Operating Above a Fire
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Operating Above a Fire

Oct 07, 2023


Firefighters operating above a fire must contend with two hazards—getting caught in a flow path and floor collapse. Operating above a fire is always dangerous, but the risk is significantly greater when firefighters are unaware of a fire below them. I will examine how differences in elevation, concealed spaces, floor coverings, utilities, and fires that start on the outside of a building can mask the true location and extent of fire. I will also examine how research into fire dynamics and the study of line-of-duty death (LODD) fires have influenced changes in the tactics that firefighters perform to attack fires below them.

Private and multiple dwellings built on a hillside can be deceiving if viewed only from the front. For example, the townhouses in photo 1 appear to be two stories, but only when you view the sides and rear can you observe the lower "walk out" or "terrace level" (photo 2). Firefighters entering the front door may believe that they are operating on the ground floor when the fire is actually below them. Ideally, a lower level would be discovered when performing a 360° size-up, but this is not always possible. Consider homes constructed in rugged terrain in which not even a mountain goat could make it to the rear.

(1) Photos by author unless otherwise noted.


Every fire needs an intake and an exhaust. Fires thrive when they have an intake low and an exhaust at a higher level. If the only opening in a structure is the front door where firefighters gain entry, that doorway will have to serve as both an intake and exhaust—drawing fresh air through the doorway's bottom and smoke and gases venting from the top. Fire researchers call this a "bi-directional" flow.

Search Operations On The Floor Above

Firefighters can descend to a fire below them if they can stay below the neutral plane, the border between the intake and exhaust. If, however, windows on the lower floor fail, conditions will rapidly deteriorate. The fire will suddenly change to a uni-directional flow, with air entering low through the broken windows and exhausting high through the front door. These are ideal conditions for a fire to rapidly intensify and create deadly conditions for firefighters who suddenly find themselves in the exhaust, caught in the flow path of the fire. The risk to firefighters operating above the fire floor is multiplied when wind is striking the rear and the rear windows fail. This has been the scenario behind several LODDs.1

When you suspect the lower floors are only observable from the structure's rear, the first-arriving company should transmit an initial size-up that will make subsequent-arriving companies aware of the possibility of fire below them. For example, "Engine 2 on the scene, smoke showing from two-story townhouse; unknown stories in the rear." A crucial benchmark in the incident command system is a transmission that confirms the completion of the 360 and its results: "360 complete; three stories in the rear." But of equal or greater importance is a transmission confirming that a 360 has not been completed. This advises incoming companies that they are beginning operations with incomplete information and must suspect that floors are below them.

I believe drones on the fireground will be commonplace; they are especially useful when the terrain or the waterfront prevents a view of the building's sides and rear. Later, I will examine hose load configurations and tactics that facilitate rapidly positioning a hoseline to a rear deck, to porches, and to outside basement entrances.

Consider a multiple dwelling with duplex apartments, with the front entrance, a kitchen, and a family room on one floor and bedrooms accessible by a stairway inside the apartments. Now consider a five-story apartment building with single-story apartments on the first floor. In photo 3, the exterior hallways on the second and fifth floors lead to the front entrances of duplex apartments. The second-floor unit bedrooms are accessed by ascending interior stairs to the third floor; fifth-floor apartment bedrooms are reached by descending stairs to the fourth floor. Firefighters advancing a hoseline down to a fourth-floor bedroom fire will be caught in the flow path if the fourth-floor windows fail, just as if firefighters were fighting a fire in a walk-out basement.


During a thunderstorm, a lightning bolt blows a hole in the roof and starts a fire in the attic of a large suburban home. Engine company firefighters advance a hoseline to the second floor where truck company firefighters will pull ceilings to access the fire and spread salvage covers. When they pull the ceiling, second-floor visibility is reduced to almost zero because torrential rain enters the hole blown in the roof by the lightning and pushes the smoke to the floor, just as if a master stream fog pattern had been directed into the hole, but it gets worse.

These firefighters are in for a rude awakening because they are not aware of a fire in the basement that is rapidly intensifying. When lightning struck the house, it energized the wiring and started a fire in the basement circuit breaker panel. The lesson learned at this fire is whenever lightning strikes a structure, expect more than one fire: a fire in the attic; a fire started at an electrical panel in the utility room, the garage, or the basement; and fires in void spaces caused by damaged electrical wiring.

When lightning causes a current surge through a structure, it can result in an electrical arc that causes a leak in the flexible corrugated stainless-steel gas tubing. This is believed to be the cause of a fire that resulted in the death of a firefighter who fell through a floor into a basement. According to the investigation, the ignition sequence of the fire was identified to be a lightning strike, which induced the failure of the residential corrugated stainless-steel tubing (CSST) system. This caused the ignition of gas escaping from the hole caused by the arc, which then ignited combustible material in the area of origin.2

The occupant of Apartment 604 is reporting smoke pushing out of the wall behind her kitchen sink (photo 4). Engine firefighters drop a rope bag and hoist a hoseline, expecting to find fire when the truck firefighters open the wall. Their suspicion is confirmed: There is a fire in the wall, but they are not aware that the intoxicated occupant of Apartment 504 directly below has passed out on the couch with food cooking on the stove. The fire on the stove quickly spreads to the kitchen cabinets and follows the plumbing in the wall to the apartment above.


Lesson learned: Any fire in a kitchen, bathroom, or basement can spread in walls where plumbing runs from floor to floor. In multiple dwellings, it is common for plumbing to share utility chases or walls where kitchens and bathrooms are stacked back-to-back on each floor.

Photo 5 shows a utility chase in a hotel constructed in the 1920s; note the back of the wood lath and plaster. Fire originating or extending in this chase will spread, following the plumbing stack, to the cockloft, with no firestopping to inhibit its rapid extension


In photo 6, looking up, the fire in a first-floor apartment followed the plumbing in the wall separating the kitchen and the bathroom, spreading to the unit directly above. Photo 7 is a view of the same plumbing stack looking down from the second floor.



In photo 8, a plumbing stack runs the height of a 1950s vintage fire-resistive multiple dwelling, allowing fire to spread vertically from floor to floor. Today, building departments in most jurisdictions meticulously inspect where plumbing penetrates floors to ensure "poke-throughs" are filled with approved firestopping.


When I was a newly promoted lieutenant, my company was first due to a report of smoke in an apartment of a two-story taxpayer with commercial occupancies on the first floor and residences on the second floor. The businesses were closed for the night, their doors and windows secured with roll-down security gates.

An occupant directed us to a stairwell leading to the second-floor apartments. This is when I made three critical errors: First, I allowed a civilian to conduct my size-up. Second, I was afflicted with a bad case of tunnel vision, intent on stretching a hoseline to the second floor. Third, I failed to check the first floor where an incendiary fire had been set in a grocery market. Fortunately, the battalion chief ordered companies to force the security gates to check for fire. I was humiliated; my mistakes endangered my company because we were unknowingly operating above the fire. Fortunately, the only injury was my bruised ego. The lesson learned here is to check the floor below (including basements) for fire before ascending to an upper floor.

Companies go to the floor above a fire to search for occupants and check for extension. Before they ascend, they must advise the incident commander (IC) and engine companies operating on the fire floor. This is very important because their lives may depend on engine companies controlling the fire. If they fail to control the fire, firefighters operating above must have an alternate means of egress, such as a fire escape or ladders that were proactively raised to windows.

Another option may be for firefighters to locate and force entry to an area of refuge, such as an apartment that is not directly above the fire. This may require coordination and timing with companies forcing entry to an apartment on the fire floor, which was a factor in the LODDs of a Fire Department of New York (FDNY) captain and two firefighters operating above the fire at 62 Watts Street in 1994.

Every student of the fire service should be as familiar with the 1994 Watts Street Fire that occurred in lower Manhattan as they are with the 23rd Street collapse (1966), Waldbaum's fire (1978), Hackensack Ford fire (1988), and Sofa Super Store fire (2007). An analysis of this tragic fire is not within the scope of this article. Read the Division 7 Newsletter report on the fire and heed the lessons learned.3 Companies operating on the floor above a fire are in a precarious position. Until they have been advised that the fire is definitely under control, they are no position to "vent as you go" because fire can be drawn to the vented windows.

It happens all the time: A sprinklered wood-frame apartment building burns to the ground, often extending to other apartment buildings within the complex (photos 9-10). Note the single-inlet, 2½-inch fire department connection (FDC) in photo 10. How is it possible for fire to destroy modern apartment buildings protected by sprinklers? Two contributing factors are building construction and the type of sprinkler system. They’re springing up everywhere—complexes of wood-frame apartments with floors supported by lightweight engineered parallel floor trusses. Without proper draft stopping, usually every 2,500 square feet, a fire originating or extending to the space between floors and ceilings can spread unimpeded as if it were balloon-frame construction laid on its side.



These are the type of buildings where the only indication of a fire may be the smell of wood burning and two hours later the building on the ground. How does this happen? Fires originating in a floor truss void space quickly become ventilation limited. It is as if the fire is breathing; when it finds oxygen, it momentarily gains in intensity, which results in a few visible puffs of smoke, followed by nothing showing since it is deprived of oxygen, which reduces its temperature and pressure to push smoke out of the space.

The second factor in the destruction of lightweight wood-frame apartment buildings is the sprinkler systems. Typically, the occupants of these buildings are protected by residential life safety sprinklers in accordance with National Fire Protection Association (NFPA) 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies. NFPA 13R sprinkler systems are designed to cool surfaces and fire gases at upper levels, preventing flashover and allowing time to escape—not to prevent the destruction of a building by fire. Consequently, NFPA 13R sprinklers are not required in combustible void spaces such as attics and spaces between ceilings and floors.

In photo 11, once the ceiling is in place, the sprinklers have no effect on a fire above it. Photo 12 shows the results of a classic "outside-in" fire. The fire started in a rear outside air-conditioning unit, spread up the vinyl siding, and entered the soffit vents, resulting in an intense fire in the attic. Note the deep charring of roof trusses and the absence of plywood roof sheathing, which the fire completely consumed, exposing the metal roof covering.



In photo 13, note that the side wall head directly below the ceiling was not activated. If FDCs with just one 1½- or 2½-inch inlet are noted in an initial size-up, firefighters should strongly suspect that the fire building is protected by an NFPA 13R system.


In photo 14, note the Ts in the plastic sprinkler piping for upright sprinkler heads to protect the space between the ceiling and the floor and the pendant sprinklers for below the ceiling. This building is in compliance with NFPA 13, which requires sprinkler protection in combustible void spaces.


Underwriters Laboratories and the Chicago (IL) Fire Department (UL/CFD) conducted tests of the fire performance of lightweight, engineered wood floor assemblies such as those supported by parallel chord floor trusses and engineered I-joists.4 The results were to be expected: Lightweight floor assemblies not protected by a plasterboard basement ceiling collapsed in a little more than six minutes. What was not expected was that the oriented strand board (OSB) subfloor, carpet padding, and carpet insulated the top of the floor to the point that the temperature on its surface, where firefighters would be crawling, never exceeded 110°F. Additionally, UL/CFD, discovered that a thermal imaging camera (TIC) never revealed a heat image indicative of fire temperature exceeding 1,200°F directly below. Shortly after the publication of the tests results and release of videos, my department, Miami-Dade (FL) Fire Rescue, experienced this phenomenon at an actual fire.

Miami-Dade units responded to a report of a smell of smoke in the bedrooms above the garage of a two-story, zero-lot-line tract home in a new suburban subdivision. The home's first-floor exterior walls were of concrete block with a wood-frame second floor (photo 15). The second floor had an OSB subfloor supported by lightweight engineered wood floor trusses and was covered with carpet padding and carpet.


The building code at the time the house was built in 1993 required the garage's walls and ceiling to have a fire resistance rating of one hour. This was achieved by installing 5⁄8-inch Type X fire-resistant drywall on each side of the walls and two layers on the ceiling (photo 16). The robust garage ceiling was required to protect the second-floor bedrooms but, in this case, it masked the indications of an electrical fire that started in the combustible void space between it and the second floor.


The officer of first-arriving Engine 56 examined the garage before ascending to the second floor. The garage was completely clear—no sign or even an odor of smoke. Companies searching for fire on the second floor found smoke that was increasing in density but no heat; accordingly, their TIC showed no indication of heat. To improve visibility, the companies operating on the second floor requested the venting of the second-floor windows. The battalion chief, sensing something wasn't right (see sidebar "Something Just Isn't Right!"), ordered the companies on the second floor back down the stairs to the first floor. When the first window was vented, it was followed by a blast of flame and the sudden collapse of the bedroom floors into the garage (photo 17).


My company and others were operating at a fire in small, one-story, wood-frame house. Smoke was from floor to ceiling with no perceptible heat, making it difficult to locate the fire.

As the incident time reached 20 minutes, the IC (my battalion chief) ordered all companies out of the building. This chief was a stern but fair leader with a strong command presence. Company officers in his battalion knew that when he ordered them out of a building, he expected immediate acknowledgment and prompt compliance. Any officer who questioned his order or tried to justify continuing operating on the interior—e.g., "We’re making good headway"—was in for a "tune-up" later in his office.

Once companies were out of the building and accounted for, the chief told us he pulled us out because "something just isn't right." A few minutes later, the entire floor collapsed into a basement packed with burning furniture. The collapsing floor acted like a giant piston, pushing flames out of every door and window opening. This scenario compels the question: How many firefighters’ lives have been saved because the boss acted on gut intuition and pulled them out of a dangerous situation? Following are some indications that "something just isn't right":

In photo 18, note that the garage walls are pristine because there was never any fire in the garage. The lessons learned at this fire reinforce the lessons of the UL/CFD tests—how much fire can be burning above a ceiling with absolutely no indication below and the importance of pulling ceilings to check for fire above them.


Floor tiles can also be misleading and mask fire conditions below the floor and add to the dead load that a floor must support, hastening its collapse when exposed to fire (photo 19).

(19) Photo courtesy of Tim Olk.

UL, the National Institute of Standards and Technology (NIST), and the FDNY have conducted several live fire experiments to evaluate the effectiveness and level of risk of tactics to fight basement fires. All the experiments reached the same conclusion: The safest and most effective way to fight a basement fire is at the same level. If this is not possible, use any method that will rapidly get into the basement.

In 2012, the FDNY acquired several town houses on Governor's Island, a former U.S. Coast Guard base. In several live fire experiments, the FDNY, NIST, and UL evaluated the traditional method of attacking a basement fire—from an interior stairway vs. attacking on the same level as the fire. For more than 100 years, firefighters were taught to attack a basement fire by taking a hoseline down the interior stairs, which has been the cause of several LODDs. Additionally, firefighters were taught that if their descent was too punishing, remain at the top of the stairs to keep the fire from extending. When firefighters are positioned directly in the flow path of the flames coming up the stairs, they can flow all the water they want but never extinguish the fire in the basement because they will be unable to get water on the seat of the fire. Additionally, if a basement has an unfinished ceiling, fire will rapidly extend from the contents on the basement floor to the floor assembly above, out of reach of a stream directed down the stairs. Basement fires also spread vertically inside the walls by following the plumbing. Consequently, firefighters intent on stopping fire extension by the basement stairs may not be aware that the fire has already passed them through the kitchen and the bathroom walls.

A walk-out basement, terrace-level apartment, or outside basement entrance can give firefighters an excellent opportunity to attack a basement fire at its same level if they can stretch a hoseline to the rear. Stretching to the rear of a structure built on a hillside can be treacherous. In rugged terrain, the rear is commonly reached by very steep outdoor stairs. Descending the stairs is more difficult when they are covered with ice and snow. Similarly, firefighters stretching to the rear may find themselves sliding down a snow-covered hill on their backsides.

Chief officers, listen carefully to radio reports from company officers—not just what they say but how they say it. If their transmissions sound distressed or give you an uneasy feeling, trust your gut! It may be time to regroup, reevaluate tactics and strategy, and reassess the level of risk.

Stretching to the rear requires a hose load that meets two requirements: First, there must be sufficient hose to stretch to the rear and then to advance a charged line back toward the front of the basement. For example, consider that a fire in a basement unit in the middle of a row of town houses could require hundreds of feet of hose and the teaming up of engine companies to provide sufficient personnel to perform the task. The second hose requirement for stretching to the rear is having a hose load configuration that a firefighter can carry on a shoulder or forearm rather than dragging. This enables stretching the hose around corners and obstacles. This is one of the reasons that Miami-Dade recently switched crosslay hose configurations from a triple layer to a modified flat load. All or a portion of this load can be inverted as it is pulled so that hose plays off the top of the bundle, similar to a minuteman load (photos 20-21). Determining the length of stretch is best determined during prefire planning, when you can substitute a rope with knot every 50 feet for hose. Another crucial prefire determination is to identify buildings in which firefighters can gain access to the rear by stretching through an adjoining unit.



Recently, UL conducted a series of tests on fighting basement fires, which included methods to get water on the fire when there was no outside entrance. UL experimented with a variety of devices such as rotating distributors and piercing nozzles. These devices can get water into a basement through basement windows or by piercing or cutting holes in the floor within reach of exterior doorways. UL also experimented with the "hockey stick" fabricated for Miami-Dade's Engine 2. It can be difficult to direct a stream into the overhead of a basement from a basement window, especially if there are window wells. The hockey stick is angled to direct a stream in an upward direction (photos 22-23).



In photos 24 and 25, Chicago area firefighters use mauls to remove brick veneer on this wood-frame home. Their objective is to access and open the rim joist to direct a stream into the bays of the burning floor joists supporting the first floor.



Photo 26 shows Toronto firefighters’ heavy-duty, battery-powered drill equipped with a four-inch core bit, perfect for drilling holes in rim joists to insert a 1½-inch rotary distributor. A rim joist is attached perpendicular to the floor joists and provides lateral support for the ends of the joists. Rim joists are at the top of basement foundation walls.


Although there are exceptions, floor joists typically span to the shortest side of a structure. For example, urban bungalows tend to be narrow, so floor joists run parallel to the front and back walls and rim joists will run parallel to the side walls. Photo 27 shows a laminated strand lumber (LSL) rim joist. LSL is composed of flakes of wood that are pressed together with heat and bonded by adhesives.


Firefighters must be career-long students of the fire service, constantly updating their knowledge according to changes in building construction, fire dynamics, and new tactics derived from an abundance of research. Firefighters who are not students endanger themselves and their fellow firefighters.

1. National Institute for Occupational Safety and Health. "Simulation of a Fire in a Hillside Residential Structure San Francisco, CA." Technical Note 1856. https://bit.ly/3KsHP43.

2. Howard County Department of Fire and Rescue Services. "Line of Duty Death Investigative Report: Lt. Nathan Flynn, 7005 Woodscape Drive, Single Family Home Fire, July 23, 2018." https://bit.ly/3Ktk8sd.

3. Division 7 Training and Safety Newsletter (June 2018) "62 Watts Street, Manhattan." https://bit.ly/41fnEwk.

4. Fire Safety Research Institute. (August 1, 2006) "Structural Stability of Engineered Lumber in Fire Conditions." https://bit.ly/3Eu0g4B.

BILL GUSTIN is a 50-year veteran of the fire service and a captain with Miami-Dade (FL) Fire Rescue. He began his fire service career in the Chicago area and is a lead instructor in his department's Officer Development Program. He teaches tactics and company officer training programs throughout North America. He is a technical editor and an advisory board member of Fire Engineering and FDIC International.

Bill Gustin will present "Management and Operations for Newly-Promoted Company Officers" at FDIC International in Indianapolis, Indiana, on Monday, April 24, 2023, 1:30 p.m.-5:30 p.m.

Caught in the Flow Path: Fighting a Basement Fire on the Fourth Floor Above the Fire Floor: Hazards and Precautions Vincent Dunn: DANGERS OF OPERATING ABOVE A FIRE Tom Brennan: The Floor Above (1) (2) Search Operations On The Floor Above (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) . (24) (25) (26) (27) BILL GUSTIN