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.
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Louver Cut with Hand Tools
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.
Once the roof joist lines are marked out, the other firefighter with the chain/vent saw can now begin the cutting operation. With the louvered cut, a total of four cuts need to be made. The first cut will be the furthest cut away from you, parallel with the roof joists. This cut should be in the middle of two roof joists. We start our cuts away from us and work back toward the roof ladder so that we are not trapping ourselves or standing on a weakened roof with heavy smoke or fire coming out. As you can see in photo 2, the cutting firefighter is making the first cut furthest away from the roof ladder. Notice how the chain/vent saw is not in line with the firefighter’s foot; this done to minimize the possibility of any accidental cutting of body parts. Always keep your feet out of the cutting path of the chain saw. Also, after you have made your cut, when the chain/vent saw is pulled out of the roof, roll your hand forward to engage the chain break. This will prevent the chain from spinning freely cutting or catching someone’s gear or body part. When setting up for the next cut, place the chain/vent saw in the proper position on the roof, then disengage the chain break.
The cutting firefighter is being guided by his partner as he cuts with the chain/vent saw. This guiding action tells the cutting firefighter that his partner is preventing him from slipping. The spot firefighter also can communicate that the cutting firefighter is not going to fall off the edge of the roof, if cutting close to it, and reassure him that the surrounding area is being watched for changes in conditions. The spot firefighter can also communicate with the cutting firefighter by tapping him to get his attention or to have him stop right away. Using verbal means of communication will not work, especially when a chainsaw is being used at full throttle.
The rest of the cuts can be made in any order so long as the last cut to be made is parallel with the roof ladder. At that point, the cutting firefighter should be back on the roof ladder with both feet, and the four sides should be cut. Be sure to intersect your cuts at each corner well beyond the cut lines. The end result should produce a cross at each corner. By doing this, you are going to have a free moving louver as opposed to one of the corners being caught because it was not cut through all the way.
The backup firefighter can now take the roof hook or pike pole and can hinge the vent hole, as seen in photo 3. Once the roof hole is hinged on its axis, the ceiling below needs to be removed to allow for exiting of smoke and hot gases. Start plunging the roof hook or pike pole at the furthest point away and work your way back to the roof ladder. You do not want to be trapped between the roof ladder and the fire as smoke and heat start to pour out of the hole. Once the hole has been made and the ceiling below is punctured all the way through, it is time to get off the roof.
If the chain/vent saw were to malfunction on the roof, the hand tools are there to allow you to complete the task. The ax is a choice tool for this, but will create some problems for you. The blade of the ax will bind with the roof material as you chop your way through. To alleviate this problem, you can use your hand tools in an unorthodox manner.
As shown in photo 4, the halligan bar is being used to cut the roof hole. The wider surface of the back of the adz end of the halligan allows for better cutting and prevents binding in the roof. The same is true for a flat head ax. The back of the ax will cut better and quicker than the blade part. The drawback in such a case is that the ax blade is facing you as you are cutting. Take caution with this and control your swings.
Mark van der Feyst has been in the fire service since 1999 and is a full-time firefighter in Ontario, Canada. He is an international instructor teaching in Canada, the United States, and India, and at FDIC. He is a local level suppression instructor for the Pennsylvania State Fire Academy and an instructor for the Justice Institute of British Columbia. He is also the lead author of Residential Fire Rescue (Pennwell).
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