Rialto | Three or More Homes

Rialto, California Three or More Homes: R-3 and R-4 Apartments, the Housing Opportunity District, By-Right Projects and the Density Bonus

In Rialto, three or more homes on one lot go in the R-3 and R-4 apartment zones, the planned development zones, the Housing Opportunity District created in April 2026, and the residential zones of the specific plans. On an R-1 house lot, the ways to more homes are ADUs and SB 9. This page covers how many homes each option allows, which approval each needs, the 20 percent lower-income rule that makes a project a by-right approval, the density bonus, and the state housing target that led to the 2026 changes. The Rialto overview has the summary.

The Options Compared

Sources: Rialto Municipal Code Sec. 18.22.020, 18.22.030, 18.22.040, 18.24.030, 18.24.070, 18.56.090 and 18.80.070 (Supplement 39); Ordinance No. 1709.

R-3: Four Homes With the Director, Five With the Commission

The R-3 Multiple Family zone allows a small multiplex with staff approval. Section 18.22.020 allows "Multiple family dwellings, consisting of four or less units" and dwelling groups outright, and five or more homes with a conditional development permit from the Planning Commission. A conditional development permit is Rialto's discretionary use permit: the Commission holds a hearing and may approve only if it makes six findings under Section 18.66.020, including that the use "will not be detrimental or injurious to the health, safety or general welfare of persons residing or working in the vicinity."

• Before you apply. Section 18.22.040 asks the developer to "meet with the director of development services or his/her representative to discuss the proposed project." Each multi-family application also needs "an environmental assessment review" under the California Environmental Quality Act (CEQA), the state law that requires study of a project's effects on the environment.
• Density and size. One home per 2,000 square feet of net lot area. A 9,000 square foot lot allows four homes and a 10,000 square foot lot five (VanPlex arithmetic). Minimum home sizes are 600 square feet for a studio, 700 for one bedroom, 850 for two, 1,000 for three and 1,200 for four.
• Building form. Three stories and 35 feet, with the second floor and above set back 35 feet from the planned street line. No more than six homes may be joined side by side, and the front wall must be offset by at least four feet for every two homes.
• Living space. Each ground floor home needs 100 square feet of private yard and each upper home a 60 square foot balcony. The project needs 400 square feet of common outdoor space per home, in areas at least 25 feet across. Washers and dryers must be installed in each home.
• Neighbors. Where R-3 abuts a single family, office, commercial or industrial zone, a six-foot solid masonry wall separates them.

The Housing Element (Program 4B) says "The City currently requires multi-family housing developments of five or more units in the R-3 zone to receive approval of a Conditional Use Permit," and commits the City to review that permit requirement and the R-3 "minimum lot size and lot coverage requirements" to remove constraints. No ordinance changing Chapter 18.22 appears in the Council records read through October 2026.

R-4: The High Density Zone

Section 18.24.030 allows one home per 900 square feet of lot area on lots of at least 7,200 square feet, buildings up to "six stories or seventy-five feet," and building coverage of 60 percent. Homes must be at least 600 square feet, but "in any construction involving four or more units on one lot, the developer is entitled to construct one unit having a minimum size of four hundred twenty-five square feet for every three units" of 600 square feet. Front and rear yards are 15 feet. Section 18.24.070 sends site plans to the Planning Commission "whenever five or more dwelling units are proposed for any lot or building site." On a 7,200 square foot R-4 lot, the density rule allows eight homes (7,200 divided by 900; VanPlex arithmetic).

By-Right Projects at 20 Percent Lower-Income

Ordinance No. 1681 of August 8, 2023 added a line to the R-3 use list: "Development projects consisting of any number of units, in which twenty percent or more of the residential units are affordable to lower-income households are permitted by-right and subject to the provisions of Government Code Section 65583.2 subdivisions (h) and (i)." Ordinance No. 1709 keeps the same line for the Housing Opportunity District. Under Government Code 65583.2(i), "use by right" means the City "may not require a conditional use permit, planned unit development permit, or other discretionary local government review," although a city may keep design review that is not itself a project under CEQA.

Section 18.56.090, added by the same 2023 ordinance, covers sites that a prior Housing Element already counted: "When a non-vacant lot has been identified in a prior housing element and at least twenty percent of the proposed units are affordable to lower income households, the maximum density shall be thirty dwelling units per acre."

The Housing Opportunity District

Ordinance No. 1709, adopted April 14, 2026, applies the R-4 rules to residential buildings in the Housing Opportunity District, with its own density, coverage of 70 percent and a height of "five stories or sixty 60 feet." It allows four or fewer homes outright, five or more with a conditional development permit, all-residential buildings 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." A minimum density of 20 homes per acre applies to every listed site. Section 4 of the ordinance says the capacity of three Housing Element sites (114, 115 and 119) "shall be accommodated on alternate sites within 180 days." The zoning districts page compares the 2026 densities with the 2023 text that Supplement 39 still prints.

The Density Bonus

A density bonus lets a project build more homes than the zone allows in return for affordable homes. Rialto's Chapter 18.101, adopted by Ordinance No. 1643 on July 14, 2020, says the bonus "only applies to housing developments consisting of five or more dwelling units." Its tables give 20 percent for 10 percent low-income homes, rising to 35 percent at 20 percent low-income or 11 percent very low income. Rental affordable homes must stay affordable "for a period of fifty-five years," and the City "will require an equity-sharing agreement for all for-sale units," an agreement on how any gain at resale is shared.

Government Code 65915(f) now allows more: 38.75 percent at 21 percent low-income, up to 50 percent at 24 percent low-income or 15 percent very low income. The Rialto low-income table also skips 16 percent, which the statute sets at 29 percent. The Housing Element says "The City's Density Bonus program allows a maximum of 35% density increase; however, AB 2345 requires an allowance of up to 50%." The statute controls. Section 18.101.100 caps parking for a bonus project at one space for a home of up to one bedroom and two for two or three bedrooms, and 0.5 per home within one-half mile of a major transit stop.

The State Housing Target and the Housing Element

Source: City of Rialto Housing Opportunity District page, "City of Rialto 2021-2029 RHNA Allocation of Dwelling Units."

The Regional Housing Needs Allocation (RHNA) is the number of homes, by income level, that each city must zone room for in each eight-year cycle. The City's HOD page says that "For Rialto, AMI is $77,500 for a family of four," where AMI is the area median income. The City Council adopted the 2021-2029 Housing Element by Resolution No. 8474 on March 10, 2026; the City's page lists the complete document's approval date as "TBA." The Housing Element lists programs to remove limits on housing: Program 2G (objective design standards, meaning measurable standards with no personal judgment), Program 3H (parking near transit) and Program 4B (review of R-3 permits, unit sizes and parking).

SB 79, Transit Parking and Small-Lot Maps

• SB 79. SB 79 allows taller and denser projects near qualifying rail and bus stops. The state Department of Housing and Community Development (HCD) says its upzoning "will take effect on July 1, 2026, in Alameda, Los Angeles, Sacramento, San Francisco, San Mateo, Santa Clara, and San Diego Counties." San Bernardino County is not listed.
• Parking near transit. Government Code 65863.2 bars minimum parking rules for a project "within one-half mile of public transit," defined as a major transit stop, unless the City makes written findings within 30 days of a complete application. The City cannot use those findings for a project of "fewer than 20 housing units." The Housing Element places the Rialto Metrolink Station next to its Central Area sites.
• Small-lot maps. On R-3, R-4 and HOD lots of up to five acres, Government Code 66499.41 allows a ministerial map of up to 10 lots for up to 10 homes. See the lot size and subdivisions page.
• A recent example. The January 13, 2026 City Council agenda listed Resolution No. 8445 approving Tract Map 20356 at Foothill Boulevard and Larch Avenue, in the "Residential-High Density (R-HD) Zone of the Foothill Boulevard Specific Plan," dividing three parcels "into Seven Lots for Condominium Purposes."

Where to Go Next

Related on VanPlex: the Rialto overview, the SB 79 page and the duplex to fourplex guide.

Frequently Asked Questions

Official sources (checked October 2026)