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Homes that are of a balloon-frame design will let a fire in any unfinished basement move vertically up throughout the building because of the lack of fire-stopping in the building’s exterior walls. Tactics often referred to with this type of fast-spreading fire focus on the quickness and mobility of the initial hoselines on the inside of the structure at the exterior walls and at the fire’s ultimate collection point, the attic.
We have all struggled with the removal of the wall area on the first floor of these occupancies in an attempt to direct water up the stud channels to slow the fire’s spread up. Add a number of small rooms cluttered with furniture, and the delay of opening up the walls to get a stream of water directed within the space is extended even further.
Alternate tactical options do exist if members can access the structure’s exterior sides. If the balloon-frame private dwelling you are operating in is not attached or close to other structures, take advantage of the accessibility to the structure’s exterior. Assign a ladder company to remove some of the structure’s exterior siding/sheathing at the first-floor area in any wall space that does not have an inherent fire stop (windows, doors and diagonal bracing are inherent fire stops within a balloon-frame design building).
Having the ability to remove vital areas of the building’s exterior skin in a clear, uncultured atmosphere allows a hoseline quicker and easier access to the void spaces all in an attempt to slow the fire’s vertical spread. It must be noted, as successful as this tactic has been for many in the past, its use must be disciplined to ensure that it does not drive fire onto firefighters operating on the inside of the building. Coordination and communication are critical requirements.
Floor- and roof-support systems
Buildings constructed with trusses, wooden I-beams and cold form steel are what I refer to as “lightweight”-designed buildings. Over the years, the fire education community has identified and discussed the inherent flaws and collapse dangers of these systems. But a design flaw that not only enhances the collapse concerns, but also promotes uninterrupted fire spread throughout the structure is the open web design associated with the truss support systems.
Let’s consider the following. In older, stick-built structures we are used to floor and roof supports systems of two-by-eight-inch or two-by-10-inch joist/rafter designs and the strength they provide. But their design within the floor plan also helped slow the fire spread. Think about it. If a fire extends from the buildings contents into the floor structure, the fire “initially” can only move 10 inches high, 16 inches wide and spread through the floor bay from bearing wall to bearing wall. A concern, yes, but when your floor and/or roof system is built of a web design, as it is with a truss system, the fire literally can and will spread quickly throughout the entire “footprint” of the building! A tremendous concern. The dimensions of the building will actually identify the unobstructed space and the fire’s ability to spread. Now add the collapse concerns, and the challenges become compounded.
Basements, cellars and attics
With many basements, cellars and attics in private and multiple dwellings having unfinished ceilings, we generally consider a fire in basement, cellar or attic to be a “structure” fire, not a “content” fire. Without over analyzing this, a fire in this area will immediately expose and quickly involve the structural members when the ceilings or support members are unfinished and not protected. If we have additional information that indicates the floor or roof system is made of “lightweight” building materials, collapse has to be anticipated.
As fire service educators continually review and discuss fire spread within the structure’s voids, we also need to remind ourselves of how and why a fire can quickly move from room to room, and floor to floor through the common areas. Over the years, we have seen a dramatic increase in the heat release of the building’s contents. This is most notably due to the increased use of plastics and synthetics in the home, but also from the increased R-Values in the walls and ceilings and energy-efficient windows, as well as the overall amount of building contents. The end result from the above is hotter fires, quicker time lines to flashover, an increased frequency of backdrafts in the field all resulting in an increase in firefighter injuries and deaths.
What can make matters worse is the how the fire department operates at a building fire. Recently, the National Institute of Standards and Technology (NIST), Underwriters Laboratories (UL) and the FDNY released an extensive study reviewing fire behavior in modern buildings with modern furnishings. One of the many points of the study focused on how a fire department ventilates a fire building, how we must take a more disciplined approach to where and when we ventilate fire buildings in direct relation to the use of water in a modern building. A condensed review of the findings is asking us to revisit some old tactics as well as add a few new ones.