BY JERRY KNAPP
The house fire is the most common type of working fire for most U.S. fire departments. Firefighters too often take them for granted and don’t recognize the risk house fires present and the important ways in which they have changed in recent years. The traditional strategy and tactics are usually really simple: Conduct a thorough size-up with a 360° walk-around, develop and execute a search/rescue operation, quickly get a line through the front door to the seat of the fire or to protect the means of egress, and ventilate as needed. However, standard strategy and tactics do not take into account new home construction materials and methods.
The combination of new building methods and materials for the single-family dwelling has created a new and dangerous dimension: extremely rapid fire spread. In these cases, the fire quickly envelops the home along several paths at the same time. This article examines the causes of residential fire envelopment, suggests some tactics to counter this dangerous new threat, and presents lessons learned from case histories and a recent fast-moving residential fire.
RESIDENTIAL FIRE ENVELOPMENT
In May 2013 at 0145 hours, the West Haverstraw (NY) Fire Department (WHFD) was dispatched to a mulch fire (as reported by the homeowner) in front of a home in a suburban neighborhood. At 0147 hours, the police officer on scene reported, “The entire front of the house is involved.” A WHFD officer arrived on scene at 0148 hours and reported a fully involved house fire (photo 1). Within three minutes, this mulch fire had spread so rapidly that when the first apparatus arrived at 0149 hours, the fire had already established flow paths that would soon allow it to envelop the entire building.
|(1) When the first WHFD officer arrived, the fire appeared to be mainly exterior, but it had already extended to the eaves/soffit on the A/B and B/C corners. [Photos courtesy of the West Haverstraw (NY) Fire Department unless otherwise noted.]|
When the first apparatus (quint) arrived, the fire was so extensive that it ranged from ground level (the shrubs and grass on the front lawn), up the entire front surface, to the eave line. Fire was aggressively pushing out of all the doors and windows on all floors. The roof rapidly collapsed, and the attic was burning and showing at the eave line, which was fully involved with fire that was silhouetted against the night sky (photo 2). Winds increased the exposure problem on the Bravo side (photo 3).
|(2) Three minutes and 58 seconds later (after photo 1), it was clear that the fire had entered the first floor, as evidenced by the first-floor window on the Bravo side and the fully involved eaves.|
|(3) Winds gusting from the east (Delta side) increased the exposure problem and created a significant flying brand problem.|
The first engine arrived approximately two minutes later (photo 4), established a supply line from a hydrant, and flowed its master stream soon after this photo was taken.
|(4) As the first-due units protected the exposures and prepared for master stream operations, the fire had taken complete posession of the house.|
The good news of the night was that the police officer on scene reported (when questioned) that everyone was out of the house, and he pointed to the family standing on the side of the road. The father asked if we could get his dog from the back yard. A wind from the east was sending brands across the neighborhood, and the radiant heat was very severe on the Bravo and Delta exposures.
The investigation revealed that the likely ignition source of the landscaping mulch in the front of the house was a carelessly discarded cigarette. Another factor in the ignition of the mulch was that the house faced due south. This orientation (and no shade trees) had the area under direct sunshine most of the day, drying the mulch to tinder dry conditions. A recent spell of very dry weather and a lack of rain completed the mix of dangerous conditions.
EXTERIOR FIRE ENVELOPMENT
The mulch burned vigorously and easily ignited the vinyl siding, threatening the Bravo exposure (photo 5). Occupants first reported a mulch fire that quickly extended to the siding. This is what the police officer saw when he reported the front of the house was on fire. As the fire burned the siding, it preheated the unburned vinyl above it, accelerating the fire spread up the front of the house. The burning vinyl added to the flammable gases in the smoke that entered the attic through the soffits.
|(5) The Bravo exposure. The damage was held in check with the first hoseline. Before the department applied water, siding and roof materials were vigorously smoking and ready to light up. (Photo by author.)|
As fire moved up the vinyl siding on the front of the house, the next modern house fire construction/material feature to add to this incident came into play: large vinyl-covered soffits (photos 6-7). The huge volume of fire racing up the front of the house quickly burned through these thin pieces of vinyl. Soffits are usually covered with perforated sheets of vinyl so natural convective air currents can ventilate the attic. Air rises, entering the underside of the soffit; enters the attic; and moves along the underside of the roof and out of a ridge or a gable vent, providing natural ventilation for the life of the home. Essentially, this is a flow path already established for the fire racing up the exterior of the building and drawing it into the unprotected attic space.
|(6) This house is the Bravo exposure and is a mirror image of the fire building. Note the large soffits on the attic over the windows. (Photo by Tom Bierds.)|
|(7) Typical perforated vinyl soffit covers.|
It is unclear how long the fire was only on the exterior. It is not known when this rapidly extending vertical exterior fire entered the structure, but the effect on the fire entering the attic was clear. Soon after our arrival, the roof collapsed. Fire had gotten in and spread throughout the attic quickly, heavily, and thoroughly. The subsequent roof collapse was actually more of a quick, nondramatic sag.
The hazards of rapid fire spread through vinyl siding were well documented and supported by various testing agencies and researched in detail in a paper by Anthony McDowell of the Henrico County (VA) Division of Fire in 2009. According to information obtained from the Vinyl Siding Institute, 78 percent of new homes in the northeastern United States in 2008 and 32 percent nationwide are clad in vinyl siding. It is a widespread problem that the fire service must deal with tactically during fireground operations and through code enforcement.
The rapid fire spread seen in the home fires in Acushnet, Massachusetts (see “Modular Construction: Hazards Within” in this issue) and West Haverstraw, New York, are not unique, as the following case histories illustrate.
- February 2007. A grass fire in Raleigh, North Carolina, spread to a vinyl-clad townhouse complex, destroying 32 townhomes.
- April 2007. Three Fairfax, Virginia, firefighters were injured during interior operations in a house when vinyl siding burned up through the soffits, resulting in what the Fairfax County (VA) Rescue Department determined to be a carbon monoxide (CO) explosion. Note that CO ignites at about 1,150°F and is very flammable in high concentrations.
- April 2007. In Prince William County, Virginia, Firefighter Kyle Wilson was killed while conducting operations in a home where fire fueled by burning vinyl siding simultaneously entered the structure at multiple points. A section of the full report, below, summarizes the events.
- Initial-arriving units reported heavy fire on the exterior of two sides of the single-family house. Crews suspected that the occupants were still inside the house sleeping because of the early morning hour. A search for possible victims in the upstairs bedroom was commenced. A rapid and catastrophic change of fire and smoke conditions occurred in the interior of the house within minutes of Tower 512’s crew entering the structure. Technician Kyle Wilson became trapped and was unable to locate an immediate exit out of the hostile environment. Wilson and crews radioed Mayday transmissions of the life-threatening situation. Fire and rescue crews made valiant and repeated rescue attempts to locate and remove Wilson during extreme fire, heat, and smoke conditions. Firefighters were forced from the structure as the house began to collapse on them and intense fire, heat, and smoke conditions developed. Wilson succumbed. The medical examiner reported thermal and inhalation injuries as the causes of death.
- May 2008. Seven Loudon County, Virginia, firefighters were injured (some suffered serious burns) in a vinyl-clad home fire that quickly went to flashover and collapse.
The complete story on rapid fire spread caused by vinyl siding fills volumes. Some resources are listed at the end of this article.
McDowell’s paper on vinyl siding contains also the following information, which should be discussed:
- A 1997 National Institute of Standards and Technology (NIST) study by Dan Madryzkowski, et al compared the combustibility of three siding materials: aluminum siding, T-111 (plywood), and vinyl siding. The results were interesting. A small focused area of the aluminum siding melted after 10 minutes of flame contact, at which point a smoldering fire developed inside the wall, but there was no vertical flame spread. The T-111 allowed burning and flame spread 200 seconds after ignition, and it took an average of 80 seconds to burn to the soffit level. The NIST report describes the test results for vinyl siding: ‘Less than 90 seconds after ignition, the flames began to spread upward, and within another 50 seconds, the flames were in the attic space.’
SHEATHING AND INSULATION
The exterior fire is fueled not only by the siding but also by the building insulation (foam or fiber board) that is directly under the siding (photo 8). Plastic house wrap may be under the insulation and, of course, the sheathing of oriented strand board (OSB) is under that. The OSB contains large amounts of glue to hold the strands together to form a usable board. All of these combustible components contribute to creating a large body of exterior fire.
In photo 8, the yellow arrow indicates the A side of the house where the fire reportedly started. Note that the intense exterior fire completely consumed the siding, insulation, and sheathing. The white arrow on the B side shows where heat caused the vinyl siding to melt and burn away, exposing the combustible foam insulation and the burned sheathing. After a reliable water supply was established, the exposure line quickly extinguished the exterior fire. Photos 9 and 10 depict the difference in how vinyl and aluminum siding burn in a fire.
|(8) The flammable exterior siding, insulation, and sheathing added to the fire. (Photo by Tom Bierds.)|
|(9) The fire quickly and intensely progressed out the window and headed directly up to the eaves/soffits and entered the attic (arrow). (Photo by author.)|
|(10) At another fire, the home on the right, clad with aluminum siding, did not sustain even minor damage despite the severe exposure to radiant and convected heat. The exposure on the left is 75 to 100 feet away, and the vinyl siding is already melting, exposing the flammable wood and insulation underneath. (Photo by Tom Bierds.)|
Windows provide another likely route for fire to enter the home. Multiple live burn tests conducted at the Rockland County Fire Training Center in Pomona, New York, compared the relative fire resistance of wood-frame single-pane windows vs. vinyl-frame double-glazed energy-efficient windows and sashes. The tests revealed that vinyl window frames, sashes, and glazing failed more quickly and catastrophically under a fire load than legacy wood-frame/sash windows (photo 11). The legacy windows failed in small amounts over time. In a 1997 NIST study by F. Mowrer, “The vinyl frames and sashes lost strength, sagged, and distorted under the imposed heat fluxes, typically within minutes.”
Well-documented research and fireground experience typically show that energy-efficient windows withstand heat and a fire load much better than legacy windows. This appears to be true only for aluminum or metal sash and frames. As you may expect, the vinyl windows fail quickly (photo 11). The vinyl frames are extruded, which means they are made of folded sheets, much as the cross-section of the A-roof post on a car. The vinyl frames and sashes are other modern components that helped this fire’s extremely rapid fire spread.
|(11) Heavy fire inside the test facility melts and burns the energy-efficient, double-pane vinyl frame and sash window (on the right) before the wooden-frame, single-pane window (on the left). (Photo by author.)|
A major component of the exceptionally rapid fire spread in the house in photo 8 was the fact that it was of modular construction. As a reminder, modular homes are brought into the home site as nearly finished modules and are placed together and secured to each other and an existing foundation (photo 12).
|(12) A second-floor module is added to complete the living area. (Photo by author.)|
Modular construction adds its own set of unique and significantly contributing factors to rapid fire spread in homes. This was first expertly detected, researched, and presented at Fire Department Instructors Conferences 2012 and 2013 by Chief Kevin Gallagher of the Acushnet (MA) Fire Department. He based his information on a fire his department responded to in 2008 (http://bit.ly/1cXdci9).
Gallagher and his department responded to a fire in a modular home and became concerned about how rapidly the fire spread. Researching the causes, he determined that the ceiling gypsum board is often attached to the ceiling joists only with thermal setting glue (photos 13-14). There are no traditional gypsum board nails or screws. After careful research and testing, he determined that the glue softens at approximately 400°F. This obviously causes the ceiling gypsum board to fall, allowing fire to enter the 20-inch void space between the first-floor ceiling and the second-floor subfloor. Obviously, something as benign as a small room-and-contents fire can lead to failure of this fire barrier, causing rapid fire spread and total loss of the home.
|(13) Polyurethane foam structural adhesive shown from above the first-floor ceiling in the void between the floors/modules. Note the parallel chord finger joint trusses supporting the second-floor subfloor. [Photo courtesy of Chief Kevin Gallagher, Acushnet (MA) Fire & Rescue.]|
|(14) The glue holding the gypsum board to the first-floor ceiling failed in this New York fire. (Photo by author.)|
The 20-inch space is similar to a cockloft, and the fire problems are the same. However, this void is between the floors. This space/void is created as a result of the construction method: stacking the second-floor module on top of the first floor (photo 12). Clearly, this is another contributing factor to the unusually rapid fire spread we saw at this house fire. The danger of fire entering the cockloft is well known and, based on recent experience, we should anticipate similar hazards at modular home fires.
Captain Bill Gustin of the Miami-Dade (FL) Fire-Rescue Department effectively compares fire spread in modular homes and legacy construction as follows:
- I compare the fire spread in the space between the first-floor ceiling and the second-floor deck this way: In older homes, the floors are supported by ‘dimensional’ lumber, usually 2×10 inch. The first-floor ceiling is attached directly to the underside of the floor joists, thus dividing the ceiling space into ‘bays’—that is, the space between the floor joists, floor above, and ceiling below. Bays are inherent fire stops that limit the horizontal spread of fire. That is hardly the case in lightweight and modular construction where the space between the floor and the ceiling is wide open with nothing to stop fire that enters or originates in the space from rapidly taking possession of the entire home and any of our members who may be inside.
These fires have taught us several important tactical lessons fire departments may be able to appropriately apply in these fast-moving house fires.
- Houses that have the aforementioned and other “fire friendly” construction characteristics that promote exceptionally rapid fire spread may require new and different tactics. During size-up and when formulating your search and rescue, ventilation, and fire attack plan, remember that a building with these dangerous characteristics will likely light up very quickly. Fire can envelop the building through several routes, trapping firefighters.
- Be conservative in deploying members for interior operations; they may be quickly surrounded by fire from various routes, both internal and external. Multiple hose streams (interior and exterior) will be needed to control the fire. If you do not have enough personnel on the scene to accomplish this, consider defensive operations before placing members in the path of a fast-moving fire. Recall that this fire is advancing in several directions at once—all contributing to the hazard: a heavy exterior fire enveloping and quickly becoming multiple interior fires creating a huge threat to interior firefighters. In homes, the fire may be coming in the first floor (and up the open stairwell), in open or failed (by fire) doors/windows, in second-floor windows, and down from the fully involved attic.
- For fires that begin outside the building (mulch, siding, or decks), one firefighter can start the fire attack from the outside—cutting off one of the main bodies of fire—in relative safety. This line can be stretched simultaneously with the conventional (in the front door line) if staffing permits. This line operated by one firefighter can serve multiple purposes: exposure protection and quickly extinguish the heavy and fast-moving exterior fire.
- At the West Haverstraw fire, the first priority of the firefighters on the first-in apparatus (quint) was to stretch a 1¾-inch line to protect severely threatened exposures. In this case, the quint concept worked exceptionally well.
Although sound arguments can be made for specific cities and personnel situations that truck companies should focus only on truck company work and their rig should not even have a pump or hose, water from the quint undoubtedly saved the exposure and additional property loss. In this case, the additional minutes and firefighters it would have taken for the engine to hit the hydrant, drop a supply line, and stretch the exposure line would certainly have enabled the fire to extend to the exposures and possibly farther. As the small 300-gallon tank on the quint ran dry, the engine company was able to get a water supply to the quint and provide sustained water to the handline to continue to protect the exposure while the truck set up to operate its master streams. What made this move possible was having adequate personnel so that the truck company split—two on the hoseline and two for setting up the tower ladder.
Positioning of this line was critical because it needed to get close enough to the exposure to ensure complete distribution of water on the exposure to prevent it from lighting up. There was, however, a huge amount of radiant and convected heat coming off the fire building. The nozzleman crouching down between the cars in the driveway used them as a shield from the intense heat, allowing him to be in an effective position to apply the limited water on the exposure.
Never position yourself or your members where you must depend on a limited or an unreliable water supply. In our case, we could have withdrawn at any moment and would have had a safe, clear, and unobstructed path to complete safety.
The calculated risk/benefit paid off, saving the exposure. Additionally, this position allowed the nozzleman to get water on the exposed cars, saving them from major damage. Blistered paint, melted plastic trim, and cracked windshields could not be prevented.
- A fast-moving fire needs quick, decisive action. Use the water you have to deliver a decisive blow to the fire. Saving it in your tank or flowing nondecisive amounts of water in weak, ineffective, and limited reach streams will not increase the probability of success. This has been the battle cry of Gustin for years. In a recent conversation, he emphatically summed it up:
- We have got to deliver water in amounts that make a difference in the fight to protect exposures or extinguish the fire, no matter what kind of fire it is. We don’t want to aggravate it or prolong the fight; we want to kill it, and kill it now, before it can destroy more property or threaten lives of firefighters and civilians. There is almost a paranoia in the fire service about running out of booster tank water before the fire is out. There are firefighters who are more comfortable with fire spreading to an exposure than running out of water; consequently, they do not apply sufficient flow to keep the exposure from igniting. When operating off tank water, you have only two options: First, put out the fire if you have sufficient water. Second, if you do not have sufficient water to put out the fire, use it to protect exposures.
Structure fires are not Class B fires; they don’t have to be extinguished completely to keep from reigniting. Three hundred gallons of water, if properly applied, can reduce a fire’s intensity, keeping it from spreading to exposures until an engine establishes a continuous water supply. Don’t forget that it takes a whole heck of a lot less water to keep something from igniting and keep exposed surfaces moist with intermittent application of water than to extinguish it once it ignites. There is no option three; saving water in the booster tank is not an option.
The first handline was directed at the most severe exposure (Bravo), which was being impacted by both radiant and convective heat as well as flying brands delivered by wind. The solid line flowing 180 gallons per minute delivered decisive amounts of cooling water on the exposure. There were no thoughts of water conservation. We had the bullet and used it—all of it. The strong stream reached the roof, eave line, and soffits and was able to wash down the entire side of the worst exposure. We knew we had about a minute and a half of water to gain control of the exposure, and we used that resource for that mission knowing two engines were en route to sustain and finish the job. The important lesson learned here is to use and sometimes totally use up the resources you have to buy time until the permanent fix (reliable water supply) is established.
- Strategic changes to fire suppression. The goal of any fire suppression plan or operation is to get ahead of the fire and cut it off or to get a hoseline to the seat of the fire and extinguish it. If a large body of fire is on the exterior of the building, it is nearly impossible to extinguish it from the inside with a traditional “aggressive interior fire attack.”
It is important to consider that there now are two main bodies of fire: interior and exterior. The exterior fire, because it is on a vertical surface, preheats the fuel above the flaming siding generating (pyrolyzing) flammable gases to intensify the fire. It also preheats fuel not yet involved, making it easier to ignite. The exterior fire has layers of fuel that contribute to the fire: vinyl siding and trim, flammable insulation (foam or fiber board), and flammable sheathing (plywood or OSB). All contribute to a large body of fire outside the structure that is providing a flow path up to the eaves or soffits that provide little or no resistance to the vertical spread. If you don’t stop this fire before it reaches the attic, there will be exceptionally high, if not complete, property loss.
You must stop this large body of exterior fire before firefighters are committed to the interior for any operations. This exterior fire is like an octopus that is wrapped around the building and has many ways to get inside. Further endangering firefighters is that if the roof structure is lightweight (trusses, I-joist, for example), it will not withstand a thermal assault very long, and a collapse will occur, trapping members inside. The well-involved attic fire can and will extend downward rapidly when gypsum board ceilings are pulled or fail. Heavy fire in the attic dropping down causing a flashover on the second floor is all too common a fatal scenario for firefighters, especially if they do not have a hoseline to defend themselves.
As Steve Kerber, PE, director of the Firefighter Safety Research Institute, said in his FDIC presentation, “If the fire starts on the outside, the fire attack should start on the outside.”
- Interior and exterior opposing streams. For years, the simultaneous use of exterior and interior streams has been a major tactical taboo, and rightfully so. Opposing streams pushing products of combustion onto interior firefighters is never a good thing. However, with vinyl siding causing intense and fast-moving fires on the outside of a home, it is imperative that the fire be controlled quickly. Obviously, the key is to train our members to use that stream only on the exterior fire if members are working inside, and there must be excellent communication between these lines and command.
- Exterior fire causes electric service lines to fall. Early in the operation, the service line from the pole to the house sparked a few times and then rapidly came down. The heavy body of fire outside the building caused this, creating a major hazard for firefighters.
- Flexible HVAC ducts. This is another firefighter killer in modern house fires that we often overlook. The flexible ductwork is nothing more than a plastic tube, possibly insulated/double wall, its shape maintained by a spiral/helix of wires (photos 15-16). When the ceiling comes down and fire in the void space has burned away the plastic covering, there is a myriad of helix curled wires that drop to trap and kill firefighters. Obviously, some type of wire cutters must be in every firefighter’s pocket so they can get out of this deadly trap. Wires from the electrical system, HVAC controls, computers, smart house systems, audiovisual systems, and other sources may compound this deadly problem.
(15) A flex duct that contains wires. (Photos by Brian Dennehy.) (16) Wires from a flex duct that have burned away, creating a significant entrapment threat to firefighters.
- Roof collapse. In a modular home, the roof rafters are often hinged. Shipped folded down to reduce the height of the load on the tractor trailer, the roof panels are hinged up on site. There is no ridge pole for structural support. Expect early roof collapse. The damage to the roof, total destruction by fire, and subsequent collapse were noted in both the Massachusetts and New York fires. They appear to be common results of fast-moving fires. This is another reason to be conservative when considering interior operations in these types of homes.
- Residential sprinklers. Note that residential sprinklers will not control the exterior fire on the siding, deck, or other exterior fire or the fire that has extended into the void between floors. These fast-moving and well-established fires may overwhelm the flow from residential sprinkler heads.
- The importance of being nice, as advocated by Chief (Ret.) Alan Brunacini. This family just lost everything it owns and a lifetime of memories and has had a life-changing experience it will never forget. As the fire was brought under control, firefighters had time to search for the family pet. The dog was rescued from under the shed in the rear of the house (photo 17). It was more of a trench rescue. We had to dig him out of the gravel under the shed. In his panic to run from the house, he wedged himself in so tight that he became stuck.
|(17) When firefighters reunited the family dog with its family members, the latter went from crying on the street corner to celebrating a happy reunion.|
Across our country, fires at modern houses are threatening firefighters’ lives with new hazards that can complete a deadly failure chain on the fireground. We must consider new strategy and tactics for these new house models that foster fire development.
The flammability of vinyl siding is not a new revelation for firefighters. We have all seen it melt on exposures and burn furiously on involved buildings. What is new is the combined effect of vinyl siding, flammable insulation, lightweight/modular construction techniques, and combustible sheathing causing rapid fire spread and large volumes of fire on the exterior of houses. This massive and fast-moving exterior fire has the combined effect of creating multiple flow paths for fire to envelop the home and kill firefighters inside who are using traditional interior attack strategies and tactics.
“The Wall of Fire: Training Firefighters to Survive Fires in Vinyl-Clad Houses,” Anthony McDowell, Henrico County Division of Fire, Richmond, Virginia. Sept. 2009. Course.
Fire Protection Study: Pine Knoll Townhome Fire, Lisa Bossert, 2007.
Madrzykowski, Dan, et al. “Durable Agents for Exposure Protection,” National Institute of Standards and Technology (NIST), NISTIR 6030; 1997.
Mowrer, F. “Window Breakage Induced by Exterior Fires,” NIST GCR-98-751; 1997, p 15.
“Career Firefighter Dies in Wind-Driven Fire.” National Institute for Occupational Safety and Health. 2008.
Thanks to Captain Bill Gustin, Fire Inspector Fred Viohl, Building Inspector George Behn, Fire Coordinator John Kryger, Assistant Chief Tom Bierds, and Driver/Operator Brian Dennehy for their help with this article.
● JERRY KNAPP is a 37-year veteran firefighter/EMT with the West Haverstraw (NY) Fire Department; a training officer at the Rockland County Fire Training Center in Pomona, New York; and an adjunct professor in the Rockland Community College Fire Technology Program. He is a battalion chief with the Rockland County Hazardous Materials Team and a former nationally certified paramedic. He has a degree in fire protection and wrote the “Fire Attack” chapter in Fire Engineering’s Handbook for Firefighter I and II and has authored numerous articles for fire service trade journals.
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