The roof position is one of the most difficult and dangerous, yet it’s also critical. Roof firefighters are the eyes and ears of the incident commander (IC), as well as all of their brother and sister firefighters operating inside the fire building.
At a flat roof building, firefighters most often go to the roof to conduct initial ventilation. Because of the challenges of this critical position, firefighters assigned to the roof must completely understand this assignment and possess the skills to carry it out.
Determine the Type of Roof
The first step in any roof operation: Determine the type of roof system that you’re going to operate on. Is it an ordinary construction roof? Is it a lightweight steel roof with a membrane covering, or a roof with a gypsum deck? It might be a rain roof, also called a built-up roof system.
These questions are best answered before you get to the fire, either because you’re familiar with the building or because the department conducted an inspection and recorded building construction information in the dispatch system. If no information is available prior to arrival at the scene, you can determine the type of roof system through a size-up, and confirm your initial assessment with a roof-level inspection.
The type of roof support system should dictate the type and duration of roof operations.
Gypsum: If you encounter a gypsum roof, discontinue all roof operations. A gypsum roof covering can disguise damage to the support system from the fire below. This damage might not be evident or visible from roof level. If you discover a gypsum roof decking system, advise the IC and all operating forces of its presence. The IC should order firefighters to abandon their roof position and to cease all interior operations.
So how do you determine whether you’re dealing with a gypsum roof? If you place a saw into the roofing material and a white dust comes from the area of the cut, that indicates the presence of gypsum. If the gypsum is denigrated by moisture, then the dust will be absent and a mud-like substance will appear in the shroud of the saw. The saw will also cut through the roof system with little or no resistance. If this happens (the saw experiences no resistance when cutting), inspect the area around the roof where the saw blade made the cut, looking for wet, mud-like gypsum. If either dust or mud appears, indicating a gypsum roof decking system, then evacuate the roof and notify command.
Lightweight Steel Bar Joist: If you discover a lightweight steel bar joist roofing system, first determine if roof ventilation is possible. If ventilation is needed, open and vent skylights, scuttle covers and other openings on the roof. If after doing this the fire conditions inside the building require the roof to be cut, the building is most likely in the decay stages and members should not be committed to the roof; the IC might have to reevaluate the offensive strategy. Note: Lightweight steel roofs have little to no fire-resistive rating, so you must limit your time on the roof.
Membrane: A membrane roof can and will burn and, if exposed to fire, can become a big problem for roof firefighters. Plus, a membrane roof system is very difficult to cut. The roof membrane will get into the saw shroud and around the blade shaft, slowing down the saw and making it ineffective. One way to address this issue: Carry a utility knife with the saw or in your turnout coat pocket. Determine where the cut is to be made and, using the utility knife, cut a large square in the area to be cut. Using a tool, remove the membrane before the roof is cut.
Rain: A rain roof or built-up roof is a roof structure that’s placed over an existing roof to control drainage. The issue with this type of roof: You might cut the deck of the roof and see no indications of fire, heat or smoke coming from the blade’s kerf. But the fire can still be impacting the original roof without showing through the hole cut in the built-up roof structure. Once the fire does enough damage to the original support system, a collapse might occur and could be catastrophic, especially if members are on the rain roof.
This happened in Sacramento, Calif., recently; fortunately, all three members operating on the roof made it to the parapet wall before a full collapse occurred. Tip: If the radio reports from the roof or the interior vary in their reported fire conditions, suspect a built-up roof. The structure might be hiding the fire’s location. This is when a thermal imaging camera (TIC) can be extremely helpful; if possible, position one camera on the roof and one under it.
On the Roof
After you determine that the roof is safe to operate on, you should conduct a few quick tasks for the benefit of all operating forces and the IC.
- Identify and communicate objects on the roof. Is there anything on the roof that isn’t visible from the street that might impact roof stability or add weight to the roof? The presence of cell phone sites, air-conditioning units or heating plants should be communicated to interior forces and the IC.
- Try to locate the fire. You might be able to determine the fire’s location by a dry spot on a wet roof, soft tar or a heat signature on the TIC. Make that location known to the interior forces and especially the engine company with the hoseline.
- Traverse the roof to get a look at the rear. As soon as radio traffic permits, report anything you observe that would be helpful for command to know.
Once these tasks are completed, then it’s time to vent the roof to allow the products of combustion to be channeled out of the building in a path that we have made. The first choice for a vent opening: any natural opening that can quickly be vented, such as a skylight, scuttle or roof opening into the structure. Usually these openings are quicker to open than cutting the roof.
The problem: Because of criminal activity, a lot of these openings have been sealed for security. If you think skylights or other openings previously existed on the roof, or if the roof covering varies in make and color, proceed with caution. The openings might have been sealed and the construction might not be up to code. It can be dangerous to walk on such roofs even without the presence of fire. In the FDNY, we call these substandard roof openings “firefighter traps” because they might not support the weight of the roof firefighter.
Next, cut the roof for further ventilation. You should have already determined the location of the fire; now it’s time to plan out a sequence of cuts on the roof. We want to make a cut that is manageable and will allow us to pull the roof quickly. A 4′ x 4′ hole is a good starting point. With the wind at your back and an escape route between you and the cut, begin your cuts. Once the 4′ x 4′ cut is made, pull the piece of roof off and place it near the hole in the path of travel. This warns other members on the roof that a hole is in that area and to use caution.
Next, push the roof down from above to allow venting of the interior of the structure. Remember to give a quick radio report to the members inside the building before pushing down or breaking through the ceiling. They might have to clear the area for safety. Tip: When you start pushing, push a small piece first if possible, as a warning to interior firefighters.
Once the hole is completed and the ceiling is down, examine the cockloft for fire extension.
They’re Counting on You
Taking the roof position at a fire in a flat roof building is an immense responsibility. Because you can see things that no one else on the fireground can, the safety of the members inside the building is one of your primary responsibilities. Remember to report conditions as you see them, identify when the roof is unsafe to operate on and, when needed, request a change of strategy (offensive to defensive). Those inside are counting on you.
