Expanding Single-Stair Housing Can Improve Housing Supply, Quality, and Safety

Council of the District of Columbia Committee of the Whole

One Front Door Act of 2025

Thank you, Chairman Mendelson and Council. I am Emily Hamilton, a senior research fellow at the Mercatus Center at George Mason University, where I am codirector of the Urbanity Project.

Two-staircase requirements have long been in place for many apartment buildings in the District and across the country. This requirement is a major impediment to housing construction, however, and is not undergirded with the type of rigorous safety analysis such a mandate deserves. In fact, research indicates that midrise apartment buildings with a single staircase are at least as safe as two-staircase housing alternatives.^[1]

Allowing taller apartment buildings to have a single staircase would lead to three concrete benefits for the DC housing market:

1. Perhaps most importantly, the reform would open up opportunities for housing construction on more lots. In a city like DC that has many narrow lots, assembling a parcel large enough to accommodate a two-staircase building can be costly and difficult. Allowing single-stair buildings would drastically expand the supply of land on which it’s feasible to build multifamily housing.
2. A building with a single staircase offers substantial cost savings relative to a similar building with two. A small midrise apartment building with a single staircase costs 6 percent to 13 percent less than a similar apartment building with two staircases, owing to factors including reduced circulation space and fewer facade materials.^[2]
3. Relative to typical double-loaded corridor buildings, single-stair buildings facilitate more units with windows on multiple sides. In turn, this makes construction of multibedroom units more attractive in more places, facilitating more construction of housing that works well for families. My own family lives in a rare three-bedroom condo in a courtyard building, but few other families with kids have the same opportunity.

These benefits are substantial, and given the large cost of barring single-stair buildings over three stories—the height at which additional egress requirements begin to apply—banning such buildings could only be justified if a second egress were proven to provide consequential life-safety benefits. The requirement for midrise apartment buildings in the US to have more than one egress dates to the 19th century.^[3] Since then, apartment buildings have become much safer due to fire sprinklers, hardwired fire alarms, self-closing doors, and fire-rated materials. Despite these safety improvements, housing code developers have not reevaluated the historic two-staircase requirement to determine if it continues to serve the public interest.

Like most US building codes, the District’s code is based on the International Building Code published by the International Code Council (ICC). While its codes impose enormous costs on new housing construction, the ICC does not provide benefit-cost analysis to ensure that its code requirements protect the public in cost-effective ways.^[4]

Housing policy experts—some of whom are here today—have stepped into this void to provide the data needed to analyze the types of housing that present elevated fire risks, and their findings are clear: Multifamily housing is safer than single-family housing, and newer housing is much safer than older housing.^[5] About one-third of the housing units in the District were built before 1940,^[6] and these units present a much larger risk of fire deaths than units in new multifamily buildings, whether the new buildings have one exit or two.

A building code based on proper regulatory analysis would consider tradeoffs, including how restricting multifamily housing beyond three stories to lots large enough to accommodate a building with two staircases limits opportunities to build new housing. A thorough analysis of the two-staircase requirement would show that expanding opportunities to build multifamily housing in the District would not only improve housing supply, but also improve safety by enabling more people to move out of older, higher-risk buildings and into newer multifamily housing.

[1] Stephen Smith et al., Small Single-Stairway Apartment Buildings Have Strong Safety Record (Pew, February 2025).

[2] Smith et al., Small Single-Stairway Apartment Buildings Have Strong Safety Record.

[3] Stephen Smith and Eduardo Mendoza, “Point Access Block Building Design: Options for Building More Single-Stair Apartment Buildings in North America,” Cityscape 26, no. 1 (2024).

[4] Emily Hamilton, “Reforming US Building Codes,” Regulation, Cato Institute, Winter 2024–2025.

[5] Liz Clifford et al., Modern Multifamily Buildings Provide the Most Fire Protection (Pew, September 2025).

[6] US Census Bureau, American Community Survey, “Physical Housing Characteristics for Occupied Housing Units,” table S2504, 2023 five-year estimates, accessed January 21, 2026, https://data.census.gov/table/ACSST1Y2024.S2504?t=Physical+Characteristics&g=050XX00US11001 .