San Luis Obispo County, CA Accessory Structures: ADU Rules (2026)

Per San Luis Obispo County Code Section 22.30.470 (Residential - Accessory Dwellings), as amended by Ordinance No. 3409 (adopted January 28, 2020), accessory dwellings are authorized under California Government Code Sections 65852.2 et seq. and are subject to ministerial review without discretionary review or public hearing. Section 22.30.470(F) governs the establishment of one ADU on a lot with an existing single-family dwelling: maximum size is 1,200 sq ft (including attics greater than six feet in height, unconditioned storage space, and lofts); minimum size is an efficiency unit as defined in California Health and Safety Code Section 17958.1. Detached ADUs must satisfy the residential accessory building setbacks of Section 22.10.140 but the minimum side and rear setbacks 'shall not exceed four (4) feet.' Attached ADUs follow the primary dwelling setbacks. No off-street parking is required for the ADU itself, and existing parking demolished or converted to create the ADU is not required to be replaced. ADUs may be rented for 30 days or more but rental for less than 30 days is prohibited. The ADU may not be sold separately from the primary dwelling. ADUs are allowed (P, permitted) in the AG, RL, RR, RS, RSF, RMF, OP, CR, and REC land use categories.