Firehouse 21st Century High-Rise Training Series: Stack Effect

Curtis Massey defines the phenomenon of stack effect and details its implications on high-rise fires.


A fire department is dispatched to a reported structure fire in a 52-story high-rise office building. It is a weekday, 4:30 P.M. The building is fully occupied. Upon arrival, first-due units report heavy fire intermittently showing out three windows on the exposure 1 side (front/north) and...


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A fire department is dispatched to a reported structure fire in a 52-story high-rise office building. It is a weekday, 4:30 P.M. The building is fully occupied. Upon arrival, first-due units report heavy fire intermittently showing out three windows on the exposure 1 side (front/north) and immediately start pulling their equipment off the rigs to begin a difficult firefight. It is early January in this northern city and the temperature is 26 degrees, with a slight northerly breeze blowing toward the building frontage.

Crews trudge up to the front entrance and experience some difficulty in opening the swinging entrance doors. Believing that the problem lies with the breeze blowing against his back, the first-due engine captain asks two men on the second engine to prop open the swinging doors and collapse the revolving doors to expedite getting equipment and manpower into the building. This is done in very short order.

As the crews enter the building, they feel a strong wind rushing past them into the lobby, almost like being in a wind tunnel, but again, figure it is just the slight breeze gaining velocity as it squeezes through the doorways along with the firefighters. Tenants who have already reached the lobby are either milling around or are leaving the building. Crews check the fire panel for confirmation of the alarm floor as they listen to the security guards and chief engineer excitedly bark out what they have seen or received in information from tenants. They are told that an entire tenant space of about 2,000 square feet on the 38th floor is afire in the unsprinklered 1960s-era steel frame skyscraper, along with a report that several people are missing and presumed to be trapped. They are advised that the lone freight elevator is down for repairs. From their position, the crews no longer feel the wind entering the building.

After gaining access to floor plans, stair master keys and fireman service keys to the elevators, the engine, ladder and rescue units head over to the elevator banks to ascend to the staging floor, two floors below the fire floor. They step into two cabs as wind whistles around them in the shaftways. They insert their keys, put the cars into phase-two service and push the designated floor and door close buttons to begin their rise into the burning office tower. The doors on both cabs close about three-quarters of the way as the whistling intensifies, then stop and go no farther.

The crews try to push the doors the rest of the way closed, but to no avail -- they remain partially open. Frustrated, both crews exit their respective cars with their keys and attempt to commandeer cars across the elevator lobby in the same bank. They experience the same situation. Time passes and stress mounts with every second they remain in the lobby while the blaze races out of control above them with occupants trapped. The decision is made to then go for the stairs and initiate a long, grueling hike up to the fire, knowing that precious time will be wasted.

After 25 minutes of intense climbing, they reach the fire floor, sweating profusely in gear that does not let their bodies breathe. One exhausted crew begins stretching the first attack line from the standpipe on the 37th floor in the now-designated "attack stair" (the north stair, closest to the fire), while the search crew deploys out onto the fire floor from the opposite stair in a concerted effort to find the missing tenants. Other occupants continue to stream down from the upper floors, trying to stay out of the firefighters' way while still keeping their momentum going in an attempt to flee the light to moderate smoke now entering the attack stairwell as the door is propped open on the 38th floor for the deployment of a 2½-inch handline. The engine captain radios the command chief in the lobby that the north stair is becoming smoky.

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