Question
Why won't we allow single-stair apartment buildings
Most people assume it's a safety thing. It's not, or at least not in the way they think. Every developed country has fire codes. France, Germany, the Netherlands, Australia—they all have them. But somehow they've figured out how to require single stairs in mid-rise residential without burning down.
The US and Canada are outliers here, and I think we've convinced ourselves it's because we're more safety-conscious when really it's just path dependency plus a specific interpretation of codes that got locked in decades ago. The International Building Code requires two independent means of egress for certain occupancy types and heights, sure. But "independent" doesn't actually require two stairs. A single stair plus an external balcony or bridge works. A stair plus a window that meets dimensional specs works. Other countries read that constraint and designed around it. We read it and decided: two stairs, every time, end of story.
The cost difference is not subtle. A single-stair plan lets you fit maybe 30% more usable floor area per level. That's not just luxury margin—that's the difference between a building penciling out at 60 units versus 40 units on the same parcel. In expensive land markets, it's the difference between feasible and infeasible. Vienna's been building 4–6 story single-stair apartment buildings for years. So has Barcelona. They're not taking crazy risks; they're just not treating a second stair as a fireproofing mandate.
I don't have a clean answer for how we unwind this. Code changes are slow and local, and cities that try them alone eat the insurance and liability risk first. But it's worth asking why we've accepted a constraint that literally no other developed country imposes. It's not keeping us safer. It's keeping us from building enough housing.
1 comment
Log in to comment.
You're right that this is path dependency, but I'd push back slightly on the "other countries figured it out" framing. They didn't really solve the problem so much as distribute it differently. Vienna's single-stair buildings work partly because Vienna also has strong rent controls, municipal housing programs, and much tighter land speculation. Barcelona's work context matters too—different insurance markets, different liability frameworks, different developer incentive structures. We can't just copy the stairwell geometry and expect the cost math to work the same way.
That said, you're identifying something real about how we've ossified around a particular *interpretation* rather than a constraint. I've watched this play out in collections storage too—a rule gets written (fire-rated barriers, climate stability ranges), and it calcifies into "this is the only way," when the actual requirement was usually something narrower. The hard part isn't changing the rule. It's that everyone's built their entire system around the old one. Insurance underwriters have priced risk around two stairs. Developers have learned to cost-optimize for two stairs. Municipalities have liability anxiety baked in. You can't just rewrite the code; you'd need to rewrite everyone's financial model at once, and nobody moves first because first-mover liability is real.
The honest answer might be messier than "just change the codes." It might require pilot programs where the liability gets absorbed deliberately—a city saying "we're going to allow this and we're going to cover the insurance gap." Which means political will plus money, not just better reasoning about fire safety.