The Single Stair Revolution: Rethinking American Housing

For decades, the American approach to apartment building design has remained remarkably consistent: multiple staircases, sprawling layouts, and a focus on single-family homes. But a growing movement is challenging these norms, advocating for the adoption of single-stair apartment buildings to address the nation’s pressing housing affordability crisis. This push, led by architects, urban planners, and housing advocates, seeks to modernize building codes and unlock a new wave of "missing middle" housing options.

The spark for this revolution can be traced back to Michael Eliason, an architect who, after experiencing European building practices, noticed a stark contrast between apartment buildings in the United States and those abroad. While working in Germany, Eliason observed that European buildings tended to be thinner, more compact, and benefited from greater natural light. Upon returning to the US, he realized that American apartment buildings were often massive, deep, and less accommodating to diverse unit sizes.

Eliason’s experience was not unique. Across Europe, South America, and Asia, single-stair apartment buildings are a common feature of urban landscapes. These buildings, often four to six stories tall, rely on a single, centrally located staircase for access and egress. The US, however, largely abandoned this model in favor of a two-staircase approach, particularly for buildings exceeding three stories.

The turning point for Eliason came during a conversation with his future boss in Germany. While discussing a 12-story housing project, Eliason questioned the absence of a second staircase, a standard requirement in the US. His employer’s puzzled response – explaining that a second staircase would render the project financially unviable – highlighted the fundamental differences in housing construction between the two countries.

Inspired by this realization, Eliason began sharing his observations on social media. He quickly connected with Stephen Smith, a New York-based urbanist writer, and together, they formed a coalition of like-minded individuals. This group introduced the concept of single-stair housing to American audiences, arguing that it could unlock significant affordability and design benefits.

The rationale behind the single-stair movement is multifaceted. First and foremost, eliminating a second staircase can substantially reduce construction costs. Research suggests that adding a second staircase to a six-story apartment complex can add hundreds of thousands of dollars to the project’s budget. By removing this requirement, developers could potentially cut costs by up to 10 percent, making it easier to build more affordable housing options.

Beyond cost savings, single-stair construction also offers design flexibility. The absence of a second staircase and its associated corridor allows for more efficient use of space, creating more diverse unit layouts. This is particularly important for accommodating families, as single-stair buildings can more easily incorporate three- and four-bedroom apartments, a rarity in modern American construction.

Moreover, single-stair construction can make it easier to develop on small, underutilized lots in dense urban areas. These lots, often deemed too small for traditional two-staircase apartment buildings, could become viable sites for "missing middle" housing, providing much-needed density and affordability.

The historical context of American building codes provides insight into the dominance of the two-staircase approach. Unlike Europe, where urban fires prompted the use of brick and stone, the US prioritized speed and cost, favoring wood construction and spacious layouts. This reliance on space as a fire safety measure meant that compact building designs were less necessary.

The devastating Manhattan tenement fire of 1860 further solidified the emphasis on multiple exits. In response, New York passed a law requiring fire escapes on new residential buildings. This "second exit" philosophy became deeply ingrained in American construction culture, culminating in the International Code Council’s (ICC) mandate for two staircases in buildings at least four stories tall.

However, advocates for single-stair construction argue that modern fire safety features, such as sprinklers and advanced alarm systems, have made multifamily housing remarkably safe. They point to the global prevalence of single-stair buildings and the lack of evidence suggesting increased fire deaths in countries that permit them.

Despite these arguments, the single-stair movement faces resistance, particularly from fire safety officials. Opponents express concerns about evacuation, fire operations, and overall resident safety in single-stair buildings. They argue that the US’s low fire death rates are due, in part, to the two-staircase requirement.

The International Association of Fire Fighters (IAFF) has been particularly vocal in its opposition, arguing that removing a second exit is an unacceptable trade-off for additional housing. They also question the validity of international comparisons, noting that fire safety resources and building codes vary across countries.

Fire officials also express concern about the growing trend of legislators revising building codes without relying on the expertise of organizations like the ICC and the National Fire Protection Association (NFPA). They argue that these organizations provide a valuable forum for technical experts to evaluate safety trade-offs.

Proponents of single-stair construction counter that these organizations are not always neutral, and that their recommendations can be influenced by commercial interests. They argue that elected officials have a responsibility to represent the interests of the public, even if those interests conflict with the views of technical experts.

Despite the opposition, the single-stair movement has gained significant momentum in recent years. Several cities and states have already carved out exceptions to the two-staircase requirement. New York City, for example, has allowed single-stairway mid-rise buildings since 1938, while Seattle permits them with additional safety features like exterior stairways or smoke-proof towers. Honolulu, Georgia, Vermont, and Puerto Rico have also adopted similar approaches.

Research comparing fire department statistics from Seattle and New York with other major US cities has found no evidence of increased fire risks in single-stair buildings. This evidence, combined with the global prevalence of single-stair construction, has fueled the growing support for building code reform.

To date, at least 15 states have passed laws or amended regulations to allow single-stair design in four- to six-story buildings, or are actively considering such changes. This rapid progress has surprised even the movement’s most ardent advocates, who attribute it to the growing awareness of the housing crisis and the potential of single-stair construction to unlock affordability and design benefits.

Minnesota, for example, has invested significant resources into studying single-stair construction, while Utah plans to prioritize single-stair reform in the coming years. In Virginia, a study group of stakeholders is evaluating the idea, bringing together fire code officials and housing advocates to find common ground.

Even the ICC has shown signs of flexibility, with plans to increase its single-stair height limit in its 2027 edition. This modest change signals a growing recognition of the potential benefits of single-stair construction.

Looking ahead, advocates for single-stair construction envision a future where American cities are more affordable, walkable, and diverse. They believe that single-stair buildings can play a crucial role in creating a broader array of housing options, including social housing, market-rate housing, condos, and co-ops. By modernizing building codes and embracing innovative design approaches, they hope to unlock a new era of urban development that meets the needs of all Americans. The push continues even with more studies on the horizon in order to better address the fire safety concerns in the adoption of the movement.