Creating a Roof Cutting Prop

WHEN IT COMES TO DRILLing, you are limited only by your imagination. If you look around your station, you can replicate any type of scenario. You can convert the bunkroom into an “apartment” in a multiple dwelling or the weight room into a mask confidence course.

At a recent “all hands” incident, our chief wanted to know if there was fire in the cockloft. The roofman cut a small inspection hole in the roof and reported that there was smoke but the fire had not spread to the loft. After the incident was over, we critiqued the operation and began to discuss roof operations. I wanted to show the firefighters in my squad how to cut a vent hole but did not have a roof prop. Our department has a few roof props that enable firefighters to practice with the circular saw, but these are large units that are very difficult to move from station to station.

On our next set of tours, I noticed a stack of wooden pallets in a parking lot and some old sheets of plywood (photo 1). We put a few of the pallets together and nailed the plywood to the top of them and were able to create an eight- × 12-foot platform on which we could similate roof cutting (photo 2).


(1) A stack of wooden pallets and some old plywood can be used to create a roof cutting prop. (Photos by author.)

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(2) Plywood was nailed to the top of the pallets to create an eight- × 12-foot platform on which firefighters could simulate roof cutting.

 

TYPES OF ROOFS

The fundamentals of roof operations begin with traditional roofs, which have the main joists at the roof level (Figure 1). You cut a hole in the roof to remove all the hot gases and smoke and prevent mushrooming.


Figure 1: When roofing is attached directly to roof joists, a soft, “spongy” roof can be a problem. You must know the difference between springy and spongy; this could save your life one day. The most common roof (above, left), features main joists at roof level. (Illustrations courtesy of Fire Department of New York.)

A flat roof can be an inverted (“raised”) roof. This type of construction has the main joists at the ceiling of the top floor and a small built-up roof made of 2 × 4s. It is normal for a raised roof to have a little spring to it.


Figure 2: A raised roof is used to more easily slope the roof for water runoff. Main roof beams are at ceiling level, and 2 × 4s are used to support roof boards. This type of roof will be normally springy.

It is important for firefighters to know the run of the main beams in any roof, because you want to open as many bays as possible. The main beams usually run on the short side of the building.

WHEN AND WHERE TO CUT

Start the slower work of cutting the roof only after you have completed your initial roof duties. First, open the bulkhead or scuttle, open any skylights, and then open the top-floor windows, so you can bring fresh air in while the gases and smoke are venting through the hole you cut in the roof. At a fire in a commercial occupancy, always get to the roof early, while it is still strong.

If possible, make your cut directly over the fire; if the location of the fire is not obvious, you will need inspection holes. An inspection hole is not meant to be finessed (you are not performing carpentry work). You want to create a quick access point to see what is going on in the cockloft. If the fire doesn’t involve the top floor, pull the ceilings on the top floor before you cut the roof. If there is fire when you pull the ceilings, then cut.

An inspection hole should be three quick kerf cuts in the form of a triangle (photo 3). It is important at this point to give a report. For example, if the incident commander (IC) has a significant top-floor fire and wants to know if fire is entering the cockloft, cut a few inspection holes and report to him exactly what you see. If you have heavy smoke, report it as follows: “Ladder 1 roof, firefighter to IC, I have heavy black smoke pushing under pressure from three inspection holes.” The IC will then decide whether to call for more assistance while you commence your roof operations at the location of the inspection holes.


(3) Create inspection holes by making three quick kerf cuts in the form of a triangle.

Don’t assume anything when you are operating on a roof. For example, if you see a parapet or a hump in the roof, don’t automatically assume that there is a firewall-this may just be an I-beam covered by tar. You must still cut an inspection hole, put your hook into the hole, and feel for the firewall. It also is useful to strike the hump with a tool to determine if it is a covered I-beam.

At a fire in a commercial building. I was in a store at the end of a row of shops. I put a hook up into the ceiling, and it was red hot. I called for a line and for a hole over the store, but the chief discounted my report because he saw a parapet on the roof and believed it was a firewall. It was not a firewall, and fire had spread across the cockloft. If someone on the roof had cut an inspection hole, we would have avoided this confusion.

HOW MUCH TO CUT

After you practice making inspection holes, you can start making a vent hole (photo 4). Each firefighter should take a leg on the vent hole. You should be able to get two three- × six-foot “coffin” cuts (the name is said to be derived from firefighters “coughing and cutting”) out of one prop. The three- × six-foot cut is the recommended size; it is easier to manage and can be expanded if necessary (photo 5).


(4) After you practice making inspection holes, start making a vent hole.

 


(5) A three- × six-foot “coffin cut” is the recommended size for a vent hole; it is easier to manage and can be expanded if necessary.


The long side of the cut should expose as many joists as possible. In a typical 25- × 75-foot structure, the short side of the cut would be across the front. If the cut is too large, it will be too time consuming, as it may be difficult to remove the tar and roof boards. If the cut is too small, you may not get the ventilation you need, and the cut may be too difficult to expand later.

It is important during roof operations that everyone work together to get that first hole. Sometimes firefighters will come up to the roof and start doing their own thing. One person should take charge of the roof and make the call (this can be a firefighter or the IC). The IC may assign an officer to supervise or, if the operation is large enough, a chief. Making too many holes creates an unsafe condition.

Do not pull any pieces before you finish cutting, or fire could blow up in your face. Overcut the legs to permit expansion of the hole without putting your face over the fire while you cut.


Figure 3: Cut with the wind to your back. The first cut is about three feet long, the second cut is the knockout piece, and the third cut is the largest (approximately six feet); all of the remaining cuts are about three feet long.

Instead of trying to pull the whole piece of roofing with your hook (that is the purpose of the knockout piece), drive the hook portion of your halligan into the roofing, just pull it up a little, and drag it off the opening. To finish off the hole, push down the top-floor ceiling with your hook.

A LESSON LEARNED

During an incident a few years ago, firefighters on the roof saw heavy fire venting through the roof. They assumed that the cockloft and top floor “self-vented.” Firefighters on the top floor in the adjoining wing were opening the ceilings to check if there was any fire in the cockloft. The cockloft exploded and firefighters were blown out of the apartment; three suffered serious burns.

An investigation after the fire revealed that the fire first burned a hole in the roof and then melted the tar over the space, effectively sealing off the cockloft. The cockloft was superheated and had plenty of fuel. The only thing missing was air. When the firefighters punched holes in the ceiling in the adjoining wing, the fire exploded in a backdraft.

Roof operations are very dangerous. A roof cutting prop will give you the ability to refine your skills and become familiar with the circular saw in a safe environment. Practicing cutting roofs beforehand helps protect you from potential injury and even death.

DANIEL P. SHERIDAN is a captain in the Fire Department of New York.

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