Accessory Structures in Ontario, CA (2026)
5 verified accessory structures rules for Ontario, California, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Ontario permits accessory dwelling units ministerially under Section 5.03.010 of the Development Code, limiting detached and attached ADUs to 850 square feet for a studio/one-bedroom and 1,000 square feet for two or more bedrooms, with 4-foot rear and side setbacks, a 16-foot detached height limit, and one parking space per unit.
Ontario ADU Rules (Dev. Code 5.03.010)
Few RestrictionsOntario Development Code Sec. 5.03.010(A)-(C)(1) (Rev. 02.17.2026)
5.03.010: Accessory Dwelling Units. A. Purpose. The purpose of this Section is to allow and regulate accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) in compliance with Chapter 13 of Division 1 of Title 7 of the California Government Code. B. Effect of Conforming. An ADU or JADU that conforms to the standards in this Section will not be: 1. Deemed to be inconsistent w...
Shed Rules
Ontario Development Code Section 5.03.011 governs detached accessory residential structures such as storage sheds, capping permitted-by-right area at 650 square feet (up to 1,100 for required garage parking) and 16 feet in height, requiring 5-foot rear and 10-foot interior side setbacks, prohibiting kitchens, and barring placement in front yards or shipping containers as storage.
Ontario Accessory Structure / Shed Rules (5.03.011)
Some RestrictionsOntario Development Code Sec. 5.03.011(A)-(B), (D)(4), (D)(10); Table 5.03-1 (Rev. 02.17.2026)
5.03.011: Accessory Residential Structures. A. Purpose. The purpose of this Section is to establish standards for the construction and use of Accessory Residential Structures (other than Accessory Dwelling Units allowed pursuant to Section 5.03.010 of this Development Code) in conjunction with existing single-family dwellings located within single-family or multiple-family zoning districts. B. ...
Garage Conversions
Ontario allows converting an existing garage or accessory structure into an ADU under Section 5.03.010, waiving replacement parking for the converted or demolished garage, requiring a 3-foot landscape planter where the garage door is removed, and allowing the existing structure's location and setbacks to be retained.
Ontario Garage Conversion to ADU (5.03.010)
Some RestrictionsOntario Development Code Sec. 5.03.010(F)(6)(c), (D)(2)(f), (H)(8)(b) (Rev. 02.17.2026)
c. No Replacement. When a garage, carport, covered parking structure, or uncovered parking space is demolished in conjunction with the construction of an ADU or converted to an ADU, those off-street parking spaces are not required to be replaced. ... f. Concurrent review of demolition. A demolition permit for a detached garage that is to be replaced with an ADU is reviewed with the application ...
Carport Rules
Ontario allows carports on residential lots subject to zoning setbacks and a building permit for any carport 200 sq ft or larger. Properly sized carports count toward required covered parking.
Ontario Carport Rules
Some RestrictionsTiny Homes
Foundation-built tiny homes qualify as ADUs under Gov Code 65852.2 in Ontario. Tiny homes on wheels are treated as RVs or park trailers and cannot be used as permanent dwellings on residential lots.
Ontario Tiny Home Rules
Heavy RestrictionsLooking for San Bernardino County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Ontario city rules.
Accessory Structures in San Bernardino County →