Single-Stair Reform Offers 6-13% Construction Cost Savings, Faces Market Headwind for Larger Units

Across the United States, a growing movement for single-stair building reform is gaining traction, promising to reduce construction costs by an estimated 6-13% and increase housing supply. This reform, which challenges traditional building codes requiring multiple stairwells in multifamily buildings above three stories, aims to enable more flexible, affordable, and diverse housing options. However, urbanist Bobby Fijan highlights a significant market dynamic that could temper the reform's impact on unit size, noting a strong demand from young, high-income professionals for single-occupancy living.

Advocates argue that single-stair buildings, common in many parts of the world, can lead to more homes on smaller lots, lower development expenses, and more flexible floor plans, including family-sized apartments with better natural light and ventilation. Research by the Pew Charitable Trusts and the Center for Building in North America indicates that modern single-stair buildings, equipped with features like sprinklers and fire-rated materials, are as safe as their dual-stair counterparts. This safety record has been demonstrated in cities like New York, Seattle, and Honolulu, which have long permitted such structures.

The International Building Code (IBC) typically mandates two stairwells for buildings exceeding three stories, a rule that housing reform proponents argue inflates costs and limits design innovation. In response to the housing crisis, at least 15 states and several cities have recently enacted or are exploring legislation to allow single-stair buildings up to six stories. This legislative momentum reflects a push to reduce regulatory burdens and stimulate the construction of "missing middle" housing.

Despite the potential for single-stair reform to facilitate larger units, Fijan points to prevailing market forces. "It is GOOD to do single stair reform," Fijan stated in a recent tweet, "BUT there are forces at work: namely that young high income 22-32 year olds REALLY want to live alone and are willing to pay high rents." This demand, he suggests, means that "single stair is unlikely to result in more larger rentals than other building types," as developers may continue to prioritize smaller, higher-rent units to maximize returns. This market reality poses a challenge to the reform's broader goal of fostering housing diversity, particularly for families.