Warehouses require open floor areas and large overhead doorways to facilitate moving stock to and from storage racks and trucks at loading docks. Today, robots are replacing forklifts in moving stock at massive E-commerce fulfillment centers. Floor areas unobstructed by bearing walls and with a minimal number of columns require a roof that is supported by some type of truss.
Fire recruits must grasp early in their fire academy training the vast difference between the classifications “fire resistive” vs. “noncombustible.” Some warehouse truss roofs are noncombustible, but no common warehouse roof can be considered fire resistive. A building that building codes classify as “fire resistive” or “Type 1” has floors, walls, and a roof that can withstand collapse and penetration by fire for as much as two to four hours.
Fire-resistive structural assemblies are tested in large furnaces in testing facilities such as Underwriters Laboratories. Although test performance does not guarantee that fire-resistive structural assemblies will perform similarly under actual fire conditions, it is unlikely that they will collapse.
Fire-resistive buildings generally have reinforced concrete structural components. When steel is used in fire-resistive construction, it must be protected by encasing it in concrete or enclosing it with a fire-rated barrier. Later, this article will examine precast “twin T” warehouse roofs, which are a perfect example of concrete roof construction that is far from fire resistive and prone to early collapse.
Warehouse Roof Construction History
The oldest warehouses in virtually every American city and small town have roofs supported by trusses, including bowstring trusses; many of these buildings are still standing today. Bowstring trusses can be constructed entirely of wood or steel, but most are hybrids of wood chords and web members tied together with metal fasteners. A bowstring truss roof has a characteristic arch profile, but this can be obscured by large parapets. You can determine the height of parapets by the location of roof drain scuppers at the roof line.
Bowstring truss roofs are firefighter killers. Multiple firefighter line-of-duty deaths (LODDs) have occurred as a result of bowstring truss roof collapses. Students of the fire service must learn the lessons of tragic fires such as the Waldbaum’s grocery (1978, Brooklyn, New York) and Hackensack Ford dealership (1988, Hackensack, New Jersey).
The height between the top chord and bottom chord of bowstring trusses can measure several feet; this space, a “truss loft,” is a tempting place for storage. The collapse danger of bowstring truss roofs increases significantly when a floor is constructed in a truss loft for storage. This creates a huge attic space that is difficult for firefighters to access, direct streams at, and determine the location and extent of the fire burning over their heads. Additionally, heavy storage places dangerous, undesigned loads on trusses that can hasten their collapse.
Expand the Collapse Zone
When fire impinges on bowstring roof assemblies, firefighters must attack them defensively with master streams operated outside the collapse zone, a distance from the building that must be at least 1½ times that of the height of the parapet. The bowstring truss’s engineering requires this large collapse zone. Similar to any truss, bowstring trusses have upper chords under compression and bottom chords under tension.
Consider an archery bow. Cut the bowstring, which is under considerable tension, and the bow will forcefully straighten itself. Similarly, when the lower chord of a bowstring truss fails, the upper chord tends to straighten and applies considerable lateral thrust to exterior walls, hurling bricks a considerable distance, greater than their vertical height.
Bowstring truss roofs present an additional collapse hazard when they are pitched at the front and rear of buildings, like hip roofs. Hip rafters support the bowstring roof’s pitched portion that spans between the front and rear trusses and front and rear parapets. Collapse of the front or rear truss can exert considerable leverage against the front and rear walls, launching bricks at a distance as much as twice their height.
When establishing collapse zones, consider the electrical service wires and utility poles that walls will bring down when they collapse. If the width of streets or alleys does not allow firefighters and apparatus to operate at an adequate safe distance from a fire building, they must take flanking positions out of the range of falling bricks. Accordingly, aerial devices should be positioned at “corner safe” areas.
Beware of Gypsum Deck Roofs
Beginning in the late 1940s, flat gypsum deck warehouse roofs became common for warehouses and supermarkets. What firefighters might call “lightweight concrete” is most likely a gypsum deck. Gypsum roofs consist of gypsum cement that can be cast into panels or poured on top of a plasterboard or corrugated metal deck. For poured-gypsum roof decks, steel wire mesh provides tensile strength.
Poured-gypsum deck construction is similar in concept to a suspended ceiling. Just as the ceiling panels rest on the flanges of inverted-T members, the gypsum form board for poured-gypsum roofs and the gypsum panels rest on the flanges of bulb T subpurlins, commonly supported at right angles by unprotected steel bar joists. The upright of a bulb T is wider at the top than at the bottom, like the profile of a light bulb. This bulbous profile helps to restrain the roof deck against the uplifting forces of the wind. Photo 1 shows the underside of a gypsum roof; unprotected steel girders support bar joists, which appear to be spaced four feet on center. The bar joists support the bulb T subpurlins, spaced two feet on center, which support gypsum form boards. Photo 2 shows a cross section of a gypsum roof; visible is the bulb T, the orange steel bar joist, the drywall form board, approximately 2½ inches of poured gypsum, and the top layer of 1½ inches of built-up roof covering. Photo 3 is another cross section, but instead of using a gypsum form board, the gypsum was poured to a three-inch depth on a corrugated metal deck. The gypsum is covered by foam insulation, rigid “recovery board” to protect the insulation, and a “cap sheet” roof covering with a granular surface.
(1) Photos by Eric Goodman unless otherwise noted.
To understand the extreme risk to firefighters operating on or under a gypsum deck roof, consider what happens to gypsum board drywall in a fire. As gypsum is heated, it loses its water content and becomes brittle. Any firefighter who has pulled a water-saturated drywall ceiling knows that it takes very little effort to drop entire four- × eight-foot sections.
Gypsum deck roofs behave similarly when exposed to fire and water. Heat attacking the underside of a gypsum deck roof will draw out the moisture, making it brittle and unable to support the weight of a firefighter. Additionally, the steel girders, bar joists, and bulb T subpurlins will start to lose their strength and warp and distort at approximately 800°F.
“It’s a Torch!”
Most professional roofing contractors pride themselves on excellent workmanship using high-quality materials. This is aimed at “fly-by-night” roofers who start roofing fires and then lie about how the fires started. Firefighters respond to a fire in an attic or cockloft and learn that a few hours ago workers were patching holes in the roof; it is no coincidence—it’s a torch!
Low-density fiberboard roof insulation is prone to smoldering combustion; consequently, a fire on a roof or in an attic may not be discovered until several hours after the roofers have left for the day. Any time there is a fire and roofers are or were working there, be very suspicious! If they were applying asphalt or an asphalt-based patch and there is no tar kettle at the job site, how was the patch applied without molten asphalt to mop on the roof? Most likely, they used a torch.
Don’t expect to find a torch, which is typically fueled by a 20-pound liquefied propane cylinder, at the job site or expect to workers to tell the truth when asked if they were using one. The torch will be long gone before the first fire company arrives on the scene.
Leaky gypsum roofs are insidious, giving no outward visual indication that they are water saturated and will not support the weight of a firefighter. As water leaks through roof coverings, over time, large water stains will be visible in the underside of the roof, but the topside will look perfectly normal.
Do not assume that steel reinforcing mesh will support the weight of a firefighter. Moisture can corrode the steel mesh to the point of near disintegration (photo 4).
Firefighters should not operate on or under a gypsum deck roof exposed to fire conditions. The Fire Department of New York (FDNY) is very clear in its directive. If ladder company firefighters performing vertical ventilation find their rotary saw blade throwing powdered cement dust, they must transmit an urgent message advising the possibility of a gypsum deck and quickly get off the roof.
Roof Insulation and Covering
Warehouse roof decks are insulated to retard the passage of the sun’s heat in hot weather and loss of heat in cold weather. Old roofs were commonly insulated by low-density particleboard consisting of wood chips or bagasse, the residue of sugar cane after it has been milled. Low-density fiberboard is notorious for smoldering combustion and, consequently, prone to rekindle. Modern roofs typically are insulated with a thermoplastic foam board such as polyisocyanurate. Coverings are installed to make roofs watertight, to resist ultraviolet (UV) light, and to prevent damage when walked on.
The following examination of roof coverings is just a general overview; the composition of roof coverings varies from region to region, depending on the climate. It is based on my experience, which may not be applicable everywhere. It is, therefore, critical that firefighters familiarize themselves with the composition of roof construction, insulation, and coverings in their areas. Generally, roof covering systems are either built up or membrane.
When a roofing contractor pulls a “tar” kettle trailer to a job site, he intends to install a built-up or “tar and gravel” roof. In a built-up roof system, layers of molten asphalt (incorrectly called tar) are “hot mopped” on and in between layers of asphalt-impregnated felt. The roof surface is commonly covered with a ballast of gravel. Instead of gravel, roofing contractors may apply a cap sheet of heavy felt impregnated with a granulated material such as slate or perlite for protection.
A membrane roof covering is installed during construction or reroofing of older warehouses. The membrane may be made of synthetic rubber—e.g., ethylene-propylene-diene-monomer (EPDM); plastic-based [thermoplastic olefin (TPO)]; or asphalt-based, such as modified bitumen. The surface is embedded with granular material, similar to a built-up roof for protection.
Membrane sheets come in large rolls. Membranes of EPDM and TPO consist of a single ply; modified bitumen is typically laid over a base sheet reinforced with fiberglass. Single-ply membranes are secured by the weight of the gravel, with mechanical fasteners, or “chemically welded” with a glue or bonding agent. A common method of applying modified bitumen is to bond it to the roof and at seams with a torch (see sidebar “It’s a Torch!”) Roof coverings vary in combustibility, depending on their chemical composition; some melt and burn readily, while other types self-extinguish when the heat source is removed.
Metal Deck Roof Fires and Collapse
Modern big-box stores and warehouses today are constructed with roofs consisting of corrugated metal decks (photo 5). Additionally, when gypsum roofs can no longer be repaired, they are commonly replaced with metal roofs. Similar to gypsum roofs, metal deck roofs are typically supported by unprotected steel girders and bar joists. Steel structural elements are noncombustible but far from fire resistive and fail after a “few minutes” of fire exposure. How many minutes is a “few”? Some fire officers apply the “20-minute rule” to unprotected steel structural members—that is, if exposed to fire longer than 20 minutes, the roof assembly is in danger of collapse.
The 20-minute rule is a guide for decision making but definitely not an absolute. Factors that influence the time to collapse include the volume and intensity of fire and dead loads on the roof such a HVAC equipment. Perhaps the most significant factor in determining the time of collapse or in preventing collapse is the ability for firefighters to cool the underside of the roof assembly.
Acres of Fire Under One Roof
Some of the largest dollar-loss fires in history have resulted from self-propagating metal deck roof fires. Massive industrial and storage buildings, measuring in acres under one roof, have been destroyed by metal deck roof fires that rapidly spread beyond the suppression capabilities of firefighters.
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How does a metal deck roof propagate fire if it is noncombustible? Fire heats the underside of a metal deck roof as if it was a frying pan on a stove burner. The heat liquifies and vaporizes the layers of combustible mopped asphalt and roof coverings. Expanding vapors push through joints where metal deck sections overlap, ignite, and can spread like a wildfire under a roof. Like a wildfire, the fire preheats the roof ahead of the flame front as flames roll across the underside of the roof (photo 6). The antidote for metal deck roof fires is the same for preventing collapse: Cool the underside of the roof.
Precast “Twin Ts” Dangers
Don’t be fooled by the appearance of warehouse roofs constructed with precast concrete twin Ts (photo 7). They may look like heavy, substantial concrete members but they are far from fire resistive. Similar to trusses, concrete Ts have elements in tension and compression. In twin Ts, stranded cables, running the length of the member, are tensioned to several thousand pounds before concrete is poured into the forms at a precast plant. Hence, precast Ts are considered “pretensioned“ (photo 8). The cables under tension exert a compressive force on the concrete, enabling the member to span without the support of a column at its center or that of a bearing wall.
Do not confuse pretensioned with posttensioned concrete; both derive their strength from cables in tension. However, the cables in precast Ts are tensioned before the concrete is formed and cured. Cables in posttensioned concrete are tensioned after the concrete is poured and cured for a prescribed amount of time. Another difference between precast and posttensioned concrete is that the cables in prestressed Ts are in intimate contact with the concrete, whereas cables in posttensioned concrete are in a plastic sheath.
Cables Are Vulnerable
The steel cables in precast twin Ts are vulnerable to heat that attacks and spalls concrete in the underside of the members. It does not require a large, intense fire or a long-burning fire to spall the concrete and expose the cables. Once the cables are heated, they lose their tension, causing the twin Ts to lose their ability to span between their supporting members, and the twin Ts begin to sag.
It doesn’t take much sag for twin Ts to pull off their bearing surface or out of a socket in a wall because building codes generally require only four inches at the end of a twin T to rest on a girder, a pilaster, or a socket in a bearing wall. Experience has shown that steel embedded in the end of twin Ts that is welded to steel embedded in supporting members often does not restrain the member sufficiently to prevent its collapse.
Swinging vs. Overhead Warehouse Doors
When indications are that a fire in a warehouse is small or held in control by sprinklers, it is in the building owner’s best interest to allow firefighters to gain entry though a swinging door and then open the overhead doors from the inside. Commercial overhead doors are typically devoid of any locks or latches on their exterior; they are lowered and secured on the inside by an occupant who exits the building through a swinging door. At serious warehouse fires, overhead doors have the following tactical advantages over swinging doors:
- An overhead doorway provides direct access to the storage and work areas.
- Overhead doors are usually directly in line with aisles, allowing the hose to be advanced in a fairly straight line.
- The height and width of overhead doorways provide a large ventilation opening and an escape route.
Master streams operated through an overhead doorway can cool the roof structure, possibly preventing a collapse. Deflecting a powerful stream off the underside of a roof will enable reaching fire in areas that can be too dangerous to enter with handlines (photo 9).
Have a Plan A, B, C …
Various forcible entry techniques may not be effective every time, on every door, or in every region. The company officer directing the forcible entry operation should have alternate techniques if plan A doesn’t work and know when it’s time to shift to plan B, plan C, and so on. Whenever possible, a company officer should not be operating the tools; he must be supervising and judging the effectiveness of the operation.
Don’t Wake Up a Sleeping Dragon
Opening overhead doors could endanger firefighters who entered a warehouse through a swinging door before opening the overhead doors. Consider a fire in an industrial park that is largely deserted at nights and on weekends. With no fire detection system, a fire can burn for several hours, consuming the available oxygen and becoming ventilation controlled or limited. If firefighters enter through a swinging doorway, it could take between 100 and 200 seconds for sufficient air to flow into a building and intensify an oxygen-deprived fire. Consider the effect on personnel operating several feet from their means of escape if the overhead doors are opened, allowing a huge in-rush of air that awakens “the sleeping dragon,” the ventilation-limited fire.
Before opening the overhead doors, seriously consider withdrawing personnel who entered through a swinging door or, preferably, reduce their exposure to hostile fire conditions by initially entering through overhead doors. If air flowing through the overhead doorways causes a fire to roar back to life, so be it, but personnel won’t be caught in a hostile fire event deep inside the building.
Fire researchers recommend not delaying the fire attack while establishing a continuous water supply. This is valid advice for fires in dwellings but not for fires in a closed commercial building. Firefighters forcing entry in a closed commercial building should expect the fire to intensify when they give it a breath of oxygen and had better be prepared with adequate, redundant water supplies and master stream appliances ready to flow water.
Primary and Secondary Cuts
In overhead doors, firefighters make primary and secondary cuts. The primary cuts are small openings through which to direct a nozzle at the fire burning directly behind a door and to access locks, latches, and hoist chains. They allow a door to be raised largely intact, minimizing property damage and maximizing the size of the opening.
In hurricane-prone areas, a small primary opening in an overhead sectional door enables a firefighter to reach inside to determine the size of horizontal wind bracing, a crucial factor in choosing the method of cutting a secondary opening. Secondary cuts in overhead doors are necessary when locks and latches cannot be manipulated or fire has damaged a door such that it cannot be raised.
Overhead Door Types
Overhead rolling. These doors consist of interlocking slats that travel up and down in tracks fastened to the sides of the doorway and a bottom bar of channel or angle iron. The slats, which hinge on each other, roll up into an overhead drum. If doors are required by building codes to resist winds, they are equipped with wind locks/tabs that are riveted to the ends of every or every other slat. Wind locks engage a channel in the tracks that resists the force of wind that makes the middle of a door bow in and pull the slats out of the tracks. Wind locks also prevent firefighters from pulling slats out of the tracks after they have cut a triangular opening unless they cut the ends of the slats where the wind locks are fastened.
Large, heavy overhead rolling doors are usually operated mechanically by a chain hoist or an electric motor. Heavy overhead doors are assisted by powerful torsion springs in the overhead drum that counterbalance the door’s weight. When a door is operated by a chain hoist, a continuous loop of chain extends from a cog at the overhead drum to a few feet above the floor where it is commonly secured by a padlock.
Firefighters should examine overhead doors during prefire planning; they may find that hoist chains in their area may tend to be predominantly on one side. In South Florida, for example, chains are usually located on the right side.
Plan A. An effective plan A for forcing overhead rolling doors is to cut a vertical slice along the track on the side of the door where the hoist chain is believed to be located (photo 10).
Rotary saws are natural gyroscopes and are relatively easy to handle when making vertical cuts; additionally, gravity is on the operator’s side. Continue cutting through the slats until the cut portion of the door can be pushed in sufficiently for firefighters to reach in with bolt cutters to cut the padlock securing the hoisting chain, not the chain itself, and operate it to raise the door (photo 11).
Doors may also be secured by L-shaped sliding latches on their bottom bars that engage holes in their tracks. If no chain is found, enlarge the cut and push in the cut portion to allow a firefighter to enter and raise the door from the inside, if conditions allow, or make another vertical cut in the other end of the door.
Plan B. You may not be able to raise an overhead rolling door by its chain hoist mechanism for the following reasons:
- The door is electrically operated. In heavy smoke, it may be difficult to engage the mechanism to allow manual operation.
- Heat or the force of an explosion may warp the slats and prevent them from rolling into the overhead drum.
- The door may be secured with difficult locks, or heat can attack the torsion springs inside the drum, making the door too heavy to raise.
When raising a door manually doesn’t work, plan B will depend on the condition of the door. See “Rotary Saws: Lessons Learned from Cutting Overhead Doors” (Training Notebook, Fire Engineering, May 2020). Author Stephen F. Shaw Jr. is correct: Pulling slats out of an overhead rolling door is not always easy and may be too labor-intensive and time consuming to be practical.
If the door is in good condition, make vertical cuts in the ends of the door as high as possible down to its bottom bar, which will effectively cut each slat away from its wind lock. Large overhead doors or ones that are deeply recessed in a doorway will require a third vertical cut in the center of the door to reduce the slat’s overall length and make it easier to slide.
Now grasp the slats with locking pliers while tapping on the other end with a flathead ax (photo 12). An alternative to using locking pliers is to drive the spike end of a halligan in with an ax, a maul, or a baseball swing and then striking the halligan, an effective method of sliding difficult slats. This method is explained in “Forcible Entry Techniques for Roll-Down Security Gates” (Fire Engineering, March 2012). Captain Daniel M. Troxell of the Washington (D.C.) Fire Department advises that you must drive the spike in before making any cuts in a door.
Caution: When pulling out slats from a large, heavy overhead rolling door, remember that the powerful springs in the drum overhead counterbalance the door’s weight. Pulling slats from an overhead rolling door effectively reduces its weight and shifts the balance of tension and the door’s weight in favor of the springs. A door separated from its bottom bar can suddenly shoot up into its drum with tremendous force and, like an old window shade, spin around in the drum until the spring tension is dissipated. Then, just as suddenly, the door can drop back down. When cutting and pulling slats from an overhead rolling door, anticipate that the door may suddenly raise at any moment and be prepared to step back for a few seconds and wait for it to fall.
Heat can cause counterbalance springs to lose tension, in which case the balance of tension/weight will shift in favor of the door, causing it to close unexpectedly behind firefighters, trapping them inside a building. Without sufficient spring tension, a door will be too heavy to raise manually to rescue the trapped firefighters. When overhead doors of any type are possibly subjected to heat, secure them open with pike poles (preferably long) that will reduce the amount of door free fall before the bottom of the door makes contact with the pike poles. As an additional safeguard, wedge a halligan vertically in the track at the bottom of the doorway. Hopefully, this will give firefighters enough room to crawl under a door if the pike poles fail to restrain it.
Plan C. The tried-and-true method of cutting a large triangular opening in an overhead rolling door is still a viable alternative to the previously described method and may be a plan A when fire is immediately behind a door and necessitates a quick opening to insert a nozzle or when heat, corrosion, or damage (e.g., from forklifts) prevents slats from sliding freely out of a door. The triangle cut or inverted V basically requires two cuts—one vertical and one diagonal—that overlap at the top. It is easier, however, to cut a triangular opening by making three cuts:
- Cut vertically next to the track as high as possible down to the angle iron bottom bar at the bottom of the door.
- Make a diagonal cut toward the bottom of the door but do not overlap with the vertical cut; leave a few slats intact to keep the cut portion from falling into the opening (photo 13). This will hold back some of the smoke that would otherwise obscure the saw operator’s vision and “choke” the saw’s carburetor. Also, if cuts 1 and 2 initially overlap, each slat will bend into the opening, which tends to pinch and bind the saw’s blade.
- When the saw operator is ready to open the triangle, connect cuts 1 and 2 with cut 3, which will drop the entire cut portion of the door into the opening.
Overhead curtain. These operate the same as overhead rolling doors but do not have slats. Curtain doors consist of sheet metal corrugated panels pressed together to form a continuous sheet that is strong yet flexible enough to roll up in an overhead drum. Plan A for forcing curtain doors is the same as for forcing overhead rolling doors: Cut a vertical slice along its track in the end of the door where the hoist chain is believed to be to access and operate the chain hoist mechanism to raise the door. If the door cannot be raised, plan B is to attempt to cut through its bottom bar. There are two techniques for cutting bottom bars of overhead curtain and rolling doors: (1) Cut a triangle in the bottom of the door large enough to insert the saw’s blade and guard (photo 14). (2) Position a halligan parallel and three to four inches from the door. A halligan with its adz and spike touching the ground makes an excellent fulcrum for a steel roof hook to apply considerable leverage to raise the bottom bar; this is often necessary when the bottom bar is in front of one to two inches of floor slab. If a door’s bottom bar can be severed, make a second cut horizontally across the door as high as possible to complete a “barn door cut,” allowing the cut portion of the door to be hinged out of the way (photo 15).
Cutting horizontally overhead with a rotary saw is strenuous work and requires upper body strength. Even the strongest of saw operators will begin to tire. Usually the first indication of fatigue is the saw operator will bind the blade and cannot maintain the height of the cut. Now, the company officer directing the operation has to step up and lead by rotating personnel. Do not expect a fatigued saw operator to stop cutting and willingly hand over the saw to another operator. A firefighter operating a saw is not only physically involved in the operation but has his ego in the game.
Overhead sectional. These warehouse doors have hinged panels that ride on rollers in tracks fastened to the sides of the doorway. Sectional doors are reinforced by vertical members called stiles and horizontally with wind bracing. Sectional doors that are built to withstand high winds are extremely heavy and thus are counterbalanced by torsion springs on a shaft above the door. Cables that wind on the pulley at each end of the shaft extend down to the bottom of the door where they are commonly fastened with aluminum cable clamps. Consequently, not only can overhead sectional doors close when their torsion springs are exposed to heat, but the aluminum cable clamps can fail, causing the heavy door to free fall like the blade of a guillotine. Additionally, as with overhead rolling doors, cutting and removing portions of sectional doors reduces the door’s weight; as a result, they can suddenly raise with considerable force.
Commercial sectional doors are commonly secured with L-shaped sliding latches that engage holes in the tracks. Latch assemblies are fastened to the framework of the door with sheet metal screws and are commonly located on one or both ends of the second up from the bottom-most section. Accordingly, plan A for forcing sectional doors is to cut triangular openings in the second section from the bottom. The openings should be large enough to reach in and throw the latches (photo 16). If the latches are secured in the tracks with inexpensive padlocks, enlarge the openings and cut them with bolt cutters. In photo 17, firefighters were unable to raise this sectional door or cut a barn-door opening. By default, they resorted to a box cut—two vertical cuts at each end and one horizontal cut across the door.
(17) Photo by Robert Hernandez, courtesy of Miami-Dade (FL) Fire Rescue.
“Skinning” wind-rated overhead sectional doors. In photo 18, a firefighter reaches into a triangular primary cut to find that the horizontal wind bracing is large, which means that the overall thickness of the door exceeds five inches, the maximum depth of a rotary saw with a 14-inch blade. Reaching into this opening also enables the firefighter to locate the stiles so he avoids cutting them when cutting the skin of the door. In this situation, immediately advise the incident commander of a delay in cutting a large opening; the door must first be “skinned.”
Skinning the door requires two parallel vertical cuts to allow the space for the saw’s blade to completely cut through wind bracing (photo 19). Make the first vertical cut no closer than six inches from the edge of the door to avoid cutting the thick steel hinges. Tip: Whenever a saw operator encounters difficulty in cutting the skin of an overhead sectional door, the blade is most likely cutting hinges or stiles. If the saw operator feels resistance and is having difficulty maintaining the saw’s revolutions per minute, he should move over a few inches and try another cut. In photo 20, a roof hook and halligan are used as a lever and a fulcrum to lift the bottom of the door to allow it to be cut.
Firefighters open the “barn door.” If firefighters are unable to cut completely through the bottom of a sectional door, then a box cut would be an effective alternative.
Prefire Planning Is Key
Fire companies must determine from among the many methods available which ones work for them by getting out in their districts and familiarizing themselves with local door assemblies. Additionally, consult with overhead door contractors, who are valuable sources of information on door design construction and forcible entry techniques.
Author’s note: Special thanks to Assistant Chief Stephen F. Shaw Jr., Fort Lauderdale (FL) Fire Rescue, for his technical advice.
BILL GUSTIN is a 48-year veteran of the fire service and a captain with the Miami-Dade (FL) Fire/Rescue Department. He began his fire service career in the Chicago area and is a lead instructor in his department’s Officer Development Program. He teaches tactics and company officer training programs throughout North America. He is an advisory board member of Fire Engineering and FDIC International.
Bill Gustin will present “Operations for Newly Promoted Officers” on Tuesday, August 3, 8:00 a.m.-12:00 p.m., and “Standpipe Operations” on Thursday, August 5, 10:30 a.m.-12:15 p.m., at FDIC International 2021 in Indianapolis.