South San Francisco, CA Accessory Structures: Carport Rules (2026)

Chapter 20.300 of the SSFMC sets development standards citywide. The minimum setback for accessory structures (including carports) is 5 feet, with one exception: detached accessory structures less than 220 square feet may be located on an interior side or rear lot line, provided the structure is built so no roof water drains onto an adjacent property and all Building Code requirements are met. No detached accessory building (inclusive of roof covering) may be closer than 6 feet to the main building. Average accessory-building height is capped at 12 feet measured between the floor slab plate and ridge pole. Combined footprint of all accessory buildings may not exceed 20 percent of the main building's footprint, or 220 square feet, whichever is greater. Chapter 20.330 (On-Site Parking and Loading), Section 20.330.004, governs required parking for single-family dwellings: at least one space per unit must be within a carport or garage. For new construction, a double-car garage must be at least 20 ft wide x 20 ft long unobstructed. Existing garages may qualify under legacy dimensions: 8.5 ft x 18 ft interior counts as one enclosed space; 17 ft x 18 ft interior counts as two enclosed spaces. Because Section 20.330.004 lists 'carport or garage' as acceptable for required parking, replacing a garage with a properly permitted carport is generally allowed (subject to setbacks, height, and lot-coverage limits) — a notable contrast with cities that require enclosed garages only. Any permanent carport requires a building permit. State law (Government Code Section 65852.2) prohibits the City from requiring replacement parking when a garage or carport is demolished or converted to build an ADU.