BY BILL GUSTIN
A modern, glass-enclosed office building can present firefighting challenges not usually encountered in residential buildings of the same size. Firefighters more accustomed to fighting fires in multiple dwellings than office occupancies may endanger themselves if they fail to realize that there are fundamental differences between residential buildings and modern offices. This article examines these differences and explains why tactics commonly used to fight fires in multiple dwellings may be ineffective at a fire in a modern office building.
LACK OF COMPARTMENTATION
Residential buildings have a much greater degree of compartmentation than most of the office buildings constructed during the past two or three decades. Apartments, condominiums, and hotel rooms are typically separated from each other and the public hallway by fire-rated walls that connect directly to the underside of the floor above. This compartmentation tends to confine a fire to the living unit of origin and often limits its potential size to within the suppression capability of one 13⁄4-inch hoseline flowing 150 to 180 gallons per minute (gpm). Compartmentation, common in fire-resistant residential buildings, makes it possible to implement a protect-in-place strategy in which the fire department directs most residents to remain in their apartments while firefighters extinguish the fire. A protect-in-place strategy is the only practical way for an understaffed fire department to handle a fire in a building occupied primarily by elderly residents. The alternative to a protect-in-place strategy is for old and infirm residents to leave the relative safety of their apartments and risk evacuating through smoky hallways, stairways, and elevators.
 (1) An aerial ladder is raised inside the testing laboratory. Here, firefighters practice cutting an impact-resistant curtain wall assembly. (Photos by Eric Baum unless otherwise noted.) |
Modern office buildings are commonly constructed with little or no compartmentation on each floor. Essentially, each floor is one big potential fire area that can measure thousands of square feet and requires a complete evacuation of everyone working on the fire floor. Considering the heavy fire loading of most offices, consisting of paper and synthetic furnishings, fires in large office suites can rapidly escalate to such an extent that multiple 21⁄2-inch hoselines or master stream devices must be deployed to bring them under control.
 2, 3) A chain saw with a carbide chain is clearly most effective tool for cutting impact glass. |
This wide-open floor area allows tenants to arrange their offices to meet their specific needs. This is efficiently accomplished by installing moveable cubicles (to separate workstations) and lightweight partitions that reach only to the underside of the ceiling between offices. This leaves a large, undivided space between the ceiling and the floor above that is commonly used for electrical wiring, telephone and computer cables, and supply-air ductwork for the HVAC system. Many modern office buildings also use this space as a return air plenum for the HVAC system, eliminating the need to run return-air ductwork.
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With this arrangement, the ceiling space is placed under negative pressure, which draws return air through ceiling registers from all areas of a floor back to a fan room, where it is reheated or cooled, dehumidified, and mixed with a small percentage of fresh, outside air. Using office ceiling space as a return-air plenum may be efficient from an economic standpoint but not from the perspective of fire safety. It can spread the smoke from one burning plastic wastepaper basket so that it contaminates an entire floor. And, as we shall see, venting this smoke may not be as simple as simply opening a few windows. We are totally reliant on the building code-mandated smoke detector in the air-handling system to shut it down.
DIFFICULTIES IN VENTILATION
Another major difference between residential and modern office buildings is that, with the exception of some hotels, residential buildings generally have windows that can be readily opened for ventilation. On the other hand, this is definitely not the case in modern office buildings, where an Allen wrench or a special key is needed to open them, or the windows have fixed sashes that cannot be opened. In our jurisdiction, there are several large, modern office buildings that do not have a single window that can be opened. This is primarily for energy conservation: Building management does not want tenants to open windows and allow air, which is very expensive to cool and dehumidify, to escape. Some older building codes in the 1980s did require the use of tempered glass windows for firefighters to break for ventilation.
The problem of ventilating a building with fixed-sash windows is compounded when the glass is impact resistant and windows are insulated with two or more panes of glass. Building codes in most coastal areas of states on the East and Gulf coasts now require shutters or impact-resistant windows that will resist hurricane-force winds and flying debris. Impact-resistant glass is similar to that in automobile windshields, but it is much stronger and more difficult to cut. Impact-resistant glass is laminated with a center of tough, clear plastic between two sheets of heat-strengthened or tempered glass. On impact, both layers of glass may shatter, but the inner ply of plastic resists penetration and keeps the window intact.
 (5) Striking impact glass to �soften it up� will increase the cutting speed of any saw. (Photos by Enrique Rodriguez.) |
I am very fortunate to have within my jurisdiction an independent testing laboratory that tests impact-resistant window and door assemblies. Full-size assemblies are tested by subjecting them to hurricane-force winds and impacting the glass with 2 4s and ball bearings shot from a pneumatic cannon. Once an assembly is tested, the director of the laboratory allows our companies to experiment and practice with various tools and techniques to find the most expedient way to cut impact glass for ventilation, entry, and rescue (photo 1). The director of the laboratory also provides us with a wealth of technical information on impact-resistant glass and advice on how to penetrate it.
 (6) This impact-resistant curtain wall is insulated with a layer of conventional glass, which yields large and dangerous shards. (Photo by Enrique Rodriguez.) |
We have learned that manufacturers are constantly developing stronger windows that resist greater impact and increase our difficulty. Increases in strength are primarily attributed to the development of new plastic inner plies and improvements in mounting glass to its frame.
 (7, 8) The smoke control system panel shows details relative to exhausting and pressurizing floors, stairways, and elevator shafts. |
It is practically impossible to cut a large opening in state-of-the-art impact glass with an ax or by any manual means. Our tests compare favorably with those conducted by the Sarasota County (FL) Fire Department. We both determined that, without question, a chain saw with a carbide-tip chain will cut through the strongest impact glass with very little resistance (photos 2, 3).
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We also tested battery-powered electric saws to find the best tool for cutting impact glass to ventilate windows from the inside of a building, where smoke and oxygen deficiency may prevent the use of a gasoline-powered saw. We found that a battery-powered circular saw equipped with a carbide-tip blade was somewhat faster than a reciprocating saw (photo 4). You can significantly increase the cutting speed of any saw by first shattering the inside and outer layers of glass by striking the window with a tool such as a steel roof hook. This tends to “soften up” the window, allowing the saw to cut, primarily, the plastic center ply (photo 5). Additionally, you can eliminate the time it would take for a saw to “plunge” through impact glass by first beginning the cut with an ax. This, of course, must be done when using a reciprocating saw.
 (9) Powerful fans exhaust smoke from the fire floor and pressurize the floors above and below. |
In our tests, we found the most difficult windows to cut were those that were impact resistant and insulated with layers of conventional glass. Some of these windows are manufactured to form the outside walls of office buildings, covering two or more floors. This will require that firefighters first break large panes of conventional glass before they cut through the impact-resistant layers. Unlike tempered glass, the insulating layers of conventional glass in some windows yield large, jagged shards when they are broken, similar to the glass fragments that can seriously cut firefighters when they break plate-glass storefront windows (photo 6).
 (10) Stairwell doors locked for security purposes can trap office workers who encounter smoke rising up the stair shaft. |
The ultimate solution to ventilating a modern office building equipped with fixed, insulated impact-resistant windows is a properly designed and operating smoke control system. These systems consist of an elaborate array of powerful fans, large air supply and exhaust ducts, and dampers to control the movement of air and smoke (photos 7, 8). A smoke-control system can be automatically activated by a fire alarm system or manually operated by the fire department or building engineers. These systems are designed to exhaust smoke from the fire floor while pressurizing floors above and below the fire floor to prevent the spread of smoke (photo 9). Additionally, smoke-control systems can pressurize stairwells and elevator shafts to keep them clear of smoke. Be aware that in new sprinklered office buildings today, smoke-control systems are no longer required under the building code simply because a building is a high-rise.
DANGEROUS STAIRWAYS
Compartmentation in modern office buildings is further compromised when a tenant rents two or more floors and then connects them with a private, open stairway, known as access stairs. Access stairs make it convenient for employees to move from floor to floor without having to use the public stairway. They, however, allow smoke and fire to move freely from floor to floor because the stairs are not enclosed in a fire-rated stair shaft.
Occupants attempting to escape a fire in an office building have been trapped and killed when doors in exit stairwells were locked on the stairway side. This is a common security practice in offices to prevent unauthorized entry from the stairwells. Occupants can exit into a stairway but can get out of the stairway only on the ground floor. Doors at every other floor landing require the use of a key, a swipe card, or an entry code (photo 10).
 11) “Gapping” the locked stairwell door by driving a flathead ax blade between the door and the jamb |
It is standard procedure for firefighters to stretch hoselines up stairwells to fight fires on upper floors. Opening a stairwell door to advance hose on the fire floor unavoidably allows smoke to enter a stair shaft and, in effect, turns it into a chimney. If occupants descending the stairs from floors above the fire encounter smoke rising up the stair shaft, they may find themselves trapped in the stairwell by locked doors. To prevent this, stairwell doors should automatically unlock on activation of the fire-alarm system; unfortunately, many do not. That is why it is critical for firefighters to identify and designate a fire attack stairway and to direct occupants to use only escape stairwells. Additionally, firefighters must ensure that the fire attack stairway above the fire is clear of occupants before they open the stairwell door to the fire floor.
 12) allows the blade to spin freely. |
Locked stairwell doors also present a forcible entry problem. Firefighters searching floors above a fire will become exhausted and expend a considerable amount of their air supply if they must force several locked stairwell doors. Because fire exit doors leading into stairwells must swing in the direction of exit travel, firefighters who must force them from the stairwell side will be unable to use a hydraulic forcible entry tool. If you are faced with the need to force several stairway doors, strongly consider taking a rotary saw and a supply of spare metal cutting blades. Cutting the door’s lock bolt or latch will be much faster if you first “gap” the door by driving a flathead ax blade between the door and the jamb. “Gapping” creates a space that allows the saw blade to spin freely and to immediately start cutting the latch, avoiding the door and jamb (photos 11, 12).
NO TWO FLOORS ARE THE SAME
When preparing to attack a fire on an upper floor of a residential building, firefighters often take a few moments to familiarize themselves with the floor below the fire. This helps them navigate in the smoke on the fire floor because they know that floor plans of most residential buildings, except for the first floor, are laid out essentially the same. For example, apartment 302 will be directly below apartment 402 and will have the same path and distance from the fire attack stairway.
This is seldom the case with modern office buildings, where no two floors are laid out the same. Rather, each office suite will be a different, confusing maze of cubicles, making it extremely difficult to locate a fire and advance hose. When responding to a fire in an office building, attempt to determine the fire’s location and how to reach it, and estimate the length of the hoseline needed before you advance a hoseline into a dark, smoky office suite. Using guide ropes and a thermal imaging camera can be extremely valuable when attempting to locate a fire and mark a path for reaching it.
If you are attempting to locate a fire without the protection of a hoseline, use extreme caution. Constantly monitor heat conditions, and play out a guide rope as you proceed.
A company searching for a fire in a modern office building must open the ceiling immediately on entering the fire floor. As they proceed, they must again pull ceiling at regular intervals to make sure that fire is not burning over their heads.
 (13) Firefighters take their position along the hoseline to feed hose up the stairs and around corners. (Photo by Eric Goodman.) |
Advancing a hoseline in a large office suite filled with partitions and cubicles necessitates the coordinated effort of several firefighters who are positioned along the hoseline to move it around corners and obstacles. First, lay out the hoseline on the floor below the fire. Arrange it carefully in a series of “S”s to facilitate a smooth advance and ensure that all potential kinks are removed before it is charged. Then, firefighters should line up on the hoseline behind the nozzleman. The last firefighter on the hoseline, farthest from the nozzleman, should be the first to take a position and feed hose; this will usually be at the bottom of the stairs. Similarly, the next firefighter may stop at the stair half-landing, and the next at the top of the stairs. As corners are encountered, each firefighter on the line, in succession, takes his position and feeds hose (photo 13).
This is a basic engine company evolution, but it takes teamwork, discipline, and strong leadership. If firefighters crowd at the nozzle, the hoseline will never make it past the first corner. I have seen this operation fail miserably because of a lack of practice. Companies in my battalion used the second floor of an abandoned movie theater to practice advancing hose. This was an excellent drill site before it was torn down because it was a maze of offices and projection rooms.
FIRE DETECTION AND SUPPRESSION SYSTEMS
It is fortunate that many modern office buildings are equipped with alarm systems that will detect a fire, indicate its location on an annunciator panel, and shut down the HVAC system. It can, however, be difficult or impossible to determine the location of a fire if the annunciator panel is not adequately labeled-for example, Zone 1 may not necessarily indicate an alarm condition on the first floor. Fire companies should visit the office buildings in their response district to familiarize themselves with the alarm systems and to have building management or the alarm company help them to interpret the annunciator panel.
Automatic sprinkler protection may not be required in office buildings if they are below a certain height. Until recently, the building code in my jurisdiction did not require sprinklers in office buildings less than 50 feet in overall height. It is no coincidence, therefore, that there is an abundance of four-story office buildings in Miami-Dade County that measure 49 feet and a few inches.
Modern office buildings are a perfect example of why firefighters must keep abreast of the changes in building design, code requirements, and building materials. This is most effectively accomplished through prefire planning. We must, however, never forsake the basic skills of our profession because no matter how sophisticated and “high tech” our job becomes, firefighting is and always will be about getting water on the fire. ■
Special thanks to Dr. Wakar Ali, president of Hurricane Engineering and Testing, Inc., for his technical assistance.
