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One of the ways that local governments regulate residential development is through minimum lot size requirements. Back when land was relatively inexpensive, large lots ensured privacy and a pleasant neighborhood aesthetic. Today, land is no longer cheap, and zoning codes that mandate larger minimum lot sizes can substantially increase housing development costs. Amending these codes to allow smaller lots and houses in areas zoned for higher-density may reduce land and construction costs, and increase housing affordability for low- and middle-income families. This article will highlight some of the ordinances and code provisions adopted by local governments to encourage affordable housing development, such as allowing lots under 5,000 square feet to be developed for single-family housing.

Small Lot Subdivisions in Los Angeles, California

Townhomes developed by EHOP utilizing the small lot subdivision ordinance in Los Angeles, California.
Photo Credit: Enterprise

Single-family home prices in Los Angeles, California are usually out of reach for the average first-time homebuyer. To increase homeownership opportunities for residents looking for affordable detached or attached single-family homes, the city adopted the Small Lot Subdivision Ordinance in January 2005. The ordinance allows subdivision of multifamily or commercially-zoned properties into lots for detached single-family or attached townhomes. Developers can build several detached units as small as 600 square feet on subdivided lots, without the liability issues and insurance costs associated with a condominium project. In addition to the smaller lot sizes, the ordinance waives setback requirements and allows lot coverage of up to 80 percent. As of March 2008, the ordinance has resulted in the construction of 1,117 homes on lots ranging from 1,000 to 2,000 square feet in size. Utilizing the small lot subdivision ordinance, Enterprise Home Ownership Partners, a nonprofit organization, recently completed eight affordable and environmentally sustainable townhomes in the city. The for-sale townhomes, available to households earning up to 150 percent of the area median income, were built on a 10,562 square foot lot. Jeff Schaffer, Southern California director for Enterprise Community Partners said that, "This particular city ordinance has invigorated our ability to craft unused urban land, such as vacant lots, into structures that offer great benefit to the community and the tax base."

Seattle's Residential Small Lot Zone

Heiwa Commons  a small lot single-family development in Seattle, Washington.

The Residential Small Lot (RSL) zoning district in Seattle, Washington allows detached single-family homes on 2,500 square foot lots. Additional classifications within the RSL zone permit development of tandem and cottage housing units. Tandem housing allows two detached single-family homes per lot, while cottage housing allows four to twelve single-family houses to be developed on a single lot. Minimum density requirements for tandem and cottage housing are one house per 2,500 square feet of lot, and one cottage per 1,600 square feet, respectively. The city recently adopted changes to the zoning ordinance, limiting the building footprint of homes on lots less than 5,000 square feet. This restricts developers from building large homes on small lots and selling them at higher prices. The changes also allow parking requirement waivers for lots that do not have alley access, and are under 3,000 square feet or less than 30 feet wide.

San Antonio's R-3 Single Family Residential District

In order to increase affordable housing options, the city of San Antonio, Texas designed the R-3 Single Family Residential zoning district, which allows detached single-family houses, townhouses, and zero-lot line houses on parcels having a minimum area of 3,000 square feet. There are no side-yard setback requirements for lots within this zone, and the code allows lot coverage of up to 70 percent. So far, 45 new lots have been created using this zoning designation.


Reducing minimum lot sizes can lower residential development costs and increase opportunities for the development of affordable housing. In communities with expensive real estate, high land costs can decrease housing affordability for low-income families. Allowing higher densities by adopting zoning designations to allow smaller lot and house sizes with reduced setbacks can increase the single-family housing supply and provide homeownership opportunities for many buyers who would otherwise be excluded by high prices and limited availability.

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