San Bernardino County, CA Accessory Structures: ADU Rules (2026)
ADU rules in San Bernardino County, CA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Max attached ADU size
- 1,200 sq ft (50% of home)
- Side/rear setback
- 4 feet
- Detached height limit
- 18 feet
- Review timeline
- 60 days, ministerial approval
- Parking required
- 1 uncovered space per unit
Summary
San Bernardino County caps attached ADUs at 1,200 square feet, limits floor area to 50% of the primary home, and sets 4-foot side and rear setbacks under Development Code Chapter 84.36.
Except as otherwise provided in this Chapter, the development standards for an accessory dwelling unit and junior accessory dwelling unit shall comply with the requirements set forth in Table 84-0 (ADU Building Form) and the restrictions provided herein. ... If there is an existing primary dwelling, the total floor area of an attached accessory dwelling unit shall not exceed 50 percent of the existing primary dwelling and at no time exceed 1,200 square feet.
Full Breakdown
Chapter 84.36 of the Development Code implements state ADU law with the County's own Table 84-0 building-form standards. Attached and detached ADUs are capped at 1,200 square feet, with attached units limited to 50% of the primary dwelling's floor area. Side and rear setbacks are 4 feet, detached units must sit at least 5 feet from other structures, and height is capped at 25 feet attached / 18 feet detached. One uncovered parking space per unit is required. The Planning Department must approve or deny a complete application ministerially within 60 days, per § 84.36.050(b).
Violations & Fines
Building without required ministerial ADU permit approval, or exceeding Table 84-0's setback, height, size, or parking standards, blocks issuance of a certificate of occupancy.
Frequently Asked Questions
Can San Bernardino County deny my ADU for being too close to the property line?
Do I need a discretionary hearing to build an ADU in the county?
Sources & Official References
Other rules in San Bernardino County
How San Bernardino County compares: Easiest Cities to Build an ADU·California rules heatmap·Compare San Bernardino County to another location·View the California accessory structures overview
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