Rialto | Zoning Districts

Rialto, California Zoning Districts: R-1, R-3, R-4, Planned Developments and the 2026 Housing Opportunity District

A zoning district, or zone, is an area where the same land use rules apply. Rialto's zones are set out in Title 18 of the Rialto Municipal Code and drawn on the City's land use zoning map. The house zones are the R-1 family and A-1. Apartments go in R-3, R-4, the planned development zones and, since April 2026, the Housing Opportunity District. Large parts of the city sit inside specific plans with their own zones. This page lists each zone, how many homes it allows and where the 2026 changes are not yet in the printed code. The Rialto overview has the summary.

The Zoning Map and the Printed Code

Section 18.06.010 says the zones and their boundaries "are shown on the 'land use zoning map' maintained by the director of development services." Where a boundary follows a street, alley or lot line, that line is the boundary; where any doubt remains, "the planning commission determines the location of boundaries." The map is a separate document, so the first step for any lot is to ask the Planning Division at (909) 820-2535 or [email protected] for its zone and any specific plan that covers it. The City's Applications and Forms page also offers a zoning verification letter.

The Municode copy read for this guide is Supplement 39. Its preface says it "brings the Code up to date through Ord. No. 1713, passed April 28, 2026." The Supplement History Table lists each ordinance as "Include" or "Omit." Ordinance No. 1709, which rewrote the residential overlay on April 14, 2026, does not appear in that table at all, and Chapter 18.116 in Supplement 39 still prints the 2023 text. The City's signed copy of Ordinance No. 1709 is the current rule, and this page uses it. Ordinances Nos. 1710 and 1711, which amended two specific plans in March 2026, are marked "Omit."

The Zones That Allow Homes

Sources: Rialto Municipal Code Sec. 18.08.030, 18.10.030, 18.12.030, 18.14.030, 18.16.030, 18.18.060, 18.22.030, 18.24.030, 18.80.070 and 18.90.070 (Supplement 39).

The R-1 Single Family Zones

Chapter 18.10 sets the base rules for "any R-1 single family zone," and the R-1A-10,000, R-1B and R-1C chapters adopt those rules by reference and change only lot size, lot width and house size. Section 18.10.020 allows "A single one-family dwelling of a permanent character, placed in a permanent location on each lot." The same list adds accessory dwelling units (ADUs) under Section 18.10.070, a "Two-unit project" under Chapter 18.113 (the City's SB 9 chapter), supportive and transitional housing, home occupations, and manufactured homes on a permanent foundation built no more than ten years before the permit application.

Note one inconsistency in the text: Section 18.10.020 begins "Uses permitted in the R-1 A zone are as follows," while Section 18.10.010 applies the chapter to "any R-1 single family zone." Other sections name R-1A as a zone of its own, and Section 18.08.020 lets an A-1 lot hold a house that conforms "to R-1A zone regulations as set forth in Chapter 18.10." In practice, Chapter 18.10's lot size of 8,400 square feet is the R-1A standard, and the other R-1 chapters list their own exceptions.

• Lot size. 8,400 square feet in R-1A and R-1B, 7,700 in R-1C and 10,000 in R-1A-10,000. Every R-1 zone requires a lot depth of 100 feet.
• House size. Each zone sets a median and average house size and a smallest allowed house: 1,600 and 1,440 square feet in R-1A, 1,800 and 1,620 in R-1A-10,000, 1,400 and 1,260 in R-1B, and 1,200 and 1,000 in R-1C, not counting garages and porches.
• Building. Two and one-half stories and 35 feet, a 25-foot front yard, a 20-foot rear yard and building coverage of 30 percent of the lot.
• Older lots. A lot that is smaller than the zone requires, but "was held under separate ownership or was of record" when the title took effect, may still be used for any use the zone allows.
• Animals. Horses are allowed on lots of at least 23,000 square feet for one horse and 20,000 more for each extra horse, up to three. Stables must be 40 feet from any house on the lot and 100 feet from houses on next-door lots.

The minimum house sizes apply to the primary house. Section 18.10.070 says the primary house "shall contain the minimum living areas required by the zone," and sets separate size limits for ADUs. See the ADUs and SB 9 page.

A-1 and R-1D

A-1 Agricultural. Section 18.08.030 sets a lot area of "one acre, forty-three thousand five hundred sixty square feet" and a width of 120 feet. Height and yards follow the R-1A zone. The zone allows farming, a house built to R-1A rules, and animals: no more than two horses, goats, cows or similar animals on a lot under one acre, with one more for each half acre above one acre. Animal pens must be 40 feet from houses on the lot and 70 feet from any other place people live.

R-1D. Chapter 18.18, added in 2007, is a single family zone for "medium density housing opportunities that are not otherwise allowed by the strict interpretation of the existing R-1 zones." It applies only after a zone change, and Section 18.18.060 sets a minimum site of ten acres and a density of no more than "six units per acre," measured after public streets are taken out. Lots must be 100 feet deep and 60 feet wide (65 on corners), houses must have at least 1,800 square feet of living area, and buildings may cover 50 percent of each lot. Front yards are 20 feet and must be "staggered by five feet." R-1D is meant for new subdivisions of ten acres or more.

R-3 and R-4: The Apartment Zones

R-3 Multiple Family. Section 18.22.020 allows any R-1 use, "Multiple family dwellings, consisting of four or less units," dwelling groups (two or more detached buildings of homes on one lot), and five or more homes "subject to the issuance of a conditional development permit by the city planning commission," a permit the Commission grants after a public hearing. Since Ordinance No. 1681 of August 8, 2023, projects of any size where 20 percent or more of the homes are affordable to lower-income households "are permitted by-right," meaning with no discretionary permit. Section 18.22.030 sets a minimum site of one acre and 150 feet of width "when developed pursuant to this chapter," but a smaller lot of record may still be used. Density is one home per 2,000 square feet of net lot area, and buildings may rise three stories and 35 feet.

R-4 High Density Multiple Family. Section 18.24.020 allows any R-1 or R-3 use plus "Group dwellings, multiple family dwellings, apartment houses, boarding and rooming houses." Section 18.24.030 sets a minimum lot of 7,200 square feet, 60 feet wide and 100 feet deep, one home per 900 square feet of lot area, building coverage of 60 percent and a height limit of "six stories or seventy-five feet." Site plans go to the Planning Commission "whenever five or more dwelling units are proposed for any lot or building site."

On the same 10,000 square foot lot, R-3 allows five homes and R-4 allows eleven (10,000 divided by 2,000, and 10,000 divided by 900 rounded down; VanPlex arithmetic). R-3 counts net lot area, which leaves out public streets. The three or more homes page covers the permits, open space and unit size rules for both zones.

Planned Residential Developments

Two zones let a developer plan a group of homes as one project. Both need a zone change with a development plan, and the Planning Commission reviews the plan before the City Council acts.

• PRD-A (attached). Section 18.80.050 allows "Condominiums, community apartments, row houses, townhouses, cluster projects" and similar projects. The minimum net site is one acre, and density "shall not exceed twelve dwelling units per net acre." The Planning Commission may add up to two homes per acre for building design and up to four for solar design that cuts energy use. Coverage is 35 percent and height three stories or 35 feet, dropping to 16 feet or one story within 25 feet of a single family zone.
• PRD-D (detached). Section 18.90.070 sets a minimum gross site of five acres within an R-1 zone, density set by the General Plan (the City's long-range land use plan), houses of at least 1,200 square feet, 35 percent coverage and a height of two and one-half stories or 35 feet.

The Housing Opportunity District (Ordinance No. 1709)

An overlay is a set of extra rules placed on top of a lot's base zone; the owner may use either set. Chapter 18.116 first created a residential overlay in 2023, through Ordinance No. 1681. The overlay puts into effect the City's Housing Element, the state-required plan for how a city will provide sites for its share of new homes. On April 14, 2026 the City Council adopted Ordinance No. 1709, 4-0 with one member absent, which adds the name Housing Opportunity District (HOD) to the chapter and changes its densities. Its recitals say the rezone program covers "315 parcels."

Sources: Rialto Municipal Code Sec. 18.116.060 (Supplement 39); City of Rialto Ordinance No. 1709, Section 3.

Under the new text, the HOD allows four or fewer homes, five or more with a conditional development permit from the Planning Commission, buildings that are "100 percent residential" where the base zone is commercial, mixed-use or residential, and mixed projects with "a maximum of 50 percent commercial of the total floor area." Projects where 20 percent or more of the homes are affordable to lower-income households are allowed by right. All other rules come from the R-4 zone. The ordinance states the density twice and the two statements differ in form: a list of 35 and 40 homes per acre by area, and a sentence giving "35-40 du/ac in areas with an underlying residential zone and 50 du/ac in areas with an underlying commercial zone." Ask the Planning Division which figure applies to a given parcel.

Ordinance No. 1710, adopted March 24, 2026, adds the HOD to the Foothill Central Specific Plan and says "Where conflicts occur between this Specific Plan and Chapter 18.116, the provisions of Chapter 18.116 shall govern." Ordinance No. 1711 does the same for the Gateway Specific Plan. The City's HOD page links a site list that can be searched by address or parcel number and six maps.

Specific Plans

A specific plan is a detailed plan for one area that replaces the citywide zones there. The City's Specific Plans page lists nine: Agua Mansa, Elm Park, Foothill Central, Gateway, Lytle Creek Ranch, Northwest Rialto, Pepper Avenue, Renaissance and Rialto Airport. The Housing Element says the Renaissance Specific Plan "is located on 1,439 acres" and mixes logistics, business, shopping and homes, and that in the Pepper Avenue plan "The maximum density is 30 dwelling units per acre and a total maximum of 275 units." It also says the City "adopted the Foothill Central Specific Plan (Specific Plan) on February 11, 2025," merging the Foothill Boulevard and Central Area plans. Lots inside a specific plan follow that plan's zones; this guide does not cover them in detail.

Where the Code Disagrees With Itself

• Supplement 39 prints the 2023 overlay at 50 homes per acre in five areas; Ordinance No. 1709 sets 35 or 40 per acre by area and 50 where the base zone is commercial. The ordinance controls.
• Section 18.10.020 calls its list "Uses permitted in the R-1 A zone," while Section 18.10.010 applies the chapter to "any R-1 single family zone."
• Section 18.47.040 lists an "R-6,000" single family zone, which has no chapter in Title 18.
• Section 18.80.060 sends a PRD-A zone change to "Chapter 18.48," the interim zone chapter, for its procedure, while zone changes are governed by Section 18.06.030.

Where to Go Next

Related on VanPlex: the Rialto overview, the SB 9 page and the duplex to fourplex guide.

Frequently Asked Questions

Official sources (checked October 2026)