Introduction
In this proposal, we identify a building code that heavily restricts the type of housing that can be built and propose solutions. Indiana, Bloomington, and most cities and states in the US have adopted the International Building Code (IBC) to regulate the construction of all new buildings. Most of these regulations are reasonable, and critical for ensuring the safety of residents. However, there is a regulation that heavily restricts the type and cost of housing that can be built, leading to the monolithic style of development that many residents despise. It is the requirement that buildings over three stories tall must have two stairways, connected by a hallway on each floor (a “double-loaded corridor”). Although it does not sound like a critical code, it severely restricts architecture and home layouts. The original intention was fire safety, but this code is now antiquated due to modern innovations in fire-resistant building materials, sprinkler systems, and other fire safety technologies. It was put in place in a time when apartment fires were frequent and devastating due to flammable building materials and lack of other fire safety precautions. Studies have shown that this requirement is not necessary, or particularly effective, as we discuss later.
The double-loaded corridor rule promotes massive apartment complexes and obstructs small-scale, family-oriented apartments
The double-loaded corridor requirement makes it nearly impossible to develop anything but low-density homes on small lots, like the ones often found in and around downtown. To incorporate two stairways that are connected by a hallway, a substantial portion of a building’s footprint has to be allocated to the stairways and hallways. In other words, any building design that does not have a lot of living units does not make economic sense to build. As a result, only massive apartment complexes become viable, and developers are pushed to buy up and merge multiple lots, which often results in more opposition.
The double-loaded corridor has some fire safety drawbacks as well. Residents should never be too far away (125 feet) from the stairway in case of a fire, even in these large complexes, for good reason. However, when combined with a double-loaded corridor, this limit leads to narrow apartments, where only one side has windows, the other side has a door, and few units have more than two bedrooms, since the path from additional rooms to the nearest stairway would be too long. The corridor design allows for up to 500 occupants per floor, or about 250 people per stairway per floor, which could lead to crowding during fire evacuation. This configuration also reduces smoke and fire compartmentation, by connecting all of the apartments in the building to any fire via halls and stairs.
Point access blocks enable a wide variety of designs and can facilitate more organic, in-character developments, without compromising on safety
The alternative is the single-stair or “point access block” apartment design, which benefits from lower land demands, much higher living space to stairway/hallway ratio, more comfortable apartments suited to families, shorter fire egress paths, and improved compartmentation. By removing the double-loaded corridor, apartments can fit in small lots, because less of their floor space is taken up by hallways. By allowing up to four homes per floor, per stairway, crowding is minimized, and each unit could be a corner apartment with ample lighting from two or more sides. Apartments in these buildings are typically accessed through a landing that includes a stairway and an elevator, eliminating most of the distance in the fire egress path, allowing deeper apartments with more rooms. Connecting multiple point access blocks can allow building types like the “Chicago Courtyard Apartment”, whose homes have windows on their front and back for natural ventilation, while maintaining short fire egress paths for every home, and the land and material efficiency of a larger apartment block. Compartmentation is improved by point access blocks, even in larger developments, because at most four homes per floor are connected to any fire, reducing smoke inhalation deaths and excess spread of fire. Tying point access blocks to other building requirements like fire resistant construction, sprinklers, and pressurized or outdoor stairwells brings these modern advancements into the most economical type of housing to build, and ensures no corners are cut on safety.
Are there prior examples?
Seattle, NYC, and most of Europe have implemented this change, bundled with a few fire safety requirements like fire-resistant materials, sprinklers, and pressurized or outdoor stairways, with great success in fire safety, housing affordability, and architectural beauty. Virginia, and many other states, are evaluating changes similar to Seattle’s. Legalizing this efficient building model can open up our town’s economic and architectural potential, and incentivize the replacement of older buildings that don’t meet modern building codes with newer ones that include modern sprinklers and stairway pressurization.
i want to buy this thing and live in the top floor with my family. can you imagine if every site in the city allowed this? 13 apartments on a 5,500 sq ft standard lot in seattle. single stair! pic.twitter.com/v6iGEQh01F
— push the needle (@pushtheneedle) February 21, 2024
Proposed solution
- Amend Indiana Building Code 1021.2 to adopt 1006.3.3.6 and 1006.3.3.7 of Seattle’s building code.
- Justification: This would allow single-stair buildings with up to 6 stories, with at most 5 residential stories. It also requires that these buildings be constructed with materials rated for 1 hour of fire resistance, sprinklers, and pressurized or outdoor stairways to reduce the spread of smoke.
- One Modification: After careful consideration, we believe it would be best to remove section 1006.3.3.7.5, which restricts the number of point access blocks per property to 2. New York City, and European countries like Switzerland and the Netherlands, which have better fire outcomes than the US, don't have this limit. Removing this restriction allows for construction with better land and material efficiency, and can incentivize developers to replace, over time, older, less fire-safe buildings with modern buildings of the same size that include the associated fire safety measures.