Truck Company Ops: Louver Cut
By Mark van der Feyst
Vertical ventilation is an effective way to remove the products of combustion quickly and efficiently. Going to the roof to make a vertical vent hole is a dangerous task, with the payoff being quick removal of hot gases and smoke and the replacing of fresh air. There are many types of vent holes that we can make in the fire service, depending on the type of roof we are faced with. The most common type of vent hole is the louvered or hinged cut. This type of vent hole takes advantage of the nailed sheeting resting on the roof truss to act as a hinge point for our finished product.
As discussed last time, we need to use our roof ladder to aid us with adequate slip protection and for weight distribution. The roof ladder also serves as a resting or staging area for our various tools needed for the task. By placing our equipment on the roof ladder, we are ensuring that we will be able to locate them easily and quickly when we need them. Once the roof ladder is in place on the roof, ensure that the roof hooks are snug against the peak of the roof and that they will not slip off once stepped upon.
Before we step off our ground ladder and onto the roof ladder, sound the roof with your hand tool to ensure that the roof can support your weight. A roof that feels spongy or sounds very hollow are signs of a weakened roof and should be avoided, if possible. When you are sounding the roof, make sure you are sounding it with some force, not just with light little taps. Little taps will tell you nothing about the condition of the roof.
Once you are on the roof, stage of all your equipment on the roof ladder. As you make your way up the roof ladder and into position for your vent hole to be made, keep sounding the roof with your hand tool. Once in position, one firefighter can make themselves a support step on the roof using the halligan or the pickhead ax, as shown in photo 1. By doing this, you are giving yourself the option to step off the roof ladder to make your cuts without compromising your safety. The hand tool spiked into the roof will prevent your foot from slipping.
One firefighter can now take either a roof hook or a pike pole and can start sounding out the joists. The edge of the pike pole or roof hook can be used to inscribe lines that will mark out the approximate locations of the roof joists. This allows the firefighter with the chain or vent saw to avoid cutting through the roof joist as he is making the vent hole. Depending on what type of chain/vent saw you are using, you may have a depth gauge and you may not. Either way, avoid cutting through the roof joists. This will weaken the roof and will accelerate the potential for a partial roof collapse.