The Single Stairway to Heaven

February 01, 2023

While the broader housing shortage is driving up housing costs for a huge share of the population, many cities face an acute shortage of family-sized units in particular. In a new blog post, Andrew Justus of the Niskanen Center argues that out-of-date building code rules related to stairways may be partly to blame.

Key takeaways: 

  • Building code rules requiring two stairwells in buildings of more than three stories essentially mandate what’s known as a “double-loaded corridor,” or hallways lined with apartments on either side – an inefficient use of space. 
  • These types of corridors displace other uses in a building, such as larger, family-sized apartments, or community rooms. 
  • Stairway reform could therefore increase housing abundance and affordability by making better use of a building’s floor area. 

Between 2006 and 2020, family-sized apartments fell from 24 to 10.1 percent of new apartments built. As a result of a lack of family-sized units, young couples may often delay or forgo family formation, or leave cities altogether. One reason for this increased focus on single-bedroom and studio apartments is simply that such units lease up faster.

But as Justus points out, a provision of the International Building Code (IBC) requiring two exit stairways for every unit above three stories may also be contributing to the shortage. Such mandates effectively require that buildings take the form of a double-loaded corridor, wherein a hallway is lined on either side by apartments. This configuration can often make it difficult to include many family-sized units.

Much of the rest of the developed world allows what are called point-access blocks, or residential buildings with a single exit stairway, in buildings ranging from six to 10 stories. In addition to allowing for more family-sized units, such developments grant each unit more natural light and access to natural ventilation. Crucially, there is scant evidence that this comes with any safety tradeoffs, assuming other mitigation measures are taken.

While elected officials have become comfortable with the need to reform land-use regulations to ensure housing affordability, this evidence suggests that prudent building code reform may also be necessary—especially if we would like to build more family-sized homes in California.

Flickr photo of a Berkeley apartment building by kallenemvalts