In the quest for speed, safety, and efficiency, fire officers must continually review what is referred to as “the basics.” In our day-to-day operations, the basics allow us to operate efficiently, effectively, and safely. Practices and procedures that seem as though they have been around since the beginning of time also must be reviewed to ensure compliance in an ever-changing environment. At a recent multicompany drill, members were reviewing roof-cutting procedures on flat roofs of Class 3 (ordinary) and Class 5 (wood-frame structures). The drill started with the company officers asking some of the newer members the question, “How do you know where to cut your primary ventilation hole?” A number of responses were what some might view as questionable, if not dangerous.
A LOOK AT THE RESPONSES
Some of the responses given most often included “melting snow,” “steam on a rain-soaked roof deck,” and the ever-popular “bubbling tar.” Let’s take a look at each.
- Melting snow on a roof deck may provide a clue to a fire’s location if the snow has recently fallen, if it is only a few inches deep, and if the melted area is in a concentrated section. Significant accumulations of snow will take a long time to show a melted area. At the same time, if observations show that there is an area of melted snow on the roof deck after a recent heavy snow, what is the stability of the roof deck and its supporting members? During winter operations, ladder company members in the Jersey City (NJ) Fire Department make it a policy to bring a shovel to the roof to clear an area before dropping the saw into the roof deck. If the deck has already been cleared by the heat of the fire, BE CAREFUL! (see Figure 1).
- Detecting steam on a rain-soaked roof deck during a good rain shower is a questionable sign if not fully evaluated. Chances are that if it is raining, the rain will jeopardize normal visibility and the low smoke buoyancy. During a rainstorm, it would be extremely difficult to see a fixed point of steam emanating from the roof deck. If the sign is there, by all means factor it into your decision making, but don’t go out of your way looking for it.
- Looking for bubbling tar on the roof of a Class 3 or Class 5 constructed building during roof-cutting operations is a procedure that must be examined more fully. If the roof deck is actual bubbling, ask yourself again, What is the stability of the roof deck and its supporting members? In older Class 3 and Class 5 constructed buildings, more than one roof covering may have been applied to supporting members over the years. The fire station I first worked in had 15 roofs on it before it was decided to rip them off and install a new roof deck. Can you imagine the “stability” of those roof joists if you saw bubbling tar on that roof deck surface?
Today, many buildings of all classes have undergone some type of renovation. New and lightweight construction components are replacing older dimensional lumber. A lightweight wood truss with metal gusset plates is a favorite type of roof deck supporting system. If you see bubbling tar on a roof deck with this type of supporting system, the gusset plates would have long peeled away with the stability of the wooden two-by-four members that make up the truss sections.
Bubbling tar will be more pronounced on a metal roof deck of a Class 2 (noncombustible/limited combustible) building. This type of roof design acts like a giant frying pan that is heating the built-up roofing material from below. However, if you see this “sign” on a metal deck roof surface, chances are you have a combustible gas roof fire below the deck that is seriously affecting the stability of the roof and its open web steel bar joist supports. If you have a serious enough fire below the roof of a Class 2 constructed building that warrants you drop your saw into the roof deck, you might want to reconsider working over that area in the first place.
My intention here is not to eliminate these signs/considerations but to stress that you must act cautiously in what can be a dangerous situation. Firefighters and fire officers have used additional, and at times more reliable, signs for deciding where to drop the saw. It’s important to review some of them.
The ladder company assigned to the primary search or the engine company conducting the initial hose stretch will hopefully encounter the fire quickly. Procedures should dictate that these personnel give a preliminary report of the fire location and the anticipated spread. A report as simple as “Fire is located on the top floor in the rear” will provide valuable information to members who may need to channel the fire products through a ventilation hole. Listen to the radio.
Make your own “visual size-up” as you make your way up to the roof. Let your education in building construction and the location of the fire be your guides. When you’re making your way up to the building, note where any fire is venting. Fire showing from the top floor, in the A/B corner of a Class 3 building, barring any unusual circumstances, will most likely require that a ventilation hole be placed in that corner over the involved apartment. The visual cue (fire location-top floor) with the class of construction (Class 3) and its inherent construction feature (undivided cockloft) should start to direct your thoughts on where you need to place the opening.
Smoke Volume and Intensity
Smoke volume and intensity may give clues as to the fire’s location and avenue of spread. Many times on arrival there is no real focus on the location of the fire from the street address side of the building. This may be because of attached exposures and/or deep buildings, which may eliminate your ability to initially view more than one side. In these types of structures, ladder company members must make it a standard procedure to walk the perimeter of the roof, looking over the side for a number of items that can be relayed to the incident commander. Among them are smoke volume and intensity.
Large volumes of smoke under pressure pushing from a number of top-floor windows in the rear may indicate that a fire is well into the growth phase and closely approaching the fully developed stage in that general area. Keep in mind that this visual cue is not etched in stone. Closed thermal-pane windows may not allow the products of combustion to show at their source area. Open windows with heavy smoke showing may be the fire’s destination. The time of year, whether windows are open or closed, and the windows’ construction are some additional points to consider in this category.
Thermal Imaging Cameras
The use of thermal imaging cameras has increased and will continue to improve the effectiveness of our day-to-day operations. When first introduced into the fire service a number of years ago, it seemed as if their only use was to determine a bad light ballast or to check for “hot spots” after the main body of fire had been knocked down. Today, these cameras are becoming standard pieces of equipment in our attempts to locate trapped occupants, determine fire location and spread, and identify any infrared energy in and around a building. Using thermal imaging cameras on the roof of a building to determine an effective location for placing a ventilation hole can be helpful. However, members must be educated in how to use such a camera before attempting to work with it. Its effectiveness on a roof will depend on many variables, namely the type of building construction, the type of roof deck construction, the thickness of the roof deck, and the integrity of the roof’s supporting members.
When cutting a roof, observe the following guidelines:
- Ensure the stability of the area before entering.
- Establish two means of escape from the roof.
- Determine the location for making the cut.
- Determine the thicknesses of the roof deck and rafter run.
- Plan your cut, and inform other members of its layout.
- Keep the wind at your back.
- Establish a guide man with the saw man.
- Do not step on your cuts or projected opening.
- Pull the hole; push down the ceiling.
- Enlarge the hole as needed.
- Report observations to Command or to the Interior Division.
Make an examination hole with three plunges of the saw blade into the roof deck in the shape of an overlapping triangle; the triangle could easily be knocked out so the area below can be inspected (see Figure 2). This will give an eight- to 10-inch triangular view of the area below. If warranted, examination holes can also give two other pieces of information necessary for efficient roof operations: roof deck thickness and roof beam placement.
Placing a tool in the hole and hooking it below the deck will help you to determine the thickness of the roof deck, which will indicate how far the blade has to penetrate into the roof deck. This does two things: It eliminates blade binding associated with cutting too deeply into a thinly layered deck and eliminates the possibility of cutting through the roof’s supporting members.
Next, determine the location of the roof beam. A quick probe in the opening with a tool may give you an idea of whether you’re in the middle of the roof bay, alongside the beam, or on the opposite side of the beam. The objective is to cut alongside the beam as you draw the saw away from the examination hole. Too many times, the first cut in the roof is made as a single draw of the saw with no consideration of beam placement, let alone giving consideration to how far the saw should be dropped into the deck. Determining the beam run will help you maximize the size and the efficiency of the primary vent hole. A properly placed draw of the saw will eliminate your having to fight any more rows of nails than those called for by the size of your opening.
Another advantage of this procedure is that as you draw your cut away from the initially placed examination hole, you have already made your purchase area for placing your hook to pull back the roof deck after you’ve finished cutting. The examination hole can yield many advantages for the ladder company, if it takes advantage of them. Use the examination hole to determine the fire’s location as well as to maximize the size, speed, and efficiency of that first hole.
Roof cutting is not an exact science, and it should not be viewed as one. Obtaining information through listening and looking in a number of forms will be an invaluable and safe approach when you need to go to work. Our education and experience provide us with sensory cues that will allow us to achieve our assigned objectives with speed and efficiency. Continue to let your senses work for you: Listen and look before you cut.
- “Thermal Imaging for the Fire Service,” six-part series, Steven P. Woodworth, Fire Engineering, July 1996-August 1997.
- Safe I.R. Inc., Thermal Imaging Training & Education, Roseland, NJ 07068.
MICHAEL A. TERPAK, a 23-year veteran of the fire service, is chief of the 2nd Battalion in the Jersey City (NJ) Fire Department. He is a New Jersey state-certified Firefighter Instructor II and a frequent lecturer on topics related to the fire service.