San Mateo County, CA Home Business: Signage Rules (2026)

Signage for home-based businesses in the unincorporated County is tightly limited by the home-occupation standards in the County Zoning Regulations (historically Section 6102.46, now within the reorganized Title 8 Development Code). Per the County Planning and Building Department, in connection with each home occupation only one sign or name plate is permitted, and that sign or name plate may not exceed two (2) square feet in area. The sign may contain the name and occupation only - it cannot advertise products, prices or services beyond identifying the resident and their occupation. It must be attached flat to the dwelling (not freestanding or projecting) and shall not be illuminated. This sign rule works together with the broader home-occupation condition that no display pertaining to the occupation be visible from the street, so the overall intent is that the residential property continue to look residential. Owners should also remember that any other on-site signage may be regulated by the County's general sign provisions, and that a home occupation that requires larger or illuminated signage would generally not qualify as a permitted home occupation. These standards apply specifically in the unincorporated areas governed by the County; incorporated cities have their own sign codes.