California ADU Laws in 2026: What You Can Build
Carlos Moreno, Assoc. AIA
Founder, KĒĒP
Published August 20, 2026 · Updated August 24, 2026 · 7 min read
The short answer
California law makes ADUs broadly permissible on most single-family and multifamily lots. The state guarantees at least an 800-square-foot ADU at 16 feet of height regardless of local rules, requires cities to approve complete, compliant applications within 60 days, and removes added-parking requirements near transit. Cities can set objective standards, but cannot ban ADUs.
What the state guarantees
Over the past several years California has passed a series of laws specifically to remove local barriers to ADUs. The throughline: cities must treat a compliant ADU application ministerially — approving it against objective standards, without the discretionary hearings that can stall a project for months.
Key protections that apply statewide:
- A minimum ADU of 800 square feet and 16 feet in height must be allowed, even where local rules are stricter.
- Cities must act on a complete application within 60 days.
- No additional parking may be required within a half-mile of public transit.
- Owner-occupancy of the main house cannot be required for new ADUs through the current statutory window.
Not sure what your lot allows? Get a free feasibility report.
Get a free feasibility reportWhat cities can still control
State law sets the floor, not every detail. Cities retain the ability to set objective standards — specific setback distances, height within the state ceiling, and design criteria — as long as they don't effectively prohibit the ADU.
That's why two neighboring cities can feel different to build in. One may permit in four months with predictable standards; another may run six or seven with more review. It's also why a feasibility assessment matters: it reads both the state rules and your specific city's objective standards against your actual lot, so you know what you can build before you spend on design.
Laws change, and interpretations vary by jurisdiction. Confirm current rules with your city's planning department, or let KÄ’Ä’P handle that step in the feasibility report.
Common questions
Most single-family and multifamily lots qualify under state law, which was written to make ADUs broadly permissible. Setbacks, lot coverage, and utility access still determine what physically fits. A feasibility assessment confirms your specific lot.