Accessory Structures in San Marcos, CA (2026)
5 verified accessory structures rules for San Marcos, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
San Marcos allows one ADU plus one JADU per single-family lot per SMMC Chapter 20.410.060. One-bedroom ADUs up to 850 sq ft, two-bedroom up to 1,000 sq ft. ADUs generally cannot be in the front yard. A soils report is required over 500 sq ft.
San Marcos ADU Rules
Some RestrictionsShed Rules
San Marcos exempts detached sheds under 120 square feet from building permits. Sheds must comply with zoning setbacks. Larger accessory buildings require permits and must meet building code standards.
San Marcos Shed & Accessory Building Rules
Few RestrictionsGarage Conversions
San Marcos allows garage conversions to ADUs per CA Gov Code Section 65852.2. Replacement parking is not required. Parking may be located in setbacks and driveways as tandem parking. Building permits required.
San Marcos Garage Conversion Rules
Some RestrictionsCarport Rules
Carports in San Marcos require building permits and must comply with SMMC Title 20 zoning setbacks. Carport area counts toward maximum lot coverage for the applicable zone district.
San Marcos Carport Permit & Setback Rules
Some RestrictionsTiny Homes
San Marcos permits tiny homes on permanent foundations as ADUs under California ADU law (Government Code 65852.2). Tiny homes on wheels are not recognized as permanent dwellings under SMMC.
San Marcos Tiny Home & Movable Tiny House Rules
Some RestrictionsLooking for San Diego County county-wide rules?
County ordinances apply to unincorporated areas and may supplement San Marcos city rules.
Accessory Structures in San Diego County →