Stair Tower

Stair Towers

A stair tower, also known as a staircase tower or stairwell, is a vertical structure that contains a flight of stairs. It’s used in multi-story buildings to provide vertical circulation, allowing people to move from one floor to another. Stair towers are an essential element of building design, not only for regular use but also as a critical component of emergency exit routes.

Stair towers are primarily used to facilitate vertical movement in multi-story buildings.

What are the primary uses:

  1. Circulation: The main function of a stair tower is to provide a way for people to move between different levels of a building. This is particularly important in high-rise buildings where elevators may not always be practical or sufficient for everyone’s use.
  2. Emergency Exits: Stair towers are a crucial component of a building’s fire safety strategy. In the event of a fire or other emergency, elevators may not be operational or safe to use. Stair towers serve as emergency exits, allowing building occupants to evacuate safely. They are typically designed to resist fire and smoke for a certain period of time to provide a safe escape route.
  3. Accessibility: For individuals who may have difficulty using elevators, or during times when elevators are in high demand or under maintenance, stair towers provide an alternative means of moving between floors.
  4. Exercise: In some buildings, particularly residential or office complexes, occupants may choose to use the stairs for physical exercise.
  5. Roof Access: In some cases, stair towers can also provide access to the roof of a building, either for maintenance purposes or for roof-top activities.
  6. Service Access: In certain types of buildings like industrial facilities or warehouses, stair towers may provide critical access for maintenance, repair, and inspection of equipment located at different levels.

While the primary role of a stair tower is to facilitate vertical movement within a building, its design and placement also play a crucial role in defining the building’s architectural character.

When designing and constructing a stair tower, compliance with Occupational Safety and Health Administration (OSHA) regulations is crucial to ensure safety for all users. Here are some of the key requirements for an OSHA-compliant stair tower:


  1. Stair Width: Stairs must have a minimum width of 22 inches according to OSHA.
  2. Stair Treads and Risers: The riser height should not exceed 9.5 inches and the tread depth must be at least 9.5 inches. Furthermore, the stair treads should be uniform, with a variation of no more than 1/4 inch.
  3. Handrails and Guardrails: Handrails are mandatory on stairways with four or more risers. The height of handrails must be between 30 and 37 inches as measured from the leading edge of the stair tread. Guardrails are required on the open sides of the stairway to prevent falls.
  4. Landings: Landings are required at the top and bottom of each flight of stairs. If the stairway changes direction, intermediate landings should be included.
  5. Stairway Angle: Stairs should be installed at angles between 30 to 50 degrees to the horizontal.
  6. Slip-Resistant Surfaces: Stair treads must be slip-resistant to prevent potential accidents, especially in potentially wet or outdoor environments.
  7. Vertical Clearance: The vertical clearance above any stair tread to an overhead obstruction should be at least 6 feet 8 inches.

Remember, these are just general guidelines. Depending on the specific application and location of the stair tower, there might be other regulations and building codes to adhere to. Always consult with a knowledgeable professional when planning and installing a stair tower to ensure safety and compliance with all relevant regulations.

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