San Marcos | Three or More Homes

San Marcos, California Three or More Homes: R-2 Fourplexes, R-3 and Mixed Use Apartments, Open Space and Parking, Inclusionary Housing, the Density Bonus and SB 79

This page covers projects of three or more homes on one site in San Marcos: triplexes, fourplexes, townhomes and apartments. San Marcos has no separate "missing middle" chapter. Small multifamily buildings are allowed in its R-2 zone, and larger ones in R-3-10, R-3-6 and the two mixed use zones that allow homes, all under Title 20 of the San Marcos Municipal Code. Two City rules add cost or time to every such project: an inclusionary housing chapter that reaches projects of one or more units, and a Planning Commission hearing for every attached project in R-2 and R-3. The San Marcos overview has the summary.

Standards by Zone

Sources: San Marcos Municipal Code Tables 20.215-3 and 20.215-4 and Section 20.215.060(B). Setbacks are measured from the back of the right-of-way.

R-2. The R-2 zone is the City's small multifamily zone. Note 2 of Table 20.215-2 limits multifamily use there to "small lot single-family homes, attached single-family homes, duplexes, and 3-unit buildings and/or 4-unit buildings designed in massing/character to appear as a single-family home." Lots are at least 3,500 square feet, density is 12 homes per gross acre, and buildings are 35 feet or 2 stories, whichever is less. The minimum single-floor living space width in R-2 is 14 feet, against 20 feet in the R-1 zones. By VanPlex arithmetic, three homes need 10,890 square feet of lot and four homes need 14,520. An attached single-family home may sit on a "0-foot lot line on the attached side."

R-3-10 and R-3-6. Table 20.215-4 sets the multifamily standards. R-3-10 allows 20 homes per gross acre on a 10,000 square foot minimum lot, and R-3-6 allows 30 on a 6,000 square foot minimum lot. Buildings may be 35 feet or 2 stories in R-3-10 and 45 feet or 3 stories in R-3-6. The street setback is 15 feet. Other project edges need 10 feet, except that R-3-6 projects of up to 3 units need 7.5 feet. Parking areas must be 8 feet from any property line in R-3-6 and 5 feet in R-3-10. Driveways along alleys and private drive aisles must be 3 feet or at least 18 feet deep; "Driveway dimensions between 3 feet and 18 feet in depth are prohibited."

Mixed use. MU-1 allows 20 to 30 homes per acre and MU-2 allows 30 to 45, with buildings of up to 4 stories and 48 feet in MU-1 and 5 stories and 60 feet in MU-2. Each unit must have at least 600 square feet. Table 20.225-2 parking for homes in mixed use projects is lower than in the R zones: 1 space for a studio, 1.25 for one bedroom, 1.75 for two bedrooms and 2.0 for three or more.

Design, Open Space and Operations

Sections 20.215.060 to 20.215.080 apply to new projects and unit conversions in R-2 and R-3 and to attached PRD projects. They begin with a required pre-application meeting "to discuss guideline criteria and specific project application direction." The rules that change a site plan most are:

• Common open space. "Common open space is required for all multifamily projects, in addition to private open space," with at least three of eight listed amenities, such as a pool, barbecue area, playground or sport court. Parking areas, private roads and land over 10 percent slope do not count.
• Tot lots. "For every twenty-five (25) dwelling units, one (1) tot-lot shall be required", each with at least 400 square feet of usable area. Projects of 75 or more units add a play area of at least 800 square feet.
• Laundry. "All developments of five (5) units or more shall be required to provide a laundry room, unless laundry facilities are provided within each unit."
• Storage. Units without an enclosed garage need "a minimum of fifty (50) square feet of enclosed exterior storage for each unit."
• Walkways and directory. On-site walkways are at least 4 feet wide; projects of 25 or more units need a unit location map at each main entrance.
• Building design. Section 20.215.080 requires stepped massing, layered wall planes, staggered setbacks and upgraded detailing on every elevation facing a street or common area.

By VanPlex arithmetic, a four-unit R-3 project whose units each have 1,000 square feet of livable ground floor area needs 1,200 square feet of common open space, on top of 250 square feet of private patio for each ground floor unit.

Parking for Multifamily Homes

Table 20.340-1 sets parking for multifamily dwellings: "Studio: 1 space/unit; 1 Bedroom Unit: 1.5 space/unit 2+ Bedroom Unit*: 2 spaces/unit; 1 space shall be covered Guest Parking: 1 space/3 units." The note adds that "1 garage space shall be provided for condominiums, duplexes, townhomes, patio homes" and that apartments provide one covered space. A duplex needs 2 spaces per unit and one guest space for every 3 units. Section 20.340.040(D) rounds a fraction of 0.5 or more up and drops a smaller fraction.

By VanPlex arithmetic: a fourplex of two-bedroom units needs 8 spaces plus 1.33 guest spaces, so 9 in all; a fourplex of one-bedroom units needs 6 plus 1, so 7; a duplex needs 4 plus 0.67, which rounds to 1, so 5. Deed-restricted affordable housing is parked "based on State's" standards, and in R-2 and R-3 a rental unit's assigned space must be covered and at least 12 by 20 feet. The parking, setbacks and height page has the full tables.

Inclusionary Housing

Source: San Marcos Municipal Code 20.310.020 to 20.310.050 (Ordinances 2024-1550 and 2025-1568).

Inclusionary housing means homes in a market-rate project that must be rented or sold at prices that lower-income households can afford. San Marcos Chapter 20.310 "shall apply to all residential projects of one (1) or more units", including rentals, for-sale homes, condominium conversions and time extensions of earlier approvals. "Target households" are extremely low, very low, low and moderate income households.

For rentals of more than six units, 15 percent of the units are reserved, and the mix by income follows "the deficit identified in the City's most recent Annual Housing Element Report." No more than 25 percent of the inclusionary units may be for moderate income. The units must match the market units in look and in bedroom count and size, be built before or with them, and stay affordable "for a minimum of fifty-five (55) years." Rental inclusionary units may never be turned into condominiums. For for-sale single-family homes the default is the in-lieu fee, and "the final determination if an in-lieu fee will be accepted or if the development must provide the required inclusionary units shall be based on review by the City Council."

The in-lieu fee amount "shall be established by resolution of the City Council", applies to the total number of units, and is due "at the time of issuance of building permits for the first residential units." VanPlex could not read the current fee resolution, because the City's website refused automated requests. A developer who must provide units signs an inclusionary housing agreement that is recorded before the final map or the building permit, with a City right of first refusal on for-sale inclusionary units.

The Density Bonus and Streamlined Routes

The state density bonus law, Government Code 65915, gives extra homes and relief from some standards to a project of five or more units that includes affordable homes. San Marcos applies it through Chapter 20.305. The chapter uses the state definition of a housing development, "a development project for five or more residential units, including mixed use developments," and grants the bonus "after review by the City Council." Density bonus units are rounded up "to the next larger integer." The City must decide within 30 days whether a density bonus application is complete, and a denial of a bonus, incentive or concession by the Director may be appealed to the Planning Commission within 10 days.

The inclusionary chapter still applies. Section 20.310.020 says its provisions "must still be met for density bonus projects", and for for-sale homes the in-lieu fee is figured on "the total number of housing units in the development prior to including any increase" from a density bonus.

Chapter 20.350 writes two state processes into the code. A preliminary application under SB 330 locks in the rules in effect when it is filed, if the full application follows "Within 180 days." Ministerial streamlined approval under Government Code 65913.4, the SB 35 process, sends qualifying affordable projects to the Development Advisory Committee, with parking capped at one space per unit and none within one-half mile of public transit. Section 20.350.030 says it applies to applications "deemed complete before January 1, 2026" unless the state extends the statute; VanPlex did not read the current Section 65913.4, so ask the City which date it uses.

SB 79 Near Transit

SB 79, the 2025 transit housing law, makes housing of five or more units an allowed use on residential, mixed use and commercial land within one-half mile of a "transit-oriented development stop", at a minimum of 30 homes per acre and an average unit size of no more than 1,750 net habitable square feet. HCD's advisory of March 20, 2026 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." Its table of commuter rail lines includes the "Sprinter", with the warning that "Not all commuter rail stops and stations are necessarily TOD stops."

Where SB 79 applies, Government Code 65912.157 sets floors that the City may not go below: from 55 to 75 feet of height and 80 to 120 homes per acre, depending on whether the stop is Tier 1 or Tier 2 and whether the lot is within one-quarter or one-half mile. The half-mile ring applies "within a city with a population of at least 35,000", and San Marcos has 94,908 people. The City may keep inclusionary rules that do not prevent those standards, but "shall not adopt any requirement ... that applies to a project solely or partially on the basis that the project is seeking approval as a transit-oriented housing development."

The San Marcos code chapters read for this guide contain no SB 79 provisions. The City may have acted after the March 10, 2026 ordinance that ends Municode's list, and VanPlex could not read City Council agendas. Ask the Planning Division whether a qualifying stop lies within one-half mile of your lot, which tier it is, and whether the City has adopted SB 79 rules of its own.

Where to Go Next

Related on VanPlex: the San Marcos overview, the California SB 79 page and the California impact fees page.

Frequently Asked Questions

Official sources (checked October 2026)