Michael Eliason was an undergraduate studying architecture at Virginia Tech University when he went to live for a year in Germany. While interning in Freiburg in 2003, he worked on projects including apartment buildings four or five stories tall. After returning to the US and graduating, Eliason began his architecture career in Seattle, where he soon noticed that all the buildings he worked on kept getting “bigger and bigger.” It felt to him “like the exact opposite of my experience working in Germany.”

Reviewing his portfolio years later, Eliason noticed a stark contrast: All the US apartment buildings were massive and deep, while the European ones were relatively thin, featured different unit layout sizes, and welcomed significantly more natural light. He couldn’t quite articulate the significance yet, but he began to recognize that the German approach seemed to be the standard for urban housing throughout Europe, South America, and Asia.

In 2019, Eliason moved back to Germany with his wife and children. Before the first day at his new job, he and his soon-to-be boss discussed a 12-story housing project that had recently won a competition. Eliason was confused by the blueprint.

“There needs to be a second stair, right?” he asked. “Because in the US we would require a second stair for anything over three stories.” His new employer was puzzled by the question and explained that adding a second staircase would make the project financially infeasible.

“That was really the turning point for me,” Eliason told Vox. “The realization that the way we do housing in the US is radically, radically different from the rest of the world.”

He began sharing his observations on Twitter (since renamed X) and was joined by Stephen Smith, a New York-based urbanist writer who also frequently posted about architecture and real estate. Eliason, Smith, and a group of like-minded thinkers soon formed an informal coalition (and a group chat), introducing the concept of single-stair housing to American audiences. Ever since, they’ve been making the case that modernizing US building codes to permit this design could unleash more affordable housing nationwide — and their approach is winning even in the face of opponents who warn it’s unsafe.

How the US developed its double-staircase standard

In the United States, abundant forests and rapid westward expansion made wood the building material of choice. Unlike Europe, where dense cities and a long history of urban fires pushed builders toward brick and stone, Americans prioritized speed and cost — decisions that shaped building safety norms for generations.

“The US just had a lot of land, and so our fire protection measures ended up relying more on space,” explains Alex Horowitz, the project director of Pew Research Center’s housing policy initiative. This strategy of spacing out homes meant that compact building just wasn’t as necessary in America as it was elsewhere. Even today, multifamily housing makes up less than a third of America’s housing stock.

For centuries, most American apartment buildings had a single interior staircase. Then came a devastating Manhattan tenement fire in 1860. In response, the New York legislature passed a law requiring fire escapes on new residential buildings. This second exit safety philosophy became deeply rooted in American construction culture. As National Fire Protection Association engineer Val Zeevris put it, “In the United States in particular, free egress is just one of the fundamental concepts that we use as fire protection engineers. … So there’s that underlying concern that when there’s only one exit stair, we’re taking away people’s choice.”

Tragedies like the Triangle Shirtwaist Factory fire only deepened this mindset. When a fire broke out on the upper floors of a 10-story factory in 1911, firefighters arrived quickly, but their ladders couldn’t reach the blaze. Dozens of workers — many of them young immigrant women — were trapped behind locked exit doors, a common anti-theft practice at the time. With no way out, some jumped from windows to escape the flames. In just 30 minutes, the fire killed 146 people.

Today, nearly all American cities require apartment buildings at least four stories tall to have two staircases, following standards set by the International Code Council (ICC), a nonprofit that develops building codes. This remains the case even as other modern safety features have made multifamily housing remarkably safe.

Easing the housing crunch

It typically costs less to rent in smaller buildings, yet such “missing middle” housing options — buildings with just two to 19 units —........

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