Flat Roof Operations: Multiple Dwellings The majority of multiple-dwelling fires to which the fire department responds are in buildings of either ordinary construction (Type 3) or wood frame (Type 5). It is recognized that in certain high-concentration areas, fires in high-rise, Type 1 buildings are a normal occurrence. This article is limited to Type 3 (see photo 1) and Type 5 (see photo 2) flat roof, multiple dwellings.
The term “roof operations” has many firefighters thinking “cut the roof,” but with flat-roof operations there is much more to consider. Peak-roof operations usually involve accessing, cutting, and getting off. While peak-roof operations are generally more dangerous due to the difficulty of operating on them, it is the flat roof that requires more thought and therefore more work. Roof operations are almost always conducted on flat-roof multiple dwellings regardless of fire location. The roof is opened (cut) when the fire is on the top floor or in the attic/cockloft space. The exception is the balloon-framed building. Since fire in any location in this type of building has a high potential of spreading vertically to the attic and laterally through the joist spaces, it is wise to open this roof even if the fire is located on a lower floor or basement. STANDARD CONSTRUCTION There is a distinction between roof operations and cutting the roof. Roof operations involve a number of tasks, of which cutting may be one. Once the roof is accessed, attempt to identify the type of roof support system. It may be possible to do this before accessing it. On older buildings, it will most likely be standard construction using “two-by” lumber. Rafters will usually be 2 x 10, 2 x 12, or even 2 x 14. On inverted flat roofs, the rafters will be of smaller dimension, such as 2 x 6, while the joists will be of larger dimension. The smaller dimension lumber allows for ease of constructing a slight slope to assist in draining of water. There will be some “spring” to this type of roof, but do not let it fool you into thinking it is time to vacate. Flat roofs using standard construction usually give a warning of collapse such as sagging and sponginess. Any added weight, such as air conditioning equipment, may alter these warning signs and result in a more rapid collapse. In photo 2.1, a significant fire in a San Francisco multiple dwelling burned with great intensity within the attic/cockloft space. Although it burned through the roof deck and significantly damaged the joists and rafters, the roof did not collapse suddenly. Its demise was easily detected.
LIGHTWEIGHT TRUSS CONSTRUCTION Lightweight-truss construction is designed to span larger areas than that found in standard construction. While it performs its function well from an engineering standpoint, it has proven to be deadly under fire conditions. Rapid collapse without warning is the norm rather than the exception. Most firefighters are well aware of the hazards of truss construction but should not rule out opening this type of roof simply because of its reputation. Cutting a roof of this type will require the hole not be placed directly over the fire, rather back to a safer location. While this may cause a greater loss of attic/cockloft and roof it is the sacrifice that must be made in the name of safety. The decision to access a lightweight truss roof will require judgment based on experience and education. If significant burning is occurring in the truss space or if the length of time the trusses have been subjected to fire is unknown or in doubt it is best not to access it. Remember: “Risk little to save a little. Risk a lot to save a lot.” Because this article deals with multiple dwellings the risks will be great. Most multiple dwellings are occupied and if “vacant” will probably be occupied by vagrants. And finally, if the decision is made not to access the roof, there should not be anyone under it either. ROOF RESPONSIBILITIES Those assigned to roof operations on a flat roof must address the following:
Opening the penthouse/bulkhead door. An interior stairwell which terminates at the roof level will have a door that accesses the roof. The door is called a bulkhead door in some areas of the country and a penthouse door in others. Regardless of what you call it, it is critical that the door is opened immediately to relieve this primary means of egress of any smoke or heat (see photo 3). It is not uncommon for owners/managers of these buildings located in the lower income areas to chain and padlock the door in an effort to keep the “criminal element” out. Unfortunately, in a fire it will keep the occupants in. For this reason, after the door has been forced and rendered unable to accidentally close, the area immediately inside should be checked for victims. Remember to communicate these actions to the incident commander. In photo 3 firefighters are using the best tools for forcing these outward opening doors, the eight-pound flathead axe and Halligan bar.
Checking the rear and sides of the building, lightwells and shafts. How many times have you responded to a fire and found nothing showing upon arrival even though people are streaming out of the building screaming “fire”? Upon entry, smoke is abundant but not being able to locate the fire you begin the search floor by floor. This is where the roof team can provide invaluable service. From this vantage point they can often locate the fire as well as any occupants who may be trapped. A quick check of these areas can save time as well as lives. Photo 4 shows the rear of two, type 3 multiple dwellings. Fire in this location would be difficult to detect from the front. It is easy to see how fire in this area may trap occupants and expose the other building. All of this information needs to be communicated to the incident commander.
Photo 5 shows an interior lightwell where the potential of rapid fire spread across and above the shaft is obvious, as is the possibility of occupants being trapped. For more information on lightwells, go to Know Your Enemy.
Venting skylights and scuttle covers. A skylight is located on a roof surface and provides light to the floor below. By removing the skylight the floor is relieved of heat and smoke. They should be removed as rapidly as possible. Some text books take great effort in explaining intricate ways to neatly remove a skylight so that the least amount of damage results. This is nonsense. In a serious fire threatening the lives of occupants and firefighters, there is no time to be “cute.” “Take” the skylights quickly. In most cases, the best way is to take the point of the Halligan bar or pick of an axe and lightly strike the corner of the glass pane. A small amount of glass will drop to the floor below, serving as a “warning signal” to firefighters below that the skylight is about to be “taken.” The warning will allow firefighters to hug the wall or duck into a room. A few seconds after the pane is broken (perhaps 2 or 3 seconds), every effort is then made to remove all of the panes expeditiously (see photos 6 and 7). It is best to pull the glass up and out onto the roof, but this is not always possible. In some instances there will be a draft stop below the skylight that will have to be removed to complete the ventilation process. Push it down with a Halligan hook, pike pole or some other type of hook.
Scuttle covers are located on the roof, and, by removing them, they will usually provide access to the top floor via a small ladder. This is not always the case. In some instances, removing the cover will only provide access to the attic/cockloft space (see photo 8).
It is very important that, as a firefighter assigned to the roof, you make a determination as to which type you have. By removing the cover that accesses the top floor you will not have opened the roof; rather, it will have relieved the top floor of products of combustion. In this instance, leave the cover off. On the other hand, if you remove a cover that accesses the attic/cockloft only, you will, in effect, have opened the roof. In this case, you must determine if this is the location you want your vent hole. If the cover is not located over the fire and will draw fire across the attic/cockloft space, put it back. Remember, you only want one hole. The following diagrams illustrate the two different types of scuttle covers. To determine which type, remove the cover and use a hook to feel if sides are present. If you encounter sides, indicating it is enclosed, it bypasses the attic/cockloft space and opens onto the top floor. Usually it accesses a closet which would require that you attempt to open it with the hook. If you do not encounter sides, it indicates the scuttle accesses the attic/cockloft space. Diagrams A and B illustrate a scuttle that accesses the top floor, bypassing the attic/cockloft space. By leaving the cover off, it relieves the top floor and has no affect on the attic/cockloft space.
Diagrams C and D illustrate a fire in the attic/cockloft space under the scuttle cover. In this case, the scuttle opens directly into the attic/cockloft space. With the cover left on, fire continues to spread laterally throughout the space. By removing the cover, fire will be drawn up and out slowing and even reversing the lateral fire spread.
Diagrams E and F illustrate a fire in the cockloft, remote from a scuttle cover that opens directly into it. If the cover is removed and left opened, fire will be drawn towards it, involving more of the attic/cockloft space.
Safety Note: Never attempt to access the top floor through a scuttle cover. You will be entering a “chimney” and may get stuck or overcome by heat and smoke. Opening the roof, if necessary. Opening the roof (cutting a hole) will be necessary if the fire is located on the top floor or attic/cockloft space. As was previously mentioned, if the fire is in a balloon framed building it is best to open the roof regardless of the fire floor location. The hole should be located directly over or as close as directly over the fire as possible. Lightweight-truss construction will require more distance between the hole and fire location as a safety measure. In many instances it will be obvious as to the location of the fire such as visible fire, melting tar, steam rising off of the roof, and vent pipes hot to the touch. If fire location cannot be determined you will have to “guesstimate.” Mentally divide the roof into quadrants. More than likely you will, at the very least, have a rough idea as to which quadrant the fire is located. Cut the hole in the middle of that quadrant. When the cut is complete and the decking is removed, the final step is to push the ceiling down. A word of caution: when the decking is removed, large quantities of superheated fire gases will be pushing from the hole. If fire is not already visible, there is a high likelihood these gases will ignite once in contact with fresh air (photo 9). Keep your head to the side and out of these gases.
Although photo 10 is on a peak roof, it nevertheless illustrates the need for pushing down the ceiling. Make certain not to use the hook end. It will catch and hang up in lath and plaster or other obstructions in the attic/cockloft.
When pushing down the ceiling avoid using too much force, unless you are confronted with a wood ceiling. Pushing too hard will only result in creating a hole the diameter of the hook handle. Sheet rock, wood lath and plaster and metal lath and plaster take a bit of finesse. Sheet rock in particular will take a lighter touch than the rest. Using the end opposite the hook, locate the ceiling joists below the cut area (photo 11). Striking along each joist will loosen the nails. Sometimes you can actually hear them squeak as they loosen. By the time you begin working on the last joist, the sheetrock will drop in large pieces. Photo 11 was taken during a training session in a vacant structure. This is the best place to develop your skills with this technique.
The act of cutting a hole will of course be much easier with the assistance of a power saw, either a rotary type or a chain saw. My personal preference is to use a chain saw on a peak roof and a rotary saw on a flat roof. Never use a rotary saw on a peak roof because the weight and gyroscopic action make it very difficult to handle on such a dangerous surface. Regardless of which saw you use, keep in mind that if it fails to start, the axe always does! If you are using a chain saw, the teeth should be carbide tipped. Some “vent” saws come with an adjustable depth guide which I like to remove because they limit its capabilities.
An excellent method for cutting with a chain saw requires the blade be inserted into the roof deck at a depth of approximately ten inches. The saw is held as close to vertical as possible. With the throttle fully open, begin cutting until you feel the resistance of a roof rafter. Keeping the saw near vertical will provide more chain surface making contact with the rafter. It will be easier to feel and thus you won’t cut through it. Bring the blade up, out of the cut, over the rafter, plunge back into the deck, continuing with the cut. This is called rolling the rafter (Diagrams G,H, and I). Some people like to mark the rafter location with a notch made by the saw. Once the cuts are made it is easy to cut between the rafters, forming segments that can be louvered. Make sure to louver in such a way as to direct the smoke away from you. It is important to note that the objective is to cut through the roof deck and not the rafters. If you have never tried this method, I suggest you practice on an old vacant building or a roof prop. You will be amazed at how fast you develop your skills.
When encountering a heavy built up tar and gravel roof with many layers, a chain saw is useless as are most rotary saws. For this reason, it is worth it to spend a little more and get a GOOD rotary saw. I wisely took this advice from Captain Jay Comella of the Oakland Fire Department after conducting research on a donated multiple dwelling in downtown San Francisco. The roof had approximately two inches of built up tar and gravel that was attacked with various saws, blades, and chains. It took at least 20 minutes to make a four-foot by four-foot hole. Often, the work had to be completed with an ax. This is totally unacceptable on the fireground. For liability reasons, I will not mention the brands used. After our failed attempts to rapidly open the roof, Captain Comella produced a Partner 950 rotary saw with a 12-point, carbide tipped “Chopper” blade. The efficiency of this combination was truly stunning. We were able to open a four-foot by four-foot hole in less than five minutes; the single pass of the saw cutting completely through all layers of roofing material AND the roof deck. It has been my experience that the stand on the bottom of the saw hinders cutting operations because it tends to snag the roofing material when drawing it backwards (photo 13). I prefer to remove it. Furthermore, placing a hand on the forward handle (photo 14) causes firefighters to “push” the blade deeper into the deck than it should (photo 15). I prefer to rest that hand on the top of the housing. And finally, the guard should be in the proper position as seen in photo 14. Note: The saw pictured is a Partner 950 but has a metal cutting blade, not the 12 point “Chopper” blade recommended for tar and gravel roofs.
Safety Note: Operation of a rotary saw on a roof requires the operator to work moving backwards. For this reason a second firefighter should act as the eyes and ears, keeping one hand on the saw operator’s truck belt, guiding him or her backwards. This person should also pay attention to the current situation and the possibilities they may change. When cutting a four foot by four foot hole, extend the legs of the cut so that if the hole needs to be expanded it will only require two cuts to connect the legs. The remaining pieces can be removed, resulting in an eight foot by eight foot hole. Diagram J indicates the cuts to be made and in what order. You may wish to change the order. Safety Note: When making the cuts be sure to keep outside of the cut area. This will require that you have the ability to cut both left-handed and right-handed.
Cutting “knockouts” will facilitate the placement of the Halligan hook for easier removal of the roof deck. (photo 15.1)
Another method of cutting a flat roof, particularly when a large
hole is called for such as in a commercial occupancy with an
extensive roof deck, uses the chain saw and can prove to be very
effective. Utilizing the
technique described earlier and illustrated in Diagrams G, H, and I,
make the cuts in the order shown in Diagram K.
The segments created by cutting between rafters will make their removal relatively easy. In the event of a cross wind, louvering the panels will greatly assist in removing smoke. Make sure the louvers are pointed in the direction that will assist the air flow and not force it back into the building.
Horizontal ventilation from the roof. Vertical ventilation is one of the primary reasons going to the roof is considered. Often, however, we tend to overlook horizontal ventilation when it can be easily accomplished from the roof position or any vertical position for that matter. Interior companies making the push with attack lines will need the windows vented. From the roof position above, a firefighter can tie a line to a tool and throw it over the parapet wall, striking the window below. For this reason, firefighters assigned to ladder companies should carry a 25 foot length of rope. Consider placing clips at the ends to facilitate easy connection onto the loop welded near the fork end of the Halligan bar (NOT the adze end). With the piece of rope or webbing secured to the tool, lower it over the parapet to the upper pane of the window to be removed. Grasp and secure the rope with one hand to mark the designated length. With the other hand, retrieve the tool. Now take the tool, with the rope still grasped at the designated length, throw it outward with the other hand, striking the glass below. The window that should be taken first is the one which looks like it will be the first to “go” or burn through. After it has been removed, work away from it, taking additional windows if necessary. Safety Note: Horizontal ventilation requires coordination and COMMUNICATION with the fire attack group. Indiscriminate venting of windows without the interior crews knowledge may cause a flashover, a smoke explosion, or a wind driven fire, seriously injuring or killing firefighters. Sometimes the communication with the interior crews may not be verbal rather the audible sound or visible signs of water flowing. Assisting interior crews. In the old days, some firefighters would go to the roof, cut a hole, step back and light up a cigarette…their work was done! There is plenty to do from the roof but once you have finished, your service will be needed down below. Proceed to the top floor and assist the other companies with a primary search, ventilation, and the opening of ceilings and walls, or any other task assigned by the incident commander. Safety Note: When accessing the top floor from the roof, avoid using the bulkhead/penthouse door unless it is certain that the fire is out. The stairway is a “chimney.” Use the fire escape. WHAT TO WEAR…WHAT TO TAKE Make sure you are wearing the proper safety equipment and have the appropriate tools when you go to a flat roof. The minimum equipment to carry is shown in photo 16. The roof ladder can be used to remove occupants who may be trapped on the top floor window, in a lightwell, or other area inaccessible to ground ladders or aerial apparatus. It does not necessarily have to go up to the roof right away but should be considered.
FINAL THOUGHTS What you have read here is nothing new. This represents my understanding and interpretation of what I have learned and experienced over the years of reading, networking, training, going to fires and doing. I am merely attempting to pass it on. Proper credit should be given to the pioneers like Tom Brennan, John Mittendorf, Vincent Dunn, John Norman and the countless others I have had the honor to meet over the years. There is a tremendous amount of information available to the serious student. I suggest they refer to texts written by the aforementioned fire service icons in addition to archiving past issues of Firenuggets.com, W.N.Y.F. (With New York Firefighters) and Fire Engineering magazine. © Copyright Firenuggets.com 2008 • Click here for Terms and Conditions of Use
|
||||||||||||||||||||||||||||||||||||||
