California has passed some of the most homeowner-friendly ADU legislation in the country over the past five years. If you own a single-family home in the Bay Area, you almost certainly have the right to build an ADU — and the process is simpler than you might think.
What Changed in California ADU Law
Between 2017 and 2024, California passed a series of laws (AB 68, AB 881, SB 13, AB 3182, AB 2221, SB 897, and more) that dramatically streamlined ADU approval. The key changes:
- Ministerial approval: Cities must approve ADUs that meet objective standards — no discretionary review, no neighborhood hearings.
- 60-day approval deadline: Cities must approve or deny ADU applications within 60 days.
- Reduced setbacks: Detached ADUs need only 4-foot side and rear setbacks in most cases.
- No owner-occupancy requirement: As of 2020, California removed the requirement that the property owner live on-site.
- Junior ADUs (JADUs): Up to 500 sqft within the existing home footprint, with minimal permit requirements.
- Garage conversions: Converting an existing garage to an ADU is now streamlined and does not require replacement parking in most cases.
ADU Rules by Bay Area City
While state law sets the floor, each Bay Area city has its own ADU standards for size, height, setbacks, and design. Here's a quick overview of the key cities where Homee Renovation works:
| City | Max ADU Size | Max Height | Setbacks |
|---|---|---|---|
| San Francisco | 1,200 sqft | 25 ft | 4 ft side/rear |
| San Mateo | 1,200 sqft | 16 ft (detached) | 4 ft side/rear |
| Los Gatos | 1,200 sqft | 16 ft | 4 ft side/rear |
| Cupertino | 1,200 sqft | 16 ft | 4 ft side/rear |
| Palo Alto | 1,200 sqft | 16 ft | 4 ft side/rear |
How Much Does an ADU Cost in the Bay Area?
ADU construction costs in the Bay Area typically range from $300–$600 per square foot, depending on the type of ADU, finish level, and site conditions. Here's a rough breakdown:
- Garage conversion: $100,000–$250,000 (lowest cost, existing structure)
- Attached ADU (addition): $200,000–$400,000
- Detached ADU (new construction): $300,000–$700,000+
Homee Renovation clients save an average of 30% on ADU materials — cabinets, fixtures, flooring, windows, and finishes — through our wholesale dealer relationships. This can represent $50,000–$150,000 in savings on a full detached ADU.
What is the ROI of Building an ADU in the Bay Area?
Bay Area ADUs are among the best real estate investments available to homeowners:
- Rental income: $3,000–$6,000/month for a well-located Bay Area ADU
- Property value increase: $400,000–$800,000+ added to property value
- Payback period: Typically 5–10 years on construction cost
Homee Renovation's ADU at 33 W Bellevue Avenue in San Mateo — a 2,194 sqft detached ADU — is a prime example of what's possible. The project added significant rental income potential and resale value to the property.
How to Get Started with an ADU in the Bay Area
The first step is a feasibility assessment — understanding what you can build on your specific property given your city's zoning, setbacks, and lot coverage rules. Homee Renovation offers free ADU feasibility assessments for Bay Area homeowners.
From there, we handle the full process: design, structural engineering, permit application, plan check coordination, construction, and final inspection. One team, one contract, one point of contact.
Ready to Build an ADU?
Get a free ADU feasibility assessment and estimate from Homee Renovation. We serve San Francisco, San Mateo, Los Gatos, Cupertino, Palo Alto, and the entire Bay Area.
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