An architects office building rarely becomes a tourist attraction. But just east of Seattles downtown, the offices of Schemata Workshop, built in 2016, draw national and international visitors.Thats because the overall project, Capitol Hill Urban Cohousing (CHUC), represents a rare contemporary example of single-stair architecture. The term refers to structures above 4 stories with a single stairway, meaning they have one means of egress. But a combination of zoning codes, fire safety concerns, and financial pressures have made single-stair construction impossible to build across roughly 97 percent of the United States. CHUC, which includes ground-floor offices and 4 stories of housing, has become an aspirational model of this building type and a symbol for efforts to legalize it across North America. I do a monthly tour with legislators and building officials because theres been so much interest, said Mike Mariano, cofounder and principal at Schemata.Since gaining more widespread attention in 2021 due to then-emerging social media discourse on the subject, the campaign to legalize single-stair development has activated a growing cadre of architects and advocates interested in code reform. Last years AIA Conference on Architecture featured a panel on the topic, while Denver architecture firm SAR+ recently held a single-stair design contest. According to the Single-Stair Tracker, which chronicles this movements legislative and regulatory efforts, 21 states, cities, and provinces across North America have instituted some form of reform, or more commonly, commissioned safety and code studies to pursue future reform. In Canada, there are proposals to change the national code, while British Columbia updated its code last August to allow single-stair residences up to 6 stories tall.Grassroots support is something the building code world often does not see, said Stephen Smith, executive director of the Center for Building in North America, which runs the tracker. The YIMBY movement has become interested in codes and standards in a way [building code decision makers] havent seen before, and theres a big culture clash.The Capitol Hill Urban Cohousing project represents a rare contemporary example of single-stair architecture. (Courtesy Schemata Workshop)The repercussions of such a shift mean much more than simply eliminating a stairway. Coming at a time when many designers have pushed for buildings to better respond to current crises, such as housing affordability and sustainability, the single-stair crusade shows architects becoming more engaged in building code and zoning reform.Architect and author Mike Eliason, principal of Seattles Larch Lab, author of the recent book Building for People, and an early and influential single-stair advocate, argues that pushback by code and fire-safety officials highlights the need to democratize decision-making around what and how we build. Nobody in the U.S. really talks about the interface between the building code and the zoning code and the built environment, he observed. But if we want more highquality spaces, these conversations need to happen more often. The nonprofit International Building Code, which forms the basis for most state and local U.S. building codes, mandates that buildings over 3 stories have two separate staircases for fire safety, resulting in larger, chunkier apartments with double-loaded corridors. These requirements began entering local building codes in the late 19th and early 20th centuries in response to large urban fires and safety concerns.Single-stair projects, also called point-access blocks, exist around the globe and provide a type of small-building living experience and community that isnt achievable here, as just a handful of jurisdictions in urban North America permit them, including Seattle, New York City, and Honolulu.Single-stair reforms potential shouldnt be seen as a silver bullet to solve larger housing issues, said Conrad Speckert, a Canadian intern architect who has written extensively on the topic and submitted national single-stair changes to building codes. It can help affordabilityPew Trusts data shows single-stair designs can lower apartment costs by 6 to 13 percent compared with standard construction.Freeing space taken up by a stairway allows for exciting design and development possibilities and opens thin urban lots that would otherwise be financially infeasible. Subtracting a second form of egresswhich Speckert estimates can cost up to $300,000 for a small buildingwould also allow funds and square footage that could be used for a small elevator for ADA access; this strategy is seen in European versions of single-stair buildings. The move also creates the chance for two- and three-bedroom units to have improved daylighting and airflow, as layouts can span the full depth of a block versus being aggregated on either side of a double-loaded corridor. Schematas CHUC, for instance, was able to incorporate all manner of passive ventilation and daylighting strategies in the buildings eight housing units, including more shared social space.In Austin, Councilmember Jos Chito Vela, who represents a district with a sizable apartment-dwelling population, sponsored the citys single-stair resolution, which passed last May. He believes that legalizing these kinds of buildings can add more fine-grained apartment projects. Single-stair development can help push the unit price down to an ownership price point, Vela said. His stance speaks to the evolving political support around this shift in building codes. Vela believes that even if the fire department has some objections, the current pro-housing council could ultimately vote in favor of the change.Most of the existing single-stair efforts have resulted in mandated study periods to gauge how single-stair projects would impact fire safety and existing codes, most of these studies will be completed by 2026. Vela hopes that in Austin, where single-stair reform is now being debated by the city council, fire officials wont let the perfect be the enemy of the good.The National Fire Protection Association (NFPA), which has substantial impact on building safety codes, held a symposium on the single-stair effort in September 2024, inviting a range of fire safety officials, regulators, and advocates like Smith. Its clear the group has felt pressure from the grassroots push; its own publication noted last August that fire officials were blindsided by the speed of reform initiatives, with some fire chiefs stating that we must do all we can to defeat these misguided efforts.At CHUC, passive ventilation and daylighting strategies were also incorporated into the buildings eight housing units along with more social space. (Courtesy Schemata Workshop)In the organizations November report summarizing the symposium and its findings, the NFPA didnt quash the single-stair concept, but it did push for adherence to the traditional process it oversees. When this process is substituted by uninformed legislative action, special interests, or misguided local policy decisions, there is great risk to the protection and safety of people and property, the summary reads.As more jurisdictions embark on single-stair reform and currently authorized studies get completed and published, advocates seek to maintain the pressure by mandating objective research and studies, advocating for code reforms and ideally using the results of these studies to push for rapid change to the building codes.Existing evidence suggests single-stair buildings dont have a significantly worse safety record than traditional buildings. New York City records show only three serious fire incidents in the citys 4,400 single-stair buildings since 2012. The overall fire safety record in the U.S. remains worse than in peer countries, despite our mandate for more stairways. The British Columbia governments June 2024 report on single-stair safety found that just 8 to 10 percent of fires in apartments start in egress routes, and those that do are mostly small trash fires, which rarely spread beyond the room of origin. The doubts about safety recall the recent movement to legalize mass timber in the U.S., which also required extensive efforts at code reform and testing to allay material safety concerns. Now the structural system is safely being used across the country.Fire and code officials werent happy that the debate wasnt confined to the normal processes. I suspect that if it hadnt been for all the legislation, [single-stair] wouldnt have been taken as seriously as it was in the code world, said Smith.As the reform process plays out and more and more jurisdictions embrace or explore the idea of single-stair buildings, advocates hope these forthcoming changes unlock a tool for better housing design and improved affordability.Patrick Sisson is a Chicago expat living in Los Angeles who covers design, policy, and the trends that shape our cities.