By California Construction & Remodeling Experts | February 2026 Three Cities, Three Sets of Rules, One Very Confused Homeowner If you own property in the greater Los Angeles area and you're thinking about building an Accessory Dwelling Unit, you've probably already Googled "ADU rules California" and found pages of state-level information. State law says you can build up to 1,200 square feet. State law says the city must approve your permit within 60 days. State law says no ow