FIREFIGHTING IN “DISPOSABLE BUILDINGS”

BY JEFF SHUPE

“Disposable buildings” are everywhere, in cities and towns across the country, from rural hamlets to crowded urban centers. This term, coined in the fire service, refers to newer buildings, especially those built using Type II Noncombustible construction, and that employ lightweight structural materials. These buildings meet code requirements and may be required to have internal fire protection systems. However, the materials used in their construction are lacking in size and mass. This lack of structural mass or density will have a direct correlation to the building’s time to failure under heavy fire conditions.

(1) The fire was located inside the building’s B/C corner. The upper left corner of the wall shows a long vertical crack resulting from the movement of structural members distorted by exposure to heat. The presence of such unsafe conditions must be communicated to all hands operating at the scene. (Photos by author.)

One example of lightweight material is the open-web steel bar joist, commonly used in building structural systems, specifically in floor and roof applications. These metal structural members, with a high surface-to-mass ratio, are manufactured from ordinary structural steel. During working fire conditions, they will absorb and conduct heat and begin to lose much of their strength at temperatures of around 1,000°F. This loss of strength may be indicated by sagging roofs or floors, bowed metal exterior walls, or brick or concrete block walls that have cracked from structural movement. Of greatest concern is the possibility of structural failure or collapse, especially while firefighters are operating in or near these buildings during fire conditions.

(2) Windows used in these structures have two thick plates of glass with a plastic membrane sandwiched between them, making ventilation difficult and time-consuming. In this fire, firefighters noticed that the glass panels did not break and fall out as would most conventional windows. Instead, the material just ripped or tore, leaving glass pieces in place and inhibiting the ventilation of heat and gases. Here, some of the membrane can be seen between the glass panels.

Building construction and its terminology can be misleading and deadly to the unsuspecting or untrained firefighter. Take, for example, the terms “fire resistive” construction and “noncombustible” construction. Without understanding these terms or knowing how building materials will react during fire conditions in one of these buildings, firefighters may think they have whatever time is needed to get their job done and need not concern themselves with collapse, flashover, or other associated hazards. Actually, just the opposite is true, especially where lightweight structural members are used. Even a quick fire department response to a fire in this type of building may find early signs of weakening structural members.

One particular type of “disposable building” that needs to be looked at closely for its fire potential is the chain drugstore building found in every community across the country. These structures are built using Type II construction methods. Fires in these buildings have the potential to kill or injure firefighters. Good, relevant training in fireground strategies, tactics, and building construction can help make for a safer fireground when confronted with fire in one of these buildings.

A LEARNING EXPERIENCE

During the early morning of July 14, 2004, at 0134 hours, a box alarm assignment consisting of two engines, one ladder, and one rescue squad, commanded by a battalion chief, was transmitted for fire in a drugstore at the intersection of Fulton and Clark Avenues in Cleveland, Ohio. The dispatcher stated the call was for “fire in the Rite Aid drugstore.” Engine 24, the first-due engine, located only eight blocks away, arrived quickly to find a well-advanced working fire with heavy fire venting from windows on two sides of the building. Dense black smoke was also pushing out of the building under pressure. The fire dispatch center, on receiving Engine 24’s initial report of a well-involved drugstore, dispatched one additional engine and one additional ladder company to the scene.

(3) Firefighting strategies and tactics for large-area commercial buildings are not the same as those used in day-to-day fire operations at residential dwellings. A greater volume of water is necessary for cooling and covering a larger floor area, which will hold a much larger volume of fire. Consider fire stream volume, reach, and penetration when selecting the attack hoseline size.

The building had closed hours earlier (approximately 10:00 p.m.) and had a steel roll-down gate over the only entrance door-typical for an inner-city neighborhood. Engine 24 positioned itself in the parking lot adjacent to the B side of the building, and firefighters stretched a 21⁄2-inch attack line. At the same time, the officer looked for another way into the structure, but this was the only feasible one. A squad company or ladder company would have to cut the roll-down gate first.

Fire was now showing above the roof. At this point, firefighters noticed that a large vertical crack had opened up in the B/C corner of the building where the fire was located, running downward from the roof approximately 10 feet. The building’s structural system was beginning to weaken.

As Squad 4 used a power saw to cut the roll-down gate, Engine 24 hit the fire on the B side through two small windows to slow the fire’s progress. The size and configuration of the windows required that the attack team come close to the wall where the crack had developed. Once the roll-down gate was opened, the attack line was brought into the entranceway, and the attack was finished from there.

This building was saved despite heavy fire damage and has undergone extensive repairs. The drugstore chain reopened the store for business. Total loss was estimated at $1.3 million, with structural loss set at $200,000. As stated before, this “disposable building” is typical of others like it across the country. The building is constructed of materials that will not support combustion, so it receives a Type II building “Noncombustible” rating.

TYPE II BUILDING FEATURES

The interior of this kind of Type II structure is wide open with no compartmentalization. The only thing that occupies the floor area is the shelving for merchandise, in-wall coolers, and business transaction counters. The fire load consists mainly of the merchandise, which depends on the type of business operating in the store. However, that is not to say there won’t be any highly flammable products found! The newer chain drugstores carry a wide variety of products for all kinds of needs, making them more like a large convenience store.

(4) This is the underside of the roof deck, made up of sheet metal Q-decking and supported by open-web steel bar joists. The decking sags downward because it lost its normal strength when exposed to heat.

The framing system for this type of building consists of unprotected thin structural steel columns; they are not wrapped in gypsum board, drywall, or any other material that would protect them from heat or flame. Between the perimeter columns are metal studs to which the interior walls are attached. The exterior masonry walls are of brick veneer.

The roof supporting system consists of girders and beams with open-web bar joists spaced between four and six feet apart. This network will support the sheet metal Q-decking for the roof, which will most likely be a finished, built-up type. Atop the roof will be air- conditioning units, a weight and collapse concern under any fire conditions.

Inside the store, the ceiling (if there is one) will be suspended with drop-in or lay-in tiles or panels. There are some ceiling assemblies with flame spread ratings that may act as membrane protection. However, under any appreciable fire conditions, they will do little to resist heat or flame spread. If there is no ceiling at all, fire will directly attack the roof-supporting system, causing it to weaken quickly and possibly fail early in the incident.

(5) Note the distorted open-web bar joists with remains of the suspended ceiling assembly hanging loosely. Notice also the amount of deflection in the bar joist in the center of the photo and the one to the immediate left.

The windows installed in this particular structure were small and square but positioned at an angle to resemble a diamond. The approximately 36- by 36-inch window glass panels, engineered for energy efficiency and strength, each consisted of two 1⁄2-inch-thick glass panels, with a thick plastic membrane sandwiched between them. During this fire, firefighters venting windows were having trouble breaking these windows; it seemed the glass was just “tearing” open, making venting a slow, incomplete process. As a result of these factors-window size and positioning and lack of total vent area-it was evident that the building was retaining a lot of heat.

Sprinklers or other types of fire protection systems may or may not be found in these structures, depending on local code. Although the floor area may exceed 5,000 square feet, a sprinkler system may not be present. If there is, sprinkler heads will most likely be positioned below the ceiling or the roof-supporting members. In the case of a severe fire or other problems such as heads blocked by stock piled too closely to them, any fire getting above the sprinklers and into the ceiling plenum will affect the roof’s stability.

FIRE ATTACK AND STRATEGY

The strategy at this particular fire was to regain control of an out-of-control situation. There were no exterior exposures to worry about, and internal exposures were covered by hoseline placement. The 21⁄2-inch attack line was selected for the job and proved itself again for its obvious knockdown power, primarily because of the volume of water it discharges and its cooling capability. More important, however, is the safety factor it provides firefighters-large-area buildings like this one need powerful streams with reach to get to the fire, knock it down, and absorb the heat. Here, the 21⁄2-inch line reached all points of the fire area from a safer location in the vestibule, and the fire was extinguished. From the doorway to the fire area was approximately 60 feet. Other floor areas of the store where stock was heating up were cooled quickly and effectively.

Attacking a large fire offensively with a small- or low-volume hoseline makes firefighters work longer to gain control and perhaps at a closer distance than necessary. Streams with inadequate volume will soon put firefighters in defensive mode, since they will not be able to get enough water on the fire. In this particular fire, however, knockdown occurred quickly because stream volume and reach were adequate for the job. If a body of fire is not knocked down and heavy fire continues to burn, personnel must consider that structural members are weakening.

With respect to the crack that had developed in the corner where the fire was located, after overhaul firefighters noticed the distorted open-web bar joists and that the roof overhead was sagging over the area where they had been working. Because of the 21⁄2-inch stream’s power and ability to blow apart the ceiling and penetrate the fire area, water cooled down the steel members and stopped further loss of strength.

LEARNING FROM EXPERIENCE

When it’s time for fire attack, remember, size does matter. Every fire has a critical flow rate that must be achieved for extinguishment; big fires need big fire flow.

(6) This close-up view shows the crack that had developed from the fire, the result of weakness in the steel structural members. Firefighters noticed the crack on arrival and communicated its presence to everyone to make them aware of the hazardous operating conditions.

This means fire departments should deliver big water in a big way! Several hoselines with less volume on a large fire do not add up to large-volume fire flow! Fighting a large body of fire in a structure with less than adequate streams will not extinguish the fire in a timely manner-in fact it may make fireground operations defensive!

(7) The extensive fire damage required the store to be completely rebuilt. Here, you can easily see the amount of distance between the thin steel columns and metal studs used in the construction of this type of building. Less mass and density, coupled with a lack of “in-place fire protection” can lead to greater damage and a greater potential for structural collapse.

An old fire service adage says, “As the first line goes, so goes the fire!” Under intense, growing fire conditions, using a low-volume attack line first and then trying to put a larger line in service later will put fireground operations in a reactive mode in which the incident now dictates to the fire department. Many fire departments are unable to rebound from a bad tactical decision early in the incident. This is when control of the situation is lost. This can be the result of any number of reasons, such as a lack of resources, poor training, or poor fireground control. In any case, loss will be greater, and the longer the fire burns, the less stable the structure becomes. More importantly, however, fireground safety could be jeopardized.

(8) This corner of the building shows a thin, steel column that supports two intersecting steel I-beams that act as girders. They were located directly over the fire area. As the steel members conducted heat from the fire and distorted, the resulting movement caused the wall to crack.

For large fires at which handlines are needed, the 21⁄2-inch attack line should be the handline of choice. It has excellent knockdown power because of its superior flow volume and stream reach. Coupled with a low-pressure, high-volume solid-bore nozzle, it can increase the fire attack efficiency of an understaffed fireground. After the fire has been brought down in size, the fire department can then use smaller, more mobile handlines to finish the job.

Smaller fire departments and those with poor staffing should not be intimidated by the large handline. Use the large line when the situation requires it! Departments should train to know when and how to initially stretch a 21⁄2-inch attack line and where to position it for maximum effectiveness. Because it is heavy, it does require that personnel are trained in its use and how to make it an offensive tool. Firefighters must keep in mind that the 21⁄2-inch handline is not just for defensive operations-it can be a mobile attack line.

(9) Fire departments should arrange their engine company hosebeds to provide multiple attack lines of different diameters. Attack hose should be loaded with company staffing in mind: It should play out easily and with minimal effort so firefighters can get water flowing quickly on a fire.

A Type II building may have no fixed interior walls to break up or compartmentalize the main floor area. Without a sprinkler system or detection system on-site, a fire that starts after hours may get a good head start before it’s noticed and reported. Heat from the fire can flow freely throughout the building; as it does, the building, its structural components, the contents, and stock will begin to heat also. Because of the high amount of plastics, synthetics, and other man-made items, along with paper products and wrappings found in these stores, there will be plenty of fuel for the fire to feed on. Firefighters arriving at a working fire where there is high heat and heavy smoke conditions must recognize the fire potential that exists. These buildings can also present numerous collapse hazards to personnel. That crack in the outer wall noticed soon after the first company’s arrival was a warning sign of collapse, a result of steel structural members moving after being weakened from the heat of the fire.

(10) Attack hoses should be loaded with nozzles attached, ready to go to work. The last length loaded on should be folded in such a way as to give the nozzleman 50 feet of hose, a working length providing enough hose to cover the fire area and a little more.

Well-trained firefighters make good, informed decisions that lead to smooth fireground operations. Regular training in fireground strategy and tactics, along with knowledge and respect for building construction, allow for safer firefighting operations. Fire-ground awareness and cognizance also in-crease firefighter safety. Watchful eyes and ears must constantly look for signs and sounds of a weakening building. If you see an unsafe situation on the fireground, pass the information on to everyone as soon as possible. Your safety and that of everyone else depends on it! ■

References

Clark, William E. “Critical Rate for Each Fire,” Firefighting Principles & Practices, second edition (Fire Engineering Books & Videos, 1991), 34.

“Open Web Bar Joists-Early Failure Under Heavy Fire Conditions,” illustration, Building Construction Principles and Practices course, National Fire Academy.

Sylvia, Dick, “Dangers of Steel Bar Joists and Noncombustible Buildings,” Fire Engineering, May 1977, 14.

Sylvia, Dick, “Noncombustible Buildings-Death Traps for Fire Fighters,” Fire Engineering, March 1979, 9.

■ JEFF SHUPE is a career firefighter with more than 30 years of service. He is a firefighter in Cleveland, Ohio, and a former volunteer firefighter. He is a certified fire instructor for the State of Ohio and has served as training coordinator for volunteer and full-time fire departments. He has an associate’s degree in fire technology from a local community college and attended the University of Cincinnati Fire Protection Engineering program. He is an FDIC H.O.T. team member for Engine Company Operations and an FDIC classroom presenter.