Port Costa Home Business: Signage Rules Rules (2026)

Chapter 82-4 of the Contra Costa County Ordinance Code prohibits any display of advertising or signs on the property to indicate from the exterior that the residence is being used for anything other than a dwelling. This means no yard signs, no window signs, no magnetic door signs on a commercial vehicle parked at home, no banners, no posted price lists, and no lighted displays associated with the business. The vehicle-sign prohibition extends to commercial vehicles with body-mounted advertising parked visibly at the home; owners may keep a personal van with magnetic signs if removed when parked. The county sign ordinance (Chapter 88-6) also separately limits sign size, height, and illumination in residential zones. Violations are cited by code enforcement through the Department of Conservation and Development. Typical enforcement is complaint-driven: a first notice gives 10 to 14 days to remove the sign; continued violation can lead to administrative citations of $100 first, $200 second, and $500 third and subsequent (under Chapter 14-12). Internet listings, business cards, and remote advertising (websites, social media, ads) are not restricted—only physical signs on the premises.