By BRETT SNOW
Scenario: At 6 a.m. the Chicago (IL) Fire Department (CFD) responded to a reported fire in a Home Depot. While we were en route, the first-arriving company reported nothing showing. A minute later, there was radio traffic confirming a fire. On our arrival, the first truck was setting up and placing the main ladder to Sector 1 (Division A), the first engine was stretching a 2½-inch line, and the second engine was hooking up to the sprinkler connections to feed the first engine with water (in-line operation). The second truck was placing its main ladder to sector 2 to provide a secondary means of egress off the roof. Although there are many things that could be discussed with this type and size of building, this article will focus on skills used to locate the fire and lessons learned during vertical ventilation.
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| (1) The exterior of the fire building. (Photos by author.) |
As with every structure fire, especially a structure this size, it is good to deploy a few crews to each sector for further size-up, forcible entry, and search. By using multiple crews (search teams) from other sectors, the search area is divided among other teams, minimizing the distance and time needed by each team. Besides the typical tools needed to perform these tasks such as radios, irons, metal cutting saws, and so on, it is beneficial to have a 150-foot search rope, which increases team members’ safety by providing a guide to the exit if there is an immediate need for egress. The skills needed to use a search rope require formal training and take practice and coordination among the team members. Rope assisted search procedures (RASP) are a separate topic of discussion and training. If your department members have not been trained on RASP or if it is not a part of any tactical operations in large areas or commercial structures, I strongly recommend it be considered.
Another valuable tool is the thermal imaging camera (TIC). Using a TIC, like all tools and skills, takes practice. By using the TIC, as was used here by the captain of Squad 2, the incident commander (IC) and the roof teams were informed of the fire’s location, the type of roof support system (open bar joist truss), and the condition of the trusses from underneath. In large areas such as in a Home Depot, using the TIC helped navigate the engine crew to the seat of the fire.
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| (2) The scupper indicating the roof line. |
There may be some concern about entering a building without a hoseline; in most situations, I would agree. However, in a building this size with available entrances at all sectors, you can use recon crews using rope and TICs to locate the fire. Trying to stretch a 2½-inch hoseline to all four sectors and navigating it around storage racks is time consuming and requires a lot of initial staffing. Always assess the conditions at the door, especially above your head, before entering a structure with or without a hoseline.
A two-member team entering the structure from the sector 4 side located the fire with the help of a search rope and a TIC and transmitted the findings to the IC. After anchoring the rope to a fixed object outside the structure, they entered the building, scanning the area with a TIC. The sound of sprinkler heads spraying water to their right directed the search in that direction. Fifty-plus feet in, the fire was located halfway down an isle by the TIC showing heat waves traveling up the storage racks and a blackish gray cone shape coming from the ceiling, indicating water from a sprinkler head. The fire was then fully suppressed by a 2½-inch handline before it spread to a rack stacked with lighter fluid. If the search teams were sent through the front door only, they would likely have run out of rope, delaying the search operations and placing members in danger of getting lost and running out of air.
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| (3) Cockloft vents, which may be found on buildings with cocklofts. |
There were a few lessons learned in relation to operations on this style of roof. First, remember when placing a ladder to the roof, whether it is a ground or main ladder, the potential distance from the parapet to the roof deck can be several feet. This may be determined by looking for scuppers and or cockloft vents indicating the roofline behind the parapet. In this incident, the first ladder placement resulted in a distance beyond the use of a 14-foot roof ladder to get from the parapet to the roof deck. The ladder was then relocated to a location in sector 1, feasible for the use of a roof ladder. Also, for safety, if possible, place the main ladder on the sides of the building to help avoid the high parapets and over a blank wall (an area without windows) to prevent heavy fire and smoke conditions from compromising the use of the ladder by the roof team.
Ideally, ventilating a building such as a Home Depot or any other big box-type structure would require a very large hole to adequately ventilate in relation to the square footage. However, we had a significant amount of smoke release out of the vent holes with some push.
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| (4) Type and size of roof vents found on this building. |
Once we were on the roof, it was difficult to determine where to make the first hole. At this time, the location of the fire was not yet known. Two members from the first truck and my partner and I were the first two teams to the roof. Understanding that, on most commercial roofs, it is ideal to first look for and take out the natural ventilation such as skylights, roof hatches, bulkheads, and so on, but the roof vents on this building were large and would have been time consuming to remove. Our first cut was toward the sector 2/3 side, where we noticed some smoke coming from a vent. Being familiar with building construction and confirmed by interior crews, members knew that this style of roof was an open steel truss construction approximately five feet apart with a corrugated metal (pan roof) decking.
Cutting this style of roof can be done in various ways. Regardless of the method used, the first step is to remove the roofing material to expose the corrugated decking to help determine the direction in which the trusses are running, which helps in determining where and how to make the first cut. Also, this particular roof had four to six inches of foam insulation under a rubber (one-ply) top layer. These two layers of material prevented the cutting depth of the saw from penetrating the metal decking. Using a 14-inch wood blade with carbide tips on a K-950 saw worked just fine on this style of roof.
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| (5) The style of the underside of the roof. |
One way of cutting this style of roof, which was suggested and performed by an experienced roof man, is to cut a small (1×1) triangular-shape inspection hole and then extend the cut. A quick inspection hole gives the roof team a look at the smoke and fire conditions of the interior as well as the space on the underside of the roof. Also, because the corrugation acts as a hinge, extending and keeping the hole in a triangular shape reduces the number of needed cuts from three to four sides down to two.
Another method is to cut three sides. Once the cuts are complete, let the section either hang down, leaving it attached, or flap it back out of the hole. Do not completely cut out a section of decking and allow it to fall into the hole. The weight of the cut out section and the sharp edges could sever the interior hoselines and injure or kill firefighters below.
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| (6) The roof. |
The sprinklers were not shut off during the initial attack, and they proved to be effective in controlling the spread of fire on the top shelf. However, they were not working well in controlling the fire spread on the shelves below. The entire shelving unit (top to bottom about 20 feet across mid-aisle) was on fire, which was extinguished by the engine company minutes before it spread to a large crate of lighter fluid.
After the fire was fully suppressed and overhauled, a positive pressure ventilation (PPV) unit was put in operation at the front of the store to remove residual smoke. I do not advocate using PPV during the initial operation and prior to locating and controlling the fire. There was no telling what was burning and, in this scenario, the fire was moments away from involving a pallet of plastic containers filled with lighter fluid. Adding wind and intensifying the fire in this situation may have proven to be counterproductive.
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| (7) Repaired section of one of the holes in the roof. |
When venting a roof with rafters that span five feet or more, it is very dangerous to use a traditional 4×4 method. You will find yourself standing on unsupported roof decking, creating a trap door that you or other members can fall through. A good rule is to know in which direction the rafters are running and to alternate your cuts on each side by never going beyond the reach of the saw or the blade of the ax. This will help prevent standing on cut or unsupported roof decking.
Not everyone may agree on cutting the roof at this fire. However, the CFD’s culture is quite aggressive with vertical ventilation. Some may argue that sprinklers produce dense, heavy smoke that will tend to hang rather than rise. Even though this may be true, while the roof was being opened, the location of the fire was unknown; we could not be sure the fire was being controlled by the sprinkler. Also note that we had a significant release of smoke from the holes over the location of the fire. Horizontal ventilation was also used by way of opening the overhead doors and the wide sliding doors. However, because of the height of the ceilings and the loadings docks were separated from the main store area by walls, horizontal ventilation alone would have been less effective.
BRETT SNOW is a 24-year fire service veteran and a firefighter for the Chicago (IL) Fire Department, where he has worked for 12 years and is assigned to Squad 2. He began his career as a volunteer firefighter in 1988 and has also worked as a paramedic in Champaign, Illinois, and for a fire protection district in a suburb of Chicago.
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