Photo 1
For many years, fire departments have had to contend with multi-floor tenants who possess an internal staircase somewhere out on their floor, allowing for quick and efficient travel of employees between floors rather than wasting precious time waiting for an elevator cab to come by. This increases worker productivity. Firefighters have always known though, that these stairs (commonly referred to as “privacy”, “convenience”, “tenant” or “access” stairs) are as convenient for the fire as they are for the tenants. Fire, heat and smoke can travel vertically through this floor penetration very quickly and easily. Even in sprinklered buildings, there can be multiple floors of water, heat and smoke damage. They can be straight-run, u-return or spiral stair configurations (see photos 1-3). They can be open or enclosed, although most are open for efficiency and aesthetics. Some have fire dampers or even fire curtains that drop down if the floor’s alarm is activated or a detection device at that location trips, but these are the exception rather than the rule.
Photo 2
Logistical issues: With modern, state-of-the-art high-rises, the building’s fire alarm computer takes over during a fire and activates certain fire protection and safety related features. It can recall elevators to lobby or recall level, activate stairwell and possibly elevator shaft pressurization fans, release stairwell door locks, activate the alarm notification system for both the tenants (strobes, horns, etc) and the central monitoring agency, and send a signal to the HVAC system which performs certain functions. It will either shut down the fans to the fire floor, while possibly pressurizing floors above and below or it may go into “smoke purge” while pressurizing the floors above and below the floor of alarm (no return/full supply — utilizing fresh outside air as “make-up air” on the supply side).
Photo 3
Two very important things can occur during alarm sequence that must be considered, both of which can affect firefighter safety. For instance, if the fire originates near the bottom of an open internal access/tenant staircase that serves 3 floors (e.g. — 28-30), the smoke can drift up and initially trip the detector on the floor at the top of the staircase (floor 30), two floors above the fire (see graphic 1). The first-due engine is riding around on building inspections and is only a block away when the call comes in. They arrive in less than one minute, rush into the building and check the alarm panel. It reads Floor 30 as the alarm floor. They choose Floor 28 as the staging floor and their level to exit the elevator, as per their department SOPs. They hop in the elevator and head upstairs 2 floors below the “fire floor” and they arrive right at the actual fire floor on 28, with the fire nearby. In a non-sprinklered building, this could prove to be quite dangerous if the crew cannot quickly get the cab doors shut and move back down to a lower floor to regroup. Of course, by now other detectors would have tripped on the true fire floor but they may not be aware of it without direct communication with security or engineering personnel in the lobby (which is doubtful).
Graphic 1
Another thing that can happen is that the smoke can drift up and set the first detector off on the floor above the fire (see graphic 2) and get the HVAC system activating the smoke purge feature on the wrong floor — having been fooled by the stairwell. The computer thinks that the fire is on 29, when in fact it is on 28. The system then begins pressurizing the floors above and below the alarm floor (28 and 30). Unbeknownst to the fire crews, the supply fans are forcing large volumes of fresh air onto the fire floor, feeding the fire plenty of oxygen. Not good. Granted, there are many variables involved in this as many building’s smoke purge will not activate without a water flow (sprinkler) alarm first, while still others will have it set-up where any floor getting a smoke activation has that floor’s fans shut down. Also some buildings (albeit rarely) have it set-up where all the floors served by a tenant stair are considered to be their own “zone” in alarm sequence (all pertinent floors are purged together or have fans shut down collectively) — all of which would eliminate the above scenario as a possibility. However, it can happen in buildings in quite a few cities out there. The key issue here is always, always try to determine whether or not the fire floor is served by an access stair. If there is no pre-fire plan available, then ask the engineer (if he is around). If you should have any doubts, then play it safe and take the elevator 3 floors below the fire, then walk-up. Although not fool-proof, it can further lessen the possible exposure problems that much more.
Graphic 2
Note that in non-sprinklered buildings, vertical fire travel can happen quite rapidly with multiple floors of fire extension occurring in a matter of just a few minutes if the fire originates near that location — and its not always just traveling upwards. A good case in point that should be studied is the Meridian Plaza Fire in Philadelphia in 1991. The fire started on floor 22, but when the first fire attack crew began deploying the line out of the core stairwell onto the floor, the fire had already burned down a tenant stair and began advancing back towards the core — directly beneath the crew working above. Again, not good. Fire traveling to other floors obviously dictates getting additional lines laid as soon as possible to cut-off further fire travel and extension into void spaces.
Graphics 3, 4, and 5
Some buildings have access stairs that penetrate a ridiculous amount of floors (see graphics 3-4). However, there are many cities that restrict the amount of floors served to no more than 2 or 3. Your objective should be to know which buildings in your first-due area have them and note it in your on-board vital building information form or have it noted on site in the fire command center(s) in the form of a stair riser graphic near the alarm panel as a reminder before ascending up into the tower. If floor plans exist for fire attack and search crews, they should be noted on these drawings as well (see graphic 5). Try to always avoid letting the building throw you a curve in “crunch-time”. Be prepared for the unknown and be safe always.