoning Administrator decides within 60 days. Contra Costa County issues the building permit.
- Plans: the county Pre-Approved ADU program, plus the Lamorinda pre-approved ADU prototypes now in draft.
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.
Lafayette allows one detached new-construction ADU today. A second detached unit sized like a Class A ADU (800 sq ft, 16 ft, 4 ft setbacks) fits the new law closely. The four draft Lamorinda prototypes, from 495 to 796 sq ft, are all under 800 sq ft. Lafayette will need to update its ordinance, and we confirm how the two-unit option fits its ADU classes as the city adopts changes.
Recent Axiom work
Professional photos from a recent Axiom Renovation full remodel and addition in Los Gatos.
Planning two detached ADUs on a Lafayette lot
- Trees: trees of 12 inches or more, including coast live, valley and blue oaks, must be mapped. A tree removed for an ADU must be replaced on site with a 15-gallon tree of the same species.
- Hillsides: site plans must show Class I, II and III ridgelines and 2 ft topography. ADUs do not need the Hillside Development Permit that other construction in the overlay needs.
- Fire: Much of Lafayette is in High fire hazard areas on 2025 state maps. An ADU needs sprinklers only if the main house has them, and it does not trigger sprinklers in the existing home.
- Septic: lots on septic need a percolation test from the last five years (ten if recertified). Elsewhere, Central San serves Lafayette for sewer.
- Utilities: two units usually need a load calculation and often an electrical service upgrade, plus sign-off from your water provider.
Building ADUs in Lafayette 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 Lafayette ADU builder page, our Lafayette service area page, the AB 956 overview, and guides for nearby Moraga and 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.
Lafayette Two-ADU FAQ
Can I build two detached ADUs in Lafayette?
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. Today Lafayette allows one detached new-construction ADU.
How large can each ADU be in Lafayette?
Today a Class A detached ADU is up to 800 sq ft, and a Class C ADU can reach 1,200 sq ft. 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 Lafayette?
A Class A ADU is limited to 16 ft. A Class C ADU can be 17 ft, or 18 ft within half a mile of transit.
How long does ADU approval take in Lafayette?
Staff review plans within 30 days, and the Zoning Administrator decides within 60 days of a complete application. Contra Costa County then issues the building permit.
Are there pre-approved ADU plans for Lafayette?
Yes. The county Pre-Approved ADU program covers Lafayette, and four Lamorinda prototype plans from 495 to 796 sq ft are in draft for Lafayette, Moraga and Orinda.
Who builds two-ADU projects in Lafayette?
Axiom Renovation designs, permits and builds ADUs in Lafayette 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.