Key takeaways

  • Family-sized apartments are an important component of the broader housing ecosystem and critical to meeting the demand for family-sized housing.
  • Restrictive building codes lead to mismatches between the housing supply and people’s needs. This either locks families into units that are too small for their needs or leads families to leave places they want to live in.
  • The national shortage in urban-core, multi-bedroom units can be reversed with regulatory reforms.

Families, especially middle-class families with school-aged children or multigenerational households, struggle to find the housing they need in most cities. Many decamp to suburban or exurban digs that fit their needs and budgets. Progressives generally want to make cities affordable and kid-friendly; conservatives want to encourage family formation. Growing the supply of apartments for families is a naturally transpartisan goal — yet today’s building codes assume all middle-class families will always leave cities for the suburbs. 

Recently, I explained how land use regulations and building codes generally ban small and congregate apartments. Here, I explore how building codes also discourage family-sized apartments.

Before World War II and modern building codes, apartment configurations were more diverse than today. Building designs routinely accommodated varying apartment layouts and sizes to meet people’s needs while providing natural light, privacy, and ventilation. These days, restrictive building codes stifle development of housing for families and contribute to the market conditions that make suburban flight more attractive. 

Part of the solution is to build more small places. Small apartments, both in terms of bedrooms and square footage, are an essential part of the housing ecosystem. Many people who live in group homes would prefer to have their own place, and enabling them to live alone would free up multi-bedroom units for families and multigenerational households. But there is still more we can do to boost the number of apartments for families.

Where did all the family-sized apartments go?

 As late as 2006, we built 79,000 family-sized apartments annually, representing 24 percent of then-new multifamily units. By 2020, only 38,000 apartments for families were completed, representing 10.1 percent of new multifamily units.

There are two main reasons for this trend. First, one-bedroom units generate more revenue per square foot and rent faster than units with more bedrooms. In fact, the market for one-bedroom apartments is strong enough to quickly fill every unit built in many metro areas

But those economics are driven in part by the second, more enduring factor: Design restrictions like the International Building Code (IBC) require multiple exit stairways accessible from each apartment for buildings over a few stories tall in most places. This rule in particular puts apartment developers and architects into a tight box, often literally a box, where family-sized apartments are harder to build than one-and-two-bedroom units. (The industry term for this tight box in architecture is called a “double-loaded corridor” floor plan, to be discussed in more detail later.)

As a result, the few family-sized apartments available are beyond the budgets of most families with kids or other relatives living with them. 

​​Instead, family-sized units typically rent to groups of employed roommates even though they would rather live alone. In fact, a 2015 survey showed that 59 percent of roommates would prefer to live in their own place if one were affordable. But splitting the high cost of a multi-bedroom unit is typically cheaper than renting a studio or one-bedroom. As a result, groups of roommates can outbid families with more members than wage-earners. Playing into this trend, more builders are catering to the roommate market by equalizing bedroom sizes and providing en suite bathrooms, which would be unnecessary for a family.

This mismatch forces families to live in smaller units that are more readily available and/or trade their transit pass for a suburban home and a car payment. 

What should we be building?

Families do not inevitably need the amount of space we now associate with suburbia. In fact, when they get built, modern apartments for families often compare favorably to postwar suburban detached homes. For example, the Levittowner, a popular home model in the early Levittown suburbs of the 1940s and 50s, included two bedrooms and about 860 square feet. Another popular model, the Rancher, had a third bedroom and approximately 1,200 square feet of floor area. Modern two- and three-bedroom apartments in the U.S. are often a similar size or larger.

But under the IBC, new apartment buildings above three stories usually have units on each side of the main hallway, a set-up often called a “double-loaded corridor.” These designs make it difficult to provide a diversity of unit sizes and layouts

The most common floor plans, where apartments are lined up like books on a shelf, evolved in response to local IBC variations that require each unit to have access to multiple stairways to the outside as a fire safety measure. These requirements date back to a time when buildings, their fixtures, and the items we keep inside them were less resilient to fire than they are today. In fact, most residential fires don’t happen in multifamily buildings at all. The most common residential fire occurs in a single-family home around dinnertime due to a cooking accident. 

The unfortunate and unintended result of the double-loaded corridor requirement: restricted apartment designs where windows are only practical on one wall, often the one furthest from the main door; limited access to outside light and air; and windowless side walls that are completely shared with neighboring units. Multi-stairway building layouts force these compromises because it is the most spatially efficient layout when the long hallways are needed to connect the stairways. As the tweet below shows, central hallways leave few alternatives other than placing units on either side. 

Where more spatially efficient designs are allowed, most cities restrict them to relatively short buildings. Most communities restrict single-stair set-ups or point access blocks, where multiple single-stair buildings are joined together, to the IBC maximum of four stories and four units per floor. 

How do we do it?

Seattle, a leader in permitting single-stair apartment buildings, allows up to six floors plus a mezzanine to be served by a single stairway. By comparison, European building codes often allow buildings up to 10 stories with a single stairway. Despite the more permissive stairway access requirements, European apartment buildings have lower rates of fire deaths than we see in the U.S. Generally, modern fireproof masonry buildings within reach of fire truck ladders, and sprinklered wooden buildings, do not need two fire exits to deliver modern life-saving performance.

With more design flexibility, larger apartments with multiple bedrooms could have windows in each bedroom. Eliminating a second stairwell also makes room for more living space.

A more livable alternative to the double-loaded corridor

This hypothetical single-staircase apartment building floor plan shows how large apartments could have windows on multiple sides of the same unit, including in each bedroom, while also accommodating a range of unit types. This would not be possible where one of the four walls must abut a hallway, and two other walls must touch neighboring apartments. Also, note the presence of an elevator in the stairwell area for freight and accessibility. Source: LarchLab

a classic double-loaded corridor

A classic “double-loaded corridor” from Mies van der Rohe’s Lafayette Apartments, Detroit, 1956. Non-corner apartments can only have windows on one side, preventing cross-breeze airflow; corridor circulation space is wasted — the residents can’t live in it, and it doesn’t generate revenue for the owners. Source: 

Land use and building code reforms are two paths to eliminate the barriers to multi-bedroom apartment construction that meets the needs of America’s diverse and growing households. Permitting construction of a full range of apartment types, from small single-room units to large family-sized apartments, would allow people to live where they want, whether they desire a small or large space — for themselves alone or their whole family.

Photo credit: iStock