What state law standardised

Ministerial approval for qualifying units, limits on how much parking a city can require, protection for conversions of existing space, and time limits on how long a city may take to act on a complete application. These are real protections and they apply everywhere.

What still varies, city by city

The remaining variation is where projects actually get slow or expensive.

• Coastal review. In Venice, parts of Santa Monica, Newport Beach, Seal Beach, Huntington Beach and Malibu, a coastal development permit can be a longer process than the building permit itself.
• Objective design standards. Santa Monica and Culver City publish detailed standards for massing, materials and openings. Designing against them from the start is faster than adjusting later.
• Preapproved plan programmes. Several cities maintain preapproved ADU plans that skip most of the design review step. Where the geometry fits, this is the fastest route in existence.
• Fees. School, water capacity and sewer charges differ by tens of thousands of dollars between adjacent jurisdictions, and the district, not the city, is often what determines them.
• Plan check culture. Some departments issue one thorough correction letter. Others issue three shorter ones. That difference alone can be two months.

How to find your own answer quickly

Confirm three things before spending money on design: which department reviews your address, whether you are in the coastal zone or another overlay, and whether your city has a preapproved plan programme your lot can use. Those three answers narrow the schedule and the budget more than any other early research.