Accessory Structures in Walnut Creek, CA (2026)
3 verified accessory structures rules for Walnut Creek, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Walnut Creek must allow Accessory Dwelling Units (ADUs) and Junior ADUs on all residential lots under California Government Code Section 65852.2, as strengthened by AB 68, AB 881, and SB 13. Permitted detached ADUs up to 800 sq ft require 4-foot side/rear setbacks, no replacement parking within half-mile of transit, and 60-day permit processing.
Accessory Structures: Adu Permits
Few RestrictionsShed Rules
In Walnut Creek, detached storage sheds under 120 square feet and 12 feet tall are exempt from building permits under the California Building Code, but must still meet zoning setback requirements — typically 3 feet from side and rear property lines and behind the front building setback. Sheds over 120 sq ft require a building permit.
Accessory Structures: Sheds
Few RestrictionsGarage Conversions
Detached garages in Walnut Creek are regulated as accessory structures with zoning setbacks typically 3–5 feet from side/rear property lines and height limits around 15 feet. Garage conversions to living space or ADUs are expressly permitted under state law (AB 68) and the city cannot require replacement parking within half a mile of major transit.
Accessory Structures: Garage Rules
Some RestrictionsLooking for Contra Costa County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Walnut Creek city rules.
Accessory Structures in Contra Costa County →