Pittsburg, CA Accessory Structures: Garage Conversions (2026)

Under PMC Chapter 18.50 and Schedule 18.50.315, an attached or detached garage may be converted to an ADU or JADU in the R-1, R-2, R-3, and R-4 residential zones, consistent with state ADU law. Conversion ADUs preserve the existing garage's footprint and setbacks (height limits do not apply to conversions of existing spaces). Any new square footage added beyond the original walls must meet the 4-foot rear/side setback for new construction. The maximum allowable ADU floor area on a single-family property is 800 sq ft (with a 150 sq ft minimum), though state law requires the City to allow up to 1,200 sq ft for a detached ADU with 2+ bedrooms. JADUs in attached garages are capped at 500 sq ft within the walls of the primary dwelling and require owner-occupancy of one unit. Per state law and PMC §18.50, no replacement parking is required when a garage, carport, or covered parking structure is converted or demolished to construct an ADU. Building permits are issued by Pittsburg Building Division on a 60-day ministerial timeline.