Accessory Structures in Hercules, CA (2026)
6 verified accessory structures rules for Hercules, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Hercules ministerially approves ADU building permits within 60 days, caps detached units at 850 or 1,000 square feet by bedroom count, requires only a 4-foot side and rear setback, and limits height to 16 feet (18 feet near transit), under Section 13-35.320.
Hercules Accessory Dwelling Unit Zoning Rules
Some RestrictionsHercules Municipal Code § 13-35.320(2), (5)
Building Permit Required. The Community Development Director shall ministerially approve building permits for ADUs in compliance with this Section. No public hearing or any additional permit shall be required... Attached ADUs... If the attached ADU contains 1 bedroom, it shall not exceed 850 square feet. If the attached ADU contains more than 1 bedroom, it shall not exceed 1,000 square feet... ...
ADU Impact Fees
Hercules waives impact fees entirely for ADUs under 750 square feet or built within existing space, and prorates Master Fee Schedule charges by square footage for larger units, under Municipal Code Section 13-35.320(4)(B).
Hercules ADU Impact Fee Rules
Some RestrictionsHercules Municipal Code § 13-35.320(4)(B)
ADUs containing 750 or more square feet are subject to any fees for residential units required by the City's Master Fee Schedule as it exists at the time the ADU application is filed. Fees shall be charged in proportion to the square footage of the primary dwelling (e.g., a 1,000-square-foot ADU would be charged 50 percent of the applicable fee if the primary dwelling is 2,000 square feet)... A...
ADU Owner Occupancy
Hercules allows one junior accessory dwelling unit per single-family lot, but the property owner must live in either the JADU or the remaining part of the house. Government agencies, land trusts and housing organizations are exempt from that occupancy rule.
Hercules JADU Owner-Occupancy Requirement
Some RestrictionsHercules Municipal Code Sec. 13-35.320(11)
Junior Accessory Dwelling Units (JADUs). One JADU may be built per residential lot zoned for single-family residences with an existing or proposed single-family residence. The owner of the existing or proposed single-family residence must reside in the JADU or the remaining portion of the single-family residence unless owner is a governmental agency, land trust, or housing organization.
ADU Rental Restrictions
Hercules bars ADUs from being rented for stays under 30 days and from being sold apart from the main house. The City requires a recorded deed restriction confirming both limits before it will issue a building permit for the unit.
Hercules ADU 30-Day Rental Minimum
Some RestrictionsHercules Municipal Code Sec. 13-35.320(4)(A) and (10)(C)
A copy of a recorded deed restriction that complies with Government Code Section 27281.5, and states that the ADU will not be rented for less than 30 days and that the ADU will not be sold separately from the primary residence... ADUs constructed pursuant to this Section cannot be rented for a term less than 30 days.
Shed & Carport Rules
Hercules lets homeowners build a shed or other freestanding accessory structure without a use permit if it totals under 120 square feet, but every structure still owes a 5-foot setback from side and rear lines and a 15-foot height cap under Municipal Code Section 13-35.210.
Hercules Accessory Structure & Shed Setbacks
Some RestrictionsHercules Municipal Code § 13-35.210
A freestanding accessory structure shall be located at least 5 feet from all side and rear property lines. Structures made with wood or other combustible material (for example, decks, gazebos and similar construction) may not be located in the 5-foot setback... The maximum height of an attached accessory structure shall be as specified for the main structure, and for a freestanding accessory st...
Garage Conversions
Converting a Hercules garage into an ADU is allowed with no setback or design-review hurdles beyond fire safety, but the garage doors must be replaced with code-rated walls, windows, or doors built for habitable space.
Hercules Garage-to-ADU Conversion Rules
Some RestrictionsHercules Municipal Code Sec. 13-35.320(5)(A)(2)
ADUs Within Existing Space. An ADU within existing space and a JADU within existing space are permitted as long as the side and rear setbacks are sufficient for fire and safety... Garage spaces converted to ADUs shall replace garage doors with walls, windows, and/or doors rated by building code for habitable spaces.
Looking for Contra Costa County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Hercules city rules.
Accessory Structures in Contra Costa County →