Study: Alley-loaded Development Can Save Money Vs. Front-loaded Homes

Alleys became a signature element of urban development as industrialism took hold, a time before the “missing middle” of housing affordability went missing. Major U.S. cities grew up with alleys behind homes to keep deliveries and sanitation out of sight of the main street.

The garage, however, became the hallmark of sprawling suburban development fed by a rising car culture as residents left urban areas.

Buyers appreciate the convenience and visible security of pulling directly into their garages—perks that also enhance curb appeal in suburban neighborhoods. For the home builder, the front-loaded design avoids the added infrastructure and maintenance costs often associated with alleys.

The Center for New Urbanism, which favors alleys, challenged the prevailing preference for garages in a new study by Michael Mehaffy, president of Structura Naturalis Inc., and Laurence Qamar, principal at the town planning firm Qamar & Associates.

“This analysis is focused on the cost issue alone and is separate from the consideration of the other documented benefits from alley-loaded homes, including more pedestrian-friendly streetscapes, greater walkability, a more attractive public realm, support for more social interaction and sense of community, and other public goods,” the study says.

Mehaffy and Qamar show evidence that driveway costs often offset alley paving costs, especially with standard lot sizes. Wider streets for front-loaded, garage-front homes raise infrastructure costs. Alley-loaded homes use narrower lots, providing additional affordable housing options.

Price to build alley-loaded

Their study compares alley-loaded and front-loaded residences using infrastructure costs per lot. Researchers analyze, compare, and contrast pavement, utility costs, and land yield for both development types.

Alley-loaded developments often cost less per lot than front-loaded ones, researchers find. They also determine that alley-loaded homes require less street width, further reducing paving expenses.

For 40-ft.-by-125-ft. lots, alley-loaded homes cost about $2,500 less per lot compared with front-loaded ones. Smaller and narrower alley-loaded lots can cut costs, dramatically improving a housing affordability solution.

Front-loaded lots require more pavement because driveways interrupt street parking, the study shows. Pavement in front of driveways in front-loaded homes cannot function as parking spaces or as travel lanes.

Utilities and frontage lengths also affect costs, with front-loaded lots driving expenses up due to their greater width. The study uses industry benchmarks for construction and utility costs in its calculations.

Builder experience with alleys

Mehaffy and Qamar cite Denver as an example where builders have favored alleys, resulting in higher-density neighborhoods that appeal to buyers and foster walkable streets.

According to the study, alley-loaded homes create attractive community layouts and functional outdoor spaces.

The researchers also highlight a diversity of homebuilder perspectives. In Redmond, OR, homebuilders pushed back against alley-loaded mandates, arguing that narrow homes with rear garages cost more to build and are harder to sell.

Builders in Redmond asked for flexibility, not a strict alley-loaded requirement.

The researchers cite a National Association of Homebuilders 2019 report titled “Diversifying housing options with smaller lots and smaller homes,” which encourages small lots and alleys for both housing affordability and variety.

However, the report notes that a challenge arises when local utility, public works, and fire department officials tend to advocate for larger and more conventional easements, streets, and alleys.

“This affects development costs as well as unintended consequences of overly wide alleys, then being considered streets and additional requirements,” the NAHB report says.

In the CNU study, Mehaffy and Qamar offer guidance to help planners avoid overly prescriptive lot rules.

The study says builders may be able to optimize costs and neighborhood appeal if given clear guidelines.

Across the country, cities have been working to modestly increase density through new laws that support building “missing middle” housing, such as duplexes, triplexes, and small apartment buildings. It’s the type of housing built when alleys were more popular.

Much of the planning of these modest-density developments has focused on street parking rather than garages or more limited front-loaded houses.

The researchers highlight that homebuilders can not only avoid extra costs with alleys, but also save money compared with conventional front-loaded development.

“The win-win result can be a much more walkable, more attractive, and ultimately more successful neighborhood,” the researchers said.