Ontario ADU Regulations & Building Guide

Ontario is located in Southern California and offers a blend of urban and suburban experiences, attracting residents and visitors alike.

California State ADU Laws

California has some of the most progressive ADU legislation in the country. Recent laws including AB 68, SB 13, and AB 881 have significantly streamlined the ADU approval process and reduced barriers for homeowners.

Key California ADU Regulations:

• Size Limits: Detached ADUs can be up to 1,200 sq ft. Attached ADUs can be up to 50% of the primary dwelling or 1,200 sq ft, whichever is less.
• Setbacks: Minimum 4-foot side and rear setbacks for detached ADUs.
• Height: Generally up to 16 feet, with some exceptions for two-story ADUs (up to 25 feet in certain zones).
• Parking: No additional parking required in most cases, especially near transit.
• Owner Occupancy: No owner-occupancy requirement until 2025 for most ADUs.

Ontario Local Requirements

While California state law provides baseline regulations, Ontario may have additional local requirements. GatherADU's team stays current with Ontario's specific zoning codes, architectural guidelines, and permit processes to ensure your ADU project meets all requirements.

Common local considerations in Ontario include:

• Design review requirements and architectural standards
• Utility connection fees and impact fees
• Fire department access requirements
• Neighborhood-specific overlay zones

California law (AB 68, AB 881, SB 9, and subsequent legislation) guarantees your right to build ADUs. Cities cannot:

• Require owner-occupancy for ADUs permitted after 2020
• Require additional parking for ADUs near transit
• Charge impact fees for ADUs under 750 sq ft
• Deny ADUs that meet state minimum standards
• Impose lot coverage limits that prevent a 800 sq ft ADU

If you believe your ADU application is being unfairly denied, California HCD can intervene on your behalf.

California ADU Legislation Overview

California leads the nation in ADU-friendly legislation. The state has passed numerous laws to encourage ADU construction as a solution to the housing crisis.

Key California ADU Laws:

• AB 68 (2020): Reduced local government review time and expanded ADU construction options.
• SB 13 (2020): Limited impact fees and reduced owner-occupancy requirements.
• AB 881 (2020): Prohibited minimum lot size requirements and allowed JADUs in all zones.
• AB 2221 (2022): Further streamlined the ADU approval process.
• SB 897 (2022): Increased height limits for ADUs in certain zones.

California ADU Benefits:

• Property value increase of 20-30% on average
• Rental income potential of $1,500-$3,500+ monthly
• Housing flexibility for family members
• No owner-occupancy requirements (until 2025)

Ontario, California, is a bustling city in San Bernardino County with a population of approximately 181,107. Known for its strategic location near major transportation hubs and its strong economic base, Ontario offers a mix of suburban living and urban conveniences.

Geography and History

Situated in the Inland Empire region, Ontario benefits from its proximity to major highways and the Ontario International Airport. Established in the late 19th century, the city has evolved from a modest agricultural town into a major urban center with a diverse community and a robust economy.

Local Economy

Ontario’s economy is driven by several key sectors:

• Logistics and Distribution: The city’s location near major highways and the airport makes it a hub for logistics and distribution centers.
• Retail: Ontario boasts significant retail centers, including the Ontario Mills shopping mall and various commercial districts.
• Manufacturing: Includes industries such as aerospace and electronics.
• Healthcare: Several healthcare facilities, including the Kaiser Permanente Ontario Medical Center, contribute to the local economy.
• Education: Includes institutions such as Chaffey College, which support local economic and educational development.

Popular Neighborhoods

Ontario offers a range of neighborhoods catering to different lifestyles:

• Downtown Ontario: Features a mix of historic buildings, local shops, and cultural attractions.
• Ontario Ranch: A newer, master-planned community known for its family-friendly environment and modern amenities.
• Cucamonga: Offers a suburban feel with access to parks, schools, and shopping areas.
• Northeast Ontario: Known for its established homes and proximity to outdoor recreational areas.
• South Ontario: Includes a mix of residential and commercial areas, providing a diverse living environment.

Real Estate Market

Ontario’s real estate market is characterized by its affordability relative to other areas in Southern California. The market includes a range of options from single-family homes to apartment complexes. The city's growing appeal, driven by its location and amenities, continues to attract both homebuyers and investors.

ADU Regulations in Ontario

Ontario has implemented Accessory Dwelling Unit (ADU) regulations that align with California state laws to facilitate the development of additional housing units. These regulations are designed to streamline the ADU approval process and encourage the creation of more residential units.

• Zoning: ADUs are permitted in residential zones, including single-family and multifamily districts.
• Types of ADUs: Both attached and detached ADUs are allowed, as well as Junior ADUs (JADUs).
• Size Limits:
  • Detached ADUs: Up to 1,200 sqft.
  • Attached ADUs: Up to 50% of the primary dwelling's living area or 1,200 sqft, whichever is less.
  • JADUs: Up to 500 sqft.
• Height Restrictions: Detached ADUs are typically limited to 16 feet in height, though some exceptions may apply depending on zoning district and specific conditions.
• Parking: Generally, no additional parking is required for ADUs if they are located within half a mile of public transit. Parking requirements may be reduced or waived in certain circumstances.
• Owner Occupancy: As of 2020, there is no owner-occupancy requirement for ADUs built between January 1, 2020, and January 1, 2025. Owner occupancy is required for properties with JADUs.
• Approval Process: ADUs that meet the city's criteria are eligible for ministerial approval, which simplifies and expedites the approval process.
• Multiple ADUs: In multi-family properties, up to two detached ADUs are allowed, or ADUs for 25% of the existing units within the structure, whichever is greater.
• Impact Fees: Reduced impact fees are applied to ADUs smaller than 750 sqft to encourage development.
• Design Standards: ADUs must be designed to complement the primary residence and fit the character of the neighborhood.

These regulations aim to promote the development of ADUs and enhance housing options in Ontario.

Cultural Landmarks and Unique Aspects

Ontario is known for several unique aspects and cultural landmarks:

• Ontario Mills: A major shopping and entertainment destination with a wide range of retail stores, restaurants, and attractions.
• California Speedway: A prominent motorsports venue hosting various racing events.
• Ontario Convention Center: A versatile facility hosting conventions, trade shows, and community events.
• Graber Olive House: A historic site known for its olive production and rich history.
• Museum of History and Art: Offers exhibits and educational programs related to local history and culture.

Ontario’s ADU regulations reflect the city’s commitment to expanding housing options and addressing local needs. With its diverse neighborhoods, strong economy, and cultural landmarks, Ontario offers a desirable living environment. The city’s progressive approach to ADU development supports its goals of increasing housing availability and fostering community growth.

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