Single-stair building code reforms, once a niche subject of mere speculation by disgruntled architects, have become law in several states and have positive legislative momentum in several others. Single-stair reforms allow construction of new residential buildings, typically above three stories, with only one exit stairway. These reforms have quickly become part of the playbook that housing supply reformers are running across the country. Bills in several states are moving these reforms one step closer to implementation, but opponents of single-stair legalization still have opportunities to derail them.
International Building Code requirements
The International Building Code (IBC), which state and local governments in the United States use as the foundation for their own building codes, requires buildings above three stories to have at least two separate staircases accessible from all points on each floor. Initially imposed in the name of fire safety, this requirement increases construction costs and limits the range of sizes and floor plans available to architects and residents of multifamily buildings in the U.S.. The U.S. nonetheless trails many peer countries in fire safety outcomes. None of the countries with better fire safety outcomes use the IBC, and, in most cases, they do not require all buildings over three stories to have two sets of stairs. Despite its name, the IBC is not a broadly international building code. It’s been adopted most extensively in the U.S., its territories, and the Caribbean, and it has also influenced legislative building codes in Mexico, Abu Dhabi, and Haiti. It plays no part in building codes of other OECD countries.
Support for the IBC standard often comes from U.S. firefighters’ associations. The International Association of Fire Fighters union, for example, seeks to maintain a maximalist “belt and suspenders” approach to fire safety, insisting that a second exit pathway for tall buildings is essential in addition to other fire safety measures such as sprinklers and fireproof building materials. Single-stair advocates, on the other hand, contend that advances in these other fire prevention techniques have rendered the requirement largely redundant.
Current deviations from the International Building Code
Some U.S. jurisdictions already diverge from the 3-story limit in the base IBC. New York City and Seattle have allowed single-stair buildings up to six stories for decades, and Honolulu legalized them in 2012. In New York City, single-stair buildings up to four stories must be less than 2,500 square feet per floor, and those up to six stories must be less than 2,000 square feet per floor with no more than three units per floor. Seattle and Honolulu do not limit the floor area of single-stair buildings, but they require additional fire protection measures and limit the number of units on each floor to four.
Two other cities and one state have unique exceptions to the IBC’s hard cap on single-stair building height. Chicago allows single-stair townhouses up to four stories, but keeps the three-story restriction on other building types. Dallas allows buildings of up to 75 feet (5-6 stories) to have one set of interlocking or ‘scissor’ stairs, which are two sets of stairs contained in one stairwell. According to one design study, allowing scissor stairs enables some–though not all–of the same design flexibility and cost savings as allowing single-stairs. The state of Vermont, because it uses the National Fire Protection Association building code instead of the IBC, allows single-stair buildings up to four stories with less than four units per floor.
State-led reforms
Housing supply reformers are working to expand the map of single-stair jurisdictions, with prominent single-stair advocacy group The Center for Building in North America, documenting eleven state-level single-stair reform efforts in the last two years. Seven of those efforts, in California, New York, Virginia, Washington, Tennessee, Minnesota, and Oregon, have since borne some fruit. Tennessee legislators are leading the way, explicitly allowing single-stair buildings up to six stories in the state building code this spring, giving local governments the option to adopt the provision as they update their own codes. The other states do not directly amend state building codes. Instead, they require state agencies or other bodies to issue recommendations and reports on single-stair reforms to the legislature or the state agency responsible for building code updates. Figure 1 lays out the timeline for each state.
Figure 1
The studies and recommendations that the laws in the six other states commissioned are due by 2026. Although the exact language varies, the five state legislatures all appear to allow either themselves or their state building code councils the option not to implement reforms once the studies are finished. These bills put states one step closer to legalizing single-stair buildings over 3 stories, but since they just launch studies, they leave the door open to a wide range of possibilities. The commissions could:
- recommend liberalizing building code restrictions or tightening them; and
- enact reforms with unintended consequences that blunt the benefits of single-stair construction.
Advocates will need to stay vigilant to ensure building code study committees reach fact-based conclusions that don’t unreasonably bend to interest group pressure.
In California, Minnesota, and Washington, single-stair study bills began as more substantive changes to state law, but were amended to require reports and recommendations from state agencies instead. AB 835 in California initially required the Fire Marshal to propose a code change to the Building Code Commission allowing single-stair buildings up to six stories, but, at the behest of the California Professional Firefighters union, the Emergency Management Committee amended the bill to only require a research report. In Minnesota, SF 3538, which would have required the Labor and Industry Commissioner to amend the building code to allow single-stair buildings up to 75 feet, died in committee. Legislators passed a single-stair study as part of a budget omnibus instead. Washington’s SB 5491 initially included single-stair reform as an exception to Washington’s requirement that cities adopt building codes at least as stringent as the state code, but it was also reduced to a study requirement in committee.
Future opportunities and challenges for single-stair reform
Having won qualified victories in state legislatures, single-stair advocates now face the task of seeing their reforms through to implementation. Opposition from misguided fire safety organizations and other opponents could still derail these initial steps toward reform. In the next year, reformers should maintain their efforts to educate policymakers about single-stair successes at home and abroad. Once existing state studies are published, reformers will either have more resources to push for concrete changes to state building codes, or an argument to rebut in future outreach to policymakers. The next few years will test reformers’ ability to translate legislative curiosity into building code text, and then into new homes for the housing-starved residents of America’s cities.