Napa County, CA Home Business: Zoning Restrictions (2026)

Section 18.104.090 of Napa County's Title 18 zoning code sets the operational and dimensional rules for home occupations in residential zoning districts. The threshold step is permitting: no home occupation is allowed unless an administrative permit has first been issued. Administrative permits in Napa County are processed through the Planning, Building and Environmental Services Department under Chapter 18.124 (Use Permits) and its administrative-permit subprocess; the applicant must submit a floor plan of the entire dwelling showing the area proposed for the home occupation. Standards under Section 18.104.090 include: (1) only persons who are regular residents on the premises may engage in the occupation - employees who do not live there are not allowed; (2) the use must be clearly incidental and subordinate to the residential use, with no more than 25% of the gross floor area of the dwelling devoted to the home occupation; (3) there must be no change in the outside appearance of the building or premises and no other visible evidence of the home occupation (no exterior signage, no commercial-grade lighting, no storefront treatment); (4) the home occupation may not be conducted in any accessory building (no detached studio, garage workshop, or barn as the primary site); (5) traffic generated must not exceed volumes normally expected in a residential neighborhood, and any parking generated must be met off the street and not in the required front yard; and (6) no equipment or process may be used that creates noise, vibration, glare, fumes, odors, or electrical interference detectable off the lot to the normal senses. Common uses approved as home occupations include consulting, professional services, online retail with no on-site customer pickup, telehealth, instruction with a small number of students by appointment, and similar quiet professional or creative work. Uses that generate retail walk-in traffic, deliveries by commercial truck, hazardous materials, mechanical repair, or amplified sound are generally not eligible. The county also separately prohibits short-term rentals of dwelling units under Section 18.104.410, so an STR cannot be approved as a 'home occupation.'