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

The County Land Use Services Department processes ADUs ministerially under Development Code Chapter 84.01 (the official March 2026 ADU handout also cites Chapter 84.36 of the County Code) together with state ADU law, Gov. Code Chapter 13, Division 1, Title 7 (Sections 66310-66342). A standard single-family lot may add up to two ADUs, plus a junior ADU; on lots of 5 acres or greater up to three units are allowed. Per the County's ADU Standards table, a detached ADU may not exceed 1,200 square feet (an attached ADU is capped at 50 percent of the existing primary dwelling, not to exceed 1,200 sq ft). Maximum height is 18 feet for a detached unit and 25 feet for an attached unit; an extra 2 feet is allowed if the roof pitch matches the primary dwelling. Side-street, interior-side and rear setbacks are 4 feet, with 5-foot separation between detached structures. The table also guarantees an 800-square-foot ADU with 4-foot setbacks regardless of other limits. One uncovered parking space per ADU is required, but parking is waived within one-half mile of transit or for conversions. State law (AB 976) eliminated owner-occupancy requirements through 2025. Land Use Services must confirm completeness within 15 business days and approve or deny within 60 days.