BY MIKE DALEY
Making an aggressive interior attack on a well-involved structure will require a considerable effort from the initial-arriving companies. However, any time that the suppression forces have to deal with a considerable fire in an overhead space, there will be some monumental obstacles to overcome. Below are some of the characteristics that the on-scene companies will have to identify to efficiently handle fires in these spaces.
ATTIC, COCKLOFT, VOID SPACE
First, it is imperative that the first-arriving units determine what type of overhead space they are dealing with. For our discussion, we will stick to attic spaces and point out some similarities they share with cocklofts and overhead void spaces. By attic, we mean an upper floor space, usually built with a steep-pitched roof to shed snow and rainwater, usually high enough for storage, and that can be modified to provide usable living space (photo 1). Conversely, a cockloft is a top-floor area that is not large enough to incorporate occupied living space. It is a structural space between the top-floor ceiling joists and the roof rafters, connecting similar occupancies at the roof line. These spaces are usually unfinished, with nothing more than roof rafters or trusses, with a floor consisting of the top floor’s ceiling joists and insulation (photo 2). From time to time, you may come across plywood that is set on the ceiling joists to allow for storage and mobility around the floor area. Access to these spaces will vary but is usually by means of a spring-loaded, pull-down stairwell. Most attic stairs have maximum weight ratings of 250 pounds and are limited in opening size. A firefighter in full personal protective equipment (PPE) and self-contained breathing apparatus (SCBA) will find it quite difficult to use this opening for access. Instead, crews are much better served opening these spaces and using fire service ladders for access.
|(1) Photos by author unless otherwise noted.|
|(2) In many commercial buildings, cocklofts run the entire length of the structure without any horizontal draftstopping.|
Once you have identified the type of space, consider how residents use that space. Many residential dwellings maximize living space by converting the available attic space into a top-floor bedroom or living area (e.g., office, playroom). You can identify these spaces during the 360° size-up. Decorative window treatments and dressings, window decals and pictures, and flower boxes around window areas can be sure signs of upper-floor occupancy. Furthermore, many of these top-floor bedrooms will have an exterior means of access/egress for emergency evacuation (photo 3), but it is not recommended that you use these stairways during fire suppression operations. The location and accessibility of the top-floor stairs compound this access problem. Many times, access to these areas is in somewhat unorthodox places, and all too often renovations may reduce the structural integrity of the building (photos 4, 5).
|(3) Although it is better to access the upper living space through the dwelling, if possible, these stairs may provide the only access to the upper floors to allow for privacy for the first-floor residents. Where possible, such stairways should be used only for emergency egress.|
|(4) At first glance, the main access into the attic would seem to be the scuttle hatch in the ceiling at the left. It is actually through the door to the right of the curio cabinet.|
|(5) A look through the door shows that attic trusses have been compromised by the occupant; the webs were cut away to facilitate storage in this area. The truss assembly is no longer under designed load, which can result in early catastrophic failure, especially in a fire.|
The incident commander (IC) must also consider the construction methods and alterations that may exist in these areas. Older residential wood-frame dwellings were constructed using balloon framing, in which the wall studs run from the foundation sill plate all the way up to the top attic/void space. This allows for an unimpeded vertical shaft for fire extension. Newer wood-frame structures have made changes that limit the vertical travel of products of combustion within the wall studs; however, many of these “starter castles” will have additional voids built in the structure that allow for vertical fire spread to these areas.
Overhead spaces that traverse over multiple occupancies may or may not have inherent draftstops in place. Even in those with draftstops, utilities and other breaches between the walls will provide an avenue for heat and smoke to travel horizontally throughout the space, involving multiple structures. Many of these newer buildings will also contain lightweight engineered structural components throughout the structure, and the attic space is no exception (photo 6). Triangular peaked-roof trusses are used consistently in attic spaces. Fires in these spaces or that originate in these spaces will significantly damage the structural integrity of the building, and launching an aggressive interior attack is not recommended when these components are present. Finally, upper-floor ceilings may be suspended from the roof area using vertical tension rods. These rods may be hidden in the structure, and since they have less mass they have less fire resistance. An attic fire that has been attacking the support system can drop the ceiling of the attack floor on advancing suppression teams.
|(6) Roof trusses are often used in attic spaces.|
Knee walls are another significant concern for the suppression team. Attic living spaces may have nonload-bearing partition walls constructed from the underside of the roof down to the attic floor. The space created within the partition walls makes up the living spaces. Many of these knee wall spaces provide added storage for seasonal items, decorations, clutter, and other possessions (photo 7). These spaces may contain a great amount of fuel for a fire, which can result in a significant dynamic event for the entire floor. A door may provide access into these spaces, or there may be only a small trapdoor of plywood or plasterboard. Stretching handlines into these spaces is not a wise decision; there is a safer way to handle this situation.
|(7) This knee wall is serving a dual purpose as a separation wall for the attic space and a side closet on the left side of the attic.|
One of the primary factors to consider when dealing with an upper-area fire condition is, How did the fire get into that space? Did the fire originate there, or did it spread there from a lower floor? Crews must make sure that they are not starting their attack above the fire floor. Many documented injuries and fatalities have occurred when companies were positioned over the seat of the fire and the floor below them catastrophically failed or a dynamic fire event occurred (e.g., a backdraft or flashover) within the lower floors. Send suppression companies into all of the floors below the attic space to confirm that there are no surprises waiting below for the attack teams.
Handling this fire will require effective coordination of ventilation and suppression. Fire that reaches the attic will find a large lumberyard of fuel and unlimited air supply based on the exchange of air within the structure. Consider the wood stove; if you want the fire to get bigger, open the damper (the horizontal vent). Close the damper, and the flames dissipate. As long as there are fuel and heat, adding sufficient air will support the combustion process. Open the flue (the roof) to the stove, and the smoke is allowed to exit and is replaced with fresh air. So the bottom line is simple: Control strategic ventilation, and you control the fire. Strategic ventilation coupled with sufficient water flow will knock out any fire. An insufficient flow rate, the result of limited pump capabilities or the lack of personnel to position enough handlines, will compound fire conditions and heat release rates (HRR). Bringing the right amount of water for British thermal unit (Btu) consumption and steam conversion is what tackles HRR in its tracks (photos 8-10). Getting the water up there may be an arduous task, considering the crew has to climb a number of floors and then locate the access path to the attic space. As a rule of thumb for hoseline length, figure on one length to the door, one per floor, and one length to cover the top space.
|(8) This attic space fire shows smoke from the B/C side of the residence; what is missing here is topside ventilation. (9) Significant changes in attic fire conditions are evident around the roof line. (10) Fire is venting from the D side of the structure since the delta wall has been displaced, along with the ceiling on the floor below, from the force of the blast in the attic space. (Photos 8-10 by Keith Addie, www.NJFiregroundPhotos.com.)|
Be sure to have the vertical vent team in place to open up the attic space prior to pulling any ceiling/floor area from below. Consider the amount of heat and fire under the roof and the type of roof framing, particularly the presence of lightweight construction; if enough exists to require ventilation, the roof is probably unsafe, and you should consider supporting firefighters from an elevated aerial device. As a rule, you can vent from a roof ladder on a roof of traditional “legacy” construction (not lightweight construction) with a slope of 30° or less; any slope greater than that will require an aerial device. The accumulation of heat and smoke can result in a significant dynamic event in the space, including a backdraft or flashover. If such an event is possible, venting the roof first will direct these products up and away from the suppression teams opening up from below. When venting the roof, if the vent team suspects a knee wall is within the space, it should first cut an inspection hole no more than three feet up from the soffit line; this will allow smoke and heat to exit from the knee wall space and alert companies of the presence of a dangerous condition in the space. Second, the team should increase the size of the initial vent hole to allow venting from the living area and the knee wall area. Make a coffin cut, which is an expandable roof vent hole, roughly 3 × 6 or 4 × 8 feet in size, with the long legs of the cut running in the same direction as the roof rafters. You can make a perpendicular cut at the midpoint of the vent hole, making the cut sections more manageable. Make the final (lower) cut just before you exit the roof. This additional area of the roof vent will allow smoke and heat to exit from both the attic area and the knee wall area (photo 11). If you make the vent over a roof rafter, it will be much easier to push the cut section inward, hinging it on the rafter rather than pulling it up from the roof. Keep in mind that in some areas, truss assemblies may be placed more than three feet from one another and so the cut section may fall inward during the final cut.
|(11) This simulation shows how making the coffin cut vertically will open up the space above and below the knee wall, allowing smoke and heat to exit the roof instead of moving down toward the suppression teams.|
Depending in the roof’s size and construction, you may need to make a trench cut on the roof to stop the horizontal spread of fire. As the fire vents, crews can begin pulling ceilings from below. Be ready for anything; I have been surprised when pushing through a plasterboard ceiling only to find thick plywood flooring directly above the plasterboard. This added flooring will allow the fire to gain a considerable amount of energy ahead of the suppression teams. If this is the case, crews should move toward the exterior wall, where the slope of the roof meets the wall. Many times, flooring does not run beyond the usable living space within the attic.
If the fire is in a much larger void space, such as one found in a strip mall, a multiple dwelling, or any other large building, it’s possible to pull the ceilings below to stop the fire. This is advantageous for a few reasons. First, pulling ceilings from below takes a lot less energy than opening up a three-foot trench the entire depth of the structure in a multilayered roof assembly. Second, it is easier to access the void space from the inside than to set up companies on the roof. Also, a considerable amount of reflex time may pass before sufficient personnel arrive to perform a trench cut on the roof. Be sure to position a 2½-inch handline in the hall to darken any advancing fire in the attic/void space area. Applying water on the underside of the roof area will slow or stop the fire and the spread of convection currents. Operate this line only if fire is evident or imminent. You can use this technique from two sides of the spreading fire in a pincer fashion to squeeze off the extension and extinguish the fire.
Should the attic space become fully involved, operating large-caliber streams may be the only option; however, without a route to the underside of the roof assembly, this tactic may be ineffective and may result only in additional water damage to the rest of the structure. If the attic is opened up and the stream can get a good shot into the attic void, then the operation may be successful. If not, then the roof assemblies will most likely burn off, and you can make the attack from above the fire (photo 12).
|(12) To be effective, suppression streams need access into the space. With ventilation from above and suppression from the underside, suppression can make significant progress, but you must consider structural integrity before committing interior companies.|
Fires in attics and void spaces will be difficult to handle without proper coordination between ventilation and suppression forces. Underestimating the amount of energy that may be present during operations will tax even the most seasoned firefighters. Be sure to have the right resources on scene to mount the attack to ensure the best results for your personnel.
Know your buildings: Recognize the hidden vertical and horizontal voids that travel through the building. If the fire gets hold of these voids and the attic, plan for early collapse, and keep a safe distance.
● MIKE DALEY has spent more than 25 years in the fire service and is a lieutenant and training officer with the Monroe Township (NJ) Fire District. An instructor with the Middlesex County Fire Academy, he is responsible for fire and rescue training curriculum development and also serves as a rescue officer with USAR NJ-TF1. Daley has degrees in business management and public safety administration. He is the founder and managing member of Fire Service Performance Concepts, a consulting group that provides assistance and support to fire departments wanting aid with their training divisions, in-house course development, and procedures.
Mike Daley will present “Tactical Considerations for Attic and Cockloft Fires” on Thursday, April 25, 2013, 10:30 a.m.-12:15 p.m., at FDIC 2013 in Indianapolis.
Fire Engineering Archives