Before You Build in Ontario, CA: Permit & Rule Checklist (2026)

Ontario requires any pool, spa, pond, or decorative water body deeper than 1.5 feet to be enclosed by a minimum 5-foot nonclimbable decorative fence or wall with self-closing gates. California's Swimming Pool Safety Act independently requires new or remodeled residential pools to have at least two drowning-prevention features, including a 60-inch enclosure that meets state standards.

Ontario prohibits razor wire on any wall or fence citywide, and bans barbed wire and electrified fences in residential, commercial, and residential mixed-use districts. Residential fences must be ornamental steel/iron, wood, PVC, or decorative masonry; chain link in front and street-side yards is allowed only where it is the predominant existing material.

Where grade differs between properties or a property and the public right-of-way, Ontario allows a wall or fence combined with a retaining wall above the normal height limit, but a retaining wall adjacent to the public right-of-way is capped at 3 feet, with a free wall up to 6 feet and an overall height of 9 feet; deeper cuts must be tiered.

Ontario lets neighbors build a wall or fence on a common interior side or rear property line for division or security. On corner lots and in front yards the area between a fence and the sidewalk or curb must be fully landscaped and maintained, and nothing may be placed in the public right-of-way without an encroachment permit.

In Ontario residential zones, walls and fences within a front yard may not exceed 3 feet, while interior side, rear, street-side, and subdivision-perimeter walls or fences may not exceed 6 feet. Anything in a required front or street-side setback that affects safe sight lines is capped at 3 feet.

Every wall, fence, and gate in Ontario is subject to Planning Director design review regardless of whether a building permit is needed. A building permit is separately required for fences and walls over 3 feet high and for retaining walls over 2 feet, and a right-of-way encroachment permit is required for anything in the public right-of-way.

Ontario hot tubs and spas require a building permit, electrical permit, bonding to Article 680, and either a locking safety cover meeting ASTM F1346 or full pool-barrier compliance under state law.

A City of Ontario Building Department permit, plan check, and engineered drawings are required to build a residential swimming pool, and site plans must show all property lines, structures, slopes, walls, gates, fences, and barriers controlling access to the pool.

Above-ground pools in Ontario deeper than 18 inches need a building permit, barrier compliance, and electrical bonding. Removable mesh fencing or a self-latching ladder gate typically satisfies code.

The City of Ontario Building Department requires every outdoor swimming pool, spa, or hot tub to be surrounded by a barrier at least 60 inches high with no more than a 2-inch gap at the bottom, self-closing and self-latching gates, and no climbable design features, in line with the California Swimming Pool Safety Act.

Beyond the perimeter fence, Ontario recognizes ASTM-rated safety pool covers and pool alarms as compliant barriers and applies the California Swimming Pool Safety Act, which requires new or remodeled pools to carry at least two of seven drowning-prevention safety features.

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 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.

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 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 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.

Backyard fire pits, fire rings, chimineas, and barbecues are allowed in Ontario but must follow the 2022 California Fire Code. Barbecue/BBQ pits outside of buildings must be at least 15 feet from a structure, recreational fire pits must keep a 25-foot clearance from structures and combustibles, and the fire must be attended with extinguishing equipment available. Portable outdoor fireplaces and gas fire pits are the lower-smoke alternative.

Open burning to dispose of residential waste, leaves, brush, or trash is prohibited in Ontario. The city is in the South Coast Air Quality Management District, whose Rule 444 (Open Burning) expressly prohibits residential burning, and the Ontario Fire Prevention Bureau enforces the 2022 California Fire Code open-burning rules.

Private yard trees in Ontario can usually be removed without a city permit, but parkway street trees are city-owned and need a Public Works permit. Commercial landscape plan trees require plan revision.

Ontario Municipal Code Sec. 7-3.13 makes the abutting property owner responsible for watering, trimming, and maintaining parkway vegetation, including trimming trees to a minimum clearance of eight (8) feet from grade. Planting or removing any parkway tree requires a City permit and must conform to the Master Plan of Parkway Trees; major pruning and tree surgery are handled by the City.

Ontario is in the Voluntary Conservation Stage of its Water Conservation Plan (Ontario Municipal Code Chapter 8A, sections 6-8.20 through 6-8.35). The City's WaterWise program asks residents to avoid watering lawns between 6:00 AM and 6:00 PM, prevent irrigation runoff, and stop hose-washing of paved surfaces; mandatory restrictions take effect only if the City Council declares a Stage 1 through Stage 6 shortage.