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Keeping a fire confined to its room, floor, building or neighborhood of origin is a critical objective of every incident commander. Anticipating how a fire can spread from one area to another has always been a challenge for the members of the fire service.
Our difficulty, most notably comes from the lack of personnel on the fire scene to check and protect all the avenues of fire spread. But as that battle continues, fire service educators must continue to identify and discuss how fire will move within and beyond the structure.
Exposures are often categorized into two reference areas: interior and exterior exposures. Interior exposures are those areas that surround the fire area or fire floor. They are identified from the avenue and direction of fire travel from within the building. Direction of fire travel is referenced from the fire’s ability to move vertically up through the building, horizontally left or right from the point of origin, as well as any areas below where the fire may be able to drop down.
It is from this simple geometric thought that we gather the association that all fires have six sides, and depending on the possible avenues of fire travel within a building, all six sides must be examined for potential extension. But as easy as that sounds, we need to be more detailed regarding the possibilities and further identify what actions we can take to check and protect.
The location of the fire
We often refer to this as one of the most influencing size-up factors in our decision-making. Knowing that the life hazard is the most important, where the fire is and where it can extend, has continually been one of the most influencing factors. Because of this reference, we need to clarify the concerns. Let’s continue.
Generally speaking, lower-floor fires present a more immediate challenge for fire forces simply from the fact that more of the building and its occupants are exposed to the fire from below.
In a multi-story building, the interior stairs will be the largest unenclosed vertical opening in the building. If we quickly go back and reference the floor location, we are continually reminded of why incident commanders always direct one of their first hoselines to protect the building’s interior stairs.
When interior crews report that they have a fire in a kitchen or a bathroom, our experience and education reminds us of the concerns that fire extends beyond the room and contents and into the utility voids found within those rooms. If we present more specific information and inform you that you are going to work at a fire in a multiple dwelling, our concern extends to the challenges of stacked kitchens and baths.
If I change the occupancy and tell you that your fire is now in the kitchen or bathroom of a garden apartment, we would need to modify the concern to now reflect the challenges of not only stacked, but also back-to-back kitchens and baths.
Let’s go one step further. Anyone who has operated at a fire in a large frame dwelling, often called a “Queen Anne” or a “Victorian,” will tell stories about how difficult and challenging fires in these types of buildings are. The specific challenges often focus around when a fire in one of these buildings has originated or extended into a concealed space. The void spaces in Queen Anne or Victorian structures are extremely large. Their ability to hide fire, spread fire and produce explosive, often overwhelming fire growth, is well known. If there was ever one type of building where you need disciplined coordination of your ventilation, a number of hoselines in the building, numerous means of egress and a true understanding of what can happen when you introduce air into a concealed space, it is here.
Fires in concealed spaces and voids present numerous challenges, but when they involve the size and number of void spaces that these buildings possess, unsuspecting members will get hurt. These are some of the nastiest structure fires you will ever fight. The last thing you want to do when opening up is make the fire angrier than it already is. When discussing structure fires, the late Frank Brannigan would often say you need to “know the enemy!” He was referring to the building and how it behaves when being attacked by fire. A quote that many of us refer to each day; but consider adding the above to your list.