Riverside | Lots and Subdivisions
Riverside Lot Size and Subdivisions: Minimum Lots, Small Lots, SB 9 Splits and SB 1123 Maps
To subdivide is to divide one lot into two or more lots that can be sold apart. In Riverside, lot sizes come from the Zoning Code (Title 19) and the way lots are divided comes from the Subdivision Code (Title 18). This page covers the minimum lot in each zone, the rules for older lots that are smaller than today's minimum, the SB 9 urban lot split in Chapter 18.085, the SB 1123 small-lot map, and who approves each type of map. The Riverside overview sums up the whole guide.
Riverside lots and subdivisions in six facts
- The smallest standard house lot in Riverside is 7,000 sq ft and 60 feet wide in R-1-7000; RA-5 lots start at 5 acres. Source: RMC Table 19.100.040 A
- Legal R-1 lots under 5,500 sq ft use their own table, with three stories and lot coverage of up to 55 percent. Source: RMC 19.100.065
- An SB 9 urban lot split makes two lots, each at least 1,200 sq ft and at least 40 percent of the original lot. Source: RMC 18.085.040
- Urban lot splits are approved by the City Surveyor with no hearing, and the decision cannot be appealed. Source: RMC Table 18.140.040
- The City SB 9 checklist lists a lot split filing fee of $5,117.46 plus $61.56 per parcel, $5,240.58 for two parcels. Source: City SB 9 checklist
- A tentative parcel map or parcel map waiver costs $11,849 in the City fee schedule effective July 1, 2026. Source: Planning Services Fee Schedule
Minimum Lot Size by Zone
Section 18.210.080 says "The minimum area and dimensions of all lots shall conform with the requirements of the Zoning Code." Those minimums are in Tables 19.100.040 A and B. Lot area is measured net of streets, and width is measured at the building line.
| Zone | Min lot area | Min width | Min depth |
|---|---|---|---|
| RA-5 | 5 acres | 300 ft | 500 ft |
| RC | Varies (1/2 acre to 5 acres by slope) | 130 ft | 100 ft |
| RR | 20,000 sq ft | 100 ft | 150 ft |
| RE | 1 acre | 130 ft | 150 ft |
| R-1-1/2 Acre | 21,780 sq ft | 125 ft | 150 ft |
| R-1-13000 | 13,000 sq ft | 100 ft | 110 ft |
| R-1-10500 | 10,500 sq ft | 90 ft | 110 ft |
| R-1-8500 | 8,500 sq ft | 80 ft | 100 ft |
| R-1-7000 | 7,000 sq ft | 60 ft | 100 ft |
| R-3 (all five) | 30,000 sq ft | 80 ft | 100 or 150 ft |
| R-4 | 30,000 sq ft | 100 ft | 150 ft |
Source: Riverside Municipal Code Tables 19.100.040 A and B; RC lot areas from Section 19.100.050.
The notes to Table 19.100.040 A add details that change real lots:
- Narrow old lots. Where a lot is under 65 feet wide and "was of record prior to November 23, 1956," or before it was annexed to the City, the interior side yards shrink to five feet.
- RA-5 lots. Lot area in RA-5 "is measured to the centerline of the adjoining street." An owner may build one house on an RA-5 lot under five acres that existed on May 15, 1979, if the owner lives in it after it is built.
- Curved streets. On cul-de-sac and knuckle lots (lots on a bend in the street), Section 18.210.080 measures width at one-third of the required depth, with at least 45 feet along the curb.
- RC lots. Lot size in the hillside RC zone depends on the slope and on the date the land was zoned RC, from one-half acre to five acres. See the hillsides page.
Section 18.210.080 also sets a test that every new lot must pass. Lots must be usable: "No subdivision shall create lots for building purposes which are impractical for improvement or use due to steepness of terrain, location of watercourses, size, shape or other physical conditions." Each lot meant for a home must allow a driveway "with a grade not in excess of 15 percent" from the street to a garage or parking spot.
Older Lots Smaller Than the Zone Minimum
Riverside has many legal lots that are smaller than their zone now requires. Section 19.100.065 lets them be built on with setbacks that fit their size. A setback is the required distance between a building and a lot line. An R-1-8500 lot of 6,000 square feet, for example, uses the R-1-7000 standards, because the code says that for lots "equal to or greater than 5,500 square feet in area, but less than 7,000 square feet in area, the R-1-7000 standards apply." The same stepping applies in R-1-1/2 Acre, R-1-13000 and R-1-10500, and Section 19.100.060 D does the same for RR lots under 20,000 square feet.
Lots under 5,500 square feet in any R-1 zone have their own table:
| Lot size | Lot coverage | Front | Interior side | Rear |
|---|---|---|---|---|
| 1,500 to 2,499 sq ft | 55% | 10 ft | 5 ft | 10 ft |
| 2,500 to 3,499 sq ft | 55% | 10 ft | 5 ft | 15 ft |
| 3,500 to 4,499 sq ft | 50% | 15 ft | 5 ft | 15 ft |
| 4,500 to 5,499 sq ft | 45% | 15 ft | 5 ft | 20 ft |
Source: Riverside Municipal Code Table 19.100.065. All four sizes allow 35 feet and three stories, with a 10-foot street side yard; garages and carports sit 20 feet back.
These small lots carry privacy rules where they back onto RA-5, RC, RR, RE or R-1 land: "Windows within 30 feet of a structure on another parcel shall not directly align with the windows of the neighboring structure," and upper decks and balconies that face the neighbor sit at least 15 feet from the interior lot lines. In R-3 and R-4, Section 19.100.075 gives a parallel table for lots under 21,780 square feet, covered on the three or more homes page.
One more rule helps new R-1-7000 subdivisions. With a tentative tract or parcel map, "interior side yard setbacks may be reduced to five feet provided a minimum distance of 15 feet is maintained between adjacent dwellings."
SB 9 Urban Lot Splits Under Chapter 18.085
An urban lot split is the SB 9 (2021) process that divides one single-family lot into two, under Government Code 66411.7. Riverside wrote the rules into Chapter 18.085, last amended by Ordinance 7744 in November 2025. A parcel qualifies only if it is in "a Single-Family Zone (R-1, RE, RR, RC, DSP-RES, or NSP-MDR)" and is outside each of these:
- a Very High Fire Hazard Severity Zone, unless fire safety measures apply to the site;
- "a mapped 100-year floodplain, wetland, recorded Open Space Easement, mapped Arroyo," or land set aside for habitat in the Western Riverside Multiple Species Habitat Conservation Plan;
- a designated hazardous waste site;
- a Historic District or Neighborhood Conservation Area, the State Historic Resources Inventory, or a City or County Landmark or Structure of Merit.
The split may not remove housing under rent control or an affordability covenant, housing "occupied by a tenant in the last three years," or a unit taken off the rental market by an Ellis Act eviction in the last 15 years. The Ellis Act is the state law that lets an owner leave the rental business.
Section 18.085.040 sets the lot rules. The two lots should be close to equal in size, and "In no instance shall a parcel be smaller than 40 percent of the lot area of the original parcel proposed for subdivision, or smaller than 1,200 square feet, whichever is greater." VanPlex arithmetic: an 8,500 square foot lot gives a smallest allowed lot of 3,400 square feet. A rear lot without street frontage needs "A minimum ten-foot-wide direct access corridor or easement," and each lot gets "separate sewer, water and electrical utility services." The City may require easements, but street dedication and off-site work "shall not be required, except in connection with a building permit."
After the split, each new lot may hold two homes in total, counting ADUs: "A maximum of two units may be permitted on a parcel created through an urban lot split." A recorded covenant bars further subdivision "in perpetuity." Rentals must be longer than 30 days.
How the Lot Split Is Processed
Section 18.085.050 sets two steps. First, "The applicant for an urban lot split shall first submit for pre-clearance approval from the Planning Division," which checks eligibility. Second, the applicant files a final parcel map. Pre-clearance "shall expire within 36 months of the date of approval" if no map is recorded. Table 18.140.040 names the City Surveyor as the approving authority and adds: "Urban Lot Splits are subject only to ministerial approval and cannot be appealed." Ministerial means staff check the plan against written rules, with no hearing. State law adds a deadline: the City must approve or deny a complete application "within 60 days."
The City's SB 9 checklist, revised December 10, 2025, lists what to file: a chain of title for the last three years, a numbered parcel map, a notarized owner-occupancy affidavit, and a "Filing fee ($5,117.46 + $61.56 per parcel (2) per additional Lot/Parcel or $5,240.58)." It also asks for a notarized affidavit that the property "has not been used as a rental for at least three years."
The checklist and the code differ in two places. Section 18.085.060 C and Government Code 66411.7 count the three years of owner occupancy "from the date of the approval of the urban lot split," while the checklist says "three years from time of map recordation." The code and the statute control. The checklist's rental affidavit also reaches further than the code, which bars only the removal of tenant-occupied housing; ask staff how they apply it to a vacant rental. Section 18.085.060 C holds the City's owner-occupancy rule for a split, and the statute adds that the City "shall not impose additional owner occupancy standards."
Small-Lot Maps: SB 684, SB 1123 and Small Lot PRDs
SB 684 (2023) and SB 1123 (2024) let an owner divide land into as many as 10 lots for up to 10 homes with no hearing, under Government Code 66499.41. Riverside applies them through an SB 1123 checklist. It rules out a multi-family parcel "(R-3, R-4, NSP-MHDR, NSP-HDR, MU-V, MU-U) larger than 5 acres" and a single-family parcel "larger than 1.5 acres" or "with habitable, permanent structures on-site." Projects must reach at least 66 percent of the zone's maximum density, keep the average home at 1,750 square feet or less, and use the City sewer. New lots must be at least 1,200 square feet in single-family zones and 600 in multi-family zones. The land must not have had a tenant "at any time in the last five (5) years." The tentative map filing fee is $11,849.
The checklist adds a timing rule: recording the map "is conditioned on the completion of at least one (1) primary residential structure" on each new lot that does not already have one. So the homes are built before the lots can be sold. See the state rules on the SB 684 and SB 1123 page.
Riverside's own small-lot tool is the Small Lot Subdivision Planned Residential Development, allowed only in R-3 under Section 19.780.020 and limited to "16 or fewer dwelling units." No lot may be "larger than 5,499 square feet," and the project must reach at least half the density of its General Plan designation. In single-family zones, an Administrative PRD covers "four or fewer parcels" and a Minor PRD five to 16 homes. Both are discretionary permits that need findings, explained on the three or more homes page.
| Route | Lots | Smallest lot | Who decides |
|---|---|---|---|
| SB 9 urban lot split | 2 | 1,200 sq ft and 40% of original | City Surveyor, ministerial, no appeal |
| SB 1123 map, single-family zone | Up to 10 | 1,200 sq ft | Planning clearance, then tentative map |
| SB 684 map, multi-family zone | Up to 10 | 600 sq ft | Planning clearance, then tentative map |
| Tentative parcel map (4 or fewer lots) | Per zone | Zone minimum | Community and Economic Development Director |
| Tentative tract map | Per zone | Zone minimum | Planning Commission |
| Small Lot PRD in R-3 | 16 homes or fewer | Set case by case, 5,499 sq ft max | Planning Commission |
Sources: Riverside Municipal Code Chapter 18.085, Table 18.140.040, Sections 19.780.020 and 19.780.060; City SB 1123 checklist.
Ordinary Maps, Corridor Lots and Lot Line Changes
Outside the state routes, a split into four or fewer lots uses a tentative parcel map and a larger division uses a tentative tract map. Table 18.140.040 makes the Community and Economic Development Director, or the City Surveyor, the final authority on tentative parcel maps and parcel map waivers, and the Planning Commission the final authority on tentative tract maps. "Tentative RC Zone Maps require City Council approval on its consent calendar." Under Section 18.150.040 the City has 30 days to decide whether an application is complete.
A corridor access lot (often called a flag lot) is a rear lot that reaches the street through a narrow strip. Section 18.210.080 E allows one only "where there is no reasonable alternative available to develop the interior portions of excessively deep parcels," with a modification, and sets the strip at "a minimum of 20 feet" wide, except for an urban lot split. "The area of the corridor shall not count in computing lot area." For an SB 9 split, "No modification shall be required."
A lot line adjustment moves the line between two existing lots without making a new lot. The City Surveyor decides it, and must issue a written decision "within 30 days after the filing of a complete application." Where land lies in an adopted area drainage plan, Section 18.240.020 adds a drainage fee to the final map.
Best For
- ✓ R-1 lots of 7,000 sq ft or more that can split into two lots of at least 2,800 sq ft.
- ✓ Older narrow lots, which keep five-foot side yards under note 3.
- ✓ Vacant single-family parcels of 1.5 acres or less for an SB 1123 map.
Usually Fails When
- ✕ The lot is in a mapped arroyo, floodplain or historic district, which rules out an SB 9 split.
- ✕ A tenant lived in the house in the last three years.
- ✕ The lot was itself created by an earlier SB 9 split.
What To Verify Before Spending Money
- → Separate water and sewer service for each new lot with the utility providers.
- → Whether the City counts the three-year owner occupancy from approval or from recording.
- → Any area drainage plan fee that applies to the final map.
Where to Go Next
Related on VanPlex: the Riverside overview, SB 9 in California and SB 684 and SB 1123.
Frequently Asked Questions
What is the minimum lot size for a house in Riverside?
Can I build on an R-1 lot that is smaller than the zone minimum in Riverside?
How do I split my lot under SB 9 in Riverside?
How small can SB 9 lots be in Riverside?
Do I have to live on the property after an SB 9 lot split in Riverside?
Can an SB 9 lot in Riverside be split again later?
What is an SB 1123 subdivision in Riverside?
Who approves a parcel map in Riverside?
How long does Riverside take to decide a tentative map?
What is a corridor access lot in Riverside?
Official sources (checked October 2026)
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