“Engine 1 on scene, Working Fire. Ladder 3 you are assigned Support, I need you to get topside and open up.” “Ladder 3 copies, taking Support, going to the roof for vertical ventilation.”
That’s what every Truck Company wants to hear when they’re rollin’ into a structure fire, assigned to vertical ventilation. Vertical ventilation is one of the most important duties on the fire ground. It reduces the likelihood of hostile events such as flashover and back draft. It reduces heat so that the attack team can advance more aggressively toward the seat of the fire. When the smoke is lifted, the visibility is enhanced and search operations are improved and property damage is reduced. A good Truck Company prides themselves on cutting holes and cutting them well.
The chainsaw is the best tool that we have for vertical ventilation. Today’s chainsaws have powerful motors and utilize aggressive chains. A chain saw with a 20 inch bar gives the Truck fireman excellent reach for cutting heat holes in the roof. Now that we have the right tool, how are we going to use the saw? The sawyer that’s going to be successful must have good saw handling skills and smart cutting techniques. Being competent and proficient with the saw will promote your ability to work longer, lessen the chance of injuries, reduce damage to the saw and allow you to feel the structural members. Operating the chainsaw on the roof is a task that will always throw you a curve ball. So, a good truckman must be able to adapt and react quickly to whatever the roof presents.
SAW HANDLING AND CUTTING TECHNIQUES
In the middle of the night, with your face piece on, in the smoke, you will not be able to see the rafters. So, stop looking for them. The sawyer needs to feel the rafters and understand the roof he’s standing on. The following are techniques that will increase your ability to feel rafters and improve your saw handling skills.
When cutting, the saw must be running at full throttle. Cutting at full rpm’s is safer and more efficient. The consequences of not running the saw at full rpm’s is that the teeth will have a tendency to catch or grab the wood instead of cutting the material. It’s good practice to have the saw at full throttle when putting it into the work and throttle down once the saw is pulled out of the deck. A good sawyer will know what the saw sounds like at full throttle. Many times the bulkiness of the structure gloves will make it difficult to depress the trigger all the way. The key is to recognize the pitch of the saw and make the necessary adjustment.
To cut through the decking material, place the saw at a 45 degree angle. Push down on the saw with your forward hand. Push hard enough to cut the material but not too hard as to make the chain stop because it can’t keep up with the pressure being applied.
When initially cutting through the roof, have the saw at a 45 degree angle. Having the saw at this low angle will make it easier to cut through the roof covering and sheeting.
Avoid holding the saw at a 90 degree angle. Using the very tip of the bar and plunging straight down will cause the saw to roll or skip around on the deck. This will prolong the operation and make getting through the decking material more difficult. Now that you’ve cut through the deck, the bar should be plunged into the roof only as deep as necessary. The amount of the bar to be utilized will be dictated by the thickness of the roof. Obviously, the thicker the roof, the deeper the bar needs to be. This will ensure that all the decking is cut through. A 60 year old roof with 3 layers of hot mop is going to need more blade than a light weight roof with a single sheet of plywood.
On older, thicker roofs the bar must be plunged deeper into the roof. This will ensure that all the roof decking is cut.
Also, keep the saw as vertical as possible to enable you to feel the rafters. This is especially important because the thicker roofs makes it more difficult to feel the rafters.
There are many obstacles on the underside of the roof. Nailing blocks, electrical conduit, insulation, steel gas pipes, air ducting, metal straps, etc. Avoid these objects by only putting the saw in as deep as necessary to cut the deck. Also note, a flash of drywall dust is a good indicator that you are cutting over a wall or vaulted ceiling.
By just using enough of the bar to cut through the deck, the saw will fulcrum better on the rafters creating a better feel for the rafter. Keeping the saw vertical when cutting the roof will also increase your ability to feel the rafters.
This will ensure that the blade hits more of the rafter creating more resistance. The more resistance there is the better you will feel the rafter. If the saw is kept at a low angle while cutting, the blade will cut deep into the rafter before you feel the rafter. Remember, the goal is to keep the structural members in tact and not cut through them.
Many inexperienced or timid sawyers will cut too slow in an effort to feel the rafters. This will have an opposite effect on your ability to feel the rafters. As the saw hits the rafter, it will slowly cut through the wood with very little resistance. To remedy this, the sawyer must have a good tempo while cutting. Having a good smooth cutting technique will allow the blade to hit the rafter more abruptly creating a better feel for the structural members. Many times being smooth is faster. As you are cutting, be aware of how much resistance the decking material is providing. As you hit the rafter, the rafter will provide more resistance than the decking material. This will increase your ability to feel the rafters.
Once we have felt the rafter, we now want to roll the rafter. Bring the saw down from the vertical position back to a 45 degree angle. Cut through the decking on top of the rafter until you clear/pass the rafter. Cutting the deck on top of the rafter when rolling, especially on thicker roofs, will make it easier to get the saw back into the deck once you have cut passed the rafter. Now that you have cleared the rafter, put the saw back to vertical and continue cutting.
CHAIN BRAKE
The chain brake on the chainsaw is a safety feature to keep us from getting injured. It helps protect the user from kickback and pushback. There are essentially three times when the chain brake should be utilized. The first is when the saw is being passed to another fireman. This will protect the receiving fireman from getting cut with the business end of the saw if the throttle is accidentally depressed. Also, if the receiving fireman grabs the handle with the throttle, he doesn’t cut his partner. Second, the chain brake should be activated if you are traveling through a crowd on the fire ground. This will ensure that if another fireman walks into the saw he does not get injured. And lastly, activate the chain brake when you are ascending and descending the ladder.
The saw should be started as soon as you pull it off the truck. This allows the saw some time to warm up. Furthermore, you want to ensure that the saw starts. If it doesn’t start, now you can grab the second saw and you have wasted little time. The last thing you want is to be on the roof and the saw doesn’t start (i.e. the switch was left in the off position and you flooded the saw). This will unnecessarily delay the roof operations. Some firemen might say that climbing a ladder with a running chain saw is a dangerous operation. If you examine the sequence to cut yourself with a running saw on a ladder it’s almost impossible. You’d have to take your hand off the rung, deactivate the chain brake, press the dead man, pull the throttle and lay the saw into your leg. It’s not going to happen. Also, when operating the chain brake, make sure that the rpm’s have throttled down.
Activating the brake at full rpm’s will eventually damage the clutch.
To activate the chain brake simply simulate a “kick back”. While keeping your hand on the handle, pivot the saw/bar up toward you. The brake will come in contact with the backside of your hand and engage the chain brake. Avoid using the hand on the throttle handle to reach forward and push the chain brake. If you are not paying attention, your hand will skip over the chain brake and hit the spinning chain. Just rock the saw and hit the brake.
When deactivating the chain brake, the motions should be equally seamless. Simply keep your thumb hooked around the handle and reach forward with your fingers and pull the chain brake back. Sometimes this technique won’t work if your hands are small or tired. If this is the case, put the tip of the bar on the deck to support the weight of the saw. Than reach forward and pull the brake back. Avoid using the hand from the throttle handle to deactivate the brake. When you let go with this hand, the saw will balance to a neutral position. This decreases the distance between the backside of your hand and the brake enabling you to activate it. This maneuver more often than not doesn’t work and wastes time, especially when wearing structure gloves.
BODY POSITION
Having a good stance will reduce the potential for injury and fatigue. Stand with your feet about a shoulders width apart. Your back is going to give out long before your legs. So, bend at the knees and hips and try to keep your back as straight as possible. When cutting, the blade of the saw should be forward of your front foot. Avoid cutting past your front foot. Cutting past your front foot may be dangerous if the saw comes in contact with a solid object and kicks back. If you are cutting past your foot, the saw will kickback and hit your leg before the chain brake is activated. To avoid this, move or shuffle with the saw as you are making your cuts.
If you do not shuffle with the saw, more often than not, your front foot will be in the middle of the hole. This can be detrimental if the weight of you standing in your cuts is the final straw to cause an already compromised roof to fail.
It’s understandable that there will be times when you will have to cut toward yourself or cut past your feet.
If you are put into an awkward position, understand the consequences if the saw kicks back, catches or pushes back. Have good saw control and anticipate any unusual saw movements.
Also, avoid cutting into or toward your body. Stay out of the plane of the saw. Always cut as if you are standing on structural member.
Keep your back foot and body out of the plane of the saw. This will decrease the likelihood of getting cut if the saw pushes back or kicks back. Also, have a good stance when operating the saw. Bend at the knees and save your back. Be aware of the location structural members at all times and work off of them when ever possible.
A good sawyer should be proficient with both hands when using the saw. Avoid making an X with your arms. If you begin to cross up your arms, take the few seconds to switch your hands. When your hands are positioned correctly, your body will be
positioned correctly.
Having a good understanding of cutting techniques will allow you to quickly overcome the obstacles that are presented during vertical ventilation operations.
These photos show the roof on a three story apartment building. This truck company successfully cut through three roofs to put in their heat holes.
CONCLUSION
These techniques are some of the basic principles of saw handling, but they are the foundation of any good sawyer. To avoid being caught off guard when Murphy slaps you in the face, the Truckie must know his saw, how to handle the saw and be educated on building construction. The importance of vertical ventilation can not be over emphasized. It will make or break a good working fire. Besides cutting on actual fires, real world training is going to provide you with the experience you need to prove successful at cutting holes. Go down to the training center once a month to practice and discuss roof operations. Build a small roof prop behind the firehouse to practice cutting techniques. Once a tour, get out in your battalion and walk roofs. The entire roof team must have a solid understanding of feeling and rolling rafters. Train with your saw to understand it’s capabilities and limitations. A working knowledge of various roofs and building construction is necessary to apply the proper ventilation methods. Remember, we are on the roof of a burning building, cutting a hole in the roof with a chainsaw. The adrenaline will be flowing. Don’t let that adrenaline zap you of your endurance and your ability to think clearly. We can control that excitement by knowing the capabilities of the saw, know what type of roof we’re standing on and being confident in our roof operations.
