This article originally appeared in Architectural Record on May 9, 2024.
American land-use reformers intent on addressing present-day housing shortages have, for the last decade, focused their efforts on amending zoning codes—the very rules that gradually downzoned most urban land in the U.S., effectively outlawing multifamily housing, spurring suburban sprawl, and fanning the current crisis. Recently, however, a group of young architects and planners has brought attention to another code barrier that limits design options for large multifamily buildings: the multiple egress routes mandated by most American building codes. The argument, in short, is to re-legalize single-stair apartment buildings, also known as “point-access blocks”—a typology that was once commonplace and remains so in much of the world, including the European Union, where fireproof single-stair designs are allowed. If combined with zoning reform, such code reform would enable attractive, light-filled multifamily housing to be built cost-effectively on countless urban sites that would otherwise be developed as single-family homes.
Commentators often wonder why new apartment buildings across the United States tend to look alike, not-so-subtly implicating architects and developers. One key reason is that decisions around organization and massing are prescribed by, or strongly incentivized by, regulations. In the limited areas where zoning codes allow for apartments, these rules have given us the notorious “five over one.” In code lingo, these are a Type V light wood frame of up to five stories built over a single story of Type I fireproof podium (typically steel or concrete), with a double-loaded corridor and a stair at each end. Long, windowless corridors slice through the middle of deep floor plates. Non-corner units only have windows on one side, opposite the entry door—favoring studios and one-bedroom layouts.
By contrast, single-stair buildings across Europe tend to have shallower floor plates, “floor-through” light on at least two sides of each unit, and a shared central courtyard. Older American cities also feature outstanding examples of these “garden apartments”: New York’s first garden-apartment blocks, in Jackson Heights, Queens, were celebrated in Architectural Record in 1920 for their array of unit layouts and variety of outdoor spaces. Indeed, single-stair designs deliver more of the light, air, and acoustic privacy typically provided by detached single-family buildings. Light on two or three sides facilitates multibedroom suites even in compact floor plates. These buildings also facilitate community building. In Jackson Heights, for example, whole-block developments are composed of many buildings in series, each governed by its own co-op board, and each, with 20 or so units arranged around a single stair, is small enough for residents to get to know each other. (New York and Seattle are the only two American cities that continued to allow single-stair buildings throughout the 20th century.)
Single-stair designs also unlock economically feasible multifamily development on small infill lots. On such sites, two interior stairwells and a corridor would take up so much of the allowable floor plate that multifamily buildings are rendered infeasible unless adjacent lots are acquired. On some large lots, by contrast, the greater floor-plan efficiency of single-stair designs would probably be offset by the higher cost of fireproof construction and the need for a greater number of elevators, as double-loaded corridor designs enable one elevator to serve many units. In these cases, five-over-ones may continue to be built unless construction costs change dramatically. At the same time, developing large lots with multiple single-stair buildings would unlock a unique amenity: park-like shared interior courtyards. If on small lots, single-stair designs compete on both cost and quality, on large lots, they compete on quality.