For more than a century, American urban planning has “been devoted to layering on ways to all but ban apartment buildings.” As the US now tries to shift out of the anti-density policies driving the housing affordability crisis, policymakers are finding obstacles hiding in countless corners.
States and cities are beginning to roll back what is often blamed for the housing shortage: “our rigid system of zoning, which dictates what kinds of buildings can be built where.” Exclusionary zoning makes it illegal to build anything other than detached single-family homes on most residential land, leaving homes “scarce, spread out, and unaffordable.”
But fixing zoning is only the first step. Equally significant are the rules that govern how homes must be built — the materials, safety features, and other requirements that make up the complex American building codes.
Zoning Isn’t the Only Barrier
Even as cities re-legalize housing forms that once supported urban vitality, “extremely strict, sometimes ill-considered building codes and other requirements can quickly make them financially infeasible to build,” writes John Zeanah, chief of development and infrastructure for Memphis, in a report for the Center for Building in North America.
Many building codes stem from “important safety needs,” which have reduced residential fire deaths and improved utility safety. Yet in the US, “a morass of construction codes, fire safety requirements, utility rules, and even tax policies, treat even small multifamily buildings fundamentally differently from the way they treat single-family homes.” Anything larger than a duplex is regulated as a commercial building, saddling multifamily homes with costly requirements that are “not evidence-based” and can make construction prohibitively expensive.
The Pew Charitable Trusts and the Center for Building in North America found that “it costs significantly more per square foot to build multifamily homes in the US…compared to single-family homes,” a pattern not seen in peer countries where multifamily buildings benefit from economies of scale.
How Codes Penalize Small Multifamily Housing
1. Sprinklers and the Cost Cliff
Building codes focus heavily on fire safety. “The leap in complexity from duplex to triplex is dramatic,” Zeanah notes. Most new multifamily buildings require extensive sprinkler systems and other commercial-grade fire safety equipment. While sprinklers are effective, “they cost so much to install and create such high ongoing maintenance expenses that they can be a make-or-break factor” for small multifamily projects.
Zeanah recounts a Memphis developer, Andre Jones, who struggled to build fourplexes until Tennessee passed a law allowing small buildings up to four units to forgo sprinklers if walls, floors, and ceilings have two-hour fire-resistant separation. As Zeanah observes, “It’s not clear why the council chose to carve out just one- and two-family structures rather than make the cutoff at triplexes, fourplexes, or elsewhere.”
2. Stair Regulations and Design Limitations
Almost every US apartment building over three stories must have at least two staircases. This adds hundreds of thousands to construction costs and reduces livable space. Buildings designed with “double-loaded corridors” often require larger footprints and less flexible layouts.
Other countries, as well as US cities like Seattle and New York, safely build single-stair structures, and research shows they do not have worse safety outcomes. “Modern US multifamily homes are already significantly safer than single-family homes,” Pew data shows.
3. Custom Plans and Architect Costs
Buildings with three or more units often require a dedicated architect or engineer to create custom plans. Zeanah notes that “small developers looking to build a triplex or fourplex face higher upfront costs before they’re approved to build what is ultimately similar in scale to a single-family home.” He recommends allowing modest multifamily buildings to use pre-designed standards already available for single-family and duplex projects.
4. The Elevator Problem
Elevators in the US and Canada are “the most expensive in the world,” sometimes costing three times more than European equivalents, writes Stephen Smith of the Center for Building. Oversized elevator requirements and union rules that limit factory preassembly contribute to costs. Smith explains that these policies “more likely mean fewer elevators are built, fewer apartment buildings are built, and more of our housing stock is comprised of low-density, inaccessible homes.”
The Bigger Picture
As the article notes, the lesson of the housing crisis is “straight out of Econ 101: If you perpetually raise the cost of building something, it will not be built at all.” Barriers go beyond building codes, including property taxes that favor single-family homes over multifamily housing.
Building codes reveal a deeper problem: “The US has effectively handed off building code rulemaking to a private nonprofit that is enmeshed with private interests, including homebuilders and materials manufacturers,” according to Eriksen, an economist. While ICC officials say code changes are reviewed thoroughly and affordability concerns are considered, critics argue that “the organization’s processes are not well set up for…public servants to make well-informed decisions.”
In the near term, advocates are working to modify codes state-by-state, such as allowing single-stair buildings and offering flexibility for small multifamily fire safety. Some hope for a more transparent, federally guided system akin to European “performance-based” codes, which mandate safety outcomes rather than prescribing exact tools like sprinklers.
In sum, decades of planning choices and layered regulations have made “as basic a human need as housing into a luxury good.” Addressing zoning alone will not suffice; meaningful reform must confront the hidden rules embedded in the building codes themselves.
