CUTTING FLAT ROOFS
RANDOM THOUGHTS
When, how, and why do you cut the roof open at fire buildings? Sound like simple questions. So answer, and don’t read any further. However, if you’re like most of us, you can say, “I really would like to be more sure.” I’d just like to throw some random thoughts your way on the subject, and, like always, use what you’d like and reject the rest.
First, you should be prepared to cut the roof in any structural fire where the ‘tire is under the roof.” This means fires on the top floor or any fire in one-story buildings—and “prepared” doesn’t mean “always.” As always. size-up and communication w ill dictate further actions. Hut to prepare for cutting a roof w hen fire is not on the top floor is your first mistake and a time waster.
Where to cut will be indicated from the moment you arrive. Look at the building and the fire condition; you should be able to divide the structure in half from the sidewalk. Is there heavy fire indicated at the front of the structure, or is it possibly located elsewhere? Flame or how much pressure the products of combustion have or don’t have will help you w ith your initial indications. Once you arrive at the roof level, opening the available vertical arteries into the structure — the skylight, the bulkhead door, and the scuttle cover—will more clearly define the problem. How’ are these vent openings behaving? Is the smoke wispy? Maybe you shouldn’t cut, or just maybe the interior crew hasn’t opened the door to the public hall yet. If in doubt, portable radio communication or listening to interior firefighting noise will help you with your problem.
Divide the roof into four quadrants. You have divided the building in half before your arrival at the roof and know you will begin your hole more toward the front or more toward the rear of the structure. Now you additionally can divide the roof area into quarters. Look at the enclosure walls. Where are most of the products of combustion showing? Rear right or rear left? By now you are more on target.
Work with the wind —if you feel it Most books get us lost and confused with the constant use of the words “windward and leeward.” Keep it simple! Begin the cut downwind and work into the wind to finish it.
Where to cut. Once you’ve decided the quadrant in which you will operate, another rule of thumb takes over. Never cut a hole nearer than five feet to the building’s enclosure walls. Some real sharpies can cut over three rooms knowing the layout below. But for most of us that is too tricky and, to tell the truth, wastes too much time thinking. If you stay those five feet away from the walls, you w ill be in the center of any room or fire area below.
Control the hole. Those firefighters around you will be wanting to use the tools they have the minute they arrive on the roof. If they begin to “pick” at the hole you are try ing to create, it may make the area you are working in untenable at worst and very uncomfortable at least. Prevent any prying until you are finished with all the cuts you want to make. A good practice is to put a small triangular kerf cut at one corner of the rectangular cut for a tool purchase. I usually performed this operation last to avoid having to deal with the overaggressive roof-opening team.
How large? Here we are surrounded by myths, depending on what texts you have read. Some say four feet by eight feet. Others have said eight by 10. Still elsewhere you can read “as large as possible.” When you were working with axes the solution was given to you—and that was a function of exhaustion. Now, with power saws, you practically can cut an entire roof in one operation. The answer is in how fast you want the opening and how much roof sheathing in one piece you can manage.Usually a threeby four-foot or fourby fourfoot opening will be sufficient. However, you should plan to make the original opening bigger if needed. Remember, if you put the hole in the right place —as close as safely possible to over the seat of the fire— you will be driven away from the original hole and forced to cut a second hole. I once was asked by a training officer trying to prepare a training bulletin, “Where do you cut the second hole?” 1 answered, “1 never cut a second hole; 1 make the first one bigger!”
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If you believe that the hole, once opened, may make the original position untenable or if fire conditions and size-up indicate that a larger hole probably will be necessary, plan for it before you let the roof team open the sheathing. Put two or three additional “legs” into the cut pattern. They should extend in the proper direction five or six feet. Then once the original cut is opened you will be a safe distance away to make the original opening larger. If not needed, these additional cuts are easily repaired. However, they allow you to continue to open the roof by making the hole in the best location bigger and bigger.
Finish the hole. Remember, cutting the roof to vertically vent the fire compartment below means making an opening from the outer air dow n into the fire itself. You must be able to push the ceiling surfaces below down and out of the way. Plan for it by bringing the proper additional tools to do that. If for some reason they are unavailable, use pieces of the roof sheathing you just removed.
Trench cut. (Oh, am I gonna get in trouble here.) Trenching or strip cutting a roof is considered for most “a third-alarm cut.” Well, maybe not a full third alarm, but this procedure should not take the place of a primary ventilation cut. The trench, cutting the roof with twoto three-foot parallel cuts that extend from wall to wall or wall to bulkhead, is a defensive/offensive measure. What you are saying by this is that you are willing to give up the part of the structure that exists on the fire side of the trench cut. If you give the interior forces the assistance they need by rapidly and properly opening the roof for ventilation, they may put the fire out! Trenching is a long, exhaustive process. It even may encourage the unnatural spread of fire horizontally rather than halting that process. To be effective, there also should be a handline on the roof to ensure that the fire does not “jump” the trench while the interior team seeks to control and then extinguish the area you defined by the trench.
Again, you may not agree; these are only random thoughts. Be safe.
