Most high-rise buildings have stairways that travel the entire height of the building. Only one of the stairwells may provide access to the roof, either directly or via another access way such as a mechanical room. There are two major types of stairwell/stairway designs: return stairs and scissor stairs.
Also referred to as U return stairs, this type of stair is commonly found in many high-rise buildings, especially those that are older. The return stair actually returns to to the same geographic location of the building at each floor landing. For example, if you enter a stairway with return-type stairs on the 14th floor, the entrance/exit for this stairwell on the 15th floor will typically be in the same vertical location within the building. Building construction features such as setbacks or pipe chases may affect this rule of thumb although most differences will be minor.
- Return stairs have smaller landings in between floors at the half-flight level
- Return stairs will turn or reverse direction at the landing
- Orientation to the fire floor may be made by observing the floor below the fire
The scissor stair design is much more common in newer high-rise buildings. The design of scissor stairs allows for two separate stairwells to be contained in one vertical shaft. The stairwells may only be separated by rated sheetrock. Unlike return stairs, scissor stairs will exit at different geographical locations in the building.
- Odd and even floors may have access to different stairwells
- The long run of stairs between floors with fewer interruptions and turns may assist engine companies with stretching lines
- Orientation to the fire floor may be made by observing two floors below the fire
Also referred to as tenant stairs or convenience stairs, these stair types provide access between floors of individual occupancies. These stair types are primarily found in older buildings and may also be found in buildings that are not high-rises. They are typically wide open with few or no specific fire barriers. This stair type will contribute to the rapid spread of smoke and heat conditions.