Fires Below the Residential First Floor – Fire Engineering

A fire originating below the first floor of a residential structure is very vulnerable.
BY DANNY STRATTON
A fire originating below the first floor of a residential structure is very vulnerable. It is important that fire control measures are executed to stop the extension of combustion, which can overtake occupants and the structure more readily than a fire in any other location. We, the suppression specialists, must take aggressive action to save the entire structure from a fiery destruction and execute life-saving measures to make a safe environment in all areas of the building.
Concerns associated with a fire below the first floor (as opposed to one in any other compartment of the structure such as a top-floor bedroom fire) include fire spreading through the attic space and damage to the structural elements of the roof that has little or no load imposed on it. In the division below the first floor, the fire problem is amplified. The entire structure and its occupants on all levels are in the path of dangerous by-products of combustion, and there are heavy floor loads that can release on failure.
What do we have underneath the first or main floor of a residential structure? For the purpose of technical terminology, let’s define the different compartments that can be below the first floor. We need to be familiar with three types: crawl space, basement, and cellar. Each has individual characteristics.
A crawl space is common in ranches, modular type homes, and garden apartments. This space may be in combination with a cellar or a basement in some occupancies. Its purpose is to facilitate air circulation and provide access for repairs such as plumbing, electric, and so on. This tight space is usually at least a foot in height and has a dirt or gravel surface (photo 1).
Often, “basement” is the preferred layman’s term used to describe both the basement and the cellar. A basement has more than half of the height of the exterior foundation wall aboveground and standard size windows just like the upper floors (photo 2). A standard door may also be present, which provides access to the exterior from the basement. This is common in an apartment building.
In a cellar, half or more of the foundation wall is below ground (photo 3). A cellar has a limited number of windows that are one-third the size of the windows on the upper floors. It’s also possible to find no windows in a cellar. Ordinarily, most single-family dwellings and city-type row homes have cellars. Building codes define basements differently. We will use the descriptions I have provided.
Fires below the residential first floor present an array of challenges. A fire in this area can be the hottest fire an interior firefighter will experience. The most notable challenge is accessing the fire area because of the convection-influenced fire gases. The interior stairs may be the only way the fire is ventilating, causing a grueling chimney effect. Crews must enter to suppress.
Furthermore, the masonry floors and walls retain heat in the compartment, keeping the high temperatures from rapidly escaping. Moreover, the ceiling is low (common in older cellars), and the ventilation openings are limited. A below-grade area may have few or no windows and one or no doorway to the exterior. Even with the presence of windows, if they are glass block or thermal pane, they will add to the adverse environment (photo 4). Button up, have your hood on, and use the ear flaps. We seem to use the ear flaps only to keep our ears warm when drilling on a cold training ground. The attack group should stay low and descend feet first in high heat.
Another challenge is the stability of the stairs. Most stairs in a cellar have a tread that may have no riser and no protective soffit, and there may be a room with gypsum board on the walls behind the stairs, such as in a basement. Basements may be apartment units with less than half of the height below grade that are continually occupied as a living area with finished walls. These types of occupancies lend some inherent fire protection. Basic cellar stairs, commonly found in older homes, are more prone to fire from their inherent open construction; fire can easily attack the unprotected structure (photo 5).
You must verify the stability of the stairs. When descending, sound the treads before placing your weight on them. One way to do this is to use a tool to pound each tread before stepping on it (photo 6). In some cases when the nozzle firefighter does not have a tool, he can use his feet to sound the treads. A good technique is to sit with both feet out in front and use the feet to pound the steps before sitting on them. The nozzleman should be facing forward, have the tip of the nozzle in his hands, and be ready to open up the bail (photo 7).
Another option is for the suppression specialist on the nozzle tip to descend facing the stairs and placing his feet on the outer edges of each tread. This positions the firefighter at the strongest point of the tread. The only drawback is that the stream can’t be placed into operation as quickly as in the previous method if the stairway should become involved with fire (photo 8).
If the stairs are compromised from fire or are dilapidated, use a ladder to provide access by bridging the first floor to the floor below. Therefore, while at the top of the below-grade opening, if fire has possession of the stairs, extinguish it first, then position a ladder before going downward. It is good practice to place a ladder on the stairs after extinguishment in case the stairs are compromised after extinguishment (photo 9).
A basement or cellar used consistently for human occupancy will have some type of ceiling covering, such as gypsum board or ceiling tiles. In a below-grade area that is not meant to be a living space, the absence of a covering is a concern; the joists of the first floor exposed to a fire almost immediately could result in a collapse.
In interior firefighting, take measures to ensure the stability of the decking where the attack originates. Before taking any action, make sure you know the type of construction; this is important for firefighter safety. Anticipate the immediate release of the floor above in the presence of unprotected lightweight wood or wooden trusses when a fire is at the growth stage or beyond (photo 10). The incident action plan must include an attack strategy away from the collapse path that uses indirect attack methods and wall-breaching techniques. Use cellar pipes, distributors, and bent tip applicators (see “A Side-by-Side Comparison of New and Old Construction,” Fire Engineering, September 2011.) These devices can be used in combination with breaching walls and floors to stop fire spread and prevent collapse. Exercise caution in using specialty nozzles on the above questionable floor. Exterior wall breach and openings (i.e., windows) may be the best routes in using an indirect attack method at an outside location. This will be safer than using the floor for an attack platform.
In addition to unprotected structural floor elements, the interconnected vertical voids are readily accessible to fire spread because of the lack of a ceiling. Pipe chases; electrical conduits; heating, ventilation, and air-conditioning (HVAC) ductwork; and stud bays of the old balloon-frame construction all begin or terminate in the floor below (photos 11 and 12). A crawl space may be present along with the cellar or basement in some structures, particularly garden apartment buildings. These pathways will send by-products of combustion to other areas in many directions of the structure. Additional hoselines must be on the floors above along with hand tools to open up walls, floors, and chases to look for fire. In a newly constructed home with lightweight floors, breaching the exterior walls may be the safest tactic.
The limited number of openings in this area raises two concerns. The first is the lack of access and egress. It is common for a below-grade area to have only interior stairs and a lack of windows—two or four windows that are approximately 30 inches wide and as short as 12 inches at best. Should firefighters have to call a Mayday, the distressed personnel may have trouble escaping, and it would be a challenge for a rapid intervention team to reach them. The remedy is to breach the walls and floors to gain access and egress.
Breaking the glass in thermal pane windows may not provide adequate opening for egress. Because frames are larger than in the past, they may obstruct some of the window openings for access and egress (photo 13). In this situation, attack the frame to enlarge the opening.
The second concern is that the lack of ample openings will hamper the ability to conduct a coordinated interior fire attack. There is a lack of access for placing streams to achieve knockdown. In a windowless below-grade area, you must consider a new strategy for creating access for the stream if the downward interior stairs are not available. The lack of openings can also make it difficult to ventilate. Once again, breaching is an option for creating access to the area.
In an unfinished basement or cellar, clutter and hanging wires can entrap a firefighter (photo 14). Personnel who could find themselves in this compromising situation should be trained in disentanglement procedures. Extensive training in survival is needed for the interior firefighter to stay safe. All personnel and departments should be dedicated to learning and reinforcing firefighter survival techniques; our lives depend on it (photo 15).
The overall strategy is to identify the fire’s location, confine the fire, and ensure that the fire is totally extinguished. On your arrival, if there is an exterior access to the area of the below-grade fire (any type of door) along with interior stairs, you have an option for a strategy (photo 16). Position the first hoseline to where the fire is going, and use a second hose stream to knock down the bulk of the fire. The plan is to stretch the first handline to the top of the interior stairs to prevent upward extension. The second line should enter the exterior accessway to extinguish the fire in the below-grade area. Certainly, if you were taking a promotional exam, this would be the right answer. Our first priority as suppression specialists is to stop the fire’s forward progress.
In reality, with the reduction in the number of personnel and fire companies, rural and suburban departments experience slow response times. Deploying two attack streams in a coordinated timely manner is challenging, if it is possible. Furthermore, an exterior entrance to the below-grade area is not present at every occupancy.
To combat the above deficiencies, use a single line for the initial knockdown to protect the occupants and the property. If a life hazard is probable, you must immediately knock down the production of fire gases. The time lag of waiting for a second line and coordinating a tandem line strategy could delay extinguishment.
The immediate placement of a stream is the most important tactic at a structure fire. A delay in this operation could spell doom for an occupant taking his last breath of deadly by-products, and there is also the immediate need to improve conditions in the environment where firefighters are to operate.
If an exterior entrance to the cellar or basement is present, you can initiate the attack from the outside door. First, verify that the interior door is not breached by fire. A recon group from a truck company or the attack group supervisor can enter the home to determine the status of the doorway. The supervisor will determine where the attack group will begin suppression. If fire has taken the door or it is not possible to close the door, initiate the attack from the interior. This will stop the fire spread to the first floor.
As long as fire has not taken hold of the interior stairway into the first floor, use the exterior doorway for attack. Exterior accessways can be a beneficial initial attack point for three reasons. First, the stairs are usually made from concrete, so there is more stability. Second, the staircases are usually short, with fewer than seven steps down into the compartment (photo 17). Finally, attack crews can initiate their descent from a safer area instead of from the floor above the fire.
If not used for attack access, the exterior pathway to and from the area below can still be an asset to your fire control measures. An outside group can force the passageway to provide a ventilation point and a secondary egress for personnel. This large opening can serve as the best ventilation point, considering that any other openings, if present, are much smaller than the entranceway.
Descending the interior stairs to the bottom of a basement or a cellar is certainly “what separates the men from the boys.” When climbing down, the intensity of the heat can give firefighters second thoughts about being in this occupation. It’s imperative when you advance down that you cease the production of by-products for the purpose of life and to make a better working environment for personnel.
Remember that fires are hot. Feeling the heat does not mean a discontinuation of interior operations. Heat can still be felt through your hoods; just be mindful of your exposure time. The thermal energy should subside as the coordinated fire attack using streams and ventilation techniques is begun.
On arrival, determine the location of the fire. One clue is smoke showing on the first floor or all floors of the structure. Don’t be misled by smoke on the upper floors, which could lead the attack group to advance past the fire area. Be sure to determine that the fire is not below the first floor. A residence with thermal pane windows or glass block windows can mask fire conditions below the first floor (photo 18).
When advancing, as described above, verify the stability of the stairs. Assume the fire is in the compartment underneath until it has been confirmed that it is not there. The presence of a heavy floor load on legendary joists or of lightweight construction could drop firefighters into a burning chamber. The cutting off of personnel egress and firefighters falling into a fiery pit are the results of not gathering enough information. A common statement cited in firefighter line-of-duty fatality reports is “failure to conduct a complete size-up.” Complete and thorough analysis of the scene is very important. Be sure to recon the floor below when the fire appears to be on the first floor.
The attack line should be one of the following diameters: 1½, 1¾, or two inches. The length should be double the distance of the length of the residence because most of the interior and exterior access doors to the below-grade area are at the back. If a front access to the area below is readily available—at times it is—it may be the most advantageous access point for quick stream application.
The team may opt to start the attack from the interior stairs of the residence. If so, before entering the first floor to get to the below-grade stairway, charge and bleed the hoseline on the exterior. Be certain to spin the selector to straight stream if it’s not a solid stream. This will keep steam production to a minimum in a confined space, such as a cellar. In this way, the effects of steam can be more pronounced.
Do not drag a dry hose into the interior first floor. First, you are in the area to which the fire is most likely to spread next. It’s possible that by the time the nozzle is bled and you don your gear—or even just prior to arrival—fire may have taken possession of the first floor. Second, if you should fall through the floor, at least you would have some protection with the hose at the ready. Remember, you are initiating your attack from a platform above the fire.
At the entrance, consider a few things before descending. First, don’t apply agent at the entrance unless fire is on or under the staircase. Descend to the floor at the base; await your officer. No one should be on the stairway. When the pipe is opened, steam may travel up the stairs because of the lack or the presence of only a limited number of windows, turning the stairs into a chimney for the heat.
Next, consider the ventilation efforts. If the fire has not taken the windows, you must provide a by-product ejection point. It is good timing if this is done while the nozzle is at the bottom of the stairs. However, if it may aid in making the travel down the steps comfortable—and definitely if fire is under or on the steps—by all means tell the outside vent group to take the windows (photo 19).
Now you are in the below-grade area. If the fire is before you, application of the stream will be underway. However, if the exact location of the fire is yet to be discovered and only smoke is present, resist the temptation to apply water. If you suspect that flashover may happen where you are, aim the nozzle as high as possible, and do a half bail crack by simply opening the handle of the nozzle halfway (less than a second) to cool the gases above and slow the result of a flashover. To find the fire area in the darkness of a smoke environment, keep quiet for a few seconds and listen for the crackling and popping sounds of the fire.
As you meet the free-burning fire, sweep up high to protect the joists if they’re without a covering, and cease extension to the vertical voids. After knockdown, examine the stability of the joists, and check the voids that run through the rest of the structure. As in any other standard structure fire, conduct overhaul and communicate with the supervisors of the divisions on the floors above to bring the fire under control by stopping extension in hidden voids.
The second attack group should be positioned on the first floor for the purpose of preventing extension. Its primary concern should be fire extension by way of the below-grade stairs while the initial attack group is below; maintaining their egress is the foremost concern. The nozzleman of the second hoseline should go no farther than the entrance of the stairs.
After the safety of the crew below is ensured, stop the extension that may travel in the vertical voids, such as pipe chases, stud channels, and ductwork voids. The kitchen and bathrooms on the first floor are rooms of importance. Typically, they are highly probable avenues for fire extension given the number of vertical voids—pipe voids, in particular—that they contain. Any additional attack groups should position hoselines on the successive floors above to prevent extension and give attention to the same routes of fire travel.
If fire has possession of a crawl space instead of a cellar or basement, place an attack group on the interior. Once again, if a department has the luxury of stretching two lines in a timely manner, place the first inside to protect the unburned areas and the occupants. A second priority is to place a stream from the exterior through an opening to knock down the fire (photo 20). However, you can achieve a quick knockdown with the first line to stop the fire’s energy from an opening on the exterior.
Let’s not forget truck work. These tasks typically follow the same agenda as with other levels of a residential structure. Place ground ladders for the upper floors for access and egress; conduct searches of all upper areas. You may have to open voids on the upper floors to stop the upward fire extension from the lowest level.
Access the roof for assessment; examine vertical void openings for fire. Fire Department of New York Deputy Assistant Chief (Ret.) John Norman recommends cutting around soil pipes and over other vertical voids (such as a trash chute) to slow or stop the fire in the vertical voids from extending into the horizontal voids.
A word of caution: When conducting search for life independently of a hose in a below-grade area, search on a rope to ensure a direct means of egress, especially if searching ahead of a hose team. These compartments are similar to confined spaces and have limited access and egress.
A fire below the residential first floor can be the most challenging fire to stop. Prior knowledge of the below-grade compartments in your district and a proper on-scene analysis of the fire’s location and the structural type and configuration of the structure are essential for a safe, successful suppression operation.
Norman, John (2005) Fire Officer’s Handbook of Tactics, Third Edition. Fire Engineering.
Dunn, Vincent (1992) Safety and Survival on the Fireground. Fire Engineering.
Joerger, Scott (2011) “A Side-By-Side Comparison of New and Old Construction,” Fire Engineering, September 2011.
DANNY STRATTON is a 26-year veteran firefighter, with experience as a volunteer, U.S. Army, and career firefighter. He is a captain with the Camden City (NJ) Fire Department, a course coordinator at the Camden County Emergency Training Center, and an instructor for Safety and Survival LLC. He is a rescue specialist with New Jersey’s USAR team. He has an associate degree in fire science from Camden County Community College.
Danny Stratton will present “Precautionary Measures for Interior Firefighting” on Wednesday, April 18, 2012, 3:30 p.m.-5:15 p.m., at FDIC in Indianapolis.

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