Single Stair Reform

What is Single Stair Reform?

Single-stair reform updates building codes to allow mid-sized multifamily buildings (typically up to six stories) to be constructed with one stairway instead of the two required under most U.S. codes. Dual-stair requirements often force a “double-loaded corridor” layout, units on both sides of a central hallway, which limits natural light and ventilation, reduces unit size flexibility, and wastes space. While multiple stairwells are appropriate for large buildings, allowing single-stair designs for smaller projects promotes more efficient floor plans, larger family-sized units, and better light and airflow.

The Impact of Single Stair Reform

Makes “missing middle” (mid-sized, 4–6 story multifamily housing) feasible, which is often blocked by outdated safety codes.

By reducing space lost to redundant stairwells, developers can add more homes per lot without increasing building height.

With more flexible floor plans, projects can include larger two- and three-bedroom units that are often missing in urban housing markets.

Single-stair layouts allow more natural light, ventilation, and cross-breezes, making homes more comfortable and energy-efficient.

More efficient use of space and simpler designs lower construction costs per unit, helping make new homes more attainable.

Crafting Single Stair Policy

When crafting single stair legislation, advocates should clearly align it with existing codes and work to avoid mandates that increase construction costs.

Policy Features to Aim For

By explicitly stating the maximum building height, typically to 4-6 stories, single-stair buildings stay within the reach of most fire truck ladders. This approach negates a common safety argument that a single-stair building exit could become compromised during a fire.

Example Legislation
Example Language: “The building has not more than six stories above grade plane.”

While some areas of the building code receive routine updates, others are still based on outdated construction methods or fail to account for modern building technologies and practices. Building and fire codes should continuously be updated as new building technologies and practices make it possible to maintain and often exceed the old codes and standards and allow for single stair buildings to be constructed.

Example Legislation
Example Language: “The minimum performance standards of the codes and the objectives enumerated in RCW 19.27.020 shall not be diminished by any county or city amendments.”

Policy Features to Avoid

Affordability requirements, such as inclusionary zoning, make many projects financially impossible to construct.

Parking structures add $35,000–$38,000 per unit, about 8% of total project cost, a burden passed directly to renters and homeowners.

Avoid multiple, redundant fire-protection systems that will drive up the cost of construction and reduce affordability.

Implementation Guidance

Implementing single-stair reform begins with updating state or local building codes to allow single-egress stairways in mid-rise residential buildings, provided enhanced fire safety standards. To make this policy enforceable,

Ensure the legislation has a clearly defined effective date in the near future.
Establish a framework and timeline for updating relevant codes as new technology and safety standards develop.
Identify or create a clear enforcement mechanism that provides an appeals process or legal recourse when single stair cases are denied (e.g. appeals board, third party standing, referral to Attorney General’s Office).

Common Political Dynamics Around Single Stair Reform

Safety is a common concern with single-stair reform, so advocates should make every effort to ground conversations in facts instead of fears. Remind your audience that modern fire and building safety standards such as sprinklers, alarms, fire-rated construction, and proven international practices ensure that single-stair buildings can be designed and operated safely.

We are not proposing skyscrapers with a single staircase; the reform applies only to mid-rise buildings.
Single-stair buildings are standard in most of Europe, Japan, and Canada up to six stories, with excellent safety records.
Modern fire protection makes two or more stairways unnecessary for mid-sized buildings.
Architects and other building professionals note that single-stair layouts allow for larger, better-ventilated homes with more bedrooms, creating much-needed family-sized housing that is currently difficult to produce.

Subject matter experts like Single Stair TX
Urbanists like Strong Towns
Home Builder Associations
Building and Code Official Associations
Building Design Institute of America
Center for Building North America

Firefighters Associations and Unions
Fire Marshall Associations
EMS Associations

YIMBYs in the News

YIMBY Los Angeles
- Culver City became the first municipality in California to legalize the construction of mid-rise apartment buildings with a single staircase.
- Los Angeles YIMBY Action successfully worked with the L.A. City Council who voted to draft an ordinance that would allow buildings of up to six stories to have a single stairway.
YIMBY Denver
- Denver YIMBYs worked with their City Council to approve five-story single-stair buildings as part of Denver’s building and fire code amendments.
RVA YIMBY
- Richmond YIMBYs worked with state Senator Schuyler VanValkenburg to push for single stair reform across Virginia.

Resources about Single Stair Reform

Pew Research Center
- An in-depth analysis of single stair apartment buildings and their safety record.
- A report on fire protection in modern multifamily buildings and how safety improvements impact single stair reform.
The Center for Building North America has great research on key building policies including single stair reform and even has a single stair reform tracker
An organizing guide from Step Up for Single Stair Reform, explaining how local citizens can advocate for single stair reform in their communities.
YIMBY Action has a great webinar highlighting research on single stair data.

Single Stair Reform

Single Stair Reform updates building codes to allow mid-sized multifamily buildings (typically up to six stories) to be constructed with one stairway