There are differing opinions on opening the roof of a dwelling. The vast majority of dwelling fires involve only the contents, even though the fire can be accompanied by copious amounts of smoke that demands ventilation. My experience has found that fires in private dwellings of ordinary...
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• To prevent flying embers
• To extinguish any roof fire that may occur during ventilation
Directing the hoseline into any roof opening defeats the purpose of the vent hole and it will drive the heat of the fire downward, endangering the firefighters below. Fire burning through a roof that is too weak to support firefighters should be allowed to burn through, creating an opening. The tendency to hit the fire with ladder pipes or other streams must be resisted. The self-venting that is created will be beneficial to the overall control efforts.
Using a Power Saw
Before a power saw is taken to a roof, it should be checked to see that the proper blade is in the saw and it should be started when it is taken off of the apparatus. Once it starts, it can be turned off and taken to the roof. Never climb a ladder with a running saw. If the saw does not start, get another saw to do the job. Before starting the saw, make sure there is a safe operating area. The firefighter operating the saw must ensure his or her own personal safety.
Know your equipment. Start the saw into the cut and work methodically. Do not attempt to rush the cut. It will only bind the saw. When a saw blade is bound in a cut, usually the cut (referred to as kerf) has to be spread to let the saw blade be freed. Knowledge beforehand of the saw’s limitations allows for a better fireground operation.
Know the type of roof surface and roof supports you will be operating on. Is it solid-beam or lightweight construction? The firefighter operating the saw must have a feel for the operation. He or she should not cut through roof supports. When a drag on the saw is felt, indicating a roof-supporting member, the saw should be allowed to ride over the supporting member, cutting only the roofing material leaving the supporting member intact.
The entire opening should be cut before attempting to pull back the roofing material. Opening it too soon creates a dangerous situation for the firefighter operating the saw since he or she will have to deal with heavier smoke and fire conditions. Do not allow anyone to use their hands near the saw to pull back the cut sections of the roof. Keep body parts away, including the feet of the firefighter operating the saw. When not in use, the saw should be shut off and set in a safe location. Do not put the saw down while the blade is still rotating.
Firefighters operating on the roof must be concerned with their own safety and that of the firefighters operating within the building below. Safe operations start in training. Preparation is the key. It starts with knowing your apparatus, your tools and your company’s capabilities. Be prepared for a variety of situations and consider potential solutions.
Let’s review some roof safety considerations in relation to construction, entry and egress from the roof and rooftop operations:
The construction of the roof can affect firefighter safety:
• Lightweight wooden components subjected to fire will fail rapidly. This early failure endangers those beneath the roof and those operating on it.
• Steel bar-joist roofs can also be deadly to operate on. Subjected to fire, their failure times can resemble that of lightweight wood. The bar-joist is often set on much wider centers than the 16- to 24-inch centers routinely found on wood roofs. This creates a situation where failure of one roof joist can create a large opening in the roof.
• A timber-truss roof contains large wooden members. This allows the spacing of the roof members farther apart. Because of their larger size, a greater working time can be employed by firefighters operating on these roofs. However, it does not mean they will not fail. In fact, most timber-truss roofs contain various forms of steel connectors, which is the weak point of the truss. The conduction of the heat of the fire by the steel causes expansion of the steel and failure can and does occur. • The wide spacing between the individual truss means failure of one truss creates a gaping hole in a roof adding danger to those operating above it.