The surefire way to make America's apartments bigger, brighter, and cheaper

"Are you familiar with the Texas doughnut?" Chris Gannon, an Austin architect, asked me recently. The question wasn't about confections. He was riffing on apartment construction, explaining why America can't seem to get behind the kinds of buildings that he and other pro-housing advocates want to see.

The "Texas doughnut" is shorthand for a large apartment building, often spanning an entire city block, where a ring of street-facing units conceals a parking garage in the middle. In growing cities across the US, doughnuts are everywhere. In Gannon's eyes, they're clumsy solutions to our housing woes: The imposing structures offer little outdoor space and require a lot of precious land. It's much harder to find smaller apartment or condo buildings, the kind that might fit snugly between a single-family home and a local restaurant. Cities are full of these little parcels, but "missing middle" housing — bigger than a single-family home but much smaller than the popular doughnut — just isn't getting built. This reality is especially frustrating for pro-development yes-in-my-backyard activists who have spent years rewriting laws in hopes of encouraging denser, more-diverse housing — some baby carrots to go with all those doughnuts.

In their quest to build more and bring down costs, YIMBYs have identified one overlooked hang-up: stairs. Yes, the humble stairwell is an unlikely but powerful foe. More specifically, they're taking aim at a widespread rule that requires almost every new apartment building in the US to include at least two separate stairwells. This part of local codes, they say, is an outdated safety measure that really just makes apartment units smaller, more expensive, and darker (yes, darker).

When developers are forced to devote more square footage to stairs, that means less space for living rooms or bedrooms. Entire units might end up on the cutting-room floor. In many cases, the wasted square footage is enough to hamstring the builder's profit and sink a project. Instead of getting much-needed housing, we get none. Tweaking building codes wouldn't mean sacrificing safety in the name of efficiency. In a moderately sized apartment building of five or six stories, advocates argue, a single stairwell, combined with the latest fire-stopping materials, sprinkler systems, and limits on the number of units, is more than enough to ensure safety. In fact, moving to this type of layout would bring American apartments in line with European and Asian countries that have allowed this kind of development for decades. When Gannon learned of the single-stair movement a few years ago, he said, everything clicked.

"I was like, 'Oh, my god,'" Gannon told me. "A light went on, like, 'Oh, this is why apartments in the States suck.'"

Only a few US cities, most notably Seattle and New York City, allow single-stair buildings to stretch up to six stories — pretty much everywhere else in America caps it at three. But the single-stair movement is gathering steam in places like Austin, where the City Council recently directed city planners to look into updating the building code, as well as entire states like California and Minnesota. Embracing the single stair could enable apartment buildings to squeeze into vacant lots that might otherwise have turned into single-family houses or sat undeveloped. It would also make it easier to build larger units for families, who are mostly ignored in the apartment market. More apartments and condos would mean lower costs for everyone.

That's the goal, anyway. These are stairs we're talking about, not a silver bullet for the housing crisis. But this obscure part of the building code wields huge influence when it comes to how our buildings look and feel and whether they even get built. Every new apartment building needs stairs, sure. But maybe we could do with a lot fewer of them.

Stairs are a relatively new obsession in YIMBYland. For years, crusaders against the housing shortage focused on dismantling an unholy mess of local zoning rules that prohibited anything but single-family homes and fought against "minimum lot sizes," which encouraged sprawl rather than density. Pro-development advocates scored significant victories — several states, including Washington and Oregon, have basically gotten rid of single-family zoning altogether. While it's one thing to change the law of the land, the thornier question was how to get developers to actually build on it.

"You can raise the floor-area ratios, raise the height limits, lot coverage, whatever," Stephen Smith, a building-code researcher and single-stair advocate who founded the Center for Building in North America, told me. "But you're still not going to get that, like, beautiful 1970s Italian apartment that you stayed in an Airbnb once. Buildings are just not like that in America."

That's where things like stairs come in. Say you're a developer with a small piece of land in a quaint neighborhood. It's already the stuff of YIMBY dreams: The streets are lined with a blend of single-family homes and low-slung apartment buildings. Walk down the block, and you'll find restaurants and a grocery store. It's a 20-minute bike ride from downtown. The dream would be to take this land and build it up, turning the vacant parcel into a condo or apartment building where more people could enjoy this breezy lifestyle. But your lot is small — only 3,000 square feet, or about one-third of the typical lot size for a new single-family home. From a pure profit perspective, the project makes sense only if you can squeeze in enough units to get a good return on investment, which means building higher than three stories. According to the building code, however, you'd have to include two stairwells at opposite ends of the building, with a corridor running between them. This eats up so much square footage that the project goes poof — the areas of each floor simply can't accommodate the necessary units.

The Texas doughnut is a product of these limitations. Instead of building on small lots, developers are pretty much forced to assemble large parcels of land to accommodate the two-stair requirements. The apartment units in these buildings usually run on either side of the corridor that connects the two stairwells, which means the typical unit gets natural light from only one direction. A single-stair setup might allow units to cut across the building and take in light from both sides. Given more space to work with, developers could also get more creative with their floor plans or build bigger units with more bedrooms. In an op-ed last year, Michael Eliason, a Seattle architect regarded as a leading voice in the single-stair movement, described the huge ripple effects these reforms could have.

"The more I researched, the more I realized this one issue was like the Higgs boson of housing," Eliason wrote. "It connects everything."

He's among those eager to spread the gospel of Seattle. The city allows single-stair buildings up to six stories, which opens up a world of possibilities. There are guardrails, of course: Under Seattle's code, single-stair buildings can't have more than four units per floor, and there are requirements for fire safety like an updated sprinkler system plus fire-resistant materials. These are all sensible precautions. In return, you get something like 1310 East Union Condominiums, which was built on less than 3,000 square feet in Seattle's Capitol Hill neighborhood. It has eight loft-style units spread across six stories, with commercial space on the ground floor and eight parking spaces. A stairwell and elevator run down the middle.

Small projects like this one are tough to execute even with one stairwell. Brian Court, a partner at the architecture firm the Miller Hull Partnership and one of the designers of 1310 East Union, said a second staircase — something like 200 extra square feet per floor — would have made the development financially unfeasible.

"We're not trying to make buildings riskier," Court told me. "But we definitely need to do whatever we can and think creatively about ways to get more housing online sooner rather than later."

Sean Jursnick, a Denver architect and single-stair advocate, made a pilgrimage to Seattle last year to meet with Eliason and tour buildings like 1310 East Union. City planners there sometimes call these single-stair buildings "Seattle Specials" — they simply wouldn't be possible in pretty much any other city. Jursnick found more than 100 such developments in Seattle. The city, he told me, "felt like a good example of what the rest of the country could unlock with a simple code change."

Seattle may be an outlier in the US, but it's pretty normal — tame even — compared with the rest of the developed world. Almost all of Europe, as well as Asia, Mexico and South America, allows single-stair buildings of six stories or higher. Germany allows single-stair buildings to stretch to about 20 stories, while Switzerland has no such limit.

To achieve their agenda, single-stair evangelists will have to get past one huge hypothetical: fires. It's hard to persuade fire experts and city-council members to loosen up the status quo — Americans are so used to two (or more) stairwells that anything less may seem like an unnecessary risk, even reckless. But Seattle's code offers a model that, by all accounts, balances safety with the very real need for more midrise housing on smaller lots. Sprinklers, fire-retardant materials, and systems that ensure the stairway isn't filled with smoke in the event of a fire have allowed Seattle to permit this kind of single-stair development for decades without major incident. There isn't much data on how single-stair buildings, specifically, have performed against fires across the world, partially because fires are relatively rare these days. But even the National Fire Protection Association, which has argued for a limit of four stories for single-stair residential buildings, recently reported that sprinklers had proved reliable in large fires, reducing death rates by 90% compared with buildings without them.

While these smaller buildings tend to be more expensive and often operate as condos rather than rentals, more housing is more housing. They could play a crucial role as cities chart their next phases of growth.

The Seattle model has already spread to Honolulu, and advocates around the country are making progress: Lawmakers in at least 10 states, including California, Oregon, and Washington, have either considered or passed legislation that could result in updated state building codes. In the meantime, Gannon told me, individual cities could adopt similar standards: "This could be something that could come in and really help us figure out how we urbanize."

The housing crisis demands creative solutions, but even mundane and seemingly small fixes can put a sizable dent in the country's massive housing deficit. We have plenty of real-life models for single-stair development, both here in the US and abroad. It's time to take the next step.

James Rodriguez is a senior reporter on Business Insider's Discourse team.