Firefighters love to be aggressive. Like other warriors, we despise retreat—perhaps to a fault. Smart warriors know when a battle can be won and when to press ahead, but also when to retreat prudently to fight another day. Although many lives and much property have been, and continue to be, saved by aggressive firefighting, we also must do a better job of preparing our personnel to understand when it’s time to back out and switch to defensive operations.
In a July 2008 feature (Get Out, p. 40) I talked about size-up issues related to a defensive attack. I also talked about some general fire attack concepts and transitioning into a defensive attack. Let’s take that discussion a bit deeper into more specific triggers and building conditions that officers and firefighters should understand before making the decision to evacuate a building during a fire attack.
Picture this: You’re in the building and you think you’re making good progress on the fire, pushing ahead, searching and checking for exit paths as you knock the fire down. Or, say, you’re up on the roof, making several cuts and doing a great job of ventilating pent-up smoke and hot fire gases, allowing the hose crews to push ahead and knock down the fire. But either way, you feel comfortable in your element, and it doesn’t get any better than this—good, tough firefighting—right?
Maybe not. Firefighters get hurt and killed performing just these actions and having just these thoughts. What’s the difference between walking away a winner and not walking away at all? Sometimes it’s just luck. Sometimes it’s good people intensely focused on their job and the environment they’re working in. The bottom line: As firefighters, we must focus our attention on the elements we can affect.
In the past, firefighters have used the “20-minute” mark as a measuring stick to determine if interior operations can continue. There were many reasons for this timeframe, including SCBA air duration and a perception that a building could withstand 20 minutes of direct attack from a fire.
This last reason, however, no longer makes sense with newer construction techniques. Structural members are designed with a safety factor, and the more information that’s known about the material of construction, the smaller the safety factor becomes. To make matters worse, many home and building owners, or their contractors, make changes to a building structure without taking into account either the structural implications or the implications under fire conditions. We must remain alert to conditions that will compromise the structure and the safety of firefighters working within it.
Determining Factors: Exterior
There are a number of factors that provide indication of the effects of fire attack on structural members. Every firefighter and officer must be attentive to these conditions, and any of these conditions must be assumed to create a structural weakness that could present a collapse hazard.
Any evidence of movement of the building or any of its members is a clear sign that all is not well in Kansas. USAR folks carefully watch for building movement with laser sights, which can be set up and used on buildings, but probably aren’t practical on the fireground.
Another common sign of structural issues is a “spongy” roof. The “sponginess” generally results from hot tar or other roof covering materials heating up and deteriorating due to serious fire underneath.
Some roofs, particularly some newer lightweight trusses, may “bounce” normally, but roofs aren’t generally designed to have live loads of several firefighters on them while a fire is attacking the structure from underneath. Thus, any signs that the roof is moving or bouncing during a fire are signs of potential weakness and failure.
Firefighters should always consider operating from roof ladders or aerial apparatus when working on roofs, but once signs of weakness are apparent, roof operations should be discontinued and the incident commander (IC) notified immediately. When operating on the roof, keep constantly aware of the structural integrity of the surface below you.
Determining Factors: Interior
When operating on the interior of the building, firefighters must be aware of the structural stability of the floor below them, the walls and supporting columns holding up the floor/roof above them and the ceiling overhead.
Older brick mortar can be attacked and broken down by hose streams, resulting in a loss of wall integrity. Water coming through the brick walls is a sign of this.
Like the roof, firefighters must be aware of movement of any of interior structures, like walls or columns, as well as any potential weaknesses of the floor they’re working on. “Sponginess” is a much greater concern with interior floors, as this can indicate the potential for imminent failure.
Indications of fire below, such as embers and/or heat traveling upward or heavy smoke emitting from lower windows of a building, are a warning sign to watch for weaknesses or breaches of the floor. Fire traveling through walls is also a sign that there’s a significant problem below you. Audible creaking or cracking is another sign that personnel need to evacuate the fire building.
Ongoing hosestream or sprinkler operation can cause water buildup on floors. Water accumulation gets heavy fast: Each gallon of water weighs a bit more than 8 lbs., and 250 gallons weighs more than a ton! Buildings aren’t designed to support that weight, and, if significant quantities of water accumulate, structural integrity is likely being compromised. Indications of any of these conditions should result in immediate notification to the IC, and operations in these areas should be reconsidered.
The factors that can give rise to fire might compromise the integrity of the building before the fire even takes hold. If, for example, an explosion or an earthquake was part of the initiating sequence of the fire, it will become even more difficult to analyze the structural stability of a building. A backdraft or other explosion that occurs during the fire might also significantly damage the structure over and above the damage the fire has already wrought. Sudden involvement of hazardous materials, because of extreme high-heat releases, may put undue stress and strain on a building’s supports.
If a structural member has been noted to have been removed or compromised during the incident, personnel should be withdrawn from the area, and perhaps the whole building. Transfer of weight/forces to other structural members might overwhelm their safety factor, with building failure not far behind.
Transition to Defense
Once a high-risk situation is identified, the transition from an aggressive interior attack to an attack from a position of safety is critical. If conditions present an imminent problem, you must communicate these conditions to the IC who may use an “emergency traffic” broadcast to alert members. Oftentimes, there’s very little time between when conditions are identified and when the building collapses, so every second counts.
In the battlefield, sometimes soldiers must leave their equipment while they make a rapid escape, and the same holds true for firefighting. Time shouldn’t be wasted collecting tools and such; they can be replaced, unlike lives. If the problem isn’t so imminent, retreat may still be in order, but equipment and tools may be gathered and taken along. The need for immediacy of the retreat must be clearly communicated to each “soldier.”
Accountability is critical: Teams must stay together, maintain a personnel accountability report (PAR) and acknowledge the receipt of urgent messages, as well as communicate their actions to command. This is no time to maintain radio silence. An evacuation signal (airhorn blasts, siren, special radio alert tone, etc.) must be established in advance, practiced and be clearly understood by everyone on the fireground.
A Final Word
The key to a successful fire attack is to achieve a rapid knockdown, thus minimizing the opportunity for the fire to compromise the building’s structural integrity. This is best achieved by “out-gunning” the fire—making an attack with enough gpm to overcome the energy being produced by the fire. The longer the fire attack continues, the more likely it is that the building’s structural integrity will be compromised.
By preplanning the fire ratings of structural members, firefighters will better understand how long a building can survive direct fire attack. But critical information on the rating—if it’s inherent to the structural member or if the fire-rated material was added on—is important for firefighters to understand, if the actual rating hasn’t been compromised through renovations during the life of the structure. Understand the signs that a building has become too dangerous for your firefighters and have a system in place that ensures firefighters get out, and stay out, of buildings that are no longer fit for them to be in.
“Building Construction for the Fire Service,” 4th Edition, Francis L. Brannigan and Glenn P. Corbett, National Fire Protection Association, 2008.