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David Babakaiff
Written by David Babakaiff · Co-Founder, VanPlex | 25+ Years BC Construction Last reviewed: October 2026

Riverside | Three or More Homes

Riverside Three or More Homes: R-3 and R-4 Apartments, Small Lots, PRDs and the Density Bonus

In Riverside, three or more homes on one site come from the multiple-family zones (R-3 and R-4), the mixed-use zones, a Planned Residential Development, or the state density bonus. On an R-1 lot, ADUs and SB 9 can reach four homes, covered on the ADUs and SB 9 page. This page covers the rest, from Supplement 33 of the Riverside Municipal Code.

Three or more homes in Riverside in six facts

R-3 and R-4: How Many Homes a Lot Holds

Section 19.100.010 describes R-3 as the place for "apartments, town homes, condominiums, tiny homes (foundation) in tiny home communities, and single-family homes in a Small Lot Subdivision Planned Residential Development." R-4 is for higher density "in areas of the City readily served by public transit and near commercial zones." Table 19.150.020 A lists the multiple-family dwelling as permitted in both. Density is set per gross acre, a measure that counts streets as part of the land.

The table below shows what the densities mean on two common lot sizes. It is VanPlex arithmetic: lot area divided by 43,560 square feet per acre, times the zone density, using the lot alone. The City counts gross acres including streets, and outside the density bonus chapter the code read here gives no rule for rounding a fraction, so treat these figures as a starting point to confirm with the Planning Division.

Zone Max homes per gross acre 7,000 sq ft lot (0.1607 acre) 10,000 sq ft lot (0.2296 acre)
R-3-4000 10.9 1.75 2.50
R-3-3000 14.5 2.33 3.33
R-3-2500 17.4 2.80 3.99
R-3-2000 21.8 3.50 5.00
R-3-1500 29 4.66 6.66
R-4 40 6.43 9.18

Densities: Riverside Municipal Code Table 19.100.040 B. Home counts are VanPlex arithmetic, before any density bonus.

On a standard R-3 lot, buildings may be 30 feet and two stories, and "Up to 60% of units may be located in three-story buildings with a maximum height of 40 feet." R-4 allows 50 feet and four stories. Where an R-3 or R-4 site touches a single-family zone, side and rear yards grow "by two and one-half feet for each story in excess of two stories." Buildings on the same site must be 15 feet apart.

Footnote 4 of the use table also allows "One single-family detached dwelling" on an R-3 or R-4 lot of 0.25 acre or less that existed before January 1, 2018, built to R-1-7000 standards. That protects owners of small R-3 lots who want to build one house.

Small R-3 and R-4 Lots Under Half an Acre

The standard R-3 and R-4 tables assume a large site: every zone lists a 30,000 square foot minimum lot. Section 19.100.075, added by Ordinance 7683 in 2024, sets lighter rules for "residential infill development projects in the R-3 and R-4 zones on lots less than 21,780 square feet in area," which is half an acre. Infill means new homes on a lot inside an area that is already built up. These rules "supersede those listed in Table 19.100.040.B."

Standard Lots up to 10,000 sq ft Lots 10,001 to 21,780 sq ft
Height and stories 40 ft, 3 stories (45 ft with tuck-under parking) 40 ft, 3 stories
Front setback 10 ft (under 5,000 sq ft); 15 ft (5,001 to 10,000) 15 ft
Interior side 5 ft 5 ft (7.5 ft from 20,001 sq ft)
Rear 7.5 ft 10 ft
Distance between buildings 5 ft 5 ft (15 ft from 15,001 sq ft)
Common open space per home None 40 sq ft or 2% of lot (10,001 to 15,000); 50 or 75 sq ft above
Private open space per home None 40 or 50 sq ft

Source: Riverside Municipal Code Tables 19.100.075 A and B. The street side yard is 7.5 ft up to 15,000 sq ft and 10 ft above; the rear yard is 7.5 ft up to 10,000 sq ft and 10 ft above.

Three rules make these lots workable. The height is 40 feet and three stories, and on lots up to 10,000 square feet it "may be increased to 45 feet if building is designed with tuck under parking." Tuck-under parking is a garage at ground level under the homes, and "Ground floor tuck under parking shall not be considered a story." Second, "Usable open space is not required for developments with six or fewer units." Third, small lots under 10,000 square feet need no common open space at all.

Next to single-family land the rules tighten. "Where a property abuts the RA-5, RC, RR, RE or R-1 Zone, buildings with habitable space above 20 feet in height shall increase the required side and rear yards by five feet." Windows within 30 feet of a neighbor's building may not line up with the neighbor's windows, and upper decks that face the neighbor sit at least 15 feet from the lot line.

Open Space, Design and Review for Apartments

On standard lots, Table 19.100.070 sets common open space per home: 400 square feet in R-3-4000 and R-3-3000, 250 in R-3-2500 and R-3-2000, 200 in R-3-1500 and 150 in R-4. Private open space, such as a fenced patio or a balcony, is 50 to 120 square feet for a ground-floor home, by zone, and 50 square feet upstairs. Larger projects add amenities: two from a list such as a play area, pool, or dog park for 21 to 75 homes, and four for 76 homes or more. The common area may shrink "by up to 20 percent" within a quarter mile of a neighborhood park or half a mile of a community or regional park.

Section 19.100.070 also sets design rules. Building entrances face the street first. "No parking shall be permitted between the primary building or buildings and the public right-of-way." Windows seen from the street are recessed at least four inches, and each building uses at least three exterior materials. Fences between the building and the street are limited to three feet if solid.

Every new R-3 and R-4 building needs design review under Section 19.100.080. Section 19.710.020 D sends stand-alone multi-family projects to an administrative design review by the Community and Economic Development Director when the project meets every code standard and needs no other discretionary permit except variances. The fee schedule lists general design review for multi-family at $8,552. Section 19.710.020 A, which lists the zones that need design review, does not name R-3 or R-4; Section 19.100.080 B names them directly, so plan for design review.

Planned Residential Developments

A Planned Residential Development (PRD) is a permit for a group of homes designed together, with shared open space, that may exceed the normal density. Section 19.780.020 sets four types: a PRD in any single-family zone except RA-5; a Minor PRD of "five to 16 dwelling units"; an Administrative PRD of "four or fewer parcels"; and a Small Lot PRD, "Permitted in multi-family (R-3) residential zones except for R-4" with "16 or fewer dwelling units." Homes may be "Single-family dwellings attached or detached," or tiny homes on foundations outside RC.

In single-family zones, Table 19.780.050.B sets a benchmark density and a bonus for superior design: 7.3 homes per gross acre in R-1-7000 (8.0 with the bonus), 6.3 in R-1-8500 (6.9), 5.5 in R-1-10500 (6.0) and 4.8 in R-1-13000 (5.3). The bonus needs green building features from a list in Section 19.780.050 E. Administrative and Minor PRDs may have three stories, and need 300 or 500 square feet of open space per home and one guest space per three homes.

A Small Lot PRD fits R-3 sites. Lots may be no larger than 5,499 square feet, homes may be 35 feet and three stories, and the project must reach "a minimum of 50 percent of the density of the underlying General Plan land use designation." Interior side setbacks can be zero on one side for the smallest lots. A PRD is discretionary: the Planning Commission decides it, and Section 19.780.030 requires "an affirmative vote of 2/3 of the membership present and voting." The July 1, 2026 fee schedule lists $19,804 for a PRD or Minor PRD and $8,552 for an Administrative PRD.

Tiny Home Communities and Mixed-Use Zones

A tiny home community is "a group of tiny homes, constructed either on a chassis or on a foundation, that are arranged in common relationship to one another, usually surrounding a shared common open space area." The foundation version is a permitted use in R-3 and R-4, and inside one "the minimum distance between buildings shall not be less than five feet," against 15 feet for other R-3 and R-4 buildings. Each tiny home on a foundation needs one parking space under Table 19.580.060.

The mixed-use zones of Chapter 19.120 allow apartments too: up to 10 homes per acre in MU-N, 30 in MU-V and 40 in MU-U, with heights of 35, 45 and 60 feet. Within half a mile of a transit stop on Magnolia or University Avenue, or of any transit station, a project may reach 40 homes per acre in MU-V and 60 in MU-U, at the City's discretion through Site Plan Review. A mixed-use project must include shop or office space, such as 40 percent of the ground floor frontage on an arterial street in MU-V.

Along University Avenue, the City added a pilot program in 2026. Resolution 31364, adopted April 21, 2026, created the University Avenue Density Transfer Pilot Program, which lets parcels in the University Avenue Specific Plan Area, "from Park Avenue to I-215/SR 60," move unused home counts to other parcels. "The City will initially seed the development bank with the 210 units from the city-owned surplus sites." The factsheet adds that parking "is not required anywhere along the corridor" because the area is a high-quality transit corridor under AB 2097.

The Density Bonus and State Transit Laws

Chapter 19.545 carries out the state density bonus law in Government Code 65915. A project qualifies when, for example, "Five percent of the total units are designated for very low-income households" or "Ten percent of the total units are designated for low-income households." Both start at a 20 percent bonus, up to "a maximum of 50 percent." Fractions round up: "Each component of any density calculation resulting in fractional units, including base density and bonus density, shall be separately rounded up to the next whole number." A project that uses this bonus "is not eligible for an additional density bonus" under the PRD chapter.

Section 19.545.020 B refers to "Chapter 19.535 (Inclusionary Housing)." Supplement 33 has no Chapter 19.535, so the code read for this guide contains no rule that every project set aside affordable homes.

SB 79 (2025) raises zoning near rail and bus stops only in an "urban transit county," which Government Code 65912.156 defines as "a county with more than 15 passenger rail stations." HCD's SB 79 advisory says the upzoning "will take effect on July 1, 2026, in Alameda, Los Angeles, Sacramento, San Francisco, San Mateo, Santa Clara, and San Diego Counties." Riverside County is outside that list, and the advisory adds that the scope will change as new rail service opens. Parking relief under Government Code 65863.2 applies now: no minimum parking "if the project is located within one-half mile of public transit," and Section 19.580.060 A.2 of the City code says the same.

R-3, R-4 and the mixed-use MU-V and MU-U zones also qualify for SB 684 maps of up to 10 lots on parcels of 5 acres or less, under the City's SB 1123 checklist. See the lots and subdivisions page.

Best For

  • ✓ R-3-1500 and R-4 lots, at 29 and 40 homes per gross acre.
  • ✓ R-3 lots under 10,000 sq ft, with no common open space and 45-foot height over tuck-under parking.
  • ✓ MU-V and MU-U sites near Magnolia or University Avenue transit stops.

Usually Fails When

  • ✕ The plan is apartments on an R-1 lot, where they are prohibited.
  • ✕ A PRD cannot win a two-thirds Planning Commission vote.
  • ✕ The plan counts on SB 79 transit zoning in Riverside County.

What To Verify Before Spending Money

  • → How the City rounds a fraction of a home on your lot outside the density bonus.
  • → Whether the lot borders a single-family zone, which adds five feet to side and rear yards.
  • → Whether the site is within half a mile of a major transit stop for parking relief.

Where to Go Next

Parking, Setbacks, Height
Apartment parking and covered spaces.
Zoning Districts
All zones and overlays.
Permits and Fees
Design review, PRD and impact fees.

Related on VanPlex: the Riverside overview, SB 79 and duplex to fourplex.

Frequently Asked Questions

Where can I build an apartment building in Riverside? +
Riverside Table 19.150.020 A permits multiple-family dwellings in the R-3 and R-4 zones and in the MU-V and MU-U mixed-use zones. They are prohibited in RC, RA-5, RR, RE and R-1, except that older legal duplexes may stay in R-1-7000. All new R-3 and R-4 buildings need design review under Section 19.100.080, which the Director may handle administratively when every code standard is met.
How many units can I build on a 10,000 square foot R-3 lot in Riverside? +
By VanPlex arithmetic, a 10,000 square foot lot is 0.2296 acre, which gives 2.50 homes at R-3-4000 density, 5.00 at R-3-2000 and 6.66 at R-3-1500 under Table 19.100.040 B. Riverside measures density per gross acre, including streets, and the code read here sets no rounding rule for base density outside the density bonus chapter, so confirm the count with the Planning Division.
What are the setbacks on a small R-3 lot in Riverside? +
Riverside Section 19.100.075 sets small-lot rules for R-3 and R-4 lots under 21,780 square feet. A lot under 5,000 square feet has a 10-foot front setback, 5-foot interior sides, 7.5-foot street side and rear yards, and 5 feet between buildings. Where the lot borders a single-family zone, yards grow by five feet for buildings with living space above 20 feet.
Do Riverside apartments need open space for each unit? +
Yes, on standard R-3 and R-4 lots. Riverside Table 19.100.070 requires common open space of 400 square feet per home in R-3-4000 and R-3-3000, down to 150 in R-4, plus private patios of 50 to 120 square feet. Projects with 21 to 75 homes add two listed amenities, such as a play area or pool. Small lots under 10,000 square feet need none.
What is a Small Lot PRD in Riverside? +
A Small Lot Subdivision Planned Residential Development is a Riverside permit, under Chapter 19.780, that divides an R-3 site into small house lots of 5,499 square feet or less, for 16 or fewer homes. Homes may be 35 feet and three stories, and the project must reach at least half the General Plan density. The Planning Commission decides it, with a fee of $19,804.
Can I build townhomes on an R-1 lot in Riverside? +
Only through a Planned Residential Development. Riverside Chapter 19.780 lets single-family zones exceed normal density with attached or detached homes. In R-1-7000 the benchmark is 7.3 homes per gross acre, and up to 8.0 with a superior design bonus. An Administrative PRD covers four or fewer parcels and a Minor PRD five to 16 homes, both with three stories allowed.
Does Riverside have an inclusionary housing rule? +
Supplement 33 of the Riverside Municipal Code, read for this guide, has no inclusionary housing chapter, although Section 19.545.020 refers to "Chapter 19.535 (Inclusionary Housing)." Affordable homes come through the density bonus in Chapter 19.545, which grants a bonus when a project sets aside, for example, 5 percent of homes for very low income households or 10 percent for low income households.
How does the density bonus work in Riverside? +
Riverside Chapter 19.545 carries out the state density bonus law. A project with 5 percent very low income homes gets a 20 percent bonus, rising 2.5 percent for each added percent, to a 50 percent maximum. Section 19.545.030 rounds each fraction of base and bonus density up to the next whole home. A project using it cannot also get a PRD density bonus.
Does SB 79 apply in Riverside? +
No, as of October 2026. SB 79 raises zoning near rail and bus stops only in an urban transit county, which Government Code 65912.156 defines as a county with more than 15 passenger rail stations. The HCD SB 79 advisory names Alameda, Los Angeles, Sacramento, San Francisco, San Mateo, Santa Clara and San Diego Counties for July 1, 2026. Riverside County is not on that list.
What is the University Avenue Density Transfer Pilot Program in Riverside? +
Riverside adopted the University Avenue Density Transfer Pilot Program by Resolution 31364 on April 21, 2026. It lets parcels in the University Avenue Specific Plan Area, from Park Avenue to I-215/SR 60, move unused housing units to other parcels there. The City seeded a development bank with 210 units from City-owned surplus sites. No parking is required along the corridor.
How much parking do Riverside apartments need? +
Riverside Table 19.580.060 requires 1.5 spaces for each one-bedroom apartment and 2 spaces for each apartment of two or more bedrooms, with dens counted as bedrooms. At least 75 percent of required spaces must be in a garage or carport. Government Code 65863.2 bars minimum parking within half a mile of a major transit stop unless the City makes findings within 30 days.

Official sources (checked October 2026)

RMC Section 19.100.040, Table 19.100.040 B
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVBAZOREUSDEPR_CH19.100REZORCRRRE1-2AC13000105008500700040003000250020001500R-_19.100.040REDEST
RMC Section 19.100.070, rules for the R-3 and R-4 Zones
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVBAZOREUSDEPR_CH19.100REZORCRRRE1-2AC13000105008500700040003000250020001500R-_19.100.070ADREZO
RMC Section 19.100.075, undersized R-3 and R-4 lots
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVBAZOREUSDEPR_CH19.100REZORCRRRE1-2AC13000105008500700040003000250020001500R-_19.100.075REINDEUNLOZO
RMC Chapter 19.150, permitted uses tables
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVBAZOREUSDEPR_CH19.150BAZOPELAUS
RMC Chapter 19.120, Mixed-Use Zones
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVBAZOREUSDEPR_CH19.120MIEZO
RMC Chapter 19.545, Density Bonus
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVIIISIPLGEDEPR_CH19.545DEBO
RMC Chapter 19.710, Design Review
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTIXLAUSDEPEREPR_CH19.710DERE
RMC Chapter 19.780, Planned Residential Development Permits
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTIXLAUSDEPEREPR_CH19.780PLREDEPE
RMC Chapter 19.580, Parking and Loading
https://library.municode.com/ca/riverside/codes/code_of_ordinances?nodeId=PTIICOOR_TIT19ZO_ARTVIIISIPLGEDEPR_CH19.580PALO
City of Riverside, University Avenue Density Transfer Pilot Program factsheet (PDF)
https://riversideca.gov/cedd/sites/riversideca.gov.cedd/files/pdf/planning/2026/Factsheet-University-Avenue-Density-Transfer-Program.pdf
City of Riverside, SB 1123 Application Checklist and Pre-Clearance Form (PDF)
https://riversideca.gov/cedd/sites/riversideca.gov.cedd/files/pdf/planning/2026/SB-1123-CHECKLIST-PRE-CLEARANCE-FORM-9.22.26.pdf
City of Riverside, Planning Services Fee Schedule, July 1, 2026 (PDF)
https://riversideca.gov/cedd/sites/riversideca.gov.cedd/files/pdf/FEE%20SCHEDULE.pdf
HCD, SB 79 advisory (PDF)
https://www.hcd.ca.gov/sites/default/files/docs/planning-and-community/sb-79-mpo-advisory.pdf
Government Code 65912.156 (SB 79 definitions)
https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV&sectionNum=65912.156
Government Code 65863.2 (no minimum parking near transit)
https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV&sectionNum=65863.2
Government Code 65915 (state density bonus law)
https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV&sectionNum=65915
General information, not legal advice. California housing law changes every year, and each city adds its own rules on top of state law. Confirm current requirements with the city or county planning department, and with a California-licensed attorney or architect, before you buy land or file plans.

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