What Are They?

Single stair buildings, also known as “point access blocks” or buildings with a “single means of egress,” are multi-family structures served by one primary stair for occupant access and exit. In Washington, DC, and most U.S. jurisdictions, these buildings are currently allowed up to three stories in height. However, proposed updates to the building code aim to expand their use up to six stories, with as many as four to six dwelling units per floor. These buildings may also include an elevator and can be constructed using Type III (all-wood, fire retardant treated) or podium (Type V over Type I) construction.  To ensure life safety, they are typically required to have full sprinkler coverage, a supervised fire alarm system, and a standpipe. Internationally, single stair buildings are commonplace, especially in Europe, and are increasingly accepted in cities like Seattle and New York.  Unlike rowhouses, townhouses, or large-scale apartment complexes, their compact, vertical form makes them ideally suited for infill sites and smaller lots in dense urban areas like Washington, DC.

Why Design Them? What Are the Benefits?

Single stair buildings offer a wide range of design, economic, and sustainability benefits:

  • Better design outcomes: These buildings often allow for “through-units” with windows on two sides, which increases access to natural light and cross-ventilation. They also support larger, family-friendly unit layouts with greater flexibility for aging in place or multigenerational households.
  • Contextual urban density: Their smaller footprints allow them to integrate more easily into existing neighborhoods. This “gentle density” helps deliver housing at a scale that complements existing urban fabric and supports walkable communities, without requiring land assemblages or large building masses.
Single Stair Building - Infill Sites

Single Stair Building – Infill Sites

  • Cost-effective construction: Removing the second stair reduces construction costs and allows developers to redirect savings toward elevators and accessibility improvements. They also reduce the amount of unproductive circulation space, which increases usable square footage and improves financial viability.
  • Adaptive reuse potential: most older cities (DC included) have a rich inventory of older buildings that could be more easily adapted into housing if single stair configurations were permitted. This flexibility supports preservation goals and sustainability efforts by conserving embodied carbon and extending the life of existing structures.
  • Lower operational energy demand: With less circulation space to condition and light, these buildings can reduce HVAC and electrical loads, further supporting energy efficiency goals.
Why Single Stair Buildings Make Sense for Washington, DC

Washington, DC is uniquely positioned to benefit from the adoption of single stair buildings due to a combination of urban form, policy constraints, and development pressures. Several local conditions make this building type especially appropriate:

  • Fast emergency response times: DC’s compact urban layout and the well-distributed locations of Fire and EMS stations contribute to faster response times than many other cities. This high level of service helps mitigate concerns around single means of egress and reinforces the viability of this building type from a safety standpoint.
Single Stair - Fire Response Time

Single Stair – Fire Response Time

  • Abundant historic building stock: DC’s existing inventory of older and often underutilized buildings presents significant opportunities for adaptive reuse. Many of these structures were originally built with a single stair and could be sensitively converted into modern housing if current code restrictions were updated.
  • Height and zoning limitations align with the typology: DC’s zoning regulations, including strict height limits and caps on density in many Residential Apartment (RA) and Mixed-Use (MU) zones, naturally support mid-rise buildings. Single stair configurations fit well within these parameters, offering a way to maximize livability and design quality without triggering zoning variances.  They add flexibility within the existing zoning regulations.
  • Few remaining large development sites: Most undeveloped land in the District consists of narrow or irregular infill lots. Single stair buildings, with their compact footprints and vertical organization, are ideally suited for these constrained urban parcels where conventional multi-core layouts are inefficient or infeasible.
  • High construction and land costs: Rising development costs in DC demand creative, efficient design solutions. Eliminating a second stair not only increases net usable area but also lowers construction expenses. These cost savings can help make projects financially feasible while also enabling the inclusion of quality-of-life features such as elevators or larger unit layouts.

Together, these factors create a strong case for advancing single stair buildings as part of DC’s broader housing strategy. This typology isn’t just feasible—it’s a practical, context-sensitive solution to the city’s growing need for sustainable, incremental, and equitable housing.

What Challenges Do They Face?

Despite their advantages, single stair buildings face a number of regulatory and perceptual challenges:

  • Code restrictions: Current codes such as the International Building Code (IBC) and NFPA require multiple means of egress in taller multifamily buildings. The DC Building Code follows these standards, so enabling taller single stair buildings will require amendments to local codes and advocacy at the policy level.
  • Perceived safety concerns: Although international precedent and U.S. research support the safety of single stair buildings, skepticism remains among fire officials and the public. Concerns about evacuation, firefighter access, and historical performance data continue to shape resistance.
  • Design constraints: Meeting stretcher-size elevator requirements and designing for occupant safety within a single stair configuration can be challenging, particularly on constrained urban sites.

We have deep respect for Fire and Emergency responders and are committed to designing safe buildings and environments. At the same time, we must engage with data and experience from other jurisdictions to evaluate and balance life-safety concerns with the need to expand housing supply.

What’s Next?

The One Front Door Act of 2025 is currently under consideration by the DC Council. This legislation would allow taller single stair buildings by incorporating model code language already developed in other jurisdictions. Similar efforts are underway in Virginia and Maryland.  And more studies are currently being done to further support the safety of single stair buildings. For successful adoption, several key steps are needed:

  • Engaging with DC Fire and EMS to build consensus around safe implementation
  • Adapting model codes to fit DC’s urban conditions and strong emergency response capacity
  • Public education and advocacy to shift perceptions and build support for single stair buildings

Single stair buildings are not a universal solution, but they represent a vital tool for creating more sustainable, inclusive, and affordable housing in Washington, DC. As the city continues to grapple with housing challenges, this typology provides a flexible, context-sensitive strategy for delivering more housing options at a neighborhood scale.